基于LRU算法的URL过滤器代码,Java代码库,德仔网

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【Java】基于LRU算法的URL过滤器
作者:lugechao / 发布于2014/1/23/ 318
package Processer;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Random;
import java.util.Map.Entry;

import database.DatabaseCon;

public class LRUFilter {
private int CurrentCacheSize;
private int MAX;
private int MAXIP;
private HashMap<Integer,HashMap> rootMap;
private HashMap<Integer,Int> DBMap;
private Connection con;
private LinkedList<Element> lQueue;
private HashMap<Integer,Element> slQueue;
public LRUFilter(Connection c){
 this(20000,10000,c);
}
public LRUFilter(int capable,int oneip,Connection c){
 MAX=capable;
 CurrentCacheSize=0;
 MAXIP=oneip;
 rootMap=new HashMap<Integer,HashMap>();
 DBMap=new HashMap<Integer,Int>();
 lQueue=new LinkedList<Element>();
 slQueue=new HashMap<Integer,Element>();
 con=c;
 initialCache();
}
private boolean hit(HashMap<Integer,DBElement> urlMap,int ip,int url){
 boolean contain=false;
 slQueue.get(ip).hits++;
 DBElement dbe=null;
 if((dbe=urlMap.get(url))!=null){
 contain=true;
 if(dbe.flag==0){
 dbe.hits++;
 dbe.flag=1;
 }else
 dbe.hits++;
 }else{
 if(DBMap.get(ip).value<MAXIP){
 contain=false;
 urlMap.put(url, new DBElement(1,ip,2));
 CurrentCacheSize++;
 while(CurrentCacheSize>MAX)
 toDB(0);
 if(urlMap.size()>MAXIP){
 toDB(ip);
 fromDB(ip);
 }
 }else{
 contain=toDBDirect(url,new DBElement(1,ip,0));
 Int i=null;
 if(!contain&&(i=DBMap.get(ip))!=null)
 i.value+=1;
 }
 }
 return contain;
}
private boolean notHit(int ip,int url){
 return hit(fromDB(ip),ip,url);
}
/*
 * get the keyip and its count into the DBMap which are the count cache of the ip
 */
private void initialCache(){
 try{
 String sql="use crawler;select keyip,count(keyip) from visited group by keyip";
 Statement stm=con.createStatement();
 ResultSet rs=stm.executeQuery(sql);
 while(rs.next())
 DBMap.put(rs.getInt(1), new Int(rs.getInt(2)));
 rs.close();
 stm.close();
 }catch(Exception e){
 e.printStackTrace();
 }
}
/*
 * filter the url, ip is the url's ip.
 */
public boolean contain(String ip,String url){
 HashMap<Integer,DBElement> urlMap=null;
 int keyip=ip.hashCode();
 int keyurl=url.hashCode();
 if((urlMap=rootMap.get(keyip))!=null)
 return hit(urlMap,keyip,keyurl);
 else
 return notHit(keyip,keyurl);
}
/*
 * If ip is equal to 0,get the least recently use ip from the lQueue,writ all
 * the url belong the ip to the database, change the number of url belong this ip in DBMap
 * if ip is not equal to 0, write the url belong this ip to the database.renew the lQueue and slQueue and DBMap
 */
private boolean toDB(int ip){
 HashMap<Integer,DBElement> urlMap=null;
 Int count=null;
 int num;
 if(ip==0){
 Collections.sort(lQueue,new MyComparator());
 Element e=null;
 if((e=lQueue.poll())!=null){
 ip=e.ip;
 slQueue.remove(ip);
 if((urlMap=rootMap.remove(ip))!=null){
 num=writeToDB(urlMap);
 if((count=DBMap.get(ip))!=null)
 count.value+=num;
 CurrentCacheSize-=urlMap.size();
 }
 }else
 return false;//empty
 }else{
 if((urlMap=rootMap.remove(ip))!=null){
 num=writeToDB(urlMap);
 if((count=DBMap.get(ip))!=null)
 count.value+=num;
 CurrentCacheSize-=urlMap.size();
 }
 lQueue.remove(slQueue.remove(ip));
 }
 return true;
}
private HashMap<Integer,DBElement> fromDB(int ip){
 Int i=null;
 HashMap<Integer,DBElement> urlMap=null;
 if((i=DBMap.get(ip))!=null){
 if(i.value>MAXIP)
 urlMap=readFromDB(ip,true);
 else
 urlMap=readFromDB(ip,false);
 }else{
 urlMap=new HashMap<Integer,DBElement>();
 DBMap.put(ip, new Int(0));
 }
 while(urlMap.size()+CurrentCacheSize>MAX)
 toDB(0);

