HTTP协议

HTTP请求

一个HTTP请求包含三部分：

　　方法统一资源标识符（URI）-协议/版本

　　请求头部

　　请求体内容

HTTP响应

一个HTTP响应包含三部分：

　　方法统一资源标识符-协议/版本

　　响应头部

　　主体内容

简单httpserver代码如下

package com.invocationhandler.exam01;

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("use.dir")
            + File.separator+"webroot";
    public static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
    private boolean shutdown = false;
    public static void main(String[] args){
        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);
        }
        while (!shutdown){
            Socket socket = null;
            InputStream input = null;
            OutputStream output = null;
            try {
                socket = serverSocket.accept();
                input = socket.getInputStream();
                output = socket.getOutputStream();
                Request request =new Request(input);
                request.parse();
                Response response = new Response(output);
                response.setRequest(request);
                response.sendStaticResource();
                socket.close();
                shutdown = request.getUri().equals(SHUTDOWN_COMMAND);
            }catch (Exception e){
                e.printStackTrace();
                continue;
            }
        }
    }
}

package com.invocationhandler.exam01;

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

public class Request {
    private InputStream inputStream;
    private String uri;
    public Request(InputStream inputStream){
        this.inputStream = inputStream;
    }
    public void parse(){
        StringBuffer request = new StringBuffer(2048);
        int i;
        byte[] buffer = new byte[2048];
        try {
            i = inputStream.read(buffer);
        }catch (IOException e){
            e.printStackTrace();
            i = -1;
        }
        for(int j=0;j<i;j++){
            request.append((char)buffer[j]);
        }
        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;
    }
}

package com.invocationhandler.exam01;

import java.io.File;
import java.io.FileInputStream;
import java.io.OutputStream;

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;
        try {
            File file = new File(HttpServer.WEB_ROOT,request.getUri());
            if(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());
            }
        }catch (Exception e){
            System.out.println(e.toString());
        }finally {
            if(fileInputStream!=null){
                fileInputStream.close();
            }
        }
    }
}