Eclipse下MyBatis简明教程

Eclipse下MyBatis简明教程

工程搭建

  • 创建Java工程

  • 导入jar包

    把目录（mybatis-3.2.7/lib）下的文件导入到lib目录下

      asm-3.3.1.jar
  cglib-2.2.2.jar
  commons-logging-1.1.1.jar
  javassist-3.17.1-GA.jar
  log4j-1.2.17.jar
  log4j-api-2.0-rc1.jar
  log4j-core-2.0-rc1.jar
  mybatis-3.2.7.jar                       -->mybatis的核心包
  mysql-connector-java-5.1.7-bin.jar      -->数据库驱动包
  slf4j-api-1.7.5.jar
  slf4j-log4j12-1.7.5.jar

    build path -> add build path

  • 配置日志文件
    创建config文件夹用于存放配置文件

    在config文件夹中创建log4j.properties文件，输入如下内容

      log4j.rootLogger=DEBUG, stdout
  log4j.appender.stdout=org.apache.log4j.ConsoleAppender
  log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
  log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

  • 创建po类
    创建user类

      public class User {
      private Integer id;
      private String username;
      private Date birthday;
      private String sex;
      private String address;
      /**
       *  get/set也需要写，这里不展示了
       **/
  }

  • 配置数据
    在config文件夹中创建db.properties文件，输入如下内容

      jdbc.driver=com.mysql.jdbc.Driver
  jdbc.url=jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8
  jdbc.username=root
  jdbc.password=123456

  • 设置sql映射文件
    在config文件夹中创建user.xml文件，输入如下

      <?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="test">

      <select id="findUserById" parameterType="java.lang.Integer"                 resultType="User类的包名.User">
          select * from user where id=#{id}
      </select>
  </mapper>

  • 配置SqlMapConfig.xml
    在config文件夹中创建SqlMapConfig.xml文件，输入如下

      <?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"/>
      <environments default="development">
          <environment id="development">
          <!-- 使用jdbc事务管理-->
          <transactionManager type="JDBC" />
          <!-- 数据库连接池-->
          <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="config/User.xml"/>
      </mappers>
  </configuration>

  • 测试
    在测试方法中输入如下内容

      String resource = "SqlMapConfig.xml";
  //通过流将核心配置文件读取进来
  InputStream inputStream = Resources.getResourceAsStream(resource);
  //通过核心配置文件输入流来创建会话工厂
  SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
  //通过工厂创建会话
  SqlSession openSession = factory.openSession();
  //第一个参数:所调用的sql语句= namespace+.+sql的ID
  User user = openSession.selectOne("test.findUserById", 1);
  System.out.println(user);
  openSession.close();

对数据库的增删改查

1.根据id查找用户

在User.xml文件中的

 <mapper namespace="test"> </mapper>

节点内添加：

<select id="findUserById" parameterType="int" resultType="User所在的包.User">
    select * from user where id=#{id}
</select>

注：以下皆是在此节点下添加

2.根据用户名查找用户

<select id="findUserByUsername" parameterType="java.lang.String" resultType="User所在的包.User">
    select * from user where username like '%${value}%'
</select>

3.添加用户1

<insert id="insertUser1" parameterType="User所在的包.User">
    insert into user(username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address})
</insert>

4.添加用户2

<insert id="insertUser2" parameterType="User所在的包.User">
    <selectKey keyProperty="id" order="AFTER" resultType="int">
        select LAST_INSERT_ID()
    </selectKey>
    insert into user(username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address})
</insert>

5.修改用户

<update id="updateUser" parameterType="User所在的包.User">
    update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} where id=#{id}
</update>

6.删除用户

<delete id="deleteUser" parameterType="int">
    delete from user where id=#{id}
</delete>

测试

    private SqlSessionFactory sqlSessionFactory;

@Before
public void createSqlSessionFactory() throws IOException {
    String resource = "SqlMapConfig.xml";
    InputStream inputStream = Resources.getResourceAsStream(resource);
    sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}

