我的第一个 web server 程序

参考书《How Tomcat Works》这本书非常好，我觉得翻译也不错。

根据第二章的例子，我写了我的第一个 web server 程序

HttpServer.java

package ex01.xiejiaohui;

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[] ars) {
		HttpServer server = new HttpServer();
		server.await();
	}
	
	public 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);
		}
		
		// Loop waiting for a request
		while (!shutdown) {
			Socket socket = null;
			InputStream input = null;
			OutputStream output = null;
			try {
				socket = serverSocket.accept();
				input = socket.getInputStream();
				output = socket.getOutputStream();
				
				// create Request object and parse
				Request request = new Request(input);
				request.parse();
				
				// create Response object
				Response response = new Response(output);
				response.setRequest(request);
				response.sendStaticResource();
				
				// Close the socketk
				socket.close();
				
				// check if the previous URI is a shutdown command
				shutdown = request.getUri().equals(SHUTDOWN_COMMAND);
			} catch (Exception e) {
				e.printStackTrace();
				continue;
			}
		}
		
	}

}

Request.java

package ex01.xiejiaohui;

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

public class Request {

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

Response.java

package ex01.xiejiaohui;

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(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) {
			// thrown if cannot instantiate a File object
			e.printStackTrace();
			System.out.println(e.toString());
		} finally {
			if (fis != null) {
				fis.close();
			}
		}
	}
	
	

}

然后在 webroot 目录下新建 文件 index.html

运行 HttpServer.java

然后在浏览器中访问你的第一个 web server 并且是纯 Java 版的

http://127.0.0.1:8080/index.html  注意具体的文件名称，虽然只有一个html文件

eclipse 中控制台输出如下：

GET /index.html HTTP/1.1
Host: 127.0.0.1:8080
Connection: keep-alive
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.22 (KHTML, like Gecko) Chrome/25.0.1364.152 Safari/537.22
Accept-Encoding: gzip,deflate,sdch
Accept-Language: zh-CN,zh;q=0.8
Accept-Charset: GBK,utf-8;q=0.7,*;q=0.3

千万不要写错了，如果写错了，浏览器会提示：无法显示此页