ORM - 基于MyBatis入门实例

ORM: Object Relational Mapping 对象关系映射

orm是通过使用描述对象和数据之间映射的元数据，将程序中的对象自动持久化到关系数据库中

下表说明了关系型数据库和对象之间的对应关系：

数据库	类/对象
表（table）	类（class）
表中的记录（record，也称行）	对象（object）
表中的字段（field，也称列）	对象中的属性（attribute）

例如，现在有一张 user 表，它包含 id、user_id 和 user_name 三个字段，另外还有一个 Java User 类，它包含 id、userId 和 userName 三个属性，下图演示了它们之间的对应关系：

你看，数据表和类用来描述数据的表现形式，它们之间是相互对应的；记录和对象用来真正地存储数据，它们之间也是相互对应的。

http://c.biancheng.net/hibernate/orm.html

项目整体结构

依赖包

略。

SQL

set names gbk; 
drop database if exists mybatis2;
create database mybatis2 default charset utf8 collate utf8_general_ci;
use mybatis2;

drop table if exists t_student;
create table t_student(
    id int(11) primary key auto_increment,
    name varchar(20) not null,
    age tinyint(4) not null
);
 
insert into t_student values(1,'张三', 18);
insert into t_student values(2,'李四', 19);
insert into t_student values(3,'王五', 20);

日志配置文件

log4j定义了8个级别的log，优先级从高到低依次为：OFF、FATAL、ERROR、WARN、INFO、DEBUG、TRACE、 ALL。Log4j建议只使用四个级别，优先级从高到低分别是 ERROR、WARN、INFO、DEBUG。如果定义了INFO级别，则应用程序中所有DEBUG级别的日志信息将不被打印出来，也是说大于等于INFO级别的日志才输出。
https://blog.51cto.com/u_15162069/2801436

log4j.properties

log4j.rootLogger=DEBUG, stdout
log4j.logger.com.wxit=DEBUG
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p %d %C: %m%n

MyBatis配置文件

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-config.dtd">
    
<configuration>
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis2"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource=
            "cn/studybigdata/javaee/mapper/StudentMapper.xml"/>
    </mappers>
</configuration>

Mapper

映射器接口

StudentMapper.java

package cn.studybigdata.javaee.mapper;

import java.util.List;

import cn.studybigdata.javaee.pojo.Student;

public interface StudentMapper {
    public Student findStudentById(int id);  //根据id查找学生信息
    public List<Student> findAll();              //查询所有学生信息
    public int addStudent(Student student); //添加学生信息
    public int deleteStudent(int id);             //删除学生信息
    public int updateStudent(Student student); //更新学生信息
}

映射器XML

StudentMapper.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    
<mapper namespace="cn.studybigdata.javaee.mapper.StudentMapper">

    <select id="findStudentById" parameterType="Integer" resultType="cn.studybigdata.javaee.pojo.Student">
        select * from t_student where id = #{id}
    </select>   
    
     
    <select id="findAll" resultType="cn.studybigdata.javaee.pojo.Student">
        select * from t_student
    </select>   
     
    <insert id="addStudent" parameterType="cn.studybigdata.javaee.pojo.Student">
        insert into t_student values(null, #{name}, #{age})
    </insert>    
    
    <delete id="deleteStudent" parameterType="Integer">
        delete from t_student where id=#{id}
    </delete>    
    
    <update id="updateStudent" parameterType="cn.studybigdata.javaee.pojo.Student">
        update t_student set name=#{name}, age=#{age} where id=#{id}
    </update>
    
</mapper>

POJO类

Student.java

public class Student {
	private Integer id;
	private String name;
	private Integer age;
	private String sex;
}

测试类

MyBatisTest.java

package cn.studybigdata.javaee.test;

import java.io.IOException;
import java.io.InputStream;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.apache.log4j.Logger;
import org.junit.Test;

import cn.studybigdata.javaee.mapper.StudentMapper;
import cn.studybigdata.javaee.pojo.Student;

public class MyBatisTest {
	
	private final Logger LOGGER = Logger.getLogger(Test.class.getName());
	
	  @Test
	  public void findByIdTest() throws IOException{
		LOGGER.debug("DEBUG");
	    InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
	    SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
	    SqlSession sqlSession = null;

	    try{
	      sqlSession = sqlSessionFactory.openSession();
	      StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
	      Student student = studentMapper.findStudentById(1);
          LOGGER.info(student);
          LOGGER.warn("WARN");
	    }catch(Exception e){
	      e.printStackTrace();
	    }finally{
	      if(sqlSession!=null){
			sqlSession.close();
	      }
	    }
	    LOGGER.error("ERROR");
	  }
}

MyBatis配置

MyBatis配置项

属性properties

properties元素用于将一些经常修改的属性值从外部文件引入，方便管理配置。

jdbc.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis2
jdbc.username=root
jdbc.password=123456

mybatis-config.xml

<!-- configuration节点下 -->
<properties resource="jdbc.properties"/>

<!-- environments -> environment 节点下 -->
<dataSource type="POOLED">
    <property name="driver" value="${jdbc.driver}"/>
    <property name="url" value="${jdbc.url}"/>
    <property name="username" value="${jdbc.username}"/>
    <property name="password" value="${jdbc.password}"/>
</dataSource>

别名typeAliases

由于类的全限定名称很长，需要大量使用的时候，可以使用别名来代替。

少数POJO，可使用typeAlia元素指定。

<!-- configuration节点下 -->
<typeAliases>
    <typeAlias alias="student"  type="cn.studybigdata.javaee.pojo.Student" />
</typeAliases>

多个POJO，可使用package元素指定。

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<typeAliases>
    <package name="cn.studybigdata.javaee.pojo"/>
</typeAliases>

