先看段打開網頁的代碼：URL?url=new?URL("http://souljava.blog.163.com/");

URLConnection?connection=url.openConnection();

connection.getInputStream();

問題1：客戶端瀏覽器怎么判斷接受到的是什么數據類型？

回答：java的附帶瀏覽器JEditorPane會按以下方式，依次判斷

URLConnectiongetContentType()

根據?URL?的指定?"file"?部分嘗試確定對象的內容類型。

根據輸入流的開始字符嘗試確定輸入流的類型。

問題2：如果傳送的數據類型不在(RFC)?中怎么辦？

回答：自定義協議處理框架

貼幾個關鍵的類：

*abstract?classURLConnection

表示客戶程序與遠程服務器的連接。?客戶程序可以從URLConnection獲得輸入輸出流

推薦覆蓋:

StringgetContentType()從URL?判斷返回何種MIME

abstract??voidconnect()解析URL?，由自己實現的超類建立soket連接

getInputStream()從soket連接中，獲取輸入流

*public?abstract?classURLStreamHandler

協議處理器,主要負責創建與協議相關的URLConnection對象.

推薦覆蓋:

protected?abstractopenConnection(URLu)

URLStreamHandler?對象被重載URLStreamHandlerFactory的createURLStreamHandler(Stringprotocol)

*abstract?classContentHandler

內容處理器，負責解析服務器發送的數據，然后轉換成?合適的java?數據結構

推薦覆蓋:

依次遍歷classes中的元素如果匹配就返回

ContentHandler?由ContentHandlerFactory?創建

需要覆蓋：createContentHandler(Stringmimetype)?判斷產生何種ContentHandler

自定義協議處理框架

自定義的echo協議import?java.net.*;

import?java.io.*;

import?echo.*;

public?class?EchoClient{

public?static?void?main(String?args[])throws?IOException{

//設置URLStreamHandlerFactory

URL.setURLStreamHandlerFactory(new?EchoURLStreamHandlerFactory());

//設置ContentHandlerFactory

URLConnection.setContentHandlerFactory(new?EchoContentHandlerFactory());

URL?url=new?URL("echo://localhost:8000");

EchoURLConnection?connection=(EchoURLConnection)url.openConnection();

connection.setDoOutput(true);

PrintWriter?pw=new?PrintWriter(connection.getOutputStream(),true);

while(true){

BufferedReader?br=new?BufferedReader(new?InputStreamReader(System.in));

String?msg=br.readLine();

pw.println(msg);??//向服務器發送消息

String?echoMsg=(String)connection.getContent();?//讀取服務器返回的消息

System.out.println(echoMsg);

if(echoMsg.equals("echo:bye")){

connection.disconnect();?//斷開連接

break;

}

}

}

}

package?echo;

import?java.net.*;

import?java.io.*;

public?class?EchoContentHandler?extends?ContentHandler{

public?Object?getContent(URLConnection?connection)throws?IOException{

InputStream?in=connection.getInputStream();

BufferedReader?br=new?BufferedReader(new?InputStreamReader(in));

return?br.readLine();

}

public?Object?getContent(URLConnection?connection,Class[]?classes)throws?IOException{

InputStream?in=connection.getInputStream();

for(int?i=0;i

if(classes[i]==InputStream.class)

return?in;

else?if(classes[i]==String.class)

return?getContent(connection);

}

return?null;

}

}

package?echo;

import?java.net.*;

public?class?EchoContentHandlerFactory?implements?ContentHandlerFactory{

public?ContentHandler?createContentHandler(String?mimetype){

if(mimetype.equals("text/plain")){

return?new?EchoContentHandler();

}else{

return?null;

}

}

}

package?echo;

import?java.net.*;

import?java.io.*;

public?class?EchoURLConnection?extends?URLConnection{

private?Socket?connection=null;

public?final?static?int?DEFAULT_PORT=8000;

public?EchoURLConnection(URL?url){

super(url);

}

public?synchronized?InputStream?getInputStream()?throws?IOException{

if(!connected)connect();

return?connection.getInputStream();

}

public?synchronized?OutputStream?getOutputStream()?throws?IOException{

if(!connected)connect();

return?connection.getOutputStream();

}

public?String?getContentType(){

return?"text/plain";

}

public?synchronized?void?connect()throws?IOException{

if(!connected){

int?port=url.getPort();

if(port<0?||?port>65535)port=DEFAULT_PORT;

this.connection=new?Socket(url.getHost(),port);

this.connected=true;

}

}

public?synchronized?void?disconnect()?throws?IOException{

if(connected){

this.connection.close();

this.connected=false;

}

}

}

package?echo;

import?java.net.*;

import?java.io.*;

public?class?EchoURLStreamHandlerFactory?implements?URLStreamHandlerFactory{

public?URLStreamHandler?createURLStreamHandler(String?protocol){

if(protocol.equals("echo"))

return?new?EchoURLStreamHandler();

else

return?null;

}

}

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