深入剖析Tomcat-第一章

--开始学习Tomcat服务器

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;

/**
 * 处理Http请求
 * @author
 *
 */
public class HttpServer {
	public static final String WEB_ROOT =
			System.getProperty("user.dir") + File.separator + "webroot";
	private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
	private boolean shutdown = false;

	public void await() {
		ServerSocket serverSocket = null;
		int port = 8080;
		try {
			serverSocket = new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1"));
		} catch (UnknownHostException e) {
			e.printStackTrace();
			System.exit(1);
		} catch (IOException e) {
			e.printStackTrace();
			System.exit(1);
		}

		while (!shutdown) {
			Socket socket = null;
			InputStream input = null;
			OutputStream output = null;
			try {
				//为每个请求建立一个socket,和对应的输出输出流
				socket = serverSocket.accept();
				input = socket.getInputStream();
				output = socket.getOutputStream();

				//将socket的输入流绑定到Request
				Request request = new Request(input);
				request.parse();

				shutdown = request.getUri().equals(SHUTDOWN_COMMAND);
				if (!shutdown) {
					//将socket的输出流和Request绑定到Response
					Response response = new Response(output);
					response.setRequest(request);
					response.sendStaticResource();
				}
				socket.close();
			} catch (IOException e) {
				e.printStackTrace();
				continue;
			}
		}
	}

	public static void main(String[] args) {
		HttpServer server = new HttpServer();
		server.await();
	}
}

import java.io.IOException;
import java.io.InputStream;

public class Request {
	private InputStream input;
	private String uri;

	public Request(InputStream input) {
		this.input = input;
	}

	/**
	 * 从socket建立的输入管道中获取HTTP请求
	 */
	public void parse() {
		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.print(request.toString());
		uri = parseUri(request.toString());
	}

	/**
	 * 从请求行中解析出请求静态文件
	 * @param requestString
	 * @return
	 */
	private String parseUri(String requestString) {
		int index1, index2;
		index1 = requestString.indexOf(' ');
		if (index1 != -1) {
			index2 = requestString.indexOf(' ', index1 + 1);
			if (index2 > index1)
				return requestString.substring(index1 + 1, index2);
		}
		return null;
	} 

	public String getUri() {
		return this.uri;
	}
}

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;

public class Response {
	private static final int BUFFER_SIZE = 1024;
	private Request request;
	private OutputStream output;

	public Response(OutputStream output) {
		this.output = output;
	}

	public void setRequest(Request request) {
		this.request = request;
	}

	/**
	 * 发动静态资源到浏览器
	 * @throws IOException
	 */
	public void sendStaticResource() throws IOException {
		byte bytes[] = new byte[BUFFER_SIZE];
		FileInputStream fis = null;
		try {
			File file = new File(HttpServer.WEB_ROOT, request.getUri());
			if (file.exists()) {
				fis = new FileInputStream(file);
				int ch = fis.read(bytes, 0, BUFFER_SIZE);
				while (ch != -1) {
					output.write(bytes, 0, ch);
					ch = fis.read(bytes, 0, BUFFER_SIZE);
				}
			} else {
				String errorMessage = "HTTP/1.1 404 File Not Found\r\n" +
								"Content-Type: text/html\r\n" +
								"Content-Length: 23\r\n" +
								"\r\n" +
								"<h1>File Not Found</h1>";
				output.write(errorMessage.getBytes());
			}
		} catch (Exception e) {
			System.out.println(e.toString());
		} finally {
			if (fis != null)
				fis.close();
		}
	}
}