项目概览

pom.xml

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<?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>org.example</groupId>
    <artifactId>maven5</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.32</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.3.1</version>
        </dependency>
   
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

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

</project>

测试类

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public class DaoTest {
    @Test
    public void test() {
    SqlSession sqlSession = MybatisUtils.getSqlSession();
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    User user = mapper.getUser(201992001);
    System.out.println(user);

    }
}

mybatis-config.xml

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<?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">
<!-- 根标签 -->
<configuration>
    <properties>
        <property name="driver" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://8.140.166.149:39002/mybatis" />
        <property name="username" value="mybatis" />
        <property name="password" value="jamay" />
    </properties>

    <!-- 环境，可以配置多个，default：指定采用哪个环境 -->
    <environments default="test">
        <!-- id：唯一标识 -->
        <environment id="test">
            <!-- 事务管理器，JDBC类型的事务管理器 -->
            <transactionManager type="JDBC" />
            <!-- 数据源，池类型的数据源 -->
            <dataSource type="POOLED">
                <property name="driver" value="${driver}" /> <!-- 配置了properties，所以可以直接引用 -->
                <property name="url" value="${url}" />
                <property name="username" value="${username}" />
                <property name="password" value="${password}" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mappers/MyMapper.xml" />
    </mappers>
</configuration>

可在 <properties resource="db.properties">引入外部配置，加载时首先加载内部配置（<property name="url" value="jdbc:mysql://8.140.166.149:39002/mybatis" />），然后加载外部配置（db.properties），如果配置有重叠，会导致内部配置被外部配置覆盖，表现为外部配置优先级高

可设置别名（typeAliases）

MyMapper.xml

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<?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.zq.mapper.UserMapper">
    <select id="getUser" resultType="com.zq.entity.User">
        select * from student where id = #{id}
    </select>
    <select id="getUserList" resultType="com.zq.entity.User">
        select * from student
    </select>
    <insert id="addUser">
        insert into student values(#{id},#{name},#{passwd},${p_id})
    </insert>
    <delete id="deleteUser">
        delete from student where id=  #{id}
    </delete>
    <update id="updateUser">
        update  student set p_id= #{p_id} where id= #{id}
    </update>
</mapper>

MybatisUtils.java

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package com.zq.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;

public class MybatisUtils {
   private static SqlSessionFactory sqlSessionFactory;
    static  {
       try {
           // 指定全局配置文件
           String resource = "mybatis-config.xml";
           // 读取配置文件
           InputStream inputStream = Resources.getResourceAsStream(resource);
           // 构建sqlSessionFactory
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
       }catch (IOException e){
           e.printStackTrace();
       }}
public static SqlSession getSqlSession(){

           return sqlSessionFactory.openSession();
        }

}

UserMapper.java

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package com.zq.mapper;

import com.zq.entity.User;
import java.util.List;
import java.util.Map;

public interface UserMapper {
    List<User> getUserList();

    User getUser(int id);

    int addUser(User user);

    int deleteUser(int id);

    int updateUser(Map<String, Object> map);

}

User.java

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package com.zq.entity;

public class User {
    private String id;

    private String name;
    private String passwd;
    private String p_id;

    public User(String id, String name, String passwd, String p_id) {
        this.id = id;
        this.name = name;
        this.passwd = passwd;
        this.p_id = p_id;
    }

    public String getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getPasswd() {
        return passwd;
    }

    public void setPasswd(String passwd) {
        this.passwd = passwd;
    }

    public String getP_id() {
        return p_id;
    }

    public void setP_id(String p_id) {
        this.p_id = p_id;
    }

    @Override
    public String toString() {
        return "User{" + "id='" + id + '\'' + ", name='" + name + '\'' + ", password='" + passwd + '\'' + ", p_id='"
                + p_id + '\'' + '}';
    }

}