Question

虽然我按照Android开发者网站上的教程进行操作，但我无法将活动绑定到我的服务。

package com.dieselboris.motioncapture;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.dieselboris.motioncapture.LocalService.LocalBinder;

public class HelloMotionCaptureActivity extends Activity implements OnClickListener {
    private TextView textBox; 
    LocalService mService;
    boolean mBound = false;


    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        textBox = (TextView) findViewById(R.id.textView1);  
    }

    @Override
    protected void onStart() {
        super.onStart();
        // Bind to LocalService NEVER RETURNS TRUE!!!!
        Intent intent = new Intent(this, LocalService.class);
        boolean isBound = bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
        String text = Boolean.toString(isBound);
        textBox.setText(text);

    }

    @Override
    protected void onStop() {
        super.onStop();
        // Unbind from the service
        if (mBound) {
            unbindService(mConnection);
            mBound = false;
        }
    }

    //start the service when clicked
    public void onClick(View v) {

        if (v == startButton)
        {   
             //NEVER IN HERE
             if (mBound) {
                int num = mService.getRandomNumber();
                Toast.makeText(this, "incoming number: " + num, Toast.LENGTH_LONG).show();
            }
            Toast.makeText(this, "the service should run now", Toast.LENGTH_LONG).show();

        }
    }

    /** Defines callbacks for service binding, passed to bindService() */
    private ServiceConnection mConnection = new ServiceConnection() {

        @Override
        public void onServiceConnected(ComponentName className,
                IBinder service) {
            // We've bound to LocalService, cast the IBinder and get LocalService instance
            LocalBinder binder = (LocalBinder) service;
            mService = binder.getService();
            mBound = true;
            if (mBound) {
                // Call a method from the LocalService.
                // However, if this call were something that might hang, then this request should
                // occur in a separate thread to avoid slowing down the activity performance.
                int num = mService.getRandomNumber();
                String text = Integer.toString(num);
                textBox.setText(text);
            }
        }

        @Override
        public void onServiceDisconnected(ComponentName arg0) {
            mBound = false;
        }
    };
}

我尝试连接的服务：

package com.dieselboris.motioncapture;

import java.util.Random;

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;

public class LocalService extends Service {
    // Binder given to clients
    private final IBinder mBinder = new LocalBinder();
    // Random number generator
    private final Random mGenerator = new Random();

    /**
     * Class used for the client Binder.  Because we know this service always
     * runs in the same process as its clients, we don't need to deal with IPC.
     */
    public class LocalBinder extends Binder {
        LocalService getService() {
            // Return this instance of LocalService so clients can call public methods
            return LocalService.this;
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }

    /** method for clients */
    public int getRandomNumber() {
      return mGenerator.nextInt(100);
    }
}

我从模拟器获得以下输出：

错误/ AndroidRuntime（10878）：致命异常：主要   ERROR / AndroidRuntime（10878）：java.lang.NullPointerException
  ERROR / AndroidRuntime（10878）：at com.dieselboris.motioncapture.HelloMotionCaptureActivity.onClick（HelloMotionCaptureActivity.java:66）
  ERROR / AndroidRuntime（10878）：在android.view.View.performClick（View.java:2408）
  ERROR / AndroidRuntime（10878）：在android.view.View $ PerformClick.run（View.java:8817）
  ERROR / AndroidRuntime（10878）：在android.os.Handler.handleCallback（Handler.java:587）
  错误/ AndroidRuntime（10878）：在android.os.Handler.dispatchMessage（Handler.java:92）
  ERROR / AndroidRuntime（10878）：在android.os.Looper.loop（Looper.java:144）
  ERROR / AndroidRuntime（10878）：在android.app.ActivityThread.main（ActivityThread.java:4937）
  ERROR / AndroidRuntime（10878）：at java.lang.reflect.Method.invokeNative（Native Method）

  ERROR / AndroidRuntime（10878）：在java.lang.reflect.Method.invoke（Method.java:521）
  ERROR / AndroidRuntime（10878）：at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:868）
  ERROR / AndroidRuntime（10878）：at com.android.internal.os.ZygoteInit.main（ZygoteInit.java:626)
  ERROR / AndroidRuntime（10878）：at dalvik.system.NativeStart.main（Native Method）

似乎我在服务初始化之前从服务中调用了public方法，或者连接尚未设置。

我仔细地关注了开发者网站上的示例，无法弄清楚我做错了什么。

Answer 1

我的权限设置不正确。

我必须在整个应用程序中插入一个权限，并在应用程序清单中插入“uses-permission”。

没有权限，意图永远不会传递给服务。

无法绑定服务

1 个答案: