Question

我正在尝试使用binder类将一个字符串从我的MainActivity传递到我的ServiceAdapter类中。应用程序只需将已写入EditText的内容称为one，然后将该字符串传递给ServiceAdapter，ServiceAdapter将接收该字符串并将其写入文本文件。我遇到的问题是，如果我只是调用ServiceAdapter类中的方法，无论方法内部是什么，我都会遇到致命的异常错误。我甚至创建了一个方法，只打印“hello world”并且还会崩溃。所以我不确定这里有什么问题，感谢任何帮助。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

致电

时，服务不会立即启动

bindService(i, sc, Context.BIND_AUTO_CREATE);

这就是你有这段代码的原因：

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，您可以获得onServiceConnected内部服务的引用，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，将它从现在的位置移除）

Android将字符串传递给onbind服务会导致崩溃

1 个答案: