Android开发 文件读写openFileOutput与openFileInput

package com.example.androidtest;

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends Activity{
    String filestr="你好吗";
    String str = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if(fileWrite(filestr)){//写入文件
            Log.i("info","写入成功,正在读取文件");
            str=fileRead();//从文件读取
        }

    }

    //写入文件
    public boolean fileWrite(String filestr){
        boolean flag=false;
        try {
            FileOutputStream fos = openFileOutput("a.txt",MODE_PRIVATE);
            fos.write(filestr.getBytes());
            fos.close();
            flag=true;
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return flag;

    }

    //读取文件内容
    public String fileRead(){
        String content = null;
        try {
            FileInputStream fis = openFileInput("a.txt");
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len=0;
            while((len=fis.read(buffer))!=-1){
                baos.write(buffer,0,len);
            }
            content = baos.toString();
            fis.close();
            baos.close();

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

}