工具类：mybatis中使用Threadlocal开启session及关闭session

1、线程容器,给线程绑定一个Object 内容,后只要线程不变,可以随时取出.

1.1 改变线程,无法取出内容.

final ThreadLocal threadLocal = new ThreadLocal<>();
threadLocal.set("测试");
new Thread(){
    public void run() {
        String result = threadLocal.get();
        System.out.println("结果:"+result);
    };
}.start();

2、使用Threadlocal简化开发

2.1定义工具类

    将SqlSession创建出来，存放到Threadlocal中，需要时再从中取出

package com.test.util;

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

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 MybatisUtil {

    //工厂
    private static SqlSessionFactory factory;
    //线程容器
    private static ThreadLocal<SqlSession> tl = new ThreadLocal<>();
    
    
    static{
        try {
            InputStream is = Resources.getResourceAsStream("mybatis.xml");
            factory = new SqlSessionFactoryBuilder().build(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /**
     * 获取session
     * 从线程容器中获取，没有则创建session在存放到线程容器中
     * @return
     */
    public static SqlSession getSession(){
        SqlSession sqlSession = tl.get();
        if(sqlSession == null){
            sqlSession = factory.openSession();
            tl.set(sqlSession);
        }
        return tl.get();
    }
    
    /**
     * 关闭session
     * 从容器线程中获取session，有则关闭，且将线程容器的session清空
     */
    public static void closeSession(){
        SqlSession sqlSession = tl.get();
        if(sqlSession != null){
            sqlSession.close();
        }
        tl.set(null);
    }
}

将工厂的产生改成单例模式

package com.text.util;

import java.io.IOException;
import java.io.InputStream;
import java.util.logging.Level;
import java.util.logging.Logger;

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 MybatisUtil {

    //工厂
    private static SqlSessionFactory factory;
    //类线程锁
    private static final Class CLASS_LOCK = MybatisUtil.class;
    //线程容器
    private static ThreadLocal<SqlSession> tl = new ThreadLocal<>();
    //构造器私有化
    private MybatisUtil(){}
    
    public static SqlSessionFactory initSqlSessionFactory(){
        String resource = "mybatis.xml";
        InputStream is = null;
        try {
            is = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            Logger.getLogger(MybatisUtil.class.getName()).log(Level.SEVERE, null, e);
        }
        synchronized (CLASS_LOCK) {
            if(null == factory){
                factory = new SqlSessionFactoryBuilder().build(is);
            }
        }
        return factory;
    }
    
    /**
     * 获取session
     * 从线程容器中获取，没有则创建session在存放到线程容器中
     * @return
     */
    public static SqlSession getSession(){
        SqlSession sqlSession = tl.get();
        if(sqlSession == null){
            if(factory == null){
                initSqlSessionFactory();
            }
            sqlSession = factory.openSession();
            tl.set(sqlSession);
        }
        return tl.get();
    }
    
    /**
     * 关闭session
     * 从容器线程中获取session，有则关闭，且将线程容器的session清空
     */
    public static void closeSession(){
        SqlSession sqlSession = tl.get();
        if(sqlSession != null){
            sqlSession.close();
        }
        tl.set(null);
    }
}

 

2.2 定义过滤器

    过滤器可以在调用方法前及方法后添加代码

package com.test.filter;

import java.io.IOException;

import java.io.InputStream;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;

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 com.test.util.MyBatisUtil;


/**
 * 最开始是由Spring框架提出的.整合Hibernate框架是使用的是OpenSessionInView
 * 
 * 
 * @author Administrator
 *
 */
@WebFilter("/*")
public class OpenSessionInView implements Filter{

    @Override
    public void init(FilterConfig filterconfig) throws ServletException {
        // TODO Auto-generated method stub
    }

    @Override
    public void doFilter(ServletRequest servletrequest, ServletResponse servletresponse, FilterChain filterchain)
            throws IOException, ServletException {
//        InputStream is = Resources.getResourceAsStream("mybatis.xml");
//        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
//        SqlSession session = factory.openSession();        
        SqlSession session = MyBatisUtil.getSession();
        try {
            filterchain.doFilter(servletrequest, servletresponse);
            session.commit();
        } catch (Exception e) {
            session.rollback();
            e.printStackTrace();
        }finally{
            MyBatisUtil.closeSession();
        }
//        session.commit();
//        session.close();
    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub    
    }
}