android File存储

这段时间学习android存储，做些记录：

package com.example.actionbar;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.PrintStream;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.security.auth.PrivateCredentialPermission;
import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class SharedPreferencesTest extends Activity{
  final String FILE_NAME = "crazyit.bin";
  SharedPreferences preferences;
  SharedPreferences.Editor editor; 
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    System.out.println(new StringBuilder("a").append("b").append("c").toString());
    //获取两个按钮
    Button read = (Button) findViewById(R.id.readbtn);
    Button write = (Button) findViewById(R.id.writebtn);
    //获取两个文本框
    final EditText edit1 = (EditText) findViewById(R.id.edit1);
    final EditText edit2 = (EditText) findViewById(R.id.edit2);
    //为write按钮绑定事件监听器
    write.setOnClickListener(new OnClickListener() {
      
      @Override
      public void onClick(View arg0) {
        // TODO Auto-generated method stub
        //将edit1中的内容写入文件中
        Write(edit1.getText().toString());
        edit1.setText("");
      }
    });
    read.setOnClickListener(new OnClickListener() {
      
      @Override
      public void onClick(View arg0) {
        // TODO Auto-generated method stub
        //读取指定文件中内容，并显示出来
        edit2.setText(Read());
      }
    });
  }
  private String Read(){
    try {
      System.out.println("Read function");
      //打开文件输入流
      FileInputStream fis = openFileInput(FILE_NAME);
      byte [] buff = new byte[1024];
      int hasRead = 0;
      StringBuffer sb = new StringBuffer("");
      //读取文件内容
      while((hasRead = fis.read(buff)) > 0){
        sb.append(new String(buff, 0, hasRead));
      }
      //关闭文件输入流
      fis.close();  
      System.out.println(sb.toString());
      return sb.toString();
    } catch (Exception e) {
      // TODO: handle exception
    }
    return null;
  }
  private void Write(String content){
    try {
      //以追加模式打开文件输入流
      FileOutputStream fos = openFileOutput(FILE_NAME, MODE_APPEND);
      //将FileOutputStream包装成PrintStream
      PrintStream ps = new PrintStream(fos);
      //输出文件内容
      ps.println(content);
      //关闭文件
      ps.close();
    } catch (Exception e) {
      // TODO: handle exception
    }
  }
}