Android套接字异常“套接字关闭”

Question

当我尝试使用下面的代码运行由echo服务器和android客户端组成的测试时，我总是会得到异常msg“套接字已关闭”。这段代码可以简单地将msg发送到服务器，并从服务器接收msg，但是如果您想同时执行这两种操作，它就是不能工作.我很好奇它为什么会导致这样的问题，如果我希望它能够首先将msg发送到echo服务器，我应该如何解决它？

然后从回波服务器接收消息？

            // Server IP address 
            InetAddress serverIp;

            // try to connect Server
            try {

                // set up server IP address
                serverIp = InetAddress.getByName("192.168.17.1");

                // set up port
                int serverPort=12345;

                // initiate socket connection
                Socket clientSocket=new Socket(serverIp,serverPort);

                BufferedOutputStream out = new BufferedOutputStream(clientSocket.getOutputStream());
                out.write("Send From Android1111, stitch ".getBytes());
                out.flush();

                //wait to receive Server's msg 
                BufferedReader  br =new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 

                total.toString();*/
            // Display received msg with Toast
                Toast.makeText(getApplicationContext(), br.readLine(), Toast.LENGTH_SHORT ).show();

            //close connection
                clientSocket.close();             

//              out.close();
//              out = null;
            } catch (IOException e) {
                // display exception with Toast
                Toast.makeText(getApplicationContext(),e.toString(), Toast.LENGTH_SHORT).show();
            }

不幸的是，它仍然不能工作，...I按照您的指示修改代码以：

            // set up Server IP address 
            serverIp = InetAddress.getByName("192.168.2.2");

            // set up Server port
            int serverPort=12345;

            // initiate socket connection
            Socket clientSocket=new Socket(serverIp,serverPort);

                // open input and output stream
            OutputStream out = clientSocket.getOutputStream();
            InputStream in = clientSocket.getInputStream();

            //send msg
            out.write("Send From Android1111, bitch ".getBytes());


                // receive msg from server
            byte[] buffer = new byte[in.available()];
            in.read(buffer);
            String rMsg = new String(buffer);
            Toast.makeText(getApplicationContext(), rMsg, Toast.LENGTH_LONG ).show();

            //close input and output stream
            in.close();
            out.close();

             //關閉連線
       clientSocket.close(); 
        } catch (IOException e) {
            // 出錯後顯示錯誤訊息Toast
            Toast.makeText(getApplicationContext(),e.toString(), Toast.LENGTH_SHORT).show();
        }

为了方便助手，下面是服务器部分的python编写的代码：

# Practice Echo Server Program written in Python
import socket

# host = '' means it binds to any available interface
host = ''
port = 12345

# socket() function returns a socket object whose methods implement the various socket system calls.
s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)

# Bind the socket to address. 
s.bind((host,port))

# Listen for connections made to the socket. The backlog argument specifies 
# the maximum number of queued connections and should be at least 0; 
# the maximum value is system-dependent (usually 5), the minimum value is forced to 0.
s.listen(5)

# Accept a connection. The socket must be bound to an address and listening for 
# connections. The return value is a pair (conn, address) where conn is a new socket 
# object usable to send and receive data on the connection, and address is the address
# bound to the socket on the other end of the connection.
conn, addr = s.accept()
print 'Connected by', addr

# Receive data from the socket. The return value is a string representing the data received.
# The maximum amount of data to be received at once is specified by bufsize. See the Unix
# manual page recv(2) for the meaning of the optional argument flags; it defaults to zero.
# Note For best match with hardware and network realities, the value of bufsize should be 
# a relatively small power of 2, for example, 4096.

while 1:
    data = conn.recv(1024)
    if not data: break 
    print 'received data is : ', repr(data)
    conn.send(data)

conn.close()

Answer 1

我想你做得对，顺序不对。可能是服务器太快了，当您试图读取响应时，它已经接收到并消失了。

遵循教程从插座读取和写入套接字中提供的规则

1. 打开插座
2. 打开输入流并将流输出到套接字。
3. 根据服务器协议从流中读取并写入流。
4. 关闭溪流。
5. 关闭插座。

你看到区别了吗？首先打开输入和输出流，然后开始发送请求。

我相信如果你坚持这份订单，它一定会成功的。

Answer 2

我有一个类似的问题，通过编辑gradle.properties文件来允许代理连接来解决这个问题。我添加了前面的行，就像Nadeem在https://github.com/facebook/react-native/issues/2726上解释的那样

systemProp.http.proxyHost=proxyHost
systemProp.http.proxyPort=proxyPort

systemProp.https.proxyHost=proxyHost
systemProp.https.proxyPort=proxyPort

Answer 3

您的应用程序需要AndroidManifest.xml中的互联网许可

<uses-permission android:name="android.permission.INTERNET"/>