上文 MyBatis核心对象的生命周期与封装

本例在使用MyBatis Generator工具操作MySQL数据库示例基础上操作。

1.新建GetSqlSessionFactory.java类，完整代码如下：

package dbtools;

import java.io.IOException;
import java.io.InputStream;

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

public class GetSqlSessionFactory {

    private static SqlSessionFactory sqlSessionFactory;
    
    private GetSqlSessionFactory() {
        
    }
    
    synchronized public static SqlSessionFactory getSqlSessionFactory() {
        try {
            if(sqlSessionFactory==null) {
                String resource="mybatis-config.xml";
                InputStream inputStream=Resources.getResourceAsStream(resource);
                sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
            }else {
                
            }
        }catch (IOException e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        return sqlSessionFactory;
    }
    
}

这里使用单例设计模式来取得SqlSessionFactory对象。

2.创建GetSqlSession.java类，核心代码如下：

package dbtools;

import org.apache.ibatis.session.SqlSession;

public class GetSqlSession {

    private static ThreadLocal<SqlSession> tl=new ThreadLocal<SqlSession>();
    
    public static SqlSession getSqlSession() {
        SqlSession sqlSession=tl.get();
        if (sqlSession==null) {
            sqlSession=GetSqlSessionFactory.getSqlSessionFactory().openSession();
            tl.set(sqlSession);
        }else {
            
        }
        System.out.println("获得的sqlSession对象的hashCode："+sqlSession.hashCode());
        return sqlSession;
    }
    
    public static void commit() {
        if(tl.get()!=null) {
            tl.get().commit();
            tl.get().close();
            tl.set(null);
            System.out.println("提交了");
        }
    }
    
    public static void rollback() {
        if (tl.get()!=null) {
            tl.get().rollback();
            tl.get().close();
            tl.set(null);
            System.out.println("回滚了");
        }
    }
    
}

3.创建DBOperate.java类，核心代码如下：

package dbtools;

import java.util.List;
import java.util.Map;

import org.apache.ibatis.session.SqlSession;

public class DBOperate {

    public int insert(String sqlId,Map valueMap) {
        //注意这里将sqlSession创建在方法内部
        SqlSession sqlSession=GetSqlSession.getSqlSession();
        return sqlSession.insert(sqlId,valueMap);
    }
    
    public int delete(String sqlId,Map valueMap) {
        SqlSession sqlSession=GetSqlSession.getSqlSession();
        return sqlSession.delete(sqlId,valueMap);
    }
    
    public int update(String sqlId,Map valueMap) {
        SqlSession sqlSession=GetSqlSession.getSqlSession();
        return sqlSession.update(sqlId,valueMap);
    }
    
    public List<Map> select(String sqlId,Map valueMap) {
        SqlSession sqlSession=GetSqlSession.getSqlSession();
        return sqlSession.selectList(sqlId,valueMap);
    }
    
}

所有的CRUD参数值都用Map对象进行封装。

4.userinfoMapping.xml映射文件及mybatis-config.xml配置文件，数据库设计等参看使用MyBatis Generator工具操作MySQL数据库示例，在userinfoMapping.xml映射文件<mapper>标签中添加如下内容：

  <insert id="insertUserinfo" parameterType="map" useGeneratedKeys="true" keyProperty="id">
    insert into userinfo(username,password,age) values(#{username},#{password},#{age})
  </insert>
  <select id="getUserinfoById" parameterType="map" resultType="map">
    select * from userinfo where id=#{id}
  </select>
  <delete id="deleteUserinfoById" parameterType="map">
    delete from userinfo where id=#{id}
  </delete>
  <select id="getAllUserinfo" resultType="map">
    select * from userinfo
  </select>
  <update id="updateUserinfoById" parameterType="map">
    update userinfo set username=#{username},password=#{password},age=#{age} where id=#{id}
  </update>

6.修改Test.java文件进行测试

package test;

import java.util.HashMap;

import dbtools.DBOperate;
import dbtools.GetSqlSession;

public class Test {

    public static void main(String[] args) {
        try {
            HashMap valueMap1=new HashMap();
            valueMap1.put("username", "张三");
            valueMap1.put("password","123456");
            valueMap1.put("age", 100);
            
            HashMap valueMap2=new HashMap();
            valueMap2.put("username", "张三");
            valueMap2.put("password","123456");
            valueMap2.put("age", 100);
            
            DBOperate dbo=new DBOperate();
            dbo.insert("insertUserinfo", valueMap1);
            dbo.insert("insertUserinfo", valueMap2);            
            
        } catch (Exception e) {
            e.printStackTrace();
            GetSqlSession.rollback();
        } finally {
            GetSqlSession.commit();
        }
    }
    
}

Output:

获得的sqlSession对象的hashCode：1684106402
获得的sqlSession对象的hashCode：1684106402
提交了

此时可以看到数据库中多了两条数据。