Android开发之从文件中读取数据

package com.example.filepersistencetest;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.text.TextUtils;
import android.view.Menu;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

private EditText edit;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
edit=(EditText)findViewById(R.id.edit);
String inputText=load();
if(!TextUtils.isEmpty(inputText)){
edit.setText(inputText);
edit.setSelection(inputText.length());
Toast.makeText(this, "Restoring succeeded", Toast.LENGTH_SHORT).show();
}
}

@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;
}
protected void onDestroy(){
super.onDestroy();
String inputText=edit.getText().toString();
save(inputText);
}

public void save(String inputText)
{
FileOutputStream out=null;
BufferedWriter writer=null;
try{
out=openFileOutput("data",Context.MODE_PRIVATE);
writer=new BufferedWriter(new OutputStreamWriter(out));
writer.write(inputText);
}catch(IOException e)
{
e.printStackTrace();
}finally{
try{
if(writer!=null)
{writer.close();}
}catch(IOException e){
e.printStackTrace();
}
}
}
public String load(){
FileInputStream in=null;
BufferedReader reader=null;
StringBuilder content=new StringBuilder();
try{
in=openFileInput("data");
reader=new BufferedReader(new InputStreamReader(in));
String line="";
while((line=reader.readLine())!=null){
content.append(line);
}
}catch(IOException e)
{
e.printStackTrace();
}finally
{
if(reader!=null){
try{
reader.close();
}catch(IOException e){
e.printStackTrace();
}
}
}
return content.toString();
}
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<EditText
android:id="@+id/edit"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Type something here"
/>

</RelativeLayout>