映射器mappers

指定映射文件的位置。

少量映射器，可通过mapper元素的指定

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<mappers>
    <mapper resource="cn/studybigdata/javaee/mapper/StudentMapper.xml"/>
</mappers>

多个映射器，可通过package元素指定

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<mappers>
	<package name="cn.studybigdata.javaee.mapper"/>
</mappers>

Mapper.xml

映射器配置文件是由一组与增删改查有关的SQL语句组成，其常用子元素如下

元素名称	描述	备注
select	查询语句	可以自定义参数返回结果集，最常用、最复杂的元素之一
insert	插入语句	执行后返回一个整数，代表插入的条数
update	更新语句	执行后返回一个整数，代表更新的条数
delete	删除语句	执行后返回一个整数，代表删除的条数
resultMap	定义SQL到POJO的映射规则	提供映射规则，它是最复杂、最强大的元素

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.ngweb.chapter5.mapper.StudentMapper">
    <select id="findStudentById" parameterType="Integer" resultType="org.ngweb.chapter5.pojo.Student">
        select * from t_student where id = #{id}
    </select>    
    <select id="findAll" resultType="org.ngweb.chapter5.pojo.Student">
        select * from t_student
    </select>    
    <insert id="addStudent" parameterType="org.ngweb.chapter5.pojo.Student">
        insert into t_student values(null, #{name}, #{age})
    </insert>    
    <delete id="deleteStudent" parameterType="Integer">
        delete from t_student where id=#{id}
    </delete>    
    <update id="updateStudent" parameterType="org.ngweb.chapter5.pojo.Student">
        update t_student set name=#{name}, age=#{age} where id=#{id}
    </update>
</mapper>

元素	说明	备注
id	命名空间中唯一的标识符	用于引用这条语句（接口中的方法名）
parameterType	全限定类名或别名（typeAlias）	可以选择Map、List、JavaBean传递给SQL
resultType	全限定类名或别名（typeAlias）	在自动匹配的情况下，结果集将通过JavaBean的规范映射
resultMap	对外部resultMap的引用	手动映射结果集

useGeneratedKeys	是否使用JDBC的getGeneratedKeys()方法来获取由数据库内部产生的主键值（比如数据库表的自增主键）	insert操作时可选
keyProperty	标记属性名（比如自增量主键值回填到这里）	insert操作时可选

插入数据回填ID

插入数据后，MyBatis会自动将id插入到POJO对象的id属性中。

1	<insert id="addStudent" parameterType="student" useGeneratedKeys="true" keyProperty="id">

ResultMap

resultMap的作用是定义映射规则，主要负责结果集的映射关系（从SQL到POJO的映射关系定义），resultMap 元素的子元素如下表所示

元素名称	说明	例子
constructor	类在实例化时，注入结果到构造方法中
id	将主键的值映射到POJO的成员变量中	当表的主键名与POJO的主键名不相同时
result	将非主键的值映射到POJO的成员变量中	当表的其他列名与POJO的其他属性名不相同时 <result property=”username“ column=”user_name”/>
association	一对一的关联映射	（后续会详细介绍）
collection	一对多的关联映射	（后续会详细介绍）
discriminator	鉴别器	（本书不讲解）

Object

package org.ngweb.chapter5.pojo;

public class Student {
    private Integer id;
    private String name;             //name
    private Byte age;
}

Relational

create table t_student2(
    id int primary key auto_increment,
    s_name varchar(20) not null,    -- sname
    age tinyint(4)
);
insert into t_student2 values(1,'张三', 18);

Mapper

Interface

1	public Student getStudentFromOtherTable(int id);

XML

<select id = "getStudentFromOtherTable" parameterType="int" resultMap="studentMap">
    select id, s_name, age from t_student2 where id = #{id}
</select>

<!-- 结果集手动映射 -->
<resultMap type="cn.studybigdata.javaee.pojo.Student" id="studentMap">
    <id column="id" property="id"/>
    <result column="s_name" property="name"/>
    <result column="age" property="age"/>
</resultMap>

Test

public class MyBatisResultMapTest {
	
	private final Logger LOGGER = Logger.getLogger(MyBatisResultMapTest.class.getName());
	
	  @Test
	  public void findByIdTest() throws IOException{
		LOGGER.debug("DEBUG");
	    InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
	    SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
	    SqlSession sqlSession = null;

	    try{
	      sqlSession = sqlSessionFactory.openSession();
	      StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
	      
	      Student student = studentMapper.getStudentFromOtherTable(1);
          LOGGER.info(student);
          LOGGER.warn("WARN");
	    }catch(Exception e){
	      e.printStackTrace();
	    }finally{
	      if(sqlSession!=null){
			sqlSession.close();
	      }
	    }
	    LOGGER.error("ERROR");
	  }
}

动态SQL

开发人员使用JDBC或其他类似的框架进行数据库开发时，如果出现特殊的需求，这时就需要手动拼装SQL，这是一个非常麻烦且痛苦的工作

而MyBatis提供的SQL语句动态组装的功能，恰能解决这一麻烦工作。动态SQL主要元素如下表所示：

元素	说明
	判断语句，用于单条件分支判断
、	辅助元素，用于处理一些SQL拼装
、、	根据参数的值动态组装SQL
	对集合进行遍历

根据学生姓名查询学生信息

1 2	select id, name, age from t_student where 1=1 and name like '%赵%'

Interface

1	public List<Student> findStudentByName(Student student);

xml

<select id="findStudentByName" parameterType="student" resultType="student">
    select id, name, age from t_student where 1=1
   <if test="name!=null and name!=''">
        and name like concat('%',#{name},'%')
  </if>
</select>

如果参数student中的name不为空，则加上“and name like……”

