多线程的问题：如何保证界面的分页参数安全的传递到dao层？

ThreadLocal是Java语言提供的用于支持线程局部变量的类。

所谓的线程局部变量，就是仅仅只能被本线程访问，不能再

线程之间进行共享访问的变量（每个线程一个拷贝），在java

web的各种框架（spring,mybatis,hibernate）中都有使用，今天

我们的这个分页也用ThreadLocal来传递参数

package com.netease.live.admin.util;

 

import com.netease.live.common.util.Constant;

 

/**

 *

 * @author bjliuzezhou

 * @description 使用threadLocal 封装分页所必需传的参数 

 * @date 2017年11月12日

 */

public class SystemContext {

    //当前第几页

    private static ThreadLocal<Integer> currentPage = new ThreadLocal<Integer>();

    //总共的页数

    private static ThreadLocal<Integer> totalPages = new ThreadLocal<Integer>();

    //起始数据位置

    private static ThreadLocal<Integer> offSet = new ThreadLocal<Integer>();

    //总记录的条数

    private static ThreadLocal<Integer> recordCount = new ThreadLocal<Integer>();

    //每页显示数

    private static ThreadLocal<Integer> pageSize = new ThreadLocal<Integer>();

  

    /*

     * currentPage ：get、set、remove

     */

    public static int getCurrentPage(){

        Integer cp = currentPage.get();

        if(cp == null){

            return 0;

        }

        return cp;

    }

     

    public static void setCurrentPage(int currentPage) {

     

        int validPage = currentPage > 0 ? currentPage : 1;

        validPage = validPage < getTotalPages() ? validPage : getTotalPages();

        SystemContext.currentPage.set(validPage);

         

    }

    public static void removeCurrentPage(){

        currentPage.remove();

    }

     

    /*

     * totalPages ：get、set、remove

     */ 

    public static int getTotalPages() { 

        Integer tp = totalPages.get(); 

        if (tp == null) { 

            return 0; 

        } 

        return tp; 

    } 

     

    public static void calTotalPages() { 

         

        int totalPages = (getRecordCount() + getPageSize() -1) / getPageSize();

        SystemContext.totalPages.set(totalPages); 

    } 

     

    public static void removeTotalPages(){ 

        totalPages.remove(); 

    } 

     

    /*

     * offset ：get、set、remove

     */ 

    public static int getOffSet() { 

        Integer os =offSet.get(); 

        if (os == null) { 

            return 0; 

        } 

        return os; 

    } 

     

    public static void calOffSet() { 

        int offset = (getCurrentPage() - 1) * getPageSize();

        int validOffSet = offset > 0 ? offset : 0;

        SystemContext.offSet.set(validOffSet);

    } 

     

     

    public static void removeOffSet(){ 

        offSet.remove(); 

    }  

     

    /*

     * recordCount ：get、set、remove

     */

    public static int getRecordCount(){

        Integer rc = recordCount.get();

        if(rc == null){

            return 0;

        }

        return rc;

    }

     

    public static void setRecordCount(int recordCount) {

         

        SystemContext.recordCount.set(recordCount);

    }

    public static void removeRecordCount(){

        recordCount.remove();

    }

      

    /*

     * pageSize ：get、set、remove

     */

    public static int getPageSize(){

        Integer ps = pageSize.get();

        if(ps == null){

            return 0;

        }

        return ps;

    }

     

    public static void setPageSize(int pageSize) {

         

        SystemContext.pageSize.set(pageSize);

    }

    public static void removePageSize(){

        pageSize.remove();

    }

     

     

    public static void PageFilter(int recordCount,int pageSize,int currentPage){

        // 记录总条数

        SystemContext.setRecordCount(recordCount);

        SystemContext.setPageSize(Constant.PAGE_COUNT);

        SystemContext.calTotalPages();

        SystemContext.setCurrentPage(currentPage);

        SystemContext.calOffSet();

    }

}