MyBatis操作上

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最新推荐文章于 2024-09-13 13:54:52 发布

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本文链接：https://blog.youkuaiyun.com/weixin_42245220/article/details/99328500

本文详细介绍MyBatis框架的学习步骤，包括环境搭建、配置文件设置、工具类封装、实体类与接口创建、映射文件编写及测试代码实现，涵盖XML配置与注解两种方式。

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【mybaties官网: http://www.mybatis.org/mybatis-3/zh/index.html.】
具体学习步骤

(1)	框架执行流程
	①	对框架执行图解分析
(2)	具体分布细节-环境准备
	①	创建项目导入依赖包
	②	准备主配置配置文件mybatis-config.xml
		1)	配置数据库连接四要素
	③	编写MyBatisUtil工具类封装公共代码
		1)	配置文件的读取-SqlSessionFactory对象创建
		2)	提供返回SqlSession 会话操作对象的方法
(3)	入门案例
	①	创建操作表对应的实体Pojo对象 User
	②	创建表操作的接口文件 UserMapper.java
	③	创建接口对应的映射文件 UserMapper.xml
	④	主配置文件引入 UserMapper.xml映射文件
	⑤	代码编写
		1)	接口中写具体增删改查方法
		2)	映射文件写对应方法的功能标签
			a.	<insert><delete><select><update>
			b.	标签有属性，属性的配置和接口的方法都遵循一定映射规则
			a)	方法返回类型和 resultType类型相同
			b)	方法参数和 属性 parameterType 相同
			c)	方法名称和 id  的执行相同
	⑥	编写测试代码
		1)	所有操作都必须有SqlSession对象
			a.	创建SqlSession ，通过 MyBatisUtil工具直接提供方法直接获取
		2)	创建 UserMapper代理对象
		3)	执行CRUD（增删改查）具体方法

一. mybatis工程目录（使用xml配置写sql代码）
在这里插入图片描述

1.UserMapper.interface

package com.xxx.mapper;

import com.xxx.pojo.User;
import org.apache.ibatis.annotations.Param;
import java.util.List;

public interface UserMapper {
    int insert(User user);

    List<User> query();

    User queryById(int id);

    User queryByNP(@Param("name") String name, @Param("password") String password);

    int delete(int id);

    int update(User user);
}

2.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.xxx.mapper.UserMapper">
    <resultMap id="userMap" type="User">
        <id property="id" column="u_id"/>
        <result property="name" column="u_name"/>
        <result property="password" column="u_password"/>
        <result property="age" column="u_age"/>
    </resultMap>
    <insert id="insert" parameterType="User" keyColumn="id" keyProperty="id" useGeneratedKeys="true">
        insert into user(name,password,age) values (#{name},#{password},#{age});
    </insert>
    <select id="query" resultMap="userMap">
        select id u_id,name u_name,password u_password,age u_age from user ;
    </select>
    <select id="queryById" parameterType="int" resultType="User">
        select * from user where id=#{id};
    </select>
    <select id="queryByNP" parameterType="String" resultType="User">
        select * from user where name=#{name} and password=#{password};
    </select>
    <delete id="delete" parameterType="int">
        delete from user where id=#{id};
    </delete>
    <update id="update" parameterType="User">
        update user set name=#{name} where id=#{id};
    </update>
</mapper>

3.User.java

package com.xxx.pojo;

public class User {
    private int id;
    private String name;
    private String password;
    private int age;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

4.myBatisUtil

package com.xxx.util;

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 java.io.IOException;
import java.io.InputStream;

public class mybatisUtil {

    private mybatisUtil(){}

    private static SqlSessionFactory sqlSessionFactory;

    static {
        String resource = "mybatis-config.xml";
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static SqlSession openSession(){
        return  sqlSessionFactory.openSession();
    }

}

5.db.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql:///test
username=root
password=1234

6.log4j.properties

# Global logging configuration
log4j.rootLogger=ERROR, stdout
# MyBatis logging configuration...
log4j.logger.com.xxx.mapper=TRACE
# 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

