如何将EditText作为Json的输入发送到Java服务器？

Question

Recently I have done my first client-server project. It is cool actually but i have a little problem. There is no message but I wanted to have JSON with name and password full field. I am using GSON jar library for JsonObject .

My Server

public class Server extends Thread {

private static final int port = 8607;
protected static String server_IP;

public static void main(String[] args)  {


    try {
        InetAddress iAddress = InetAddress.getLocalHost();
        server_IP = iAddress.getHostAddress();
        System.out.println("Server IP : " + server_IP);

    } catch (UnknownHostException e){

    }

    try {
        //Server
        ServerSocket serverSocket = new ServerSocket(port);
        System.out.println("Server has started");

        //Accepting client
        System.out.println("Waiting");
        Socket socket = serverSocket.accept();
        System.out.println("Client has been added");

        //Send message to client
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
        bw.write("Connection accepted");
        bw.newLine();
        bw.flush();

        //receive json from client
        BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        String json_string = br.readLine();
        JsonParser jsonParser = new JsonParser();
        JsonObject user = jsonParser.parse(json_string).getAsJsonObject();

        System.out.println("JSON: " +user.toString());

    } catch (IOException e) {
        e.printStackTrace();
    }

 }
}

My server console

Server IP : 192.168.123.2
Server has started
Waiting
Client has been added
JSON: {"name":""}

Process finished with exit code 0

And my Android app

public class MainActivity extends AppCompatActivity {

    private EditText editName;
    private EditText editPassword;
    private Button send_todata;
    private ProgressBar progressBar;
    private Button category;
    private TextView output;
    private Socket socket;
    private String name;
    private String password;
    private static final String debug = "debug";
    private static final String info = "INFO";
    protected static String server_IP = "192.168.0.101";
    protected static final int server_Port = 8607;
    private static final String result = "";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        editName = (EditText) findViewById(R.id.user_name);
        editPassword = (EditText) findViewById(R.id.user_password);
        send_todata = (Button) findViewById(R.id.button_submit);
        progressBar = (ProgressBar) findViewById(R.id.login_progress);
        output = (TextView) findViewById(R.id.output);
        name = editName.getText().toString();
        password = editPassword.getText().toString();

        send_todata.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                new SendDataToServer().execute(name,password);
            }
        });

        category = (Button) findViewById(R.id.category);
        category.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this,Items.class);
                startActivity(intent);
            }
        });
    }

    class SendDataToServer extends AsyncTask<String,Void,Void> {

        @Override
        protected void onPreExecute() {
            progressBar.setVisibility(View.VISIBLE);
            output.setText("Connecting ...");
        }

        @Override
        protected Void doInBackground(final String... data) {

            final Thread thread = new Thread(new Runnable() {
                @Override
                public void run() {
                    try {

                        Log.i(debug,"Attempt to connect to server");

                        socket = new Socket(server_IP,server_Port);
                        Log.i(debug,"Connection established");

                        JsonObject user =  new JsonObject();

                        user.addProperty("name", data[0]);
                        user.addProperty("name", data[1]);

                        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
                        bw.write(user.toString());
                        bw.newLine();
                        bw.flush();
                        Log.i(info,"JSON has sent");

                        BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                        br.readLine();
                        Log.i(info,br.readLine());

                    } catch (IOException e) {
                        Log.e(debug,"Failed");
                    }

                }
            });thread.start();
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            progressBar.setVisibility(View.GONE);
            output.setText("");
        }
    }
}

Thanks.

Answer 1

Your problem is here:

name = editName.getText().toString();
password = editPassword.getText().toString();

You are already assigning the name and password variables in the onCreate() method, when you didn't yet have the chance to input any text into the fields. They will always be empty.

What you should do is move those 2 lines inside the onClick(View) method of the click listener. Like so:

send_todata.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        name = editName.getText().toString();
        password = editPassword.getText().toString();

        new SendDataToServer().execute(name, password);
    }
});

This way, you will assign the 2 variables, name and password only when you click the button. At that point you will probably have something inside the 2 input fields.