1、前言
前面一讲讲到讲到初级的Mybatis开发，现在晋级将一些他的规范开发，规范的东西更便于维护和阅读。
2、为Mybatis开发规范
1、mapper.xml中namespace指定为mapper接口的全限定名
此步骤目的：通过mapper.xml和mapper.java进行关联。
2、mapper.xml中statement的id就是mapper.java中方法名
3、mapper.xml中statement的parameterType和mapper.java中方法输入参数类型一致
4、mapper.xml中statement的resultType和mapper.java中方法返回值类型一致.
java对象:UserMapper依旧
import com.ycy.mybatis.module.User;
import java.util.List;
/**
* Created by Administrator on 2015/8/31 0031.
*/
public interface UserMapper {
public User getUserById(int id) throws Exception;
public List<User> findUserByName(String username) throws Exception;
public void insertUser(User user) throws Exception;
}
xml对象：UserMapper.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">
<!--命名空间：分类管理sql隔离，方便管理-->
<mapper namespace="com.ycy.mybatis.dao.UserMapper">
<!--id标示一个sql语句，一个Statement，封装为一个MapperStatement-->
<!--parameterType:传入参数类型;resultType:输出结果类型，指定映射的pojo-->
<!--#{}标示一个占位符，-->
<!--查询用户-->
<!--oracle-->
<!-- SELECT * FROM USER WHERE username LIKE '%'||#{_parameter}||'%'-->
<!-- mysql-->
<select id="getUserById" parameterType="int" resultType="com.ycy.mybatis.module.User">
SELECT * FROM USER WHERE id=#{id}
</select>
<select id="findUserByName" parameterType="String" resultType="com.ycy.mybatis.module.User">
SELECT * FROM USER WHERE username LIKE '%${_parameter}%'
</select>
<!--新增用户-->
<insert id="insertUser" parameterType="com.ycy.mybatis.module.User" >
<!--插入值之后返回主键值-->
<selectKey resultType="int" order="AFTER" keyProperty="id">
SELECT LAST_INSERT_ID()
</selectKey>
INSERT INTO USER (username,birthday,sex,address) VALUES (#{username},#{birthday},#{sex},#{address})
</insert>
<!--删除用户-->
<delete id="deleteUser" parameterType="int">
DELETE FROM USER WHERE id=#{id}
</delete>
<!--更新用户-->
<update id="updateUser" parameterType="com.ycy.mybatis.module.User">
UPDATE USER SET username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} WHERE id=#{id}
</update>
</mapper>
测试结果：
MybatisTest3
package com.ycy.mybatis.test;
import com.ycy.mybatis.dao.UserMapper;
import com.ycy.mybatis.module.User;
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.junit.Before;
import org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
/**
* Created by Administrator on 2015/8/31 0031.
*/
public class MybatisTest3 {
private SqlSessionFactory sqlSessionFactory = null;
@Before
public void before() throws IOException {
String resource="SqlMapConfig.xml";
InputStream in = Resources.getResourceAsStream(resource);
sqlSessionFactory= new SqlSessionFactoryBuilder().build(in);
}
@Test
public void testGet() throws Exception {
SqlSession sqlSession=sqlSessionFactory.openSession();
UserMapper userService= sqlSession.getMapper(UserMapper.class);
User user= userService.getUserById(1);
System.out.println(user.getUsername());
}
@Test
public void testFindByname() throws Exception {
SqlSession sqlSession=sqlSessionFactory.openSession();
UserMapper userMapper= sqlSession.getMapper(UserMapper.class);
List<User> userList= userMapper.findUserByName("陈小明");
for (User user : userList) {
System.out.println(user.getUsername());
}
}
}
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