how tomcat works---01

Request

Response

HttpServer

---

Request.java 

package qhf01.pyrmont;

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

public class Request {
	
	private InputStream input;
	private String uri;
	
	public Request() {
		super();
	}
	
	public Request(InputStream input) {
		this.input = input;
	}
	
	public String getUri() {
		return uri;
	}

	public void parse() {
		
		StringBuffer request = new StringBuffer(2048);
		
		int len;
		byte[] buffer = new byte[2048];
		try {
			len = input.read(buffer);
		} catch (IOException e) {
			e.printStackTrace();
			len = -1;
		}
		
		for (int j = 0; j < len; j++) {
			request.append((char) buffer[j]);
		}
		
		System.out.println(request.toString());
		
		uri = parseUri(request.toString());
	}

	/**
	 * 	第一行的第一個空格和第二個空格之間就是uri
	 * 	比如：GET /index.html HTTP/1.1
	 **/
	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;
	}
}

Response.java

package qhf01.pyrmont;

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;
	Request request;
	OutputStream output;

	public Response() {
		super();
	}

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

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

	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 {
				// file not found
				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();
			}
		}
	}
	public static void main(String[] args) {
		System.out.println(System.getProperty("user.dir") + File.separator + "webroot");
	}

}

HttpServer.java

package qhf01.pyrmont;

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;

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

	private void await() {
		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);
		}
		
		while (!shutdown) {
			Socket socket = null;
			InputStream input = null;
			OutputStream output = null;
			
			try {
				//1.服務器開機，等待連接，直到連接了執行這下面23後關socket，下次循環再連接
				socket = serverSocket.accept();
				
				input = socket.getInputStream();
				output = socket.getOutputStream();
				
				//2.解析請求
				Request request = new Request(input);
				request.parse();
				
				//3.迴應設置對應的請求，發送靜態源
				Response response = new Response(output);
				response.setRequest(request);
				response.sendStaticResource();
				
				//4.關socket
				socket.close();
				
				//5.檢查請求中的uri 中是否是shutdown 命令，如是則shutdown 爲true 會退出循環
				shutdown = request.getUri().equals(SHUTDOWN_COMMAND);
				
			} catch (Exception e) {
				e.printStackTrace();
				continue;//錯誤繼續循環
			}
		}
	}
}