 for(int j=0;j<lQueue.size();j++)
 lQueue.get(j).hits=0;
 Element e=new Element(ip,0);
 lQueue.add(e);
 slQueue.put(ip, e);
 rootMap.put(ip, urlMap);
 CurrentCacheSize+=urlMap.size();
 while(CurrentCacheSize>MAX)
 toDB(0);
 return urlMap;
}
/*
 * write to database,return the number of
 * record which is inserted into the database
 */
private int writeToDB(HashMap<Integer,DBElement> urlDBMap){
 boolean insertAble=false,updateAble=false;
 int num=0;
 try{
 PreparedStatement insertStm=con.prepareStatement("use crawler;insert into visited values(?,?,?);");
 DBElement dbe=null;
 for(Iterator i=urlDBMap.entrySet().iterator();i.hasNext();){
 Entry<Integer,DBElement> entry=(Entry<Integer,DBElement>)i.next();
 int keyurl=entry.getKey();
 DBElement e=entry.getValue();
 if(e.flag==2){
 insertStm.setInt(1, keyurl);
 insertStm.setInt(2,e.hits);
 insertStm.setInt(3, e.keyip);
 insertStm.addBatch();
 num++;
 insertAble=true;
 }
 }
 if(insertAble)
 insertStm.executeBatch();
 insertStm.close();
 PreparedStatement updateStm=con.prepareStatement("use crawler;update visited set hits=? where keyurl=?;");
 for(Iterator i=urlDBMap.entrySet().iterator();i.hasNext();){
 Entry<Integer,DBElement> entry=(Entry<Integer,DBElement>)i.next();
 int keyurl=entry.getKey();
 DBElement e=entry.getValue();
 if(e.flag==1){
 updateStm.setInt(1, e.hits);
 updateStm.setInt(2, keyurl);
 updateStm.addBatch();
 updateAble=true;
 }
 }
 if(updateAble)
 updateStm.executeBatch();
 updateStm.close();
 con.commit();
 }catch(Exception e){
 e.printStackTrace();
 }
 return num;
}
/*
 * read from database,if the number of the record
 * which belong to the ip exceed the MAXIP,just read
 * half of it from the database
 */
public HashMap<Integer,DBElement> readFromDB(int ip,boolean exceed){
 HashMap<Integer,DBElement> urlMap=new HashMap<Integer,DBElement>();
 String sql=null;
 int count=MAXIP/2;
 if(exceed)
 sql="select top "+count+" keyurl,hits from visited where keyip=?;";
 else
 sql="select keyurl,hits from visited where keyip=?;";
 try{
 PreparedStatement stm=con.prepareStatement(sql);
 stm.setInt(1, ip);
 ResultSet rs=stm.executeQuery();
 while(rs.next())
 urlMap.put(rs.getInt(1),new DBElement(rs.getInt(2)));
 rs.close();
 stm.close();
 }catch(Exception e){
 e.printStackTrace();
 }
 return urlMap;
}
/*
 * insert into the database directly
 */
private boolean toDBDirect(int keyurl,DBElement dbe){
 boolean contain=false;
 try{
 Statement stm=con.createStatement();
 String sql=null;
 ResultSet rs=stm.executeQuery("use crawler;select hits from visited where keyurl="+keyurl+";");

 if(rs.next()){
 contain=true;
 int hits=rs.getInt(1)+dbe.hits;
 sql="use crawler;update visited set hits="+hits+" where keyurl="+keyurl+";";
 }else{
 contain=false;
 sql="use crawler;insert into visited values("+keyurl+","+dbe.hits+","+dbe.keyip+");";

 }
 stm.executeUpdate(sql);
 rs.close();
 stm.close();
 }catch(Exception e){
 e.printStackTrace();
 }
 return contain;
}
/*
 * store the cache data
 */
public void store(){
 while(toDB(0));
}
/*
 * tool classes
 */
private class Element{
 public Element(int i,int h){ip=i;hits=h;}
 public int ip;
 public int hits;
}
private class Int{
 public Int(int v){value=v;}
 public int value=0;
}
private class DBElement{
 public DBElement(int h,int k,int f){hits=h;keyip=k;flag=f;}
 public DBElement(int h){hits=h;}
 public int hits=0;
 public int keyip=0;
 /*
 * 0 stand for not change
 * 1 stand for change
 * 2 stand for a new record
 */
 public int flag=0;;
}
private class MyComparator implements Comparator{
 public int compare(Object o1,Object o2){
 Element e1=(Element)o1;
 Element e2=(Element)o2;
 if(e1.hits<e1.hits)
 return -1;
 else if(e1.hits>e2.hits)
 return 1;
 else
 return 0;
 }
}
}
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