Test

Student student = new Student();
student.setName("赵");
student.setAge(18);
List<Student> stus = studentMapper.findStudentByName(student);

一对一

SQL

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for faculty
-- ----------------------------
DROP TABLE IF EXISTS `faculty`;
CREATE TABLE `faculty` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `facultyname` varchar(18) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of faculty
-- ----------------------------
INSERT INTO `faculty` VALUES ('1', '赵六');
INSERT INTO `faculty` VALUES ('2', '钱七');

-- ----------------------------
-- Table structure for schoolclass
-- ----------------------------
DROP TABLE IF EXISTS `schoolclass`;
CREATE TABLE `schoolclass` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `classname` varchar(32) DEFAULT NULL,
  `facultyid` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `facultyid` (`facultyid`),
  CONSTRAINT `schoolclass_ibfk_1` FOREIGN KEY (`facultyid`) REFERENCES `faculty` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of schoolclass
-- ----------------------------
INSERT INTO `schoolclass` VALUES ('1', '初一(1)', '1');
INSERT INTO `schoolclass` VALUES ('2', '初一(2)', '2');

pojo

Faculty.java

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private int id;
private String facultyname;
private Schoolclass schoolclass;

Schoolclass.java

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private int id;
private String classname;
private Faculty faculty;

映射器

映射器SRC

FacultyMapper.java

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public interface FacultyMapper {
    public Faculty getById(Integer id);
}

SchoolclassMapper.java

public interface SchoolclassMapper {
    public Schoolclass getById(Integer id);
    public Schoolclass getByFacultyId(Integer id);
}

映射器XML

FacultyMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.ngweb.chapter5.mapper.FacultyMapper">
    <resultMap type="org.ngweb.chapter5.pojo.Faculty" id="facultyMap">
         <id column="id" property="id"/>
         <result column="facultyname" property="facultyname"/>
         <association column="id"  property="schoolclass" javaType="org.ngweb.chapter5.pojo.Schoolclass"
                 select="org.ngweb.chapter5.mapper.SchoolclassMapper.getByFacultyId"/>
    </resultMap>
	
   <select id="getById" parameterType="int" resultMap="facultyMap">
        select id, facultyname from faculty where id=#{id}
   </select>
</mapper>

SchoolclassMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.ngweb.chapter5.mapper.SchoolclassMapper">	
    <resultMap type="org.ngweb.chapter5.pojo.Schoolclass" id="schoolclassMap">
        <id column="id" property="id" />
        <result column="classname" property="classname" />
        <association column="facultyid" property="faculty"  javaType="org.ngweb.chapter5.pojo.Faculty" 
                             select="org.ngweb.chapter5.mapper.FacultyMapper.getById">
        </association>
    </resultMap>

    <select id="getById" parameterType="int" resultMap="schoolclassMap">
			SELECT id, classname, facultyid from schoolclass where id=#{id}
    </select>
    
    <select id="getByFacultyId" parameterType="int" resultType="org.ngweb.chapter5.pojo.Schoolclass">
             select id,classname, facultyid   from schoolclass where   facultyid=#{id}
    </select>
</mapper>

Test

@Test
  public void findByIdTest() throws IOException{
    InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
    SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    SqlSession sqlSession = null;

    try{
        sqlSession = sqlSessionFactory.openSession();
        FacultyMapper facultyMapper = sqlSession.getMapper(FacultyMapper.class);
        Faculty faculty = facultyMapper.getById(1);
        System.out.println("教师：" + faculty);
        System.out.println("老师管理的班级：" + faculty.getSchoolclass());
        sqlSession.commit();
    }catch(Exception e){
      e.printStackTrace();
    }finally{
      if(sqlSession!=null){
        sqlSession.close();
      }
    }
  }

一对多

SQL

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for schoolclass
-- ----------------------------
DROP TABLE IF EXISTS `schoolclass`;
CREATE TABLE `schoolclass` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `classname` varchar(32) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of schoolclass
-- ----------------------------
INSERT INTO `schoolclass` VALUES ('1', '初一(1)');
INSERT INTO `schoolclass` VALUES ('2', '初一(2)');

-- ----------------------------
-- Table structure for student
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `studentname` varchar(18) DEFAULT NULL,
  `classid` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `classid` (`classid`),
  CONSTRAINT `student_ibfk_1` FOREIGN KEY (`classid`) REFERENCES `schoolclass` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of student
-- ----------------------------
INSERT INTO `student` VALUES ('1', '张三', '1');
INSERT INTO `student` VALUES ('2', '李四', '1');
INSERT INTO `student` VALUES ('3', '王王', '2');

pojo

Schoolclass.java

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private int id;
private String classname;
private List<Student> studentList;

Student.java

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private int id;
private String studentname;
private Schoolclass schoolclass;

映射器

映射器SRC

StudentMapper

public interface StudentMapper {
    public Student getById(Integer id);
    public List<Student> getStudentList(Integer classId);
}

SchoolclassMapper

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public interface SchoolclassMapper {
    public Schoolclass getById(Integer id);
}

映射器XML

StudentMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.ngweb.chapter5.mapper.StudentMapper">
    <resultMap type="org.ngweb.chapter5.pojo.Student" id="studentMap">
        <id column="id" property="id" />
        <result column="studentname" property="studentname" />
		<association column="classid" property="schoolclass" javaType="org.ngweb.chapter5.pojo.Schoolclass" select="org.ngweb.chapter5.mapper.SchoolclassMapper.getById">
        </association>
    </resultMap>

    <select id="getById" parameterType="int" resultMap="studentMap">
        SELECT id, studentname, classid from student where id=#{id}
    </select>
    
