JSP高访问量下的计数程序
有时要为每一篇文章统计其点击次数，如果每一次浏览都要更新一次库的话，那性能在访问量很大的情况下，服务器的压力就会很大了，比较好一点的方法就是先将要更新的数据缓存起来，然后每隔一段时间再利用数据库的批量处理，批量更新库。源码如下：
CountBean.java
/*
* CountData.java
*
* Created on 2006年10月18日, 下午4:44
*
* To change this template, choose Tools | Options and locate the template under
* the Source Creation and Management node. Right-click the template and choose
* Open. You can then make changes to the template in the Source Editor.
*/
package com.tot.count;
/**
*
* @author http://www.tot.name
*/
public class CountBean {
private String countType;
int countId;
/** Creates a new instance of CountData */
public CountBean() {}
public void setCountType(String countTypes){
this.countType=countTypes;
}
public void setCountId(int countIds){
this.countId=countIds;
}
public String getCountType(){
return countType;
}
public int getCountId(){
return countId;
}
}
CountCache.java
/*
* CountCache.java
*
* Created on 2006年10月18日, 下午5:01
*
* To change this template, choose Tools | Options and locate the template under
* the Source Creation and Management node. Right-click the template and choose
* Open. You can then make changes to the template in the Source Editor.
*/
package com.tot.count;
import java.util.*;
/**
*
* @author http://www.tot.name
*/
public class CountCache {
public static LinkedList list=new LinkedList();
/** Creates a new instance of CountCache */
public CountCache() {}
public static void add(CountBean cb){
if(cb!=null){
list.add(cb);
}
}
}
CountControl.java
/*
* CountThread.java
*
* Created on 2006年10月18日, 下午4:57
*
* To change this template, choose Tools | Options and locate the template under
* the Source Creation and Management node. Right-click the template and choose
* Open. You can then make changes to the template in the Source Editor.
*/
package com.tot.count;
import tot.db.DBUtils;
import java.sql.*;
/**
*
* @author http://www.tot.name
*/
public class CountControl{
private static long lastExecuteTime=0;//上次更新时间
private static long executeSep=60000;//定义更新间隔时间，单位毫秒
/** Creates a new instance of CountThread */
public CountControl() {}
public synchronized void executeUpdate(){
Connection conn=null;
PreparedStatement ps=null;
try{
conn = DBUtils.getConnection();
conn.setAutoCommit(false);
ps=conn.prepareStatement("update t_news set hits=hits+1 where id=?");
for(int i=0;i＜CountCache.list.size();i++){
CountBean cb=(CountBean)CountCache.list.getFirst();
CountCache.list.removeFirst();
ps.setInt(1, cb.getCountId());
ps.executeUpdate();⑴
//ps.addBatch();⑵
}
//int [] counts = ps.executeBatch();⑶
conn.commit();
}catch(Exception e){
e.printStackTrace();
} finally{
try{
if(ps!=null) {
ps.clearParameters();
ps.close();
ps=null;
}
}catch(SQLException e){}
DBUtils.closeConnection(conn);
}
}
public long getLast(){
return lastExecuteTime;
}
public void run(){
long now = System.currentTimeMillis();
if ((now - lastExecuteTime) ＞ executeSep) {
//System.out.print("lastExecuteTime:"+lastExecuteTime);
//System.out.print(" now:"+now+"\n");
// System.out.print(" sep="+(now - lastExecuteTime)+"\n");
lastExecuteTime=now;
executeUpdate();
}
else{
//System.out.print("wait for "+(now - lastExecuteTime)+" seconds:"+"\n");
}
}
}
//注：如果你的数据库驱动支持批处理，那么可以将⑵,⑶标记的代码前的注释去掉，同时在代码⑴前加上注释
类写好了，下面是在JSP中如下调用。
＜%
CountBean cb=new CountBean();
cb.setCountId(Integer.parseInt(request.getParameter("cid")));
CountCache.add(cb);
out.print(CountCache.list.size()+"＜br＞");
CountControl c=new CountControl();
c.run();
out.print(CountCache.list.size()+"＜br＞");
%＞