MyBatis研习录(04)——基于Mapper接口的增删改查操作
2019-11-27 21:26
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版权声明
- 本文原创作者：谷哥的小弟
- 作者博客地址：http://blog.csdn.net/lfdfhl
概述
在本节教程中，我们利用MyBatis的Mapper接口方式实现对数据的增删改查操作。那么什么是Mapper接口呢？其实，它非常类似于以前的DAO只不过其命名规范为xxxMapper.java，例如：UserMapper.java。在使用基于Mapper接口实现增删改查等数据库操作时不需要编写Mapper接口的实现类，而由Mybatis框架根据接口定义创建接口的动态代理对象。目前，MyBatis官方推荐使用基于Mapper接口的开发。
MyBatis基于Mapper接口的开发必须遵守以下的开发规范：
- 1、xxxMapper.xml配置文件中的命名空间namespace的值必须是xxxMapper.java接口的全类名
- 2、xxxMapper.xml配置文件中的id值必须对应于xxxMapper.java接口中的方法名
- 3、xxxMapper.xml配置文件中的parameterType参数类型必须和xxxMapper.java接口中的方法的输入参数类型一致
- 4、xxxMapper.xml配置文件中的resultType返回值类型必须和xxxMapper.java接口中的方法的返回值类型一致
示例
在此，以示例形式详细介绍MyBatis基于Mapper接口的开发。
数据准备
创建数据库mybatisDatabase和表user
DROP DATABASE IF EXISTS mybatisDatabase;
CREATE DATABASE mybatisDatabase;
use mybatisDatabase;
CREATE TABLE user(
id INT primary key auto_increment,
username VARCHAR(50),
password VARCHAR(50),
gender VARCHAR(10)
);
INSERT INTO user(username,password,gender) VALUES("lucy","123456","female");
INSERT INTO user(username,password,gender) VALUES("momo","234567","female");
INSERT INTO user(username,password,gender) VALUES("xixi","345678","female");
INSERT INTO user(username,password,gender) VALUES("pepe","456123","female");
SELECT * FROM user;
搭建开发环境
创建普通的Java工程，结构如下：
log4j.properties
# Global logging configuration log4j.rootLogger=DEBUG, stdout # Console output... log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.layout=org.apache.log4j.PatternLayout log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n
User
package cn.com.pojo;
/**
* 本文作者：谷哥的小弟
* 博客地址：http://blog.csdn.net/lfdfhl
*/
public class User {
private Integer id;
private String username;
private String password;
private String gender;
public User() {
}
public User(Integer id, String username, String password, String gender) {
super();
this.id = id;
this.username = username;
this.password = password;
this.gender = gender;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
@Override
public String toString() {
return "User [id=" + id + ", username=" + username + ", password=" + password + ", gender=" + gender + "]";
}
}
UserMapper.java
package cn.com.mapper;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.MapKey;
import cn.com.pojo.User;
/**
* 本文作者：谷哥的小弟
* 博客地址：http://blog.csdn.net/lfdfhl
*/
public interface UserMapper {
public int insertUser(User user);
public int deleteUserById(Integer id);
public int updateUser(User user);
public User queryUserById(Integer id);
public List<User> queryAllUserList();
@MapKey("id")
public Map<Integer,User> queryAllUserMap();
}
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="cn.com.mapper.UserMapper">
<select id="queryUserById" parameterType="java.lang.Integer" resultType="cn.com.pojo.User">
select id,username,password,gender from user where id = #{id}
</select>
<select id="queryAllUserList" resultType="cn.com.pojo.User">
select id,username,password,gender from user
</select>
<select id="queryAllUserMap" resultType="cn.com.pojo.User">
select id,username,password,gender from user
</select>
<delete id="deleteUserById" parameterType="java.lang.Integer">
delete from user where id=#{id}
</delete>
<update id="updateUser" parameterType="cn.com.pojo.User">
update user set username=#{username},password=#{password},gender=#{gender} where id=#{id}
</update>
<!-- 插入User至数据库
<insert id="insertUser" parameterType="cn.com.pojo.User">
insert into user(username,password,gender) values (#{username},#{password},#{gender})
</insert>
-->
<!-- 插入User至数据库并返回表自动生成的主键(方式一)
<insert id="insertUser" parameterType="cn.com.pojo.User" useGeneratedKeys="true" keyProperty="id">
insert into user(username,password,gender) values (#{username},#{password},#{gender})
</insert>
-->
<!-- 插入User至数据库并返回表自动生成的主键(方式二) -->
<insert id="insertUser" parameterType="cn.com.pojo.User">
<selectKey order="AFTER" keyProperty="id" resultType="int">
select last_insert_id()
</selectKey>
insert into user(username,password,gender) values (#{username},#{password},#{gender})
</insert>
</mapper>
mybatis-config.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"> <configuration> <!-- 配置数据源 --> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/mybatisDatabase"/> <property name="username" value="root"/> <property name="password" value="root"/> </dataSource> </environment> </environments> <!-- 配置mapper --> <mappers> <mapper resource="cn/com/pojo/UserMapper.xml"/> </mappers> </configuration>
请在mybatis-config.xml中配置xxxMapper.xml。
MybatisTest
在MybatisTest中使用两种方式实现增删改查：
- 1、SqlSessionFactory获取SqlSession，SqlSession获取xxxMapper.java接口，再由xxxMapper.java接口实现数据操作
- 2、SqlSessionFactory获取SqlSession，再由SqlSession实现数据操作
package cn.com.test;
import java.io.InputStream;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
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.Test;
import cn.com.mapper.UserMapper;
import cn.com.pojo.User;
/**
* 本文作者：谷哥的小弟