    <select id="getStudentList" parameterType="int" resultType="org.ngweb.chapter5.pojo.Student">
        SELECT id, studentname, classid from student where classid=#{classId}
    </select>
</mapper>

SchoolclassMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.ngweb.chapter5.mapper.SchoolclassMapper">
    <resultMap type="org.ngweb.chapter5.pojo.Schoolclass" id="schoolclassMap">
        <id column="id" property="id" />
        <result column="classname" property="classname" />

        <collection column="id" property="studentList"
            ofType="org.ngweb.chapter5.pojo.Student" 
                 select="org.ngweb.chapter5.mapper.StudentMapper.getStudentList" />
    </resultMap>

    <select id="getById" parameterType="int" resultMap="schoolclassMap">
        SELECT id, classname from schoolclass where id=#{id}
    </select>
</mapper>

Test

findByIdTest

@Test
  public void findByIdTest() throws IOException{
    InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
    SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    SqlSession sqlSession = null;

    try{
         sqlSession = sqlSessionFactory.openSession();
         StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
         Student student = studentMapper.getById(1);
         System.out.println("学生：" + student);
         System.out.println("学生所属的班级：" + student.getSchoolclass());
         sqlSession.commit();
    }catch(Exception e){
      e.printStackTrace();
    }finally{
      if(sqlSession!=null){
        sqlSession.close();
      }
    }
  }

getSchoolclassByIdTest

@Test
  public void getSchoolclassByIdTest() throws IOException{
    InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
    SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    SqlSession sqlSession = null;

    try{
         sqlSession = sqlSessionFactory.openSession();
         SchoolclassMapper schoolclassMapper =
                 sqlSession.getMapper(SchoolclassMapper.class);
             Schoolclass schoolclass = schoolclassMapper.getById(1);
             System.out.println("班级：" + schoolclass);
             System.out.println("班级的的学生列表：");
             List<Student> list = schoolclass.getStudentList();
             System.out.println(list);
             sqlSession.commit();

    }catch(Exception e){
      e.printStackTrace();
    }finally{
      if(sqlSession!=null){
        sqlSession.close();
      }
    }
  }

基于MyBatis的学生信息管理系统

初始化实训环境

为避免干扰，需要初始化实训环境，删除已经存在的 mybatis2 数据库（例如上次实训遗留的，或其他同学创建的）。

创建项目

在 Eclipse 中创建一个 Dynamic Web Project，名为 student_mybatis。导入相关Jar包，添加到编译Build Path中。

略；

创建数据库

根据教程中的说明，在命令行中打开 MySQL 客户端（也称为 MySQL 控制台），创建数据库和数据表，代码如下：

SQL

set names gbk;
create database mybatis2 default charset utf8 collate utf8_general_ci;

use mybatis2;
drop table if exists t_student;
drop table if exists t_type;

create table t_type(
    id int(11) primary key auto_increment,
    name varchar(20) not null
);

create table t_student(
    id int(11) primary key auto_increment,
    name varchar(20) not null,
  	age tinyint(4) not null,
  	sex char(1) not null,
  	account varchar(16) not null,
  	password varchar(64) not null,
  	type_id int(11) not null,
    foreign key(type_id) references t_type(id)
);

insert into t_type(name) values('管理员');
insert into t_type(name) values('用户');

insert into t_student(name, age,sex,account,password, type_id)
	values('张三', 18, 'f','zhangsan','123',1);
insert into t_student(name, age,sex,account,password, type_id)
	values('李四', 19, 'm','lisi','123',1);
insert into t_student(name, age,sex,account,password, type_id)
	values('王五', 20, 'f','wangwu','123',2);

编写POJO 类

在pojo包中（ cn.studybigdata.javaee.sm.student.pojo）包中，编写 Student 、Type类。

student

public class Student {
	private Integer id;
	private String name;
	private Integer age;
	private String sex;
	private String account;
	private String password;
	private Type type;
}

Type

public class Type {
	private Integer id;
	private String name;
}

注意：
（1）代码要同学自行编写；
（2）属性名、类型、以及出现的次序采用上述代码；
（3）getters 和 setters 必须自动生成，位于属性之后；

编写映射器

在dao（cn.studybigdata.javaee.sm.student.dao）包中创建映射器;

Student映射器
Type映射器

每个映射器都由 映射器interface文件和映射器XML文件组成。

Student Mapper

StudentMapper.java

public interface StudentMapper {
	//添加学生信息
	public int addStudent(Student student);
	//更新学生信息
	public int updataStudent(Student student);
	//根据id删除学生信息
	public int deleteStudent(int id);
	//根据条件查询学生信息
	public List<Student> search(Student student);
}

StudentMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

 <mapper namespace="cn.studybigdata.javaee.sm.student.dao.StudentMapper">
 	<resultMap type="student" id="studentMap">
        <id column="id" property="id" />
        <result column="name" property="name" />
        <result column="age" property="age" />
        <result column="sex" property="sex" />
        <result column="account" property="account"/>
        <result column="password" property="password" />
        <association column="type_id" property="type" 
           select="cn.studybigdata.javaee.sm.student.dao.TypeMapper.getById"/>
     </resultMap>
 
     <select id="query"  resultMap="studentMap">
         select id, name,age, sex, account, password, type_id from t_student
     </select>
     
     
     <select id="search" parameterType="student" resultMap="studentMap">
         select id, name, age, sex, account, password, type_id from t_student 
         <where>
             <if test="id!=null">
                and id=#{id}
             </if>
         
             <if test="name!=null and name!=''">
                and name like concat('%', #{name}, '%')
             </if>
             
             <if test="age!=null">
                 and age=#{age}
             </if>
             
             <if test="account!=null and account!=''">
                 and account=#{account}
             </if>
             
