Android往SD卡上存储文件

 public class DataActivity extends Activity {  
    private EditText filenameText;  
    private EditText contentText;  
    private TextView resultView;  
    private static final String TAG = "DataActivity";  
    /** Called when the activity is first created. */ 
    @Override 
        public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
        filenameText = (EditText) this.findViewById(R.id.filename);  
        contentText = (EditText) this.findViewById(R.id.content);  
        resultView = (TextView) this.findViewById(R.id.result);  
        String filename = filenameText.getText().toString();  
        Button button = (Button) this.findViewById(R.id.button);  
        Button showButton = (Button) this.findViewById(R.id.showButton);  
        button.setOnClickListener(listener);  
        showButton.setOnClickListener(listener);  
    }  
      
    private View.OnClickListener listener = new View.OnClickListener() {   
        @Override 
            public void onClick(View v) {  
            Button button = (Button) v;  
            String filename = filenameText.getText().toString();  
            switch(button.getId()){  
            case R.id.button://如果是保存按钮  
                int resId = R.string.success;  
                  
                String content = contentText.getText().toString();  
                File file = new File(Environment.getExternalStorageDirectory(),filename);  
                if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){  
                    try {  
                        //OutputStream outStream = DataActivity.this.openFileOutput(filename, Context.MODE_WORLD_WRITEABLE+Context.MODE_WORLD_READABLE);  
                        //四中操作模式  
                        //Context.MODE_PRIVATE=0 覆盖、私有  
                        //Context.MODE_APPEND=32768追加、私有  
                        //Context.MODE_WORLD_READABLE=1其他的程序可以访问  
                        //Context.MODE_WORLD_WRITEABLE=2  
                        //Environment.getExternalStorageDirectory()==new file("/sdcard")  
                          
                          
                        FileOutputStream outStream = new FileOutputStream(file);  
                        try {  
                            FileService.save(outStream, content);  
                        } catch (Exception e) {  
                            Log.e(TAG, e.toString());  
                            resId = R.string.error;  
                        }  
                    } catch (FileNotFoundException e) {  
                        Log.e(TAG, e.toString());  
                        resId = R.string.error;  
                    }  
                    Toast.makeText(DataActivity.this, resId, Toast.LENGTH_LONG).show();  
                }  
                else{  
                    Toast.makeText(DataActivity.this,"SD卡不存在或者写保护", Toast.LENGTH_LONG).show();  
                }  
                break;  
            case R.id.showButton://如果是显示按钮  
                try {  
                    InputStream inStream = DataActivity.this.openFileInput(filename);  
                    String text = FileService.read(inStream);  
                    resultView.setText(text);  
                } catch (Exception e) {  
                    Log.e(TAG, e.toString());  
                    resId = R.string.error;  
                    Toast.makeText(DataActivity.this, "读取失败", Toast.LENGTH_LONG).show();  
                }  
                  
                break;  
            }  
        }  
    };  
      
}