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

     }

 }

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

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