Mybatis快速入门：增删改查以及模糊查询拓展

1、概述

	MyBatis 是一款优秀的持久层框架，它支持定制化 SQL、存储过程以及高级映射。
	MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。
	MyBatis 可以使用简单的 XML 或注解来配置和映射原生信息，
	将接口和 Java 的 POJOs(Plain Ordinary Java Object,普通的 Java对象)
	映射成数据库中的记录

2、环境搭建

1. 创建一个maven项目
   

2. 导入依赖

<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>
<!--    父工程-->
    <groupId>org.example</groupId>
    <artifactId>mybatis</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
<!--    子工程-->
    <modules>
        <module>mybatis-01</module>
    </modules>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>

        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.3</version>
        </dependency>

<!--        数据库驱动-->
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.16</version>
        </dependency>

<!--        单元测试-->
        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

</project>

3. 在新建的子项目中src的resources文件夹中创建核心配置文件xml以及db.properties
   

（1）核心配置文件mybatis-config.xml

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">


<configuration>

    <properties resource="db.properties"/>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC">
                <property name="..." value="..."/>
            </transactionManager>
            <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="chen/dao/PersonMapper.xml"/>
    </mappers>
</configuration>

（2）db.properties

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/wjl?useSSL=true&useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT%2B8
username=root
password=123456

4. 编写mybatis工具类
   

package com.chen.utils;

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;

//获取sqlSessionFactory --> 从而获取sqlSession
public class MybatisUtils {
    
    

    private static SqlSessionFactory sqlSessionFactory;


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

    //获取sqlSession实例
    public static SqlSession getSqlSession(){
    
    
        SqlSession sqlSession = sqlSessionFactory.openSession();
        return sqlSession;
    }


}

3、编写代码

1. 实体类

package com.chen.pojo;

public class Person {
    
    
    private String userid;
    private String username;
    private String password;

    public String getUserid() {
    
    
        return userid;
    }

    public void setUserid(String userid) {
    
    
        this.userid = userid;
    }

    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;
    }

    @Override
    public String toString() {
    
    
        return "Person{" +
                "userid='" + userid + '\'' +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }

    public Person(String userid, String username, String password) {
    
    
        this.userid = userid;
        this.username = username;
        this.password = password;
    }

    public Person() {
    
    
    }
}

2. Dao接口

package com.chen.dao;

import com.chen.pojo.Person;

import java.util.List;

public interface PersonDao {
    
    
    List<Person> getPersonList();
}

3. Dao接口实现类:由原来的PersonDaoImpl转化为一个Mapper配置文件

<?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">

<!--绑定一个对应的Mapper接口-->
<mapper namespace="com.chen.dao.PersonDao">
    <select id="getPersonList" resultType="com.chen.pojo.Person">
        select * from Person
    </select>
</mapper>

4、测试

注意点：org.apache.ibatis.binding.BindingException: Type interface com.chen.dao.PersonDao is not known to the MapperRegistry.

1. junit测试

package chen.dao;

import chen.pojo.Person;
import chen.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class PersonTest {
    
    

    @Test
    public void test(){
    
    

        //第一步，获取sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //第二步，执行sql
        PersonDao personDao = sqlSession.getMapper(PersonDao.class);
        List<Person> personList = personDao.getPersonList();

        for (Person person : personList) {
    
    
            System.out.println(person);
        }

        //最后，关闭sqlSession
        sqlSession.close();
    }
}

5、结果

6、增删改拓展 以及 模糊查询

6.1、增删改

1. PersonMapper

public interface PersonMapper {
    
    

//    增
    public void addPerson(Map<String,Object> map);

//    删
    public void delPerson(String id);
//    改
    public void updatePerson(Map<String,Object> map);
//    查
    List<Person> getPersonList();


}

2. PersonMapper.xml

<mapper namespace="chen.dao.PersonMapper">

    <insert id="addPerson" parameterType="map">
        insert into Person(userid,username,password) values(#{
    
    id},#{
    
    name},#{
    
    password})
    </insert>

    <delete id="delPerson" parameterType="String">
        delete from Person where userid = #{
    
    userid}
    </delete>

    <update id="updatePerson" parameterType="map">
        update Person set username = #{
    
    name} where userid = #{
    
    id}
    </update>

    <select id="getPersonList" resultType="chen.pojo.Person">
        select * from Person
    </select>

</mapper>

3. test

public class PersonTest {
    
    

    @Test
    public void testGetPerson(){
    
    

        //第一步，获取sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //第二步，执行sql
        PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
        List<Person> personList = personMapper.getPersonList();

        for (Person person : personList) {
    
    
            System.out.println(person);
        }

        //最后，关闭sqlSession
        sqlSession.close();
    }


    @Test
    public void testAddPerson(){
    
    
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
        Map<String,Object> map = new  HashMap<String, Object>();
        map.put("id","104");
        map.put("name","陈志辉");
        map.put("password","123456789");

        personMapper.addPerson(map);


        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void testDelPerson(){
    
    
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);

        personMapper.delPerson("104");

        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void testUpdatePerson(){
    
    
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
        Map<String,Object> map = new  HashMap<String, Object>();
        map.put("id","2017110110");
        map.put("name","陈志辉");

        personMapper.updatePerson(map);


        sqlSession.commit();
        sqlSession.close();
    }
}

6.2、模糊查询

1. Mapper

//    模糊查询
    List<Person> getPersonList2(String value);

2. Mapper.xml

    <select id="getPersonList2" resultType="chen.pojo.Person">
        select * from Person where username like "%"#{
    
    value}"%"
    </select>

3. test

    @Test
    public void testGetPerson2(){
    
    

        //第一步，获取sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //第二步，执行sql
        PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
        List<Person> personList = personMapper.getPersonList2("辉");

        for (Person person : personList) {
    
    
            System.out.println(person);
        }

        //最后，关闭sqlSession
        sqlSession.close();
    }