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通过蓝牙在android应用程序之间交换消息

bluetooth android java
  •  1
  • dileepVikram  · 技术社区  · 6 年前

    我遵循了下面的示例程序URL。它曾经通过android应用程序向配对的蓝牙设备发送信息。

    https://stackoverflow.com/a/22899728/1559331

    IOException: read failed, socket might closed - Bluetooth on Android 4.3

    代码试图做的是

    1) 连接到配对设备并将数据写入outputstream。要写入的数据取自edittext

    2) 该代码还以edittext格式显示inputstream中的数据

    在设备上测试时, 我可以看到我能够连接并将数据写入outputstream,但无法读取它。甚至连阅读按钮onclick都不起作用

    main_activity_xml——用于用户界面的xml 

    <?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="wrap_content" android:orientation="horizontal"
    android:layout_width="fill_parent">
    <EditText
            android:id="@+id/editText"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:layout_width="fill_parent"

            android:inputType="number"
            />

        <Button
            android:id="@+id/button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"

            android:text="Submit"/>

<EditText
            android:id="@+id/editText2"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_width="fill_parent"


             />

        <Button
            android:id="@+id/button2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"

            android:text="Read"
             />
</LinearLayout>

    主要活动。java-主活动类 

    package com.example.dileep.blutooth_messenger;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.graphics.Color;
import android.graphics.EmbossMaskFilter;
import android.graphics.PointF;
import android.os.ParcelUuid;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.InputFilter;
import android.text.format.DateUtils;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TimePicker;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.lang.reflect.Method;
import java.util.Scanner;
import java.util.Set;
import java.util.UUID;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        final BluetoothSocketWrapper bluetoothSocketWrapper=new BluetoothSocketWrapper(getApplicationContext());

         et = (EditText) findViewById(R.id.editText);
        et.setFilters(new InputFilter[]{ new InputFilterMinMax("1", "100")});
        final Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                if (bluetoothSocketWrapper.getSocket() != null) {
                    if (!bluetoothSocketWrapper.isConnected()) {
                        bluetoothSocketWrapper.init();
                    }
                    try {
                        bluetoothSocketWrapper.getOutputStream().write(et.getText().toString().getBytes());
                    } catch (Exception e) {
                        Toast.makeText(getApplicationContext(), "Exception while writing to output stream-->" + e.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                    finally {
                        try {  bluetoothSocketWrapper.getOutputStream().close();}
                        catch (Exception e) {
                            Toast.makeText(getApplicationContext(), "Exception whileclosing output stream-->" + e.getMessage(), Toast.LENGTH_SHORT).show();
                        }
                    }
                    Toast.makeText(getApplicationContext(), "Writing completed", Toast.LENGTH_SHORT).show();

                }
                else{
                    Toast.makeText(getApplicationContext(), "Not able to connect", Toast.LENGTH_SHORT).show();
                }
            }
        });
        et2 = (EditText) findViewById(R.id.editText2);
        final Button button2 = (Button) findViewById(R.id.button2);
        Toast.makeText(getApplicationContext(), "just beofre 2 nd listner", Toast.LENGTH_SHORT).show();
        button2.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Toast.makeText(getApplicationContext(), "second listener", Toast.LENGTH_SHORT).show();
                if(bluetoothSocketWrapper.getSocket()!=null){
                    if(!bluetoothSocketWrapper.isConnected()) {
                        bluetoothSocketWrapper.init();
                    }


                StringBuilder builder=new StringBuilder();
                Scanner s = null;//.useDelimiter("\n");
                try {
                    s = new Scanner(bluetoothSocketWrapper.getInputStream());

                while(s.hasNext()){
                   builder.append(s.next());
                }
                Toast.makeText(getApplicationContext(), builder.toString(), Toast.LENGTH_SHORT).show();
              et2.setText(builder.toString());
              Toast.makeText(getApplicationContext(), "reading completed", Toast.LENGTH_SHORT).show();
                } catch (IOException e) {
                    e.printStackTrace();
                }
               finally {
                        try {  bluetoothSocketWrapper.getInputStream().close();}
                        catch (Exception e) {
                            Toast.makeText(getApplicationContext(), "Exception while closing input stream-->" + e.getMessage(), Toast.LENGTH_SHORT).show();
                        }
                    }
                }
                else{
                    Toast.makeText(getApplicationContext(), "Not able to connect", Toast.LENGTH_SHORT).show();
                }
            }});
    }


    private OutputStream outputStream;
    private InputStream inStream;
    private EditText et;
    private EditText et2;


