Android传递字符串到onbind服务导致崩溃

Question

我想从我的MainActivity传递一个字符串到我的ServiceAdapter类使用binder类。该应用程序只需将写入EditText的内容称为one，然后将该字符串传递给ServiceAdapter，然后将该字符串写入文本文件中。我遇到的问题是，如果仅从ServiceAdapter类调用方法，而不管方法内部是什么，则会发生致命异常错误。我甚至创建了一个只打印“hello world”并且崩溃的方法。所以我不确定这里有什么问题，任何帮助表示赞赏。谢谢

//主要活动

Button BtnStart, BtnStop; 
    EditText Edt; 
    TextView one; 
    ServiceAdapter mService; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     BtnStart = (Button)findViewById(R.id.button1); 
     BtnStop = (Button) findViewById(R.id.button2); 
     Edt = (EditText) findViewById(R.id.editText1); 
     one = (TextView) findViewById(R.id.textView1); 

    } 

    public String GetText() 
    { 
     String Text = this.Edt.getText().toString(); 
     return Text; 
    } 
    public void StartService(View v){ 
     //start Service 
     //startService(new Intent(getBaseContext(), ServiceAdapter.class)); 
     Intent i = new Intent(this,ServiceAdapter.class); 
     bindService(i, sc, Context.BIND_AUTO_CREATE); 
     Toast.makeText(getBaseContext(), "Service has been binded", Toast.LENGTH_LONG).show(); 
     this.mService.StringToFile(GetText()); 
     Toast.makeText(getBaseContext(), "Text Written", Toast.LENGTH_LONG).show(); 
    } 

    public void StopService(View v){ 
     //stop service 
     unbindService(sc); 
     Toast.makeText(getBaseContext(), "Service has been unbinded", Toast.LENGTH_LONG).show(); 



    } 

    private ServiceConnection sc = new ServiceConnection() 
    { 
     @Override 
     public void onServiceDisconnected(ComponentName name) 
     { 

     } 

     @Override 
     public void onServiceConnected(ComponentName name, IBinder service) 
     { 
      LocalBinder binder = (LocalBinder) service; 
      mService = binder.getService(); 
     } 
    }; 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.main, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 
     if (id == R.id.action_settings) { 
      return true; 
     } 
     return super.onOptionsItemSelected(item); 
    } 




} 

// serviceAdapter

package com.example.modulefour; 

import java.io.BufferedWriter; 
import java.io.File; 
import java.io.FileWriter; 
import java.io.IOException; 

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

public class ServiceAdapter extends Service { 

    private final IBinder mBinder = new LocalBinder(); 
    MainActivity main; 
    FileWriter fw; 
    BufferedWriter bw; 

    @Override 
    public IBinder onBind(Intent arg0) { 
     // TODO Auto-generated method stub 
     return mBinder; 
    } 

    //create new class to call binder 
    public class LocalBinder extends Binder{ 
     public ServiceAdapter getService(){ 
      return ServiceAdapter.this; 
     } 
    } 
    public void StringToFile(String x){ 
     //write EditText to text file 
     String Text = x; 
     if(!Text.trim().equals("")) 
     { 
      File file = new File("TextFile.txt"); 

      //if file doesn't exist, then create it 
      if(!file.exists()) 
      { 
       try { 
        file.createNewFile(); 
       } catch (IOException e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
       } 
      } 

      //write file 
      try { 
       fw = new FileWriter(file.getName(),true); 
       bw = new BufferedWriter(fw); 
       bw.write(Text); 
       bw.close(); 

      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
     } 




    } 


} 

Answer 1

，当你调用

bindService(i, sc, Context.BIND_AUTO_CREATE); 

这就是为什么你有这样的一块业务不会立即开始代码：

private ServiceConnection sc = new ServiceConnection() 
{ 
    @Override 
    public void onServiceDisconnected(ComponentName name) 
    { 

    } 

    @Override 
    public void onServiceConnected(ComponentName name, IBinder service) 
    { 
     LocalBinder binder = (LocalBinder) service; 
     mService = binder.getService(); 
    } 
}; 

正如您所看到的，您可以在onServiceConnected中获得对服务的引用，并且您可以安全地调用mService的方法。 尝试添加：

this.mService.StringToFile(GetText()); 

有：

private ServiceConnection sc = new ServiceConnection() 
{ 
    @Override 
    public void onServiceDisconnected(ComponentName name) 
    { 

    } 

    @Override 
    public void onServiceConnected(ComponentName name, IBinder service) 
    { 
     LocalBinder binder = (LocalBinder) service; 
     mService = binder.getService(); 
     this.mService.StringToFile(GetText()); 
    } 
}; 

（当然，从那里现在取出）