             <if test="password!=null and password!=''">
                 and password=#{password}
             </if>
         </where>
     </select>
     
     <delete id="deleteStudent" parameterType="int">
         delete from t_student where id=#{id}
     </delete>
     
     <update id="updataStudent" parameterType="student">
         update t_student
         <set>
            <if test="name!=null and name!=''">
                name = #{name},
            </if>
            
            <if test="age!=null and age!=''">
                age= #{age},
            </if>
            
            <if test="sex!=null and sex!=''">
                sex= #{sex},
            </if>
            
            <if test="account!=null and account!=''">
                account= #{account},
            </if>
            
            <if test="password!=null and password!=''">
                password= #{password},
            </if>
            
            <if test="type!=null and type.id!=null">
                type_id= #{type.id}
            </if>
         </set>
         where id = #{id}
     </update>
     
     <insert id="addStudent" parameterType="student">
         insert into t_student values 
         (null, #{name}, #{age}, #{sex}, #{account}, #{password}, #{type.id})
     </insert>
     
     <select id="isExistent" parameterType="student" resultType="int">
         select count(*) from t_student
         where account =#{account} and password = #{password}
     </select>
 </mapper>

TypeMapper

TypeMapper.java

public interface TypeMapper {
    //根据id查询类型
	public Type getById(Integer id);
}

TypeMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="cn.studybigdata.javaee.sm.student.dao.TypeMapper">
	<select id="getById"  parameterType="int" resultType="type">	 
		select id, name from t_type where id = #{id}		
	</select>
</mapper>

编写MyBatis 配置文件

1）在src 目录下新建mybatis-config.xml 文件，代码如下。

2）在src 目录下新建db.properties 文件，代码如下。

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
  
<configuration>
	<properties resource="db.properties" />
  
	<typeAliases>
		<typeAlias type="cn.studybigdata.javaee.sm.student.pojo.Student" alias="student"/>
		<typeAlias type="cn.studybigdata.javaee.sm.student.pojo.Type" alias="type"/>
	</typeAliases>
  
	<environments default="mysql">
		<environment id="mysql">
			<transactionManager type="JDBC"/>
			<dataSource type="POOLED">
				<property name="driver" value="${jdbc.driver}"/>
				<property name="url" value="${jdbc.url}"/>
				<property name="username" value="${jdbc.username}"/>
				<property name="password" value="${jdbc.password}"/>
			</dataSource>
		</environment>
	</environments>
   
	<mappers>
		<mapper resource="cn/studybigdata/javaee/sm/student/dao/TypeMapper.xml"/>
		<mapper resource="cn/studybigdata/javaee/sm/student/dao/StudentMapper.xml"/>
	</mappers>
</configuration>

db.properties

#根据数据库版本选择对应的配置
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis2
jdbc.username=root
jdbc.password=123456

#Bellow is for JDBC 8.0

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis2?serverTimezone=UTC
jdbc.username=root
jdbc.password=123456

#Do not forget to change the password

注意：数据库名、用户名和密码需要根据情况进行设置，驱动程序名、url 也可以根据 JDBC 的版本号进行修改！

编写工具类

在util包（cn.studybigdata.javaee.sm.student.util）中编写 SqlSessionFactoryUtil 类。

SqlSessionFactoryUtil.java

import java.io.IOException;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class SqlSessionFactoryUtil {
private static SqlSessionFactory sqlSessionFactory = null;

	public static SqlSessionFactory getSqlSessionFactory(){
		if(sqlSessionFactory!=null){
			return sqlSessionFactory;
		}else{
			try{
				sqlSessionFactory = new SqlSessionFactoryBuilder().
				build(Resources.getResourceAsStream("mybatis-config.xml"));
			}catch(IOException e){
				e.printStackTrace();
			}
		}
		return sqlSessionFactory;
	}

	public static SqlSession openSession(){
		if(sqlSessionFactory==null){
			getSqlSessionFactory();
		}
		return sqlSessionFactory.openSession();
	}
}

编写DAO 层

在dao包（cn.studybigdata.javaee.sm.student.dao）中编写StudentDao类

StudentDao.java

public class StudentDao{

	public int addStudent(Student student) {
		SqlSession sqlSession = null;
		int result = 0;

		try{
			sqlSession = SqlSessionFactoryUtil.openSession();
			StudentMapper studentDao = sqlSession.getMapper(StudentMapper.class);
			result = studentDao.addStudent(student);
			sqlSession.commit();
		}catch(Exception e){
			sqlSession.rollback();
		}finally{
			if(sqlSession!=null){
				sqlSession.close();
			}
		}
		return result;
	}

	public int updataStudent(Student student) {
		int result = 0;
		SqlSession sqlSession = null;

		try{
			sqlSession = SqlSessionFactoryUtil.openSession();
			StudentMapper studentDao = sqlSession.getMapper(StudentMapper.class);
			result = studentDao.updataStudent(student);
			sqlSession.commit();
		}catch(Exception e){
			e.printStackTrace();
			sqlSession.rollback();
		}finally{
			if(sqlSession!=null){
				sqlSession.close();
			}
		}

		return result;
	}

	public int deleteStudent(int id) {
		int result = 0;
		SqlSession sqlSession = null;

		try{
			sqlSession = SqlSessionFactoryUtil.openSession();
			StudentMapper studentDao = sqlSession.getMapper(StudentMapper.class);
			result = studentDao.deleteStudent(id);
			sqlSession.commit();
		}catch(Exception e){
			sqlSession.rollback();
		}finally{
			if(sqlSession!=null){
				sqlSession.close();
			}
		}
		return result;
	}

	public List<Student> search(Student student) {
		SqlSession sqlSession = null;
		List<Student> studentList = null;
		try{
			sqlSession = SqlSessionFactoryUtil.openSession();
			StudentMapper studentDao = sqlSession.getMapper(StudentMapper.class);
			studentList = studentDao.search(student);
		}catch(Exception e){
			e.printStackTrace();
		}finally{
			if(sqlSession!=null){
				sqlSession.close();
			}
		}
		return studentList;
	}

