使用Maven简单配置Mybatis

1.新建一个Maven项目

2. 在pom.xml中进行配置，在pom.xml中配置的时候，需要网速好，当网速不是很好的时候，是加载不出Jar包的。

代码如下所示.

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.whl</groupId>
    <artifactId>MyBatis01</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>MyBatis01 Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.4</version>
        </dependency>
    </dependencies>
    
    <build>
        <finalName>MyBatis01</finalName>
    </build>
</project>

<dependencies>的文件配置参考http://mvnrepository.com/

如果不知如何添加，可在此链接中输入相应jar包的名称，然后选择正确的版本，就会有示例。

3.手动导入MySQL的jar包，因为网速不好，下载不了，故采用手动导入，然后右键该jar包，build path。

4.在resources下，新建mybatis-config.xml。在此文件下需要完成数据库的连接和一组映射。代码如下

<?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>
    <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/test" />
                <property name="username" value="root" />
                <property name="password" value="123456" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/whl/mybatis/userMapper.xml" />
    </mappers>
</configuration>

mappers中的映射要与下一步操作对应。

5.在Java文件夹下建立相应的包，并在此写相应的bean类，如下

package com.whl.mybatis;

public class User {
    private int id;
    private String username;
    private String userpass;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getUserpass() {
        return userpass;
    }
    public void setUserpass(String userpass) {
        this.userpass = userpass;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", username=" + username + ", userpass=" + userpass + "]";
    }
    public User(int id, String username, String userpass) {
        super();
        this.id = id;
        this.username = username;
        this.userpass = userpass;
    }
    public User() {
        super();
    }
    

}

6.在Java文件下新建相关的包，新建一个userMapper.xml文件。在此文件中要完成相应的增删改查的编写，

代码如下：

<?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="userMapper">


    <!-- id是唯一标志符 -->
    <!-- parameterType参数类型，指明插入时使用的参数类型 -->
    <!-- useGeneratedKeys="true", 表示数据库的自动增长策略  -->
    <insert id="save" parameterType="com.whl.mybatis.User"
        useGeneratedKeys="true">
        insert into user(username, password) values(#{username}, #{password})
    </insert>
    
    <delete id="deleteById" parameterType="int">
        delete from user where uid = #{value}
    </delete>
    
    <delete id="deleteByIds">
        delete from user where uid in
        <foreach collection="list" item="uid" open="(" close=")" separator=",">
            #{uid}
        </foreach>
    </delete>
    
    <select id="likeByName" resultType="com.whl.mybatis.User" parameterType="string">
        select * from user where username like '%${value}%'
    </select>
    
    <select id="findAll" resultType="com.whl.mybatis.User">
        select uid, username, password from user
    </select>
    
    <select id="findById" parameterType="int" resultType="com.whl.mybatis.User">
        select * from user where uid = #{value}
    </select>
    
    <update id="updateById" parameterType="com.whl.mybatis.User">
        update user set username=#{username}, password=#{password} where uid = #{uid}
    </update>
    
    <!-- 
        update user set username = case uid 
            when 
                #{u.uid} then #{u.username}
            end
            where uid in (...)
     -->
    <update id="updateUserBatch" parameterType="list">
        update user set username = CASE  uid 
        <foreach collection="list" item = "u" separator=" ">
            when #{u.uid} then #{u.username}
        </foreach>
        end 
        where uid in 
        <foreach collection="list" item="user" open="(" separator="," close=")">
            #{user.uid}
        </foreach>
    </update>
</mapper>

7.测试：代码如下

package com.whl.mybatis.test;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.whl.mybatis.User;

public class TestMyBatis {
    
    private SqlSession s = null;
    private SqlSessionFactory ssf = null;
    
    @Before
    public void init(){

        String resourcesStr = "mybatis-config.xml";
        try {
            InputStream is = Resources.getResourceAsStream(resourcesStr);
            
            ssf = new SqlSessionFactoryBuilder().build(is);
            
            s = ssf.openSession();
        }catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    @Test
    public void testDeleteByIds(){
        List<Integer> list = new ArrayList<>();
        
        Collections.addAll(list, 1, 2, 3, 36, 39);
        
        //    以批量的处理方式打开数据库连接
        ssf.openSession(ExecutorType.BATCH, false);
        
        int result = s.delete("myBatis.deleteByIds", list);
        
        s.commit();
        
        System.out.println("result = " + result);
    }
    
    @Test
    public void testDeleteById(){
        int result = s.delete("myBatis.deleteByIds.deleteById", 38);
        s.commit();
        System.out.println("result = " + result);
    }
    
    @Test
    public void testSelectByLike(){
        String name = "user";
        List<User> list = s.selectList("myBatis.deleteByIds.likeByName", name);
        for (User u : list) {
            System.out.println(u);
        }
    }
    
    @Test
    public void testUpdateBatch(){
        
        List<User> users = new ArrayList<>();
        
        User u = null;
        for(int i = 0; i < 3; i++){
            u = new User(20+i, "name" + i, "pass" + i);
            System.out.println(u);
            users.add(u);
        }
        
        int result = s.update("myBatis.deleteByIds.updateUserBatch", users);
        
        s.commit();
        
        System.out.println("result = " + result);
    }
    
    @Test
    public void testUpdateUserById(){
        
        User user = new User(38, "user38", "pass38");
        
        int result = s.update("myBatis.deleteByIds.updateById", user);
        
        System.out.println("result = " + result);
    }
    
    @Test
    public void testFindById(){
        User u = s.selectOne("myBatis.deleteByIds.findById", 32);
        
        System.out.println(u);
    }
    
    @Test
    public void testFindAll(){
        List<User> list = s.selectList("myBatis.deleteByIds.findAll");
        for (User u : list) {
            System.out.println(u);
        }
    }

    @Test
    public void testAdd(){
        try {
            
            User user = new User();
            
            user.setUsername("abc");
            user.setPassword("123");
            
            s.insert("myBatis.deleteByIds.save", user);
            
            s.commit();
            s.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    @After
    public void destrory(){
        if(s != null){
            s.close();
            s = null;
        }
    }
}