sqlSession.getMapper(UserMapper.class)的使用方式

说明：

1，本文采用的Mybatis框架版本为： mybatis-3.0.4.jar

2， 以持久化一个简单的User bean为例

User实体类的代码如下：

 package bean;

    public class User {
        private String name;
        private Integer age;

        public String getName() {
           return name;
        }
        public void setName(String name) {
           this.name = name;
        }
        public Integer getAge() {
           return age;
        }
        public void setAge(Integer age) {
           this.age = age;
        }
        public User(String name, Integer age) {
           super();
           this.name = name;
           this.age = age;
        }

        public User() {
           super();
        }  //必须要有这个无参构造方法，不然根据UserMapper.xml中的配置，在查询数据库时，将不能反射构造出User实例
    }

 
User实体的映射器取名为UserMapper(接口)，其代码如下

 package Mapper;
  import bean.User;

  public interface UserMapper {
      public void insertUser(User user);
      public User getUser(String name);
  }

 

注意，该接口类似于Hibernate中的DAO层接口，唯一不同的是，MyBatis中，只声明该接口就可以，不需要去实现.

UserMapper映射器对应的配置文件如下(相当于Hibernate中的User.hbm.xml,当然这里面不是属性映射字段，而是直接是映射器中各种方法对应的sql语句)：

 "1.0" encoding="UTF-8" ?>

        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    "Mapper.UserMapper">

        "insertUser" parameterType="User">
           insert into vincent_user(name,age) values(#{name},#{age})




        "getUser" resultType="User" parameterType="java.lang.String">
            select * from vincent_user where name=#{name}

 

MyBatis的配置文件这里取名为mybatis-config.xml其配置代码如下(相当与Hibernate的hibernate.cfg.xml):

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

         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
         "http://mybatis.org/dtd/mybatis-3-config.dtd">

     <configuration>
         <settings>

             <setting name="cacheEnabled" value="false" />
             <setting name="useGeneratedKeys" value="true" />
             <setting name="defaultExecutorType" value="REUSE" />
         settings>
         <typeAliases>
            <typeAlias alias="User" type="bean.User"/>
         typeAliases>
         <environments default="development">
            <environment id="development">
                <transactionManager type="jdbc"/>
                <dataSource type="POOLED">
                   <property name="driver" value="oracle.jdbc.driver.OracleDriver"/>
                   <property name="url" value="jdbc:oracle:thin:@192.168.56.201:1521:system"/>
                   <property name="username" value="vincent"/>
                   <property name="password" value="1234"/>
                dataSource>
            environment>
         environments>
         <mappers>
             <mapper resource="resource/UserMapper.xml" />
         mappers>
     configuration>

 

加载配置文件得到sqlSessionFactory的工具类

 package Util;

     import java.io.IOException;
     import java.io.Reader;

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

     public class MyBatisUtil  {
         private  final static SqlSessionFactory sqlSessionFactory;
         static {
            String resource = "resource/mybatis-config.xml";
            Reader reader = null;
            try {
                reader = Resources.getResourceAsReader(resource);
            } catch (IOException e) {
                System.out.println(e.getMessage());

            }
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
         }

         public static SqlSessionFactory getSqlSessionFactory() {
            return sqlSessionFactory;
         }
     }

 

测试代码如下：

 package TestMapper;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.junit.Test;

    public class TestMapper {
        static SqlSessionFactory sqlSessionFactory = null;
        static {
           sqlSessionFactory = MyBatisUtil.getSqlSessionFactory();
        }

        @Test
        public void testAdd() {
           SqlSession sqlSession = sqlSessionFactory.openSession();
           try {
               UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
               User user = new User("tom",new Integer(5));
               userMapper.insertUser(user);
               sqlSession.commit();//这里一定要提交，不然数据进不去数据库中
           } finally {
               sqlSession.close();
           }
        }

        @Test
        public void getUser() {
           SqlSession sqlSession = sqlSessionFactory.openSession();
           try {
               UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
               User user = userMapper.getUser("jun");
               System.out.println("name: "+user.getName()+"|age: "+user.getAge());
           } finally {
               sqlSession.close();
           }
        }

    }