mybatis入门示例传智燕青讲解一
示例一：增删改查
sqlMapConfig.xml
UserMapper.xml
Demo.java
示例二：原始Dao开发方法
UserMapper.xml
UserDao.java
UserDaoImpl.java
Demo.java
示例三：mapper代理方法
UserMapper.xml
UserMapper.java
Demo.java
示例四：动态sql
UserMapper.xml
UserMapper.java
Demo.java
sqlMapConfig.xml
<?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">
<!--
1、properties属性
注意：mybatis属性加载顺序
（1）、在properties元素体内定义的属性首先被读取
（2）、读取properties元素中resource或url加载的配置文件，它会覆盖已读取的同名属性
（3）、最后读取parameterType传递的属性，它会覆盖已读取的同名属性
建议：不要在properties元素体内添加任何属性值
在properties文件中定义属性名要有一定的特殊性
2、settings mybatis全局参数设置
3、typeAliases别名设置
-->
<configuration>
<!-- 加载属性文件 -->
<properties resource="dbSources.properties">
<!-- 还可以配置属性名和属性值 -->
<!-- <property name="jdbc.password" value="root"/> -->
<!-- <property name="value" value="c"/> -->
</properties>
<typeAliases>
<typeAlias type="com.chen.pojo.User" alias="_User"></typeAlias>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<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="sqlMapper/UserMapper.xml" ></mapper>
<mapper resource="sqlMapper/UserMapper2.xml"/>
<!-- 通过mapper接口加载单个映射文件
需遵循一些规范：需要将mapper接口类名和mapper.xml映射文件名保持一致
且在一个目录中；前提：使用的是mapper代理方法
-->
<!-- <mapper class="com.chen.mapper2.UserMapper"></mapper> -->
<!-- 批量加载mapper
指定mapper接口的包名，mybatis自动扫描包下所有mapper接口进行加载
需遵循一些规范：需要将mapper接口类名和mapper.xml映射文件名保持一致
且在一个目录中；前提：使用的是mapper代理方法
-->
<mapper class="com.chen.mapper3.UserMapper"></mapper>
<package name="com.chen.mapper2"/>
</mappers>
</configuration>
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">
<mapper namespace="com.chen.pojo.UserMapper">
<!--
id:标识映射文件中的sql
将sql语句封装到mappedStatement对象中，所以将id称为statement的id
parameterType:指定输入参数的类型
#{}表示一个占位符号
resultType:指定sql输出结果
-->
<select id="findUserById" parameterType="Long" resultType="_User">
select * from t_user where id=#{id}
</select>
<!--
resultType:指定就是单条记录所映射的java对象类型
${}：表示拼接sql串，将接收到参数的内容不加任何修饰拼接到sql中
使用${}拼接sql,引起sql注入,存在安全隐患不建议使用
${value}：接收输入的参数的内容，如果传入的类型是简单类型，只能用value
-->
<select id="findUserByName" parameterType="String" resultType="com.chen.pojo.User">
select * from t_user where username like '%${value}%'
</select>
<insert id="insertUser" parameterType="com.chen.pojo.User" useGeneratedKeys="true" keyProperty="id">
insert into t_user(username,birthday) values(#{username},#{birthday})
</insert>
<!--
插入记录返回自增长主键方法二
SELECT LAST_INSERT_ID()：得到刚insert进去记录的主键值，只适用于自增长
keyProperty:将查询到主键值设置到parameterType指定的对象中的属性
order :SELECT LAST_INSERT_ID()执行顺序，相对于insert语句
resultType:SELECT LAST_INSERT_ID()返回结果类型
-->
<insert id="insertUser2" parameterType="com.chen.pojo.User" >
<selectKey keyProperty="id" order="AFTER" resultType="Long">
SELECT LAST_INSERT_ID()
</selectKey>
insert into t_user(username,birthday) values(#{username},#{birthday})
</insert>
<delete id="deleteUserById" parameterType="Long">
delete from t_user where id=#{id}
</delete>
<update id="updateUserById" parameterType="com.chen.pojo.User">
update t_user set username=#{username},birthday=#{birthday} where id=#{id}
</update>
</mapper>
Demo.java
package com.chen.demo;
import java.io.IOException;
import java.io.Reader;
import java.util.Date;
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 com.chen.pojo.User;
public class Demo1 {
private static SqlSessionFactory sqlSessionFactory= null;
static{
String resources = "sqlMapConfig.xml";
try {
Reader reader = Resources.getResourceAsReader(resources);
sqlSessionFactory=new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
test2();
}
public static void test1(){