}

TypeDao.java

public class TypeDao{
	public Type getById(Integer id) {
		SqlSession sqlSession = null;
		Type type = null;
		try{
			sqlSession = SqlSessionFactoryUtil.openSession();
			TypeMapper typeDao = sqlSession.getMapper(TypeMapper.class);
			type = typeDao.getById(id);
		}catch(Exception e){
			e.printStackTrace();
		}finally{
			if(sqlSession!=null){
				sqlSession.close();
			}
		}
		return type;
	}
}

前端设计

将第2章的前端设计成果 - 基于前端的学生信息管理系统复制到本项目中。

（1）在WebContent目录下创建css目录，将第2章设计好的三个层叠样式表复制到这个目录中
css/common.css 文件、css/view.css 文件和css/login.css 文件。
（2）在WebContent目录下创建js目录，将第2章设计好的一个JavaScript文件复制到这个目录中。
js/script.js 文件。
（3）在WebContent目录下创建 images 目录，找一个你喜爱的图片命名为 header.png，复制到这个目录中。

编写控制层

按照教材中的说明，在controller 包（cn.studybigdata.javaee.sm.student.controller）中，编写下述两个类：

StudentController

public class StudentController extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public StudentController() {
		super();
	}

	protected void doGet(HttpServletRequest request, HttpServletResponse response)
		throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		String operation = request.getParameter("operation");

		if(operation==null){
			query(request,response);
		}else if("delete".equals(operation)){
			deleteStudent(request,response);
		}else if("find".equals(operation)){
			findStudent(request,response);
		}else if("add".equals(operation)){
			addStudent(request,response);
		}else if("update".equals(operation)){
			updateStudent(request,response);
		}else if("getById".equals(operation)){
			getStudentById(request,response);
		}
	}

	//添加学生操作
void addStudent(HttpServletRequest request, HttpServletResponse response){
// 在这里补写代码


	StudentDao studentDao = new StudentDao();
	Student student = new Student();
	student.setName(request.getParameter("name"));
	student.setAge(Integer.parseInt(request.getParameter("age")));
	student.setSex(request.getParameter("sex"));
	student.setAccount(request.getParameter("account"));
	student.setPassword(request.getParameter("password"));

	TypeDao typeDao = new TypeDao();
	Type type = typeDao.getById(Integer.parseInt(request.getParameter("typeId")));
	student.setType(type);

	try {
		studentDao.addStudent(student);
		response.sendRedirect("StudentController");
	}catch (IOException e) {
		e.printStackTrace();
	}catch (Exception e) {
		e.printStackTrace();
	}


}

//查询所有学生操作
void query(HttpServletRequest request, HttpServletResponse response){
// 在这里补写代码


	StudentDao studentDao = new StudentDao();
	//根据StudentDao实例获得所有学生的信息
	List<Student> list=null;
	try {
		Student student = new Student();
		list = studentDao.search(student);
	} catch (Exception e) {
		e.printStackTrace();
	}
	//将学生信息存入请求域
	request.setAttribute("studentList", list);
	try {
		request.getRequestDispatcher("view.jsp").forward(request, response);
	} catch (ServletException e) {
		e.printStackTrace();
	} catch (IOException e) {
		e.printStackTrace();
	}


}

	//删除学生操作
void deleteStudent(HttpServletRequest request, HttpServletResponse response){
// 在这里补写代码


	StudentDao studentDao = new StudentDao();
	int id = Integer.parseInt(request.getParameter("id"));
	try {
		studentDao.deleteStudent(id);
		response.sendRedirect("StudentController");
	}catch (IOException e) {
		e.printStackTrace();
	}catch (Exception e) {
		e.printStackTrace();
	}


}

	//查询学生操作
void findStudent(HttpServletRequest request, HttpServletResponse response){
// 在这里补写代码


	Student student = new Student();
	String idStr = request.getParameter("id");
	if(!idStr.equals("")){
		int id = Integer.parseInt(idStr);
		student.setId(id);
	}

	String name = request.getParameter("name");
	if(!name.equals("")){
		student.setName(name);
	}

	String ageStr = request.getParameter("age");
	if(!ageStr.equals("")){
		int age = Integer.parseInt(ageStr);
		student.setAge(age);
	}

	StudentDao studentDao = new StudentDao();
	List<Student> studentList =  studentDao.search(student);
	request.setAttribute("studentList", studentList);

	try {
		request.getRequestDispatcher("view.jsp").forward(request, response);
	} catch (ServletException e) {
		e.printStackTrace();
	} catch (IOException e) {
		e.printStackTrace();
	}


}

	//更新学生操作
void updateStudent(HttpServletRequest request, HttpServletResponse response){
// 在这里补写代码


	StudentDao studentDao = new StudentDao();
	Student student = new Student();
	student.setId(Integer.parseInt(request.getParameter("id")));
	student.setName(request.getParameter("name"));
	student.setAge(Integer.parseInt(request.getParameter("age")));
	student.setSex(request.getParameter("sex"));
	student.setAccount(request.getParameter("account"));
	student.setPassword(request.getParameter("password"));
	TypeDao typeDao = new TypeDao();
	Type type = typeDao.getById(Integer.parseInt(request.getParameter("typeId")));
	student.setType(type);

    try {
    	studentDao.updataStudent(student);
		response.sendRedirect("StudentController");
    } catch (IOException e) {
		e.printStackTrace();
    } catch (Exception e) {
		e.printStackTrace();
	}