@Test
public void test(){
    SqlSession sqlSession = null;
    sqlSession = sqlSessionFactory.openSession();
    //1.根据id查找用户
    //selectUserById(sqlSession);
    //2.根据用户名查找用户
    //selectUserByUsername(sqlSession);
    //3.添加用户1
    //insertUser1(sqlSession);
    //4.添加用户2
    //insertUser2(sqlSession);
    //5.修改用户
    //updateUser(sqlSession);
    //6.删除用户
    //deleteUser(sqlSession);
}
//1.根据id查找用户
public void selectUserById(SqlSession sqlSession){
    User user = sqlSession.selectOne("test.findUserById",10);
    System.out.println(user);
    sqlSession.close();
}
//2.根据用户名查找用户
public void selectUserByUsername(SqlSession sqlSession){
    List<User> users = sqlSession.selectList("test.findUserByUsername","小明");
    for (User user : users) {
        System.out.println(user);
    }
    sqlSession.close();
}
//3.添加用户1
public void insertUser1(SqlSession sqlSession){
    User user = new User();
    user.setUsername("美娜");
    user.setSex("2");
    user.setAddress("beijing");
    sqlSession.insert("test.insertUser1",user);
    sqlSession.commit();
    sqlSession.close();
}
//4.添加用户2
public void insertUser2(SqlSession sqlSession){
    User user = new User();
    user.setUsername("小楠");
    user.setSex("w");
    user.setAddress("beijing");
    sqlSession.insert("test.insertUser2",user);
    sqlSession.commit();
    sqlSession.close();
}
//5.修改用户
public void updateUser(SqlSession sqlSession){
    User user = new User();
    user.setUsername("美娜");
    user.setSex("w");
    user.setAddress("beijing");
    user.setId(25);
    sqlSession.update("test.updateUser", user);
    sqlSession.commit();
    sqlSession.close();
}
//6.修改用户
public void deleteUser(SqlSession sqlSession){
    sqlSession.update("test.deleteUser", 25);
    sqlSession.commit();
    sqlSession.close();
}

Mapper动态代理

接口文件

  1. Mapper接口方法名和Mapper.xml中定义的statement的id相同

  2. Mapper接口方法的输入参数类型和mapper.xml中定义的statement的parameterType的类型相同

  3. Mapper接口方法的输出参数类型和mapper.xml中定义的statement的resultType的类型相同

     public interface UserMapper {
     public User findUserById(Integer id);
     public List<User> findUserByUsername(String userName);
 }

映射文件

  1. 接口的名称和映射文件名称除扩展名外要完全相同

  2. 接口和映射文件要放在同一个目录下

  3. namespace的值为UserMapper接口路径

     <?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="UserMapper所在的包.UserMapper">

     <!-- 1.通过id查找用户 -->
     <select id="findUserById" parameterType="int" resultType="User所在的包.User">
         select * from user where id=#{id}
     </select>
     
     <!-- 2.根据用户名查找用户 -->
     <select id="findUserByUsername" parameterType="java.lang.String" resultType="User所在的包.User">
         select * from user where username like '%${value}%'
     </select>
 </mapper>

加载映射文件

  1. 单个加载

     <mapper class="UserMapper所在的包.UserMapper"/>

  2. 批量加载

    1. 接口的名称和映射文件名称除扩展名外要完全相同
    2. 接口和映射文件要放在同一个目录下
    
    <package name="接口所在的包名"/>

测试

private SqlSessionFactory sqlSessionFactory;

@Before
public void createSqlSessionFactory() throws IOException {
    String resource = "SqlMapConfig.xml";
    InputStream inputStream = Resources.getResourceAsStream(resource);
    sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}

@Test
public void test() throws Exception {
    SqlSession sqlSession = sqlSessionFactory.openSession();
    UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
    // 1.根据id查找用户
    // selectUserById(userMapper);
    // 2.根据用户名查找用户
    // selectUserByUsername(userMapper);
}

// 1.根据id查找用户
public void selectUserById(UserMapper userMapper) {
    User user = userMapper.findUserById(1);
    System.out.println(user);
}

// 2.根据用户名查找用户
public void selectUserByUsername(UserMapper userMapper) {
    List<User> users = userMapper.findUserByUsername("小明");
    for (User user : users) {
        System.out.println(user);
    }
}
最后编辑于 ：
©著作权归作者所有,转载或内容合作请联系作者
平台声明：文章内容（如有图片或视频亦包括在内）由作者上传并发布，文章内容仅代表作者本人观点，简书系信息发布平台，仅提供信息存储服务。

推荐阅读更多精彩内容