SqlSession session = sqlSessionFactory.openSession();
String sql="com.chen.pojo.UserMapper.findUserById";
User user = (User) session.selectOne(sql, 1L);
System.out.println(user);
session.close();
}
public static void test2(){
SqlSession session = sqlSessionFactory.openSession();
String sql="com.chen.pojo.UserMapper.findUserByName";
List<User> users = session.selectList(sql, "c");
System.out.println(users);
session.close();
}
public static void test3(){
SqlSession session = sqlSessionFactory.openSession();
String sql="com.chen.pojo.UserMapper.insertUser";
User u = new User();
u.setUsername("冬天");u.setBirthday(new Date());
session.insert(sql, u);
session.commit();
System.out.println(u);
session.close();
}
public static void test4(){
SqlSession session = sqlSessionFactory.openSession();
String sql="com.chen.pojo.UserMapper.insertUser2";
User u = new User();
u.setUsername("春天");u.setBirthday(new Date());
session.insert(sql, u);
session.commit();
System.out.println(u);
session.close();
}
public static void test5(){
SqlSession session = sqlSessionFactory.openSession();
String sql="com.chen.pojo.UserMapper.deleteUserById";
session.delete(sql, 25L);
session.commit();
session.close();
}
public static void test6(){
SqlSession session = sqlSessionFactory.openSession();
String sql="com.chen.pojo.UserMapper.updateUserById";
String sql2="com.chen.pojo.UserMapper.findUserById";
User u = session.selectOne(sql2, 24L);
u.setUsername("冬天的忧伤");
session.update(sql, u);
session.commit();
session.close();
}
}
示例二：原始Dao开发方法
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">
<mapper namespace="com.chen.pojo.UserMapper">
<!--
id:标识映射文件中的sql
将sql语句封装到mappedStatement对象中，所以将id称为statement的id
parameterType:指定输入参数的类型
#{}表示一个占位符号
resultType:指定sql输出结果
-->
<select id="findUserById" parameterType="Long" resultType="_User">
select * from t_user where id=#{id}
</select>
<!--
resultType:指定就是单条记录所映射的java对象类型
${}：表示拼接sql串，将接收到参数的内容不加任何修饰拼接到sql中
使用${}拼接sql,引起sql注入,存在安全隐患不建议使用
${value}：接收输入的参数的内容，如果传入的类型是简单类型，只能用value
-->
<select id="findUserByName" parameterType="String" resultType="com.chen.pojo.User">
select * from t_user where username like '%${value}%'
</select>
<insert id="insertUser" parameterType="com.chen.pojo.User" useGeneratedKeys="true" keyProperty="id">
insert into t_user(username,birthday) values(#{username},#{birthday})
</insert>
<!--
插入记录返回自增长主键方法二
SELECT LAST_INSERT_ID()：得到刚insert进去记录的主键值，只适用于自增长
keyProperty:将查询到主键值设置到parameterType指定的对象中的属性
order :SELECT LAST_INSERT_ID()执行顺序，相对于insert语句
resultType:SELECT LAST_INSERT_ID()返回结果类型
-->
<insert id="insertUser2" parameterType="com.chen.pojo.User" >
<selectKey keyProperty="id" order="AFTER" resultType="Long">
SELECT LAST_INSERT_ID()
</selectKey>
insert into t_user(username,birthday) values(#{username},#{birthday})
</insert>
<delete id="deleteUserById" parameterType="Long">
delete from t_user where id=#{id}
</delete>
<update id="updateUserById" parameterType="com.chen.pojo.User">
update t_user set username=#{username},birthday=#{birthday} where id=#{id}
</update>
</mapper>
UserDao.java
UserDaoImpl.java
package com.chen.dao;
import com.chen.pojo.User;
public interface UserDao {
public User findUserById(Long id);
public void updateUserById(User u);
public void deleteUserById(Long id);
}
package com.chen.dao;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import com.chen.pojo.User;
/*
* （1）原始Dao开发方法
* 问题：1、dao接口实现类方法存在大量模板方法，设想将模板方法提取出来
* 2、sqlsession调用方法时将statement的id硬编码了（ sql="com.chen.pojo.UserMapper.findUserById"）
