打造自己的web容器（4）

上一篇我们实现了一个极其简单的servlet容器，这一章，将在上一章的基础上进行扩充。我们以Tomcat的默认连接器为蓝本，逐步解剖连接器，虽然该连接器已不推荐使用，被性能更高的coyote所代替，但它仍是一个学习的好工具。

这一章，我们将完成如下任务：
1、解决上一篇的遗留问题
2、模拟Catalina的架构，重构我们的系统
3、实现HttpRequest的部分方法，包括：解析cookies,header,parameter等

这章的应用程序由三个模块组成：connector、startup和core，其中：
startup模块只有一个类，Bootstrap，用来启动应用的。
connector模块的类可以分为五组：
* 连接器和它的支撑类(HttpConnector和HttpProcessor)。
* 指代HTTP请求的类(HttpRequest)和它的辅助类。
* 指代HTTP响应的类(HttpResponse)和它的辅助类。
* Facade类(HttpRequestFacade和HttpResponseFacade)。
* Constant类
core模块由两个类组成：ServletProcessor和StaticResourceProcessor。


启动类：Bootstrap

public final class Bootstrap {
	public static void main(String[] args) {
	        HttpConnector connector = new HttpConnector();
		connector.start();
	}
}

/**
 * 连接器
 *   1、等待HTTP请求
 * @author <a href="mailto:cwq2006@163.com">chen wen quan</a>
 *
 */
public class HttpConnector implements Runnable {

	// shutdown command
	private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";

	// the shutdown command received
	private boolean shutdown = false;

	private String scheme = "http";

	public String getScheme() {

		return scheme;
	}

	public void run() {

		ServerSocket serverSocket = null;
		int port = 8080;
		try {
			serverSocket = new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1"));
		}
		catch (IOException e) {
			e.printStackTrace();
			System.exit(1);
		}
		// Loop waiting for a request
		while (!shutdown) {
			Socket socket = null;
			try {
				socket = serverSocket.accept();
			}
			catch (Exception e) {
				continue;
			}
			// Hand this socket off to an HttpProcessor
			HttpProcessor processor = new HttpProcessor();
			processor.process(socket);
		}
	}

	public void start() {
		Thread thread = new Thread(this);
		thread.start();
	}
}

/**
 * 连接器的支撑类，其主要作用为：
 *   1 接受前来的HTTP请求的套接字
 *   2 创建一个HttpRequest、HttpResponse对象
 *   3 解析HTTP请求的第一行和头部，并放到HttpRequest对象
 *   4 解析HttpRequest和HttpResponse对象到一个ServletProcessor或者 StaticResourceProcessor
 * @author <a href="mailto:cwq2006@163.com">chen wen quan</a>
 *
 */
public class HttpProcessor {

	private HttpRequest request = null;

	private HttpResponse response = null;

	private String requestContent = null;

	public void process(Socket socket) {

		InputStream input = null;
		OutputStream output = null;
		try {
			input = socket.getInputStream();
			output = socket.getOutputStream();
			// create HttpRequest object and parse
			request = new HttpRequest(input);
			// create HttpResponse object
			response = new HttpResponse(output);
			response.setRequest(request);
			response.setHeader("Server", "Pyrmont Servlet Container");
			parse(input);
			parseRequest(input, output);
			parseHeaders(input);
			//check if this is a request for a servlet or a static resource
			//a request for a servlet begins with "/servlet/"
			if (request.getRequestURI().startsWith("/servlet/")) {
				ServletProcessor processor = new ServletProcessor();
				processor.process(request, response);
			}
			else {
				StaticResourceProcessor processor = new StaticResourceProcessor();
				processor.process(request, response);
			}
			// Close the socket
			socket.close();
			// no shutdown for this application
		}
		catch (Exception e) {
			e.printStackTrace();
		}
	}

	private void parseHeaders(InputStream input) {

		// TODO Auto-generated method stub

	}

	public void parse(InputStream input) {

		// Read a set of characters from the socket
		StringBuffer request = new StringBuffer(2048);
		int i;
		byte[] buffer = new byte[2048];
		try {
			i = input.read(buffer);
		}
		catch (IOException e) {
			e.printStackTrace();
			i = -1;
		}
		for (int j = 0; j < i; j++) {
			request.append((char) buffer[j]);
		}
		System.out.println(request.toString());
		requestContent = request.toString();
	}

	private void parseRequest(InputStream input, OutputStream output) throws ServletException {

