新建一个mybatis HelloWorld

Posted 2020-08-19 hy7873

1、下载mybatis

https://github.com/mybatis/mybatis-3/

没有梯子好像打不开

下载一个最新版本，我这里下载的是mybatis-3.4.1.zip

里面有mybatis需要的jar和文档

2、新建一个java project ,新建lib目录把jar复制到lib下面

3、新建一个简单log4j配置文件log4j.properties，内容如下：

log4j.rootLogger = DEBUG,CONSOLE

log4j.appender.CONSOLE = org.apache.log4j.ConsoleAppender  
log4j.appender.CONSOLE.layout = org.apache.log4j.PatternLayout 
log4j.appender.CONSOLE.layout.ConversionPattern=%d{yyyy-MM-dd HH\:mm\:ss} -%-4r [%t] %-5p  %x - %m%n

log4j.logger.java.sql.ResultSet  =  DEBUG 
log4j.logger.java.sql.Connection  =  DEBUG   
log4j.logger.java.sql.Statement  =  DEBUG   
log4j.logger.java.sql.PreparedStatement  =  DEBUG 

4、新建一张测试表news 和一个测试的pojo

News.java内容：

package com.hy;

import java.sql.Date;

public class News {
    private Integer id;
    private String title;
    private String content;
    private String author;
    private Date createdate;
    
    
    public News() {
        
    }
    
    
    
    
    public News(String title, String content, String author, Date createdate) {
        super();
        this.title = title;
        this.content = content;
        this.author = author;
        this.createdate = createdate;
    }




    public Date getCreatedate() {
        return createdate;
    }




    public void setCreatedate(Date createdate) {
        this.createdate = createdate;
    }




    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
    public String getAuthor() {
        return author;
    }
    public void setAuthor(String author) {
        this.author = author;
    }
    
    
    
    
    
    
}

 

5、写一个mybatis基础配置文件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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC">
            </transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://127.0.0.1:3306/hibernate" />
                <property name="username" value="root" />
                <property name="password" value="root" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/hy/map/News.xml"/>
    </mappers>
</configuration>

文件中主要包含environments连接数据库的基本配置，mappers实体操作文件主要放sql语句

6、新建New.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.hy">
    <select id="getNews" resultType="com.hy.News" parameterType="int">
        select * from news where id=#{id}
    </select>
</mapper>

parameterType 是指参数类型

7、写一个main test测试类

package com.hy;

import java.io.IOException;
import java.io.Reader;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class Main {

    public static void main(String[] args) {
        String resource = "com/hy/map/mybatis.config.xml";
        Reader reader = null;
        SqlSession sqlSession = null;
        try {
            reader = Resources.getResourceAsReader(resource);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        sqlSession = sqlSessionFactory.openSession();
        News news = sqlSession.selectOne("getNews", 1);
        System.out.println(news.getTitle());
    }

}

a、加载基本配置文件；b、获取SqlSessionFactory ；c、获取sqlsession；d、执行对应id的sql返回数据