* 博客地址：http://blog.csdn.net/lfdfhl
*/
public class MybatisTest {
static SqlSessionFactory sqlSessionFactory = null;
public static SqlSessionFactory getSqlSessionFactory() {
try {
if (sqlSessionFactory == null) {
InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
}
return sqlSessionFactory;
} catch (Exception e) {
// TODO: handle exception
} finally {
}
return null;
}
@Test
public void testQueryUserById() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
//利用SqlSession得到UserMapper
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
//利用SqlSession执行数据操作
User user = userMapper.queryUserById(1);
System.out.println(user);
//关闭SqlSession
sqlSession.close();
}
@Test
public void testQueryUserByIdNoMapperInterface() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
User user=sqlSession.selectOne("cn.com.mapper.UserMapper.queryUserById",1);
System.out.println(user);
//关闭SqlSession
sqlSession.close();
}
@Test
public void testQueryAllUserList() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
//利用SqlSession得到UserMapper
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
//利用SqlSession执行数据操作
List<User> userList = userMapper.queryAllUserList();
Iterator<User> iterator = userList.iterator();
while (iterator.hasNext()) {
User user = iterator.next();
System.out.println(user);
}
//关闭SqlSession
sqlSession.close();
}
@Test
public void testQueryAllUserNoMapperInterface() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
//利用SqlSession执行数据操作
List<User> userList = sqlSession.selectList("cn.com.mapper.UserMapper.queryAllUser");
Iterator<User> iterator = userList.iterator();
while (iterator.hasNext()) {
User user = iterator.next();
System.out.println(user);
}
//关闭SqlSession
sqlSession.close();
}
@Test
public void testQueryAllUserMap() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
//利用SqlSession得到UserMapper
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
//利用SqlSession执行数据操作
Map<Integer, User> map=userMapper.queryAllUserMap();
Set<Integer> keySet = map.keySet();
Iterator<Integer> iterator = keySet.iterator();
while(iterator.hasNext()) {
Integer key = iterator.next();
User user = map.get(key);
System.out.println(user);
}
//关闭SqlSession
sqlSession.close();
}
@Test
public void testQueryAllUserMapNoMapperInterface() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
//利用SqlSession得到UserMapper
Map<Integer, User> map = sqlSession.selectMap("cn.com.mapper.UserMapper.queryAllUserMap", "id");
Set<Integer> keySet = map.keySet();
Iterator<Integer> iterator = keySet.iterator();
while(iterator.hasNext()) {
Integer key = iterator.next();
User user = map.get(key);
System.out.println(user);
}
//关闭SqlSession
sqlSession.close();
}
@Test
public void testDeleteUserById() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
//利用SqlSession得到UserMapper
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
//利用SqlSession执行数据操作
int result = userMapper.deleteUserById(1);
System.out.println("result=" + result);
//提交
sqlSession.commit();
//关闭SqlSession
sqlSession.close();
}
@Test
public void testDeleteUserByIdNoMapperInterface() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
//利用SqlSession执行数据操作
int result =sqlSession.delete("cn.com.mapper.UserMapper.deleteUserById",1);
System.out.println("result=" + result);
//提交
sqlSession.commit();
//关闭SqlSession
sqlSession.close();
}
@Test
public void testUpdateUser() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
//利用SqlSession得到UserMapper
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = new User(2, "klkl", "123543", "male");
//利用SqlSession执行数据操作
int result = userMapper.updateUser(user);
System.out.println("result=" + result);
//提交
sqlSession.commit();
//关闭SqlSession
sqlSession.close();
}
@Test
public void testUpdateUserNoMapperInterface() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
User user = new User(2, "klkl", "123543", "male");
//利用SqlSession执行数据操作
int result = sqlSession.update("cn.com.mapper.UserMapper.updateUser", user);
System.out.println("result=" + result);
//提交
sqlSession.commit();
//关闭SqlSession
sqlSession.close();
}
@Test
public void testInsertUser() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
//利用SqlSession得到UserMapper
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = new User(null, "gugu", "123456", "female");
//利用SqlSession执行数据操作
int result = userMapper.insertUser(user);
System.out.println("result=" + result);
System.out.println(user);
//提交
sqlSession.commit();
//关闭SqlSession
sqlSession.close();
}
@Test
public void testInsertUserNoMapperInterface() {
//获取SqlSession
SqlSession sqlSession=getSqlSessionFactory().openSession();
User user = new User(null, "gugu", "123456", "female");
//利用SqlSession执行数据操作
int result = sqlSession.insert("cn.com.mapper.UserMapper.insertUser",user);
System.out.println("result=" + result);
System.out.println(user);
//提交
sqlSession.commit();
//关闭SqlSession
sqlSession.close();
}
}
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