}

	//根据学生ID查询学生信息
void getStudentById(HttpServletRequest request, HttpServletResponse response){
// 在这里补写代码


	 StudentDao studentDao = new StudentDao();
     int id = Integer.parseInt(request.getParameter("id"));
     Student s =  new Student();
     s.setId(id);
     List<Student> studentList = studentDao.search(s);
     Student student = studentList.get(0);
	 request.setAttribute("student", student);

     try {
		request.getRequestDispatcher("update.jsp").forward(request, response);
	 } catch (ServletException e) {
		e.printStackTrace();
	 } catch (IOException e) {
		e.printStackTrace();
	 }


}

	protected void doPost(HttpServletRequest request, HttpServletResponse response)
		throws ServletException, IOException {
		doGet(request, response);
	}
}

LoginController

public class LoginController extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public LoginController() {
		super();
	}

	protected void doGet(HttpServletRequest request, HttpServletResponse response)
		throws ServletException, IOException {
		HttpSession session = request.getSession();
		session.invalidate();
		request.getRequestDispatcher("login.jsp").forward(request, response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response)
		throws ServletException, IOException {
		String msg="";
		request.setCharacterEncoding("UTF-8");
		String username = request.getParameter("username");
		String password = request.getParameter("password");

		if(username!=null && password!=null){

			Student student = new Student();
			student.setAccount(username);
			student.setPassword(password);

			StudentDao studentDao = new StudentDao();

			try {
				List<Student> studentList = studentDao.search(student);
				if(studentList.size()>0){
// 在这里补写代码


					HttpSession session = request.getSession();
					session.setAttribute("account", studentList.get(0));
					response.sendRedirect("StudentController");


				}else{
					msg = "用户名或密码不正确";
					request.setAttribute("msg", msg);
					request.getRequestDispatcher("login.jsp").forward(request, response);
				}
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}
}

编写显示层

按照教材中的说明，在WebContent 目录下新建view.jsp，add.jsp，update.jsp，login.jsp JSP 文件，代码如下。

view.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>学生信息管理系统主页</title>
<link rel="stylesheet" type="text/css" href="css/common.css"/>
<link rel="stylesheet" type="text/css" href="css/view.css"/>
</head>
<body>
	<div class="main">
		<div class="header">
			<h1>学生信息管理系统</h1>
		</div>

		<div class="content">
			<p>${account.type.name}：${account.account}&nbsp;&nbsp;&nbsp;
				<a href="LoginController">注销</a></p>
	
			<c:if test="${account.type.id==1}">
				<form action="StudentController" method="post" class="formclass">
				        <input type="hidden" name="operation" value="find" />
					id: <input type="text" name="id" value="" class="information"/>
					name: <input type="text" name="name" value="" class="information"/>
					age: <input type="text" name="age" value="" class="information"/>
					<input type="submit" value="查询" class="btn"/>
				</form>
	
				<a href="add.jsp">添加</a>
	
				<h2>学生信息列表</h2>
				<table border="1">
					<tr>
					    <td>编号</td>
					    <td>名称</td>
					    <td>年龄</td>
					    <td>性别</td>
					    <td>账户</td>
					    <td>密码</td>
					    <td>类型</td>
					    <td colspan="2">操作</td>
					</tr>
	
					<c:forEach items="${studentList}" var="student">
					<tr>
						<td>${student.id}</td>
						<td>${student.name}</td>
						<td>${student.age}</td>
						<td>${student.sex=='m'?"男":"女"}</td>
						<td>${student.account}</td>
						<td>${student.password}</td>
						<td>${student.type.name}</td>
						<td><a href="StudentController?id=${student.id}&operation=delete">
							删除</a></td>
						<td><a href="StudentController?id=${student.id}&operation=getById">
							更新</a></td>
					</tr>
					</c:forEach>
				</table>
			</c:if>
	
			<c:if test="${account.type.id==2}">
				<h2>学生信息</h2>
				<table border="1">
					<tr>
						<td>编号</td>
						<td>名称</td>
						<td>年龄</td>
						<td>性别</td>
						<td>账户</td>
						<td>密码</td>
						<td>类型</td>
					</tr>
	
					<tr>
						<td>${account.id}</td>
						<td>${account.name}</td>
						<td>${account.age}</td>
						<td>${account.sex=='m'?"男":"女"}</td>
						<td>${account.account}</td>
						<td>${account.password}</td>
						<td>${account.type.name}</td>
					</tr>
				</table>
			</c:if>
		</div>
	
		<div class="footer"><p>《Java EE 应用开发及实训》第2版（机械工业出版社）</p></div>
	</div>
</body>
</html>

add.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>添加学生信息</title>
<link rel="stylesheet" type="text/css" href="css/common.css"/>
</head>
<body>
	<div class="main">
		<div class="header">
			<h1>学生信息管理系统</h1>
		</div>

		<div class="content">
			<h2>添加学生信息</h2>
			<form action="StudentController" method="post" onsubmit="return check()" class="contact_form" >
				<input type="hidden" name="operation" value="add" />
				<ul>
					<li class="usually">
						<span>用户名：</span>
						<input type="text" name="name" value="" />
					</li>
					<li class="usually">
						<span>年龄：</span>
						<input type="text" name="age" value="" id="age"/>
					</li>
					<li class="usually">
						<span>性别： </span>
						<input type="radio" name="sex" value="m" id="male"/>
						<label for="male">男</label>
						<input type="radio" name="sex" value="f" id="female"/>
						<label for="female">女</label>
					</li>
					<li class="usually">
						<span>账号：</span>
						<input type="text" name="account" value="" class="information"/>
					</li>
					<li class="usually">
						<span>密码：</span>
						<input type="text" name="password" value="" class="information"/>
					</li>
					<li class="usually">
						<span>类型：</span>
						<select name="typeId">
							<option value="1">管理员</option>
							<option value="2">用户</option>
						</select>
					</li>
					<li>
						<input type="submit" value="添加" class="submit" />
					</li>
				</ul>
			</form>
		</div>
	
