HttpURLConnection的一些使用问题

你的名字 2022-02-04 04:19 287阅读 0赞

1.getOutputStream和getInputStream返回的流都是用于输出或者输入报文实体的，而不是报文头部。

2.请求行根据设置的请求方法和URL中的信息自动拼接，首部字段通过setRequestProperty()设置，会在connect()被调用时，输出并被缓冲起来

3.通过OutputStream输出的实体，会被缓冲起来，所以content-length会自动计算，还有首部字段和实体间的CRLF会自动加入，在getInputStream的时候会被发送出去。

4.getInputStream后，OutputStream被自动关闭，如果向OutputStream中写入数据，则会报异常。

5.HttpURLConnection只能发出一次请求并接收一次反馈信息。并不能用于多次请求

与服务器通信代码：

URL url = new URL("http://localhost:8888/hsadjlgew/hsldjlgew");
            String s1 = "data";
    
            HttpURLConnection conn = (HttpURLConnection)url.openConnection();
            conn.setDoOutput(true);
            conn.setRequestMethod("POST");
    //        conn.setRequestProperty("Content-Length",String.valueOf(s1.length()));
            conn.connect();
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream(), Charset.forName("ASCII")));
            bw.write(s1);
            bw.flush();
            bw.close();
            InputStream is = conn.getInputStream();
            BufferedInputStream br = new BufferedInputStream(is);
            println("request code: " + conn.getResponseCode());
            int length = conn.getContentLength();
            println("content length: " + length);
            if(length > 0){
                byte[] bytes = new byte[length];
                int total = 0;
                int l = -1;
                while((l = br.read(bytes,total,length)) != -1){
                    if((total=l+total)>=length)
                        break;
                }
                String s = new String(bytes,0,total, Charset.forName("ASCII"));
                if(s != null)
                    println(s);
            }
            br.close();

服务器代码：

try{
                        //1、创建ServerSocket对象，指定与客户端一样的端口号
                        final ServerSocket serverSocket = new ServerSocket(8888);
                        serverPort = serverSocket.getLocalPort();
                        isbound  = true;
    
                        new Thread(new Runnable() {
                            @Override public void run() {
                                try (Socket socket = serverSocket.accept();){
                                        System.out.println("server receive from client:");
                                        InputStream is = socket.getInputStream();
                                        int i = -1;
                                        ByteArrayOutputStream headOs = new ByteArrayOutputStream();
                                        ByteArrayOutputStream dataOs = new ByteArrayOutputStream();
                                        ByteArrayOutputStream os = headOs;
                                        int flag = 0;
                                        while((i=is.read())!=-1){
                                            if(os == headOs){
                                                if(i=='\r'){
                                                    if(flag==0)
                                                        flag=1;
                                                    else if(flag==2)
                                                        flag=3;
                                                    else
                                                        flag=0;
                                                }else if(i=='\n'){
                                                    if(flag==1)
                                                        flag=2;
                                                    else if(flag==3){
                                                        flag=4;
                                                        println("has \\r\\n\\r\\n");
                                                    }
                                                }else{
                                                    flag=0;
                                                }
    
                                            }
                                            if(os == dataOs)
                                                println(new String(new char[]{(char)i}));
                                            else
                                                System.out.print(new String(new char[]{(char)i}));
    
                                            if(flag==4){
                                                System.out.flush();
                                                os = dataOs;
                                                flag = 0;
                                                break;
                                            }
    
    
                                            os.write(i);
                                        }
    
                                        String s = new String(dataOs.toByteArray(),Charset.forName("ASCII"));
                                        System.out.print(s);
    
                                        System.out.flush();
                                        System.out.println("server receive from client end");
    
                                        //4、获取输出流，向客户端发送消息回应
                                        OutputStream outputStream = socket.getOutputStream();
                                        PrintWriter writer = new PrintWriter(outputStream);
                                        writer.write("HTTP/1.1 200 OK"+"\r\n");
                                        String data = "reply from server";
                                        writer.write("Content-Length: " + data.length() + "\r\n\r\n");
                                        writer.write(data);
                                        writer.flush();
    
                                } catch (IOException e) {
                                    e.printStackTrace();
                                }finally{
    
                                    try{
                                        if(serverSocket != null)
                                            serverSocket.close();
    
                                    }catch(IOException e){
                                        e.printStackTrace();
                                    }
    
                                }
                            }}).start();
                    }