Mybatis学习——基本增删改查(CRUD)

Eclipse+Mybatis+MySql

　　1.所需jar

　　2.项目目录

　　3.源代码

package com.zhengbin.entity;

public class Student {
    private int id;
    private String name;
    private double score;
    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + ", score=" + score + "]";
    }
    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 double getScore() {
        return score;
    }
    public void setScore(double score) {
        this.score = score;
    }
    public Student(int id, String name, double score) {
        super();
        this.id = id;
        this.name = name;
        this.score = score;
    }
    // *注意这个必须加
    public Student() {
        super();
    }
}

<?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">
<!-- 每个映射文件的namespace应该是唯一的 -->
<mapper namespace="com.zhengbin.entity.studentMapper">
    <!-- parameterType 参数表示需要参数的类型 -->
    <!-- resultType 参数表示返回结果的类型，该可以写为实体包的全路径，或者在conf.xml配置文件中，声明实体的别名 -->
    <select id="getStudent" parameterType="int" resultType="Student">
        select * from student where id=#{id}
    </select>
    
    <select id="getAllStudent" resultType="Student">
        select * from student
    </select>
    
    <insert id="addStudent" parameterType="Student">
        insert into student(name,score) values(#{name},#{score})
    </insert>
    
    <update id="updateStudent" parameterType="Student">
        update student set name=#{name},score=#{score} where id=#{id}
    </update>
    
    <delete id="deleteStudent" parameterType="int">
        delete from student where id=#{id}
    </delete>
</mapper>

package com.zhengbin.entity2;


import org.apache.ibatis.annotations.Select;

import com.zhengbin.entity.Student;

public interface studentMapper {
    @Select("select * from student where id=#{id}")
    public Student testGet(int id);
}

package com.zhengbin.test;

import java.util.List;

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

import com.zhengbin.entity.Student;
import com.zhengbin.util.MyBatisUtils;

public class Test {
    @org.junit.Test
    public void testGet(){
        SqlSessionFactory sessionFactory = MyBatisUtils.getFactory();
        // 参数为TRUE，相当于session.commit();
        SqlSession session = sessionFactory.openSession(true);
        // 读取映射文件
        String statement = "com.zhengbin.entity.studentMapper" + ".getStudent";
        Student s = session.selectOne(statement,5);
        System.out.println(s);
        session.close();
    }
    
    @org.junit.Test
    public void testGetAll(){
        SqlSessionFactory sessionFactory = MyBatisUtils.getFactory();
        // 参数为TRUE，相当于session.commit();
        SqlSession session = sessionFactory.openSession(true);
        // 读取映射文件
        String statement = "com.zhengbin.entity.studentMapper" + ".getAllStudent";
        List<Student> list = session.selectList(statement);
        System.out.println(list);
        session.close();
    }
    
    @org.junit.Test
    public void testAdd(){
        SqlSessionFactory sessionFactory =  MyBatisUtils.getFactory();
        SqlSession session = sessionFactory.openSession(true);
        String statement = "com.zhengbin.entity.studentMapper" + ".addStudent";
        Student s = new Student();
        s.setName("zhengB");
        s.setScore(95.9);
        int insert = session.insert(statement, s);
        System.out.println(insert);
        session.close();
    }
    
    @org.junit.Test
    public void testUpdate(){
        SqlSessionFactory sessionFactory = MyBatisUtils.getFactory();
        SqlSession session = sessionFactory.openSession(true);
        String statement = "com.zhengbin.entity.studentMapper" + ".updateStudent";
        Student s = new Student();
        s.setId(14);
        s.setName("zhengbin");
        s.setScore(96);
        int update = session.update(statement, s);
        System.out.println(update);
        session.close();
    }
    
    @org.junit.Test
    public void testDelete(){
        SqlSessionFactory sessionFactory = MyBatisUtils.getFactory();
        SqlSession session = sessionFactory.openSession(true);
        String statement = "com.zhengbin.entity.studentMapper" + ".deleteStudent";
        int delete = session.delete(statement,21);
        System.out.println(delete);
        session.close();
    }
}

package com.zhengbin.test;

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

import com.zhengbin.entity.Student;
import com.zhengbin.entity2.studentMapper;
import com.zhengbin.util.MyBatisUtils;

public class Test2 {
    @org.junit.Test
    public void testGet(){
        SqlSessionFactory sessionFactory = MyBatisUtils.getFactory();
        SqlSession session = sessionFactory.openSession(true);
        studentMapper mapper = session.getMapper(studentMapper.class);
        Student s = mapper.testGet(14);
        System.out.println(s);
        session.close();
    }
}

package com.zhengbin.util;

import java.io.InputStream;

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

public class MyBatisUtils {
    public static SqlSessionFactory getFactory(){
        String resource = "conf.xml";
        InputStream is = MyBatisUtils.class.getClassLoader().getResourceAsStream(resource);
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        return sessionFactory;
    }
}

<?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>
    <!-- 数据库配置文件 -->     
     <properties resource="jdbc.properties"/>
     <!-- 取别名 -->
     <typeAliases>
         <!-- 方式一、为类取别名 -->
         <!-- <typeAlias type="com.zhengbin.entity.Student" alias="_Student"/> -->
         <!-- 方式二、自动以类名为别名 -->
         <package name="com.zhengbin.entity"/>
     </typeAliases>
    <!-- 
        development : 开发模式
        work : 工作模式
     -->
    <environments default="development">
        <environment id="development">
            <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>
        <!-- 这是一个路径的结构，不是包的结构 -->
        <mapper resource="com/zhengbin/entity/studentMapper.xml"/>
        <mapper class="com.zhengbin.entity2.studentMapper"/>
    </mappers>
</configuration>

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3307/student
username=root
password=950906

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
    <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) 
" />
        </layout>
    </appender>
    <logger name="java.sql">
        <level value="debug" />
    </logger>
    <logger name="org.apache.ibatis">
        <level value="debug" />
    </logger>
    <root>
        <level value="debug" />
        <appender-ref ref="STDOUT" />
    </root>
</log4j:configuration>

　　4.遇到的问题

(1)奇怪的junit：如果新建一个class，名为Test则可能出现不能使用注解@Test的情况，此时用@org.junit.Test即可，或者更改class名，不以Test开头 好奇葩

(2)实体类必须要加superclass，否则报错，因为MyBatis无法通过配置文件找到实体类