* 3、sqlsession调用方法时传入参数类型错误，编译期不会报错
*
* 问题：接口方法输入参数只能为一个
* 解决：通过包装类型包含多个参数
* 注意：持久层可以使用包装类型，service层建议不使用包装类型
*/
public class UserDaoImpl implements UserDao {
private SqlSessionFactory sessionFactory ;
public UserDaoImpl() {
}
public UserDaoImpl(SqlSessionFactory factory){
this.sessionFactory=factory;
}
public User findUserById(Long id) {
SqlSession session = sessionFactory.openSession();
String sql="com.chen.pojo.UserMapper.findUserById";
User u =session.selectOne(sql, id);
session.close();
return u;
}
public void updateUserById(User u) {
SqlSession session = sessionFactory.openSession();
String sql="com.chen.pojo.UserMapper.updateUserById";
session.update(sql, u);
session.commit();
session.close();
}
public void deleteUserById(Long id) {
SqlSession session = sessionFactory.openSession();
String sql="com.chen.pojo.UserMapper.deleteUserById";
session.delete(sql, id);
session.commit();
session.close();
}
}
Demo.java
package com.chen.demo;
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;
import com.chen.dao.UserDao;
import com.chen.dao.UserDaoImpl;
import com.chen.pojo.User;
public class Demo2_UserDao {
private static SqlSessionFactory sqlSessionFactory= null;
static{
String resources = "sqlMapConfig.xml";
try {
Reader reader = Resources.getResourceAsReader(resources);
sqlSessionFactory=new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
test1();
}
public static void test1(){
UserDao userDao = new UserDaoImpl(sqlSessionFactory);
User u = userDao.findUserById(24L);
System.out.println(u);
}
}
示例三：mapper代理方法
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">
<mapper namespace="com.chen.mapper.UserMapper">
<select id="findUserById" parameterType="Long" resultType="com.chen.pojo.User">
select * from t_user where id=#{id}
</select>
<select id="findUserByName" parameterType="String" resultType="com.chen.pojo.User">
select * from t_user where username like '%${value}%'
</select>
<insert id="insertUser" parameterType="com.chen.pojo.User" useGeneratedKeys="true" keyProperty="id">
insert into t_user(username,birthday) values(#{username},#{birthday})
</insert>
<insert id="insertUser2" parameterType="com.chen.pojo.User" >
<selectKey keyProperty="id" order="AFTER" resultType="Long">
SELECT LAST_INSERT_ID()
</selectKey>
insert into t_user(username,birthday) values(#{username},#{birthday})
</insert>
<delete id="deleteUserById" parameterType="Long">
delete from t_user where id=#{id}
</delete>
<update id="updateUserById" parameterType="com.chen.pojo.User">
update t_user set username=#{username},birthday=#{birthday} where id=#{id}
</update>
</mapper>
UserMapper.java
package com.chen.mapper;
import java.util.List;
import com.chen.pojo.User;
/*
* (2)、mapper代理方法
* 1、需要编写mapper.xml映射文件
* mapper接口编写需要遵循一些规范，mybatis就可以自动生成mapper接口实现类代理对象
* （1）、在mapper.xml中namespace等于接口mapper.java地址(com.chen.mapper。UserMapper)
* （2）、mapper.java接口中的方法名和mapper.xml中statement的id一致
* （3）、mapper.java接口中的方法输入参数类型和mapper.xml中statement的parameterType一致
* （4）、mapper.java接口中的方法返回值类型和mapper.xml中statement的resultType一致
*/
public interface UserMapper {
public User findUserById(Long id);
public List<User> findUserByName(String name);
public void insertUser(User u);
public void insertUser2(User u);
public void updateUserById(User u);
public void deleteUserById(Long id);
}
Demo.java
package com.chen.demo;
import java.io.IOException;
import java.io.Reader;
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 com.chen.mapper.UserMapper;
import com.chen.pojo.User;
public class Demo3_UserMapper {