7.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>
    <properties resource="db.properties"/>    
    <typeAliases>
        <typeAlias alias="User" type="com.xxx.pojo.User"/>
    </typeAliases>   
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/xxx/mapper/UserMapper.xml"/>
    </mappers>
</configuration>

8.maven依赖：pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.xxx</groupId>
    <artifactId>2.mybatis-curd</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.27</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.25</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.25</version>
        </dependency>
    </dependencies>
</project>

9.main

package com.xxx;

import com.xxx.mapper.UserMapper;
import com.xxx.pojo.User;
import com.xxx.util.mybatisUtil;
import org.apache.ibatis.session.SqlSession;

import java.util.List;

public class main {
    public static void main(String[] args) {
        //insert();
        query();
        //update();
    }

    public static void insert(){
        SqlSession sqlSession = mybatisUtil.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = new User();
        user.setName("张三");
        user.setPassword("123");
        user.setAge(12);
        int insert = mapper.insert(user);
        System.out.println(user);
        sqlSession.commit();
        sqlSession.close();
    }

    public static void query(){
        //List<User> query();
        SqlSession sqlSession = mybatisUtil.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<User> query = mapper.query();
        for (User user:query) {
            System.out.println(user);
        }
    }

    public static void queryById(){
        //User queryById(int id);
        SqlSession sqlSession = mybatisUtil.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.queryById(5);

    }

    public static void queryByNP(){
        //User queryByNP(@Param("name") String name, @Param("password") String password);
        SqlSession sqlSession = mybatisUtil.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.queryByNP("花满楼", "123");
    }

    public static void delete(){
        SqlSession sqlSession = mybatisUtil.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int delete = mapper.delete(9);
        sqlSession.commit();
        sqlSession.close();
    }

    public static void update(){
        SqlSession sqlSession = mybatisUtil.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = new User();
        user.setId(7);
        user.setName("李四");
        int update = mapper.update(user);
        sqlSession.commit();
        sqlSession.close();
    }
}

二.mybaties工程目录(使用注解方式)
在这里插入图片描述
区别：
1.UserMapper接口代码中使用注解

package com.xxx.mapper;

import com.xxx.pojo.User;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface UserMapper {

   @Select("select id u_id,name u_name,age u_age,password u_password from user")
   @Results({
           @Result(id = true,property = "id",column = "u_id"),
           @Result(property = "name",column = "u_name"),
           @Result(property = "age",column = "u_age"),
           @Result(property = "password",column = "u_password")
   })
    List<User> query();

   @Select("select * from user where id=#{id}")
    User queryById(int id);

   @Select("select * from user where name=#{name} and password=#{password}")
    User queryByNP(@Param("name") String name, @Param("password") String password);

   @Insert("insert into user(name,password,age) values(#{name},#{password},#{age})")
   @Options(
           keyColumn = "id",
           keyProperty = "id",
           useGeneratedKeys = true
   )
    int insert(User user);

   @Delete("delete from user where id=#{id}")
    int delete(int id);

   @Update("update user set name=#{name} where id=#{id}")
    int update(User user);

}

2.mybatis-config中mapper导入的是接口的位置
在这里插入图片描述
3.测试类的使用

package com.xxx.test;

import com.xxx.mapper.UserMapper;
import com.xxx.pojo.User;
import com.xxx.util.mybatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class UserTest {

    private SqlSession sqlSession;
    private UserMapper mapper;

    @Before
    public void before(){
        sqlSession = mybatisUtil.sqlSession();
        mapper = sqlSession.getMapper(UserMapper.class);
    }

    @Test
    public void testQuery(){
        mapper.query();
    }
    @Test
    public void testQueryById(){
        mapper.queryById(3);
    }
    @Test
    public void testQueryByNP(){
        mapper.queryByNP("段誉","123");
    }
    @Test
    public void testInsert(){
        User user = new User();
        user.setName("郭靖");
        user.setPassword("123");
        user.setAge(18);
        mapper.insert(user);
    }
    @Test
    public void testDelete(){
        mapper.delete(6);
    }
    @Test
    public void testUpdate(){
        User user = new User();
        user.setId(1);
        user.setName("小华");
        mapper.update(user);
    }

    @After
    public void after(){
        sqlSession.commit();
        sqlSession.close();
    }
}