java 实现http响应

 public class HttpServer {

     //WEB_ROOT该服务器的根目录，这个目录可以自己定义，主要是服务器响应的文件所在目录
     public static final String WEB_ROOT = System.getProperty("user.dir")+File.separator+"webroot";

     public static void main(String[] args) {
         HttpServer server = new HttpServer();
         System.out.println("WEB_ROOT:"+WEB_ROOT);
         server.await();
     }
     public void await(){
         ServerSocket serverSocket = null;
         int port = 8080;
         try {
             serverSocket = new ServerSocket(port,1,InetAddress.getByName("127.0.0.1"));
             System.out.println("等待来自浏览器的连接...");
             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) {
                     e.printStackTrace();
                     continue;
                 }
             }
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
 }

可以看到，浏览器发送过来的请求信息是通过socket.getInputStream();得到，并将其封装到Request中，让Request去处理请求信息。

2、请求对象Request

 public class Request {

     //输入流
     private InputStream input;

     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) {
                 e.printStackTrace();
                 i = -1;
             }
             for(int j = 0;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;
     }
 }

服务器处理完得到响应数据在socket.getOutputStream();封装到Response

3、Response

 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) {
                 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;
     }
 }