		String requestHeaderFirstLine = requestContent.substring(0, requestContent.indexOf("\n"));
		String headerInfo[] = requestHeaderFirstLine.split(" ");
		String method = headerInfo[0];
		String uri = headerInfo[1];
		String protocol = headerInfo[2];
		// Validate the incoming request line
		if (method.length() < 1) {
			throw new ServletException("Missing HTTP request method");
		}
		// Parse any query parameters out of the request URI
		int question = uri.indexOf("?");
		if (question >= 0) {
			request.setQueryString(uri.substring(question - 1));
			uri = uri.substring(0, question);
		}
		else {
			request.setQueryString(null);
		}
		// Checking for an absolute URI (with the HTTP protocol)
		if (!uri.startsWith("/")) {
			int pos = uri.indexOf("://");
			// Parsing out protocol and host name
			if (pos != -1) {
				pos = uri.indexOf('/', pos + 3);
				if (pos == -1) {
					uri = "";
				}
				else {
					uri = uri.substring(pos);
				}
			}
		}
		// Parse any requested session ID out of the request URI
		String match = ";jsessionid=";
		int semicolon = uri.indexOf(match);
		if (semicolon >= 0) {
			String rest = uri.substring(semicolon + match.length());
			int semicolon2 = rest.indexOf(';');
			if (semicolon2 >= 0) {
				request.setRequestedSessionId(rest.substring(0, semicolon2));
				rest = rest.substring(semicolon2);
			}
			else {
				request.setRequestedSessionId(rest);
				rest = "";
			}
			request.setRequestedSessionURL(true);
			uri = uri.substring(0, semicolon) + rest;
		}
		else {
			request.setRequestedSessionId(null);
			request.setRequestedSessionURL(false);
		}
		// Normalize URI (using String operations at the moment)
		String normalizedUri = normalize(uri);//检查URL是否合法
		// Set the corresponding request properties
		request.setMethod(method);
		request.setProtocol(protocol);
		if (normalizedUri != null) {
			request.setRequestURI(normalizedUri);
		}
		else {
			request.setRequestURI(uri);
		}
		if (normalizedUri == null) {
			throw new ServletException("Invalid URI: " + uri + "'");
		}

	}

	private String normalize(String uri) {

		if (uri == null)
			return null;

		// Create a place for the normalized path
		String normalized = uri;

		if (normalized.equals("/."))
			return "/";

		// Add a leading "/" if necessary
		if (!normalized.startsWith("/"))
			normalized = "/" + normalized;

		// Resolve occurrences of "//" in the normalized path
		while (true) {
			int index = normalized.indexOf("//");
			if (index < 0)
				break;
			normalized = normalized.substring(0, index) + normalized.substring(index + 1);
		}

		// Resolve occurrences of "/./" in the normalized path
		while (true) {
			int index = normalized.indexOf("/./");
			if (index < 0)
				break;
			normalized = normalized.substring(0, index) + normalized.substring(index + 2);
		}

		// Resolve occurrences of "/../" in the normalized path
		while (true) {
			int index = normalized.indexOf("/../");
			if (index < 0)
				break;
			if (index == 0)
				return (null); // Trying to go outside our context
			int index2 = normalized.lastIndexOf('/', index - 1);
			normalized = normalized.substring(0, index2) + normalized.substring(index + 3);
		}

		// Return the normalized path that we have completed
		return (normalized);
	}
}

public class RequestUtil {

	/**
	 * 解析cookie
	 *   Cookie: userName=budi; password=pwd;
	 * @param header
	 * @return
	 */
	public static Cookie[] parseCookieHeader(String header) {

		if ((header == null) || (header.length() < 1))
			return (new Cookie[0]);
		List cookies = new ArrayList();
		while (header.length() > 0) {
			int semicolon = header.indexOf(';');
			if (semicolon < 0)
				semicolon = header.length();
			if (semicolon == 0)
				break;
			String token = header.substring(0, semicolon);
			if (semicolon < header.length())
				header = header.substring(semicolon + 1);
			else
				header = "";
			try {
				int equals = token.indexOf('=');
				if (equals > 0) {
					String name = token.substring(0, equals).trim();
					String value = token.substring(equals + 1).trim();
					cookies.add(new Cookie(name, value));
				}
			}
			catch (Throwable e) {
				;
			}
		}
		return ((Cookie[]) cookies.toArray(new Cookie[cookies.size()]));
	}

	/**
	 * 解析请求参数
	 * @param map
	 * @param data 由 "userName=cwq&password=pwd".getBytes() 得
	 * @param encoding 字符编码
	 * @return
	 */
	public static void parseParameters(Map map, byte[] data, String encoding) throws UnsupportedEncodingException {

		if (data != null && data.length > 0) {
			int ix = 0;
			int ox = 0;
			String key = null;
			String value = null;
			while (ix < data.length) {
				byte c = data[ix++];
				switch ((char) c) {
					case '&':
						value = new String(data, 0, ox, encoding);
						if (key != null) {
							putMapEntry(map, key, value);
							key = null;
						}
						ox = 0;
						break;
					case '=':
						if (key == null) {
							key = new String(data, 0, ox, encoding);
							ox = 0;
						}
						else {
							data[ox++] = c;
						}
						break;
					case '+':
						data[ox++] = (byte) ' ';
						break;
					case '%':
						data[ox++] = (byte) ((convertHexDigit(data[ix++]) << 4) + convertHexDigit(data[ix++]));
						break;
					default:
						data[ox++] = c;
				}
			}
			//The last value does not end in '&'.  So save it now.
			if (key != null) {
				value = new String(data, 0, ox, encoding);
				putMapEntry(map, key, value);
			}
		}
	}

	private static void putMapEntry(Map map, String name, String value) {

		String[] newValues = null;
		String[] oldValues = (String[]) map.get(name);
		if (oldValues == null) {
			newValues = new String[1];
			newValues[0] = value;
		}
		else {
			newValues = new String[oldValues.length + 1];
			System.arraycopy(oldValues, 0, newValues, 0, oldValues.length);
			newValues[oldValues.length] = value;
		}
		map.put(name, newValues);
	}

    private static byte convertHexDigit( byte b ) {
        if ((b >= '0') && (b <= '9')) return (byte)(b - '0');
        if ((b >= 'a') && (b <= 'f')) return (byte)(b - 'a' + 10);
        if ((b >= 'A') && (b <= 'F')) return (byte)(b - 'A' + 10);
        return 0;
    }
}