简单的web服务器实现

HTTP请求:

一个HTTP请求包含以下三个部分:

请求方法——统一资源定位符（URI）——协议/版本

请求头

实体

请求方法如第一个红方框所示下：

请求头内容如上第二个方框内所示；

请求内容包含有请求参数l上图没有表示出来，简单示例如：lastname = zhang&fristname=san；

它与请求头之间有一个空行，该空行只有CRLF符；

HTTP响应：

与HTTP请求类似也分为三个部分：

协议——状态码——描述

响应头

响应实体段

同样响应实体段与响应头之间也有一个CRLF符空行。响应实体正文是一段html代码段。

了解了这些，就可以用套接字（socket）实现一个简单的web服务器。

首先是服务端代码实现：

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.awiat();}   public void awiat(){  try {ServerSocket serverSocket = new ServerSocket(8080,1,InetAddress.getByName("127.0.0.1"));while(!shutdown){Socket socket = serverSocket.accept();InputStream inputStream = socket.getInputStream();OutputStream outputStream = socket.getOutputStream();Request request = new Request(inputStream);request.parse();Response response = new Response(outputStream);response.setRequest(request);response.sendStaticResource();socket.close();shutdown = request.getUri().equals(SHUTDOWN_COMMAND);}} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}  }

请求实体类:

public class Request {private InputStream inputStream;private String uri;public Request(InputStream inputStream) {this.inputStream = inputStream;}public void parse() {try {StringBuffer request = new StringBuffer(2048);int i;byte[] buffer = new byte[2048];i = inputStream.read(buffer);for (int j = 0; j < i; j++) {request.append((char) buffer[j]);}System.out.println(request.toString());uri = parseUri(request.toString());} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}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;}

响应类response：

public class Response {private static final int  BUFFER_SIZE= 1024;Request request;OutputStream outputStream;public Response(OutputStream outputStream) {this.outputStream = outputStream;}public void setRequest(Request request) {this.request = request;}public void sendStaticResource() throws Exception{byte[] bytes = new byte[BUFFER_SIZE];FileInputStream fileInputStream = null;File file = new File(HttpServer.WEB_ROOT,request.getUri());if(file != null && file.exists()){fileInputStream = new FileInputStream(file);int ch = fileInputStream.read(bytes, 0, BUFFER_SIZE);while(ch != -1){outputStream.write(bytes, 0, ch);ch = fileInputStream.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>";outputStream.write(errorMessage.getBytes());}if(fileInputStream !=null){fileInputStream.close();fileInputStream = null;}}}

测试：

        启动Httpserver类，打开浏览器，输入127.0.0.1:8080 即可。虽然上述三个类很简单功能不完整，仅供了解web服务器是如何工作的。

        github地址：https://github.com/Mrfirewind/simpelWebServer.git

       参考书籍：深入剖析TOMCAT