private static SqlSessionFactory sqlSessionFactory= null;
static{
String resources = "sqlMapConfig.xml";
try {
Reader reader = Resources.getResourceAsReader(resources);
sqlSessionFactory=new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
test1();
}
private static void test1() {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
User u = userMapper.findUserById(24L);
System.out.println(u);
}
}
示例四：动态sql
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">
<mapper namespace="com.chen.mapper3.UserMapper">
<!-- 定义sql片段
经验：基于单表来定义sql片段，可重用性高
在sql片段中不要包括where
-->
<sql id="query_user">
<if test="userCust != null">
<if test="userCust.username !=null and userCust.username!=''">
and username like #{userCust.username}
</if>
<if test="userCust.sex !=null and userCust.sex!=''">
and sex=#{userCust.sex}
</if>
</if>
</sql>
<select id="findUserList" parameterType="com.chen.pojo.UserQueryVO" resultType="_User">
select * from t_user
<where>
<if test="userCust != null">
<if test="userCust.username !=null and userCust.username!=''">
and username like #{userCust.username}
</if>
<if test="userCust.sex !=null and userCust.sex!=''">
and sex=#{userCust.sex}
</if>
</if>
</where>
</select>
<select id="findUserCount" parameterType="com.chen.pojo.UserQueryVO" resultType="int">
select count(*) from t_user
<where>
<include refid="query_user"></include>
</where>
</select>
<select id="findUserByIds" parameterType="com.chen.pojo.UserQueryVO" resultType="_User">
select * from t_user
<where>
<include refid="query_user"></include>
<foreach collection="ids" item="id" open="and (" close=")" separator="or">
id =#{id}
</foreach>
</where>
</select>
</mapper>
UserMapper.java
package com.chen.mapper3;
import java.util.List;
import com.chen.pojo.User;
import com.chen.pojo.UserQueryVO;
public interface UserMapper {
public List<User> findUserList(UserQueryVO vo);
public int findUserCount(UserQueryVO vo);
public List<User>findUserByIds(UserQueryVO vo);
}
Demo.java
package com.chen.demo;
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
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 com.chen.mapper3.UserMapper;
import com.chen.pojo.User;
import com.chen.pojo.UserCustmer;
import com.chen.pojo.UserQueryVO;
public class Demo5_SQL {
private static SqlSessionFactory sqlSessionFactory= null;
static{
String resources = "sqlMapConfig.xml";
try {
Reader reader = Resources.getResourceAsReader(resources);
sqlSessionFactory=new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
test3();
}
private static void test1() {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
UserQueryVO vo = new UserQueryVO();
UserCustmer userCust = new UserCustmer();
userCust.setUsername("%C%");
userCust.setSex("m");
vo.setUserCust(userCust);
List<User> list =userMapper.findUserList(vo);
System.out.println(list);
}
private static void test2() {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
UserQueryVO vo = new UserQueryVO();
UserCustmer userCust = new UserCustmer();
userCust.setUsername("%C%");
userCust.setSex("m");
vo.setUserCust(userCust);
int count =userMapper.findUserCount(vo);
System.out.println(count);
}
private static void test3() {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
UserQueryVO vo = new UserQueryVO();
List<Integer> ids = new ArrayList<Integer>();
ids.add(10);
ids.add(12);
ids.add(15);
UserCustmer userCust = new UserCustmer();
userCust.setUsername("%C%");
vo.setIds(ids);
vo.setUserCust(userCust);
List<User> list =userMapper.findUserByIds(vo);
System.out.println(list);
}
}