?import?java.io.*;
import?java.net.*;
//java。lang。是默認導入的。
import?java.lang.*;
public?class?ProxyServer?{
????private?static?int?PORT?=?8000;
????static?private?String?CRLF?=?“\r\n“;

????
????static?class??Handler?implements?Runnable?{
????????private?Socket?socket;
???????????DataOutputStream?OutToClient;
????????BufferedReader?InFromClient;
????????DataOutputStream?OutToServer;
????????DataInputStream?InFromServer;
????????
????????public?Handler（Socket?s）?{
????????????Thread?t;
????????????socket?=?s;
????????????t?=?new?Thread（this?“Handler?Thread“）;
????????????t.start（）;
????????}
????????
????????public?void?run（）?{
????????????try?{
????????????????OutToClient?=?new?DataOutputStream（socket.getOutputStream（））;
????????????????InFromClient?=?new?BufferedReader（new?InputStreamReader（socket.getInputStream（）））;
????????????????String?getString?=?InFromClient.readLine（）;
????????????????System.out.print（getString+‘\n‘）;
????????????????String[]?checkString?=?getString.split（“?“）;
????????????????String?url;
????????????????Socket?linkServer;
????
????????????????int?urlPort;
????????????????if（checkString[0].equalsIgnoreCase（“GET“）?）{
????????????????????linkServer?=?linkToServer（checkString[1]）;
????????????????}else{
????????????????????System.out.println（“invalid?input!\n“）;
????????????????????throw?new?IOException（“invalid?input!\n“）;
????????????????}
????????????????
????????????????
????????????????
????????????????OutToServer?=?new?DataOutputStream（linkServer.getOutputStream（））;
??????????