編寫mapper.xml映射文件
程序員編寫mapper接口需要遵循一些開發(fā)規(guī)范堕仔，mybatis可以自動(dòng)生成mapper接口實(shí)現(xiàn)類代理對(duì)象
開發(fā)規(guī)范 （mapper接口和mapper.xml映射文件之間的關(guān)系）：
1.在mapper.xml中namespace和mapper接口的地址一致
2.mapper.java接口中的方法名和mapper.xml中statement的id一致
3.mapper.java接口中的方法的輸入?yún)?shù)類型和mapper.xml中statement的parameterType屬性值一致
4.mapper.java接口中的方法的返回值類型和mapper.xml中statement的resultType屬性值一致
UserMapper.xml
package cn.ztc.mybatis.mapper;
import static org.junit.Assert.*;
import java.io.InputStream;
import java.util.List;
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 cn.ztc.mybatis.po.User;
public class UserMapperTest {
private SqlSessionFactory sqlSessionFactory;
//此方法在執(zhí)行testFindUserById方法之前執(zhí)行
@Before
public void setUp() throws Exception{
String resource = "SqlMapConfig.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void testFindUserById() throws Exception {
SqlSession sqlSession = sqlSessionFactory.openSession();
//創(chuàng)建UserMapper對(duì)象擂橘，Mybatis自動(dòng)生成mapper代理對(duì)象
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
//調(diào)用UserMapper的方法
User user = userMapper.findUserById(24);
sqlSession.close();
System.out.println(user);
}
@Test
public void testFindUserByName() throws Exception {
SqlSession sqlSession = sqlSessionFactory.openSession();
//創(chuàng)建UserMapper對(duì)象，Mybatis自動(dòng)生成mapper代理對(duì)象
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
//調(diào)用UserMapper的方法
List<User> list = userMapper.findUserByName("小明");
sqlSession.close();
System.out.println(list);
}
}
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">
<!-- 使用mapper代理的方法摩骨，namespace等于mapper接口的地址 -->
<mapper namespace="cn.ztc.mybatis.mapper.UserMapper">
<!--
需求：根據(jù)id獲取用戶信息
id:表示表示映射文件中的sql通贞，將sql語句封裝到mappedStatement對(duì)象中，將id稱為Statement的 id
parameterType：指定出入?yún)?shù)類型
resultType：指定輸出參數(shù)類型
#{}表示一個(gè)占位符
#{id}接收輸入?yún)?shù)恼五，參數(shù)名為id昌罩，如果輸入的是簡(jiǎn)單類型，#{}中的參數(shù)名可以任意
-->
<select id="findUserById" parameterType="int" resultType="cn.ztc.mybatis.po.User">
select * from user where id = #{id}
</select>
<!--
需求：自定義條件查詢用戶列表 灾馒，可能返回多條數(shù)據(jù)
resultType：指定的就是單條記錄所使用的java對(duì)象類型
${}表示拼接sql串茎用，將接收到的參數(shù)不加任何修飾拼接在sql串中
使用${}可能會(huì)引起sqk注入
${value}接收輸入?yún)?shù)，如果輸入的是簡(jiǎn)單類型，#{}中的參數(shù)名只能是value
-->
<select id="findUserByName" parameterType="java.lang.String" resultType="cn.ztc.mybatis.po.User">
select * from user where username like '%${value}%'
</select>
<!--
添加用戶
parameterType:輸入?yún)?shù)類型是pojo
#{}中指定pojo的屬性名
-->
<insert id="insertUser" parameterType="cn.ztc.mybatis.po.User">
<!--
將插入數(shù)據(jù)庫的主鍵返回到對(duì)象中
select LAST_INSERT_ID():得到insert記錄的主鍵值轨功，只適用于自增主鍵
keyProperty：將查詢到的主鍵值設(shè)置到parameterType指定對(duì)象的某個(gè)屬性
order：相對(duì)于insert語句來說,select LAST_INSERT_ID()的執(zhí)行順序
-->
<selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
select LAST_INSERT_ID()
</selectKey>
insert into user (username,birthday,sex,address) values (#{username},#{birthday},#{sex},#{address})
<!--
使用mysql的uuid生成主鍵
執(zhí)行過程：
首先用過uuid()得到主鍵旭斥，將主鍵設(shè)置到user對(duì)象的id屬性中
其次在執(zhí)行insert，從user對(duì)象中取出id屬性值
-->
<!-- <selectKey keyProperty="id" order="BEFORE" resultType="java.lang.String">
select uuid()
</selectKey>
insert into user (id,username,birthday,sex,address) values (#{id},#{username},#{birthday},#{sex},#{address}) -->
</insert>
<!-- 刪除用戶 -->
<delete id="deleteUser" parameterType="java.lang.Integer">
delete from user where id=#{id}
</delete>
<!--
更新用戶
#{id}:對(duì)應(yīng)pojo的屬性值
-->
<update id="updateUser" parameterType="cn.ztc.mybatis.po.User">
update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} where id = #{id}
</update>
</mapper>
UserMapperTest.java
package cn.ztc.mybatis.mapper;
import static org.junit.Assert.*;
import java.io.InputStream;
import java.util.List;
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 cn.ztc.mybatis.po.User;
public class UserMapperTest {
private SqlSessionFactory sqlSessionFactory;
//此方法在執(zhí)行testFindUserById方法之前執(zhí)行
@Before
public void setUp() throws Exception{
String resource = "SqlMapConfig.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void testFindUserById() throws Exception {
SqlSession sqlSession = sqlSessionFactory.openSession();
//創(chuàng)建UserMapper對(duì)象古涧，Mybatis自動(dòng)生成mapper代理對(duì)象
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
//調(diào)用UserMapper的方法
User user = userMapper.findUserById(24);
sqlSession.close();
System.out.println(user);
}
@Test
public void testFindUserByName() throws Exception {
SqlSession sqlSession = sqlSessionFactory.openSession();
//創(chuàng)建UserMapper對(duì)象垂券，Mybatis自動(dòng)生成mapper代理對(duì)象
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
//調(diào)用UserMapper的方法
List<User> list = userMapper.findUserByName("小明");
sqlSession.close();
System.out.println(list);
}
}
