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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