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

    
    
        
  
        
            select * from user where id=#{id}
        
    
  

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

• 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

节点内添加：

    select * from user where id=#{id}

注：以下皆是在此节点下添加

2.根据用户名查找用户

    select * from user where username like '%${value}%'

3.添加用户1

    insert into user(username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address})

4.添加用户2

    
        select LAST_INSERT_ID()
    
    insert into user(username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address})

5.修改用户

    update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} where id=#{id}

6.删除用户

    delete from user where id=#{id}

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 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 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

    
    
    
   
        
        
            select * from user where id=#{id}
        
        
        
        
            select * from user where username like '%${value}%'
        
    
   

加载映射文件

1. 单个加载

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
    
    

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 users = userMapper.findUserByUsername("小明");
    for (User user : users) {
        System.out.println(user);
    }
}