}

    BluetoothSocketRapper类-->用作蓝牙套接字的包装 

    package com.example.dileep.blutooth_messenger;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Context;
import android.os.ParcelUuid;
import android.util.Log;
import android.widget.Toast;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Method;
import java.net.Socket;
import java.util.Set;
import java.util.UUID;

public class BluetoothSocketWrapper {
    private BluetoothSocket socket = null;
    private OutputStream outputStream;
    private InputStream inStream;
    private Context context = null;

    public BluetoothSocketWrapper(Context context) {
        this.context = context;
        init();
    }

    public void init() {
        BluetoothAdapter blueAdapter = BluetoothAdapter.getDefaultAdapter();
        if (blueAdapter == null) {
            Toast.makeText(context, "Device doesnt Support Bluetooth", Toast.LENGTH_SHORT).show();
        }
        if (blueAdapter != null) {
            if (blueAdapter.isEnabled()) {
                Set<BluetoothDevice> bondedDevices = blueAdapter.getBondedDevices();

                if (bondedDevices.size() > 0) {
                    Object[] devices = (Object[]) bondedDevices.toArray();
                    BluetoothDevice device = (BluetoothDevice) devices[0];
                    ParcelUuid[] uuids = device.getUuids();
                    //  Toast.makeText(context,uuids[0].getUuid().toString(),Toast.LENGTH_LONG).show();
                    //  BluetoothSocket socket=null;
                    try {
                        //socket = device.createRfcommSocketToServiceRecord(uuids[0].getUuid());
                        UUID SERIAL_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
                        socket = device.createRfcommSocketToServiceRecord(SERIAL_UUID);
                    } catch (Exception e) {
                        Toast.makeText(context, "exc with 1st conn", Toast.LENGTH_LONG).show();
                    }
                    try {
                        socket.connect();
                    } catch (Exception e) {
                        Log.e("", e.getMessage());
                        try {
                            Toast.makeText(context, "tryiing fallback", Toast.LENGTH_LONG).show();



                            Class<?> clazz = socket.getRemoteDevice().getClass();
                            Class<?>[] paramTypes = new Class<?>[]{Integer.TYPE};
                            Method m = clazz.getMethod("createRfcommSocket", paramTypes);
                            Object[] params = new Object[]{Integer.valueOf(2)};
                            socket = (BluetoothSocket) m.invoke(socket.getRemoteDevice(), params);
                            socket.connect();
                            Toast.makeText(context, "Connected", Toast.LENGTH_LONG).show();
                        } catch (Exception e2) {

                            Toast.makeText(context, "Couldn't establish Bluetooth connection -->" + e2.getMessage(), Toast.LENGTH_LONG).show();
                        }
                    }

                }

                Log.e("error", "No appropriate paired devices.");
            } else {
                Log.e("error", "Bluetooth is disabled.");
            }
        }

    }
    public boolean isConnected(){
        return this.socket.isConnected();
    }
    public OutputStream getOutputStream() throws IOException {
            return this.socket.getOutputStream();
    }
    public InputStream getInputStream() throws IOException {
        return this.socket.getInputStream();
    }
    public void close() throws IOException {
        this.socket.close();
    }
    public BluetoothSocket getSocket(){
        return socket;
    }
}

    用于edittext的InputFilter类 

    package com.example.dileep.blutooth_messenger;

import android.text.InputFilter;
import android.text.Spanned;

public class InputFilterMinMax implements InputFilter {

    private int min, max;

    public InputFilterMinMax(int min, int max) {
        this.min = min;
        this.max = max;
    }

    public InputFilterMinMax(String min, String max) {
        this.min = Integer.parseInt(min);
        this.max = Integer.parseInt(max);
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        try {
            int input = Integer.parseInt(dest.toString() + source.toString());
            if (isInRange(min, max, input))
                return null;
        } catch (NumberFormatException nfe) { }
        return "";
    }

    private boolean isInRange(int a, int b, int c) {
        return b > a ? c >= a && c <= b : c >= b && c <= a;
    }
}

    有人能解释一下为什么应用程序和设备被挂了吗。另外,请建议所需的更改

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