web代理服务器实验

1、Web代理服务器实验附录代码：1. ProxyCache类import .*;import java.io.*;import java.util.*;public class ProxyCache private static HashMap<String,byte> URIBuff = new HashMap<String,byte>();/ 代理入口private static int port;/* 客户链接的套接字, port是要代理侦听来自客户端的传入连接的端口号*/private static ServerSocket socket;/* 创建一个Proxy

2、对象和套接字 */public static void init(int p) port = p; try socket = new ServerSocket(port); catch (IOException e) System.out.println("Error creating socket: " + e);System.exit(-1);public static void handle(Socket client) Socket server = null; HttpRequest request = null; HttpResponse response =

3、null;/ 处理请求。 如果存在异常，就回复并终止它。 这意味着客户端将会挂起一段时间，直到超时. 读取请求try BufferedReader fromClient = new BufferedReader(new InputStreamReader(client.getInputStream();request = new HttpRequest(fromClient); String URI = request.URI; byte buff = URIBuff.get(URI);if (buff != null) DataOutputStream toClient; /* 创建一个to

4、Client 对象*/try toClient = new DataOutputStream(client.getOutputStream();toClient.writeBytes(response.toString();toClient.write(buff);/缓存/ 写响应到客户端。首先头部，然后主体client.close();System.out.print("Use Buffered"); catch (IOException e) e.printStackTrace();return;/ 不再往下走 catch (IOException e) System.

5、out.println("Error reading request from client: " + e);return;/ 向服务器发送请求try / 打开套接字并向其中写入请求server = new Socket(request.getHost(), request.getPort();DataOutputStream toServer = new DataOutputStream(server.getOutputStream();toServer.writeBytes(request.toString();/ 以下toServer不能够close，它关闭会导致连接

6、server也会关闭/ toServer.close();System.out.println("Request forwarded."); catch (UnknownHostException e) System.out.println("Unknown host: " + request.getHost();System.out.println(e);return; catch (IOException e) System.out.println("Error writing request to server: " + e);

7、return;/ 读取相应并将其转发给客户端try DataInputStream fromServer = new DataInputStream(server.getInputStream();response = new HttpResponse(fromServer);DataOutputStream toClient = new DataOutputStream(client.getOutputStream();toClient.writeBytes(response.toString();URIBuff.put(request.URI, response.body);toClien

8、t.write(response.body);/ 写响应到客户端。首先头部，然后主体client.close();server.close();/ 插入对象到缓存 填写（只有自选动作） catch (IOException e) /e.printStackTrace();/System.out.println("Error writing response to client: " + e);/ 读取命令行参数，并开始代理public static void main(String args) int myPort = 0;try myPort = Integer.pars

9、eInt(args0); catch (ArrayIndexOutOfBoundsException e) System.out.println("Need port number as argument");System.exit(-1); catch (NumberFormatException e) System.out.println("Please give port number as integer.");System.exit(-1);init(myPort);/ 主循环 侦听传入的连接，并处理它们生成一个新线程/ = null;whil

10、e (true) try Socket client = socket.accept();handle(client); catch (IOException e) System.out.println("Error reading request from client: " + e);/ 明确不能继续处理这个请求，因此跳转到而下一轮循环continue;2. HttpRequest类import java.io.*; import .*; import java.util.*; public class HttpRequest /帮助参数 final static St

11、ring CRLF = "rn" /*回车换行*/ final static int HTTP_PORT = 80; / 存储请求参数 String method; String URI; String version; String headers = "" / 服务器和端口 private String host; private int port; / 通过从客户端套接字读取它来创建Http请求 / private HashMap<> public HttpRequest(BufferedReader from) String firs

12、tLine = "" try firstLine = from.readLine(); catch (IOException e) System.out.println("Error reading request line: " + e); String tmp = firstLine.split(" "); method = tmp0; URI = tmp1; version = tmp2; System.out.println("URI is: " + URI); if (!method.equals(&qu

13、ot;GET") System.out.println("Error: Method not GET"); try String line = from.readLine(); while (line.length() != 0) headers += line + CRLF; /请求不完整，需要找出主机头部以获知去连接哪个服务器 if (line.startsWith("Host:") tmp = line.split(" "); if (tmp1.indexOf(':') > 0 ) String

14、tmp2 = tmp1.split(":"); host = tmp20; port = Integer.parseInt(tmp21); else host = tmp1; port = HTTP_PORT; line = from.readLine(); catch (IOException e) System.out.println("Error reading from socket: " + e); return; System.out.println("Host to contact is: " + host + &quo

15、t; at port " + port); / 返回请求的主机 public String getHost() return host; / 返回服务器的端口 public int getPort() return port; / 将请求转换成一个便于重新发送字符串 public String toString() String req = "" req = method + " " + URI + " " + version + CRLF; req += headers; / 这个代理不支持持久的连接 req += &qu

16、ot;Connection: close" + CRLF; req += CRLF; return req; 3. HttpResponse类import java.io.*; import .*; import java.util.*; public class HttpResponse final static String CRLF = "rn" / 用于读取对象的缓存区的大小 final static int BUF_SIZE = 81920;/8192; / 最大化代理可以处理的对象，暂时设置为100KB，可以根据需要调整 final static in

17、t MAX_OBJECT_SIZE = 100000; / 应答状态和头部 String version; int status; String statusLine = "" String headers = "" / 应答的实体 byte body = new byteMAX_OBJECT_SIZE; / 从服务器读取相应public HttpResponse(DataInputStream fromServer) / 对象的长度 int length = -1; boolean gotStatusLine = false; / 先读取状态行和响应头

18、部 try String line = fromServer.readLine(); while (line.length() != 0) if (!gotStatusLine) statusLine = line; gotStatusLine = true; else headers += line + CRLF; /获取Content-Length头部显示的内容长度，一些服务器返回头部"Content-Length"，另外一些返回"Content-Length",这里都需要确认一下 if (line.startsWith("Content-

19、Length") | line.startsWith("Content-length") String tmp = line.split(" "); length = Integer.parseInt(tmp1); line = fromServer.readLine(); catch (IOException e) System.out.println("Error reading headers from server: " + e); return; try int bytesRead = 0; byte buf = new byteBUF_SIZE; boolean loop = false; / 如果没有获得Content-Length的头部，继续循