Android数据持久化之File机制分析

package com.example.data_file;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
@SuppressLint("SdCardPath")
public class MainActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    try {
      File file = new File("/data/data/com.example.data_file/file.txt");
      Log.v("path=", file.getAbsolutePath());
      file.createNewFile();
      FileOutputStream fos = new FileOutputStream(file);
      fos.write("乌拉啦啦啦".getBytes());
      fos.close();
      FileInputStream fis = new FileInputStream(file);
      InputStreamReader isReader = new InputStreamReader(fis);
      char[] charArray = new char[2];
      int readLength = isReader.read(charArray);
      StringBuffer sb = new StringBuffer();
      while(readLength != -1)
      {
        sb.append(charArray, 0, readLength);
        readLength = isReader.read(charArray);
      }
      Log.v("file.txt文件内容是：", sb.toString());
      fis.close();
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
  @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;
  }
}