	    <div class="footer"><p>《Java EE 应用开发及实训》第2版（机械工业出版社）</p></div>
	</div>
	
	<script type="text/javascript" src="js/script.js"></script>
</body>
</html>

update.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>更新学生信息</title>
<link rel="stylesheet" type="text/css" href="css/common.css"/>
</head>
<body>
    <div class="main">
        <div class="header">
        	<h1>学生信息管理系统</h1>
        </div>

        <div class="content">
        	<h2>更新学生信息</h2>
    	    <form action="StudentController" method="post" onsubmit="return checkAdd()"
    	     class="contact_form">
    	    	<input type="hidden" name="operation" value="update" />
    	    	<input type="hidden" name="id" value="${student.id}"  />
    	    <ul>
                	<li class="usually">
                	    <span>用户名：</span>
                	    <input type="text" name="name" value="${student.name}" />
                	</li>
    
                	<li class="usually">
                	    <span>年龄：</span>
                	    <input type="text" name="age" value="${student.age}" />
                	</li>
    
                	<li class="usually">
                	    <span>性别： </span>
                	    <input type="radio" name="sex" value="m"
                	    class="information"  ${student.sex=="m" ? "checked":""} id="male"/>
                	    <label for="male">男</label>
                	    <input type="radio" name="sex" value="f"
                	    class="information"  ${student.sex=="f" ? "checked":""} id="female"/>
                	    <label for="female">女</label>
                	</li>
    
                	<li class="usually">
                	    <span>账号：</span>
                	    <input type="text" name="account" value="${student.account}" />
                	</li>
    
                	<li class="usually">
                		<span>密码：</span>
                		<input type="text" name="password" value="${student.password}" />
                	</li>
    
                	<li class="usually">
                	    <span>类型：</span>
                	<select name="typeId">
                    <option value="1" ${student.type.id==1 ? "selected":""}>管理员</option>
                    <option value="2" ${student.type.id==2 ? "selected":""}>用户</option>
    				</select>
                	</li>
    
                	<li>
                	    <input type="submit" value="修改" class="submit" />
                	</li>
                </ul>
    	    </form>
        </div>
        <div class="footer"><p>《JAVA EE开发及实训》版权归机械工业出版社所有</p></div>
    </div>
    
    <script type="text/javascript" src="js/script.js"></script>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link rel="stylesheet" href="css/login.css" type="text/css" />
<title>登录页面</title>
</head>
<body>
    <div class="loginMain">
        <p>${msg}</p>
        <form action="LoginController" method="post" onsubmit="return checkLogin()">
            <input type="text" name="username"  placeholder="用户名" />
            <input type="password" name="password" placeholder="密码"/>
            <input type="submit" value="登录" class="btn"/>
        </form>
    </div>
    <script type="text/javascript" src="js/script.js"></script>
</body>
</html>

项目配置

修改项目配置文件 web.xml，代码如下。将项目添加到 Tomcat Server 里，重启动 Tomcat，点击 http://127.0.0.1:8080/student_mybatis/login.jsp 查看结果。

web.xml

在web.xml中追加servlet配置信息。

<servlet>
  <description></description>
  <display-name>LoginController</display-name>
  <servlet-name>LoginController</servlet-name>
  <servlet-class>cn.studybigdata.javaee.sm.student.controller.LoginController</servlet-class>
</servlet>
<servlet-mapping>
  <servlet-name>LoginController</servlet-name>
  <url-pattern>/LoginController</url-pattern>
</servlet-mapping>
<servlet>
  <description></description>
  <display-name>StudentController</display-name>
  <servlet-name>StudentController</servlet-name>
  <servlet-class>cn.studybigdata.javaee.sm.student.controller.StudentController</servlet-class>
</servlet>
<servlet-mapping>
  <servlet-name>StudentController</servlet-name>
  <url-pattern>/StudentController</url-pattern>
</servlet-mapping>

ORM - 基于MyBatis入门实例

项目整体结构

依赖包

SQL

日志配置文件

log4j.properties

MyBatis配置文件

mybatis-config.xml

Mapper

映射器接口

StudentMapper.java

映射器XML

StudentMapper.xml

POJO类

Student.java

测试类

MyBatisTest.java

MyBatis配置

MyBatis配置项

属性properties

jdbc.properties

mybatis-config.xml

别名typeAliases

映射器mappers

Mapper.xml

插入数据回填ID

ResultMap

Object

Relational

Mapper

Interface

XML

Test

动态SQL

根据学生姓名查询学生信息

Interface

xml

Test

一对一

SQL

pojo

Faculty.java

Schoolclass.java

映射器

映射器SRC

FacultyMapper.java

SchoolclassMapper.java

映射器XML

FacultyMapper.xml

SchoolclassMapper.xml

Test

一对多

SQL

pojo

Schoolclass.java

Student.java

映射器

映射器SRC

StudentMapper

SchoolclassMapper

映射器XML

StudentMapper.xml

SchoolclassMapper.xml

Test

findByIdTest

getSchoolclassByIdTest

基于MyBatis的学生信息管理系统

相关jar包

初始化实训环境

创建项目

创建数据库

SQL

编写POJO 类

student

Type

编写映射器

Student Mapper

StudentMapper.java

StudentMapper.xml

TypeMapper