handlerequest.java

精通Java网络编程代码全部

import java.net.*;
import java.io.*;
import java.util.*;

class HandleRequest extends Thread {
	// socket，服务器accept的套接字
private final Socket sock;
	private final Hashtable knownRequests;
	private final String CRLF = "\r\n";

	public HandleRequest(Socket sock, Hashtable knownRequests) {
		this.sock = sock;
		this.knownRequests = knownRequests;
		//开始线程，为来自客户端的请求服务
		start();
	}
	// 继承自Thread类的run()方法
	public void run() {
		System.out.println("Handling client request,...");
		BufferedReader iStream = null;
		DataOutputStream oStream = null;
		String clientRequest = "";
		boolean first = true;
		try {
			//从socket中获取输入、输出流
			iStream = new BufferedReader(new InputStreamReader(sock.getInputStream()));
			oStream = new DataOutputStream(sock.getOutputStream());
			//从客户端读取请求信息
			clientRequest = iStream.readLine();
			String headerLine;
		while (true /*!sock.isClosed() JDK 1.4 only*/) {
				//读取HTTP请求的首部信息
				headerLine = iStream.readLine();
				System.out.println("Receiving header '" + headerLine + "'");
				if (headerLine == null || headerLine.trim().length() < 1) {
					break;
				}
			}
			System.out.println("Request from client " + getSocketInfo());
			if (clientRequest == null) {
				String info = "Empty request ignored " + getSocketInfo();
				errorResponse(oStream, "HTTP/1.1 400 Bad Request", null, true, info);
				System.out.println(info);
				return;
			}
			first = false;
			System.out.println("Handling client request '" + clientRequest + "' ...");
			StringTokenizer toks = new StringTokenizer(clientRequest);
			//一个请求字符串由三部分组成，例如“GET /Hello HTTP/1.0”
			if (toks.countTokens() != 3) {
				String info =
					"Wrong syntax in client request: '"
						+ clientRequest
						+ "', closing "
						+ getSocketInfo()
						+ " connection.";
				errorResponse(oStream, "HTTP/1.1 400 Bad Request", null, true, info);
				System.out.println(info);
				return;
			}
			String method = toks.nextToken(); // "GET"
			String resource = toks.nextToken(); // "/Hello"
			String version = toks.nextToken(); // "HTTP/1.0"
			//作为简易的HTTP服务器，只处理GET和HEAD
			if (!method.equalsIgnoreCase("GET") && !method.equalsIgnoreCase("HEAD")) {
				String info =
					"Invalid method in client "
						+ getSocketInfo()
						+ " request: '"
						+ clientRequest
						+ "'";
				errorResponse(
					oStream,
					"HTTP/1.1 501 Method Not Implemented",
					"Allow: GET",
					true,
					info);
				System.out.println(info);
				return;
			}
			//从knownRequest列表中查找响应字符串
			String responseStr = (String) knownRequests.get(resource.trim());
			//没有找到，生成错误信息
			if (responseStr == null) {
				String info =
					"Ignoring unknown data '"
						+ resource.trim()
						+ "' from client "
						+ getSocketInfo()
						+ " request: '"
						+ clientRequest
						+ "'";
				errorResponse(oStream, "HTTP/1.1 404 Not Found", null, true, info);
				System.out.println(info);
				return;
			}
			//发会服务成功的状态
			errorResponse(oStream, "HTTP/1.1 200 OK", null, false, null);
			//生成首部域Content-Length
			String length = "Content-Length: " + responseStr.length();
			oStream.write((length + CRLF).getBytes());
			//生成Content-Type首部域
			oStream.write(("Content-Type: text/plain; charset=iso-8859-1" + CRLF).getBytes());
			if (!method.equalsIgnoreCase("HEAD")) {
				oStream.write(CRLF.getBytes());
				oStream.write(responseStr.getBytes());
			}
			oStream.flush();
		//处理异常
		} catch (IOException e) {
			if (clientRequest == null && first) {
				System.out.println("Ignoring connect/disconnect attempt");
			} else {
				System.out.println(
					"Problems with sending response for '"
						+ clientRequest
						+ "' to client "
						+ getSocketInfo()
						+ ": "
						+ e.toString());
			}
		} finally {
			try {
				if (iStream != null)
					iStream.close();
			} catch (IOException e) {}
			try {
				if (oStream != null)
					oStream.close();
			} catch (IOException e) {}
			try {
				sock.close();
			} catch (IOException e) {}
		}
	}

	//调用此方法向oStream写回相应信息
//参数body指示是否在响应信息中加入在浏览器中显示的超文本页面内容提示作为错误
	private void errorResponse(DataOutputStream oStream, String code,	String extra, boolean body, String info)
		throws IOException {
		oStream.write((code + CRLF).getBytes());
		oStream.write(("Server: MiniHttpServer/" + CRLF).getBytes());
		if (extra != null)
			oStream.write((extra + CRLF).getBytes());
		oStream.write(("Connection: close" + CRLF).getBytes());
		if (body) {
			//写入可以在浏览器中显示的超文本错误信息
			oStream.write(
				(CRLF
					+ "<html><head><title>"
					+ code
					+ "</title></head><body>"
					+ "<h2>MiniHTTP server "
					+ "</h2>"
					+ "<p>"
					+ code
					+ "</p>"
					+ "<p>"
					+ info
					+ "</p>"
					+ "</body></html>")
					.getBytes());
		}
	}
	//返回关于Socket的信息
	private String getSocketInfo() {
		StringBuffer sb = new StringBuffer(196);
		if (sock == null)
			return "";
		sb.append(sock.getInetAddress().getHostAddress());
		sb.append(":").append(sock.getPort());
		sb.append(" -> ");
		sb.append(sock.getLocalAddress().getHostAddress());
		sb.append(":").append(sock.getLocalPort());
		return sb.toString();
	}
}