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java服务器简单实现
一 HTTP
http请求
一般一个http请求包括以下三个部分:
1 请求方法,如get,post
2 请求头
3 实体
一个http请求的实例如下:
GET /index.jsp HTTP/1.1
Host: localhost:8080
User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:15.0) Gecko/20100101 Firefox/15.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Connection: keep-alive
注意红色部分的url,这是我们待会要截取出来的。
http响应
与http请求类似,http响应也包括三个部分
1 协议-状态码-描述
2 响应头
3 响应实体段
二 socket类
套接字是网络连接的断点。套接字使得应用程序可以从网络中读取数据,可以向网络中写入数据。不同计算机上的应用程序可以通过套接字发送或接受字节流。java中提供了Socket类来实现这个功能,通过getInputStream和getOutputStream可以获取网络中的输入输出流。
但是,光靠Socket类还是不能够实现我们构建一个服务器应用程序的功能的,因为服务器必须时刻待命,因此java里面提供了ServerSocket类来处理等待来自客户端的请求,当ServerSocket接受到了来自客户端的请求之后,它就会创建一个实例来处理与客户端的通信。
三 服务器应用程序的实现
首先,我们要构建一个封装请求信息的类requst,一个响应请求的类response,还要有一个主程序httpServer来处理客户端来的请求。
package com.lwq;import java.io.IOException;import java.io.InputStream;/** * @author Joker * 类说明 * 将浏览器发来的请求信息转化成字符和截取url */public class Request { //输入流 private InputStream input; //截取url,如http://localhost:8080/index.html ,截取部分为 /index.html private String uri; public Request(InputStream inputStream){ this.input = inputStream; } public InputStream getInput() { return input; } public void setInput(InputStream input) { this.input = input; } public String getUri() { return uri; } public void setUri(String uri) { this.uri = uri; } //从套接字中读取字符信息 public void parse(){ StringBuffer request = new StringBuffer(2048); int i = 0; byte[] buffer = new byte[2048]; try { i = input.read(buffer); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); i = -1; } for(int j = 0;j<i;j++){ request.append((char)(buffer[j])); } System.out.println(request.toString()); uri = parseUri(request.toString()); } //截取请求的url private String parseUri(String requestString){ int index1 = 0; int index2 = 0; index1 = requestString.indexOf(‘ ‘); if(index1!=-1){ index2 = requestString.indexOf(‘ ‘,index1+1); if(index2>index1){ return requestString.substring(index1+1,index2); } } return null; } }
下面是封装了响应请求的类response:
package com.lwq;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.OutputStream;import java.io.PrintWriter;/** * @author Joker * @version 创建时间:Sep 5, 2012 9:59:53 PM * 类说明 根据相应信息返回结果 */public class Response { private static final int BUFFER_SIZE = 1024; Request request; OutputStream output; public Response(OutputStream output){ this.output = output; } public void sendStaticResource() throws IOException{ byte[] bytes = new byte[BUFFER_SIZE]; FileInputStream fis = null; File file = new File(HttpServer.WEB_ROOT,request.getUri()); if(file.exists()){ try { 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); } } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); }catch(IOException e){ e.printStackTrace(); }finally{ if(fis !=null){ fis.close(); } } }else{ //找不到文件 String errorMessage = "HTTP/1.1 404 File Not Found\r\n" + "Content-Type: text/html\r\n" + "Content-Length: 23\r\n" + "\r\n" + "File Not Found"; try { output.write(errorMessage.getBytes()); output.flush(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } public Request getRequest() { return request; } public void setRequest(Request request) { this.request = request; } public OutputStream getOutput() { return output; } public void setOutput(OutputStream output) { this.output = output; } public static int getBUFFER_SIZE() { return BUFFER_SIZE; } }
接下来是主程序,
package com.lwq;import java.io.File;import java.io.InputStream;import java.io.OutputStream;import java.net.InetAddress;import java.net.ServerSocket;import java.net.Socket;/** * @author Joker * 类说明 */public class HttpServer { /** * @param args */ //WEB_ROOT是服务器的根目录 public static final String WEB_ROOT = System.getProperty("user.dir")+File.separator+"webroot"; //关闭的命令 private static final String SHUTDOWN_COMMAND= "/SHUTDOWN"; public static void main(String[] args) { // TODO Auto-generated method stub 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")); while(true) { try { Socket socket = null; InputStream input = null; OutputStream output = null; socket = serverSocket.accept(); input = socket.getInputStream(); output = socket.getOutputStream(); //封装request请求 Request request = new Request(input); request.parse(); //封装response对象 Response response = new Response(output); response.setRequest(request); response.sendStaticResource(); socket.close(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); continue; } } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
运行httpServer,在浏览器中打下http://localhost:8080/index.jsp,就能看到服务器响应的结果了。
java服务器简单实现