Mybatids学习篇二

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使用MyBatis对表执行CRUD操作

1、添加Mybatis的配置文件conf.xml

2、定义表所对应的实体类，

3、定义操作users表的sql映射文件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.users.mapping.userMapper">


<select id="getUser" parameterType="int"
resultType="com.users.Users">
select * from users where id=#{id}
</select>


<insert id="addUser" parameterType="com.users.Users">
insert into users(name,age) values(#{name},#{age})
</insert>


<delete id="deleteUser" parameterType="int">
delete from users where id=#{id}
</delete>


<update id="updateUser" parameterType="com.users.Users">
update users set name=#{name},age=#{age} where id=#{id}
</update>


<select id="getAllUsers" resultType="com.users.Users">
select * from users
</select>

</mapper>

4、定义sql映射的接口

　　UserMapperI接口的代码如下：

package com.users.mapping;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import com.users.Users;

public interface UserMapperI {
/**
* @author w_little
* 定义sql映射的接口，使用注解指明方法要执行的SQL
*/

//使用@Insert注解指明add方法要执行的SQL
@Insert("insert into users(name, age) values(#{name}, #{age})")
public int add(Users user);

//使用@Delete注解指明deleteById方法要执行的SQL
@Delete("delete from users where id=#{id}")
public int deleteById(int id);

//使用@Update注解指明update方法要执行的SQL
@Update("update users set name=#{name},age=#{age} where id=#{id}")
public int update(Users user);

//使用@Select注解指明getById方法要执行的SQL
@Select("select * from users where id=#{id}")
public Users getById(int id);

//使用@Select注解指明getAll方法要执行的SQL
@Select("select * from users")
public List<Users> getAll();
}

5、在conf.xml文件中注册这个映射接口

 <!-- 注册UserMapper映射接口-->

  <mapper class="com.users.mapping.UserMapperI"/>

</mappers>

6、用到的MyBatisUtil工具类代码如下

package com.util;

import java.io.InputStream;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MybatisUtil {
/**
* 获取SqlSessionFactory
* @return SqlSessionFactory
*/
public static SqlSessionFactory getSqlSessionFactory() {
//mybatis的配置文件
String resource = "conf.xml";
//使用类加载器加载mybatis的配置文件（它也加载关联的映射文件）
InputStream is = MybatisUtil.class.getClassLoader().getResourceAsStream(resource);
//构建sqlSession的工厂
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);

return factory;
}

/**
* 获取SqlSession
* @return SqlSession
*/
public static SqlSession getSqlSession() {
//创建能执行映射文件中sql的sqlSession
return getSqlSessionFactory().openSession();
}

/**
* 获取SqlSession
* @param isAutoCommit
* true 表示创建的SqlSession对象在执行完SQL之后会自动提交事务
* false 表示创建的SqlSession对象在执行完SQL之后不会自动提交事务，这时就需要我们手动调用sqlSession.commit()提交事务
* @return SqlSession
*/
public static SqlSession getSqlSession(boolean isAutoCommit) {
return getSqlSessionFactory().openSession(isAutoCommit);
}
}

7、单元测试类的代码如下：

package com.user.test;

import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import com.users.Users;
import com.users.mapping.UserMapperI;
import com.util.MybatisUtil;

public class Test1 {

@Test
public void testAdd() {
SqlSession sqlSession = MybatisUtil.getSqlSession();
/**
* 得到UserMapperI接口的实现类对象， UserMapperI接口的实现类对象由
* sqlSession.getMapper(UserMapperI.class)动态构建出来
*/
UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
Users user = new Users();
user.setName("用户zxw");
user.setAge(20);
int add = mapper.add(user);
// 使用SqlSession执行完SQL之后需要关闭SqlSession
sqlSession.close();
System.out.println(add);

}

@Test
public void testUpdate() {
SqlSession sqlSession = MybatisUtil.getSqlSession(true);
/**
* 得到UserMapperI接口的实现类对象
* mUserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
*/
UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
Users user = new Users();
user.setId(1);
user.setName("用户lxw");
user.setAge(56);
// 执行修改操作
int retResult = mapper.update(user);
// 使用SqlSession执行完SQL之后需要关闭SqlSession
sqlSession.close();
System.out.println(retResult);

}

@Test
public void testDelete() {
SqlSession sqlSession = MybatisUtil.getSqlSession(true);
/**
* 得到UserMapperI接口的实现类对象
* mUserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
*/
UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
// 执行删除操作
int retResult = mapper.deleteById(7);
// 使用SqlSession执行完SQL之后需要关闭SqlSession
sqlSession.close();
System.out.println(retResult);

}

@Test
public void testGetUser() {
SqlSession sqlSession = MybatisUtil.getSqlSession();
// 得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
// 执行查询操作，将查询结果自动封装成User返回
Users user = mapper.getById(8);
// 使用SqlSession执行完SQL之后需要关闭SqlSession
sqlSession.close();
System.out.println(user);

}

@Test
public void testGetAll() {
SqlSession sqlSession = MybatisUtil.getSqlSession();
// 得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
// 执行查询操作，将查询结果自动封装成List<User>返回
List<Users> lstUsers = mapper.getAll();
// 使用SqlSession执行完SQL之后需要关闭SqlSession
sqlSession.close();
System.out.println(lstUsers);

}
}