Android File文件的讀寫操作

Android File文件的讀寫操作，本程序實現兩個文本框和兩個按鈕，其中一個文本框和一個按鈕用於讀取文件內容、另一個文本框和另一個按鈕用於寫入。

java代碼：

package com.example.activity;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.RandomAccessFile;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class FileReadWrite extends Activity implements OnClickListener {
private static final String FILE_NAME = "/zhuhuajie.bin";
private EditText readtext;
private EditText writetext;
private Button read;
private Button write;

 @Override
protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.filereadwrite);
 init();
 read.setOnClickListener(this);
 write.setOnClickListener(this);
}
 public void init(){
  readtext=(EditText)findViewById(R.id.readtext);
  writetext=(EditText)findViewById(R.id.writetext);
  read=(Button)findViewById(R.id.read);
  write=(Button)findViewById(R.id.write);
 }

 @Override
 public void onClick(View v)
 {
  switch(v.getId())
  {
  case R.id.read:
   readtext.setText(read());
   break;
  case R.id.write:
   write(writetext.getText().toString());
   writetext.setText("");
   break;
  }

 }
 private String read(){
  try {
  //如果手機插入了SD卡，而且應用程序具有訪問SD的權限
  if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))
  {
   //獲取SD卡對應的存儲目錄
   File sdCardDir=Environment.getExternalStorageDirectory();
   //獲取指定文件對應的輸入流
   
    FileInputStream fis=new FileInputStream(sdCardDir.getCanonicalPath()+FILE_NAME);
    //將指定輸入流包裝成BufferedReader
    BufferedReader br=new BufferedReader(new InputStreamReader(fis));
    StringBuilder sb=new StringBuilder("");
    String line=null;
    while((line=br.readLine())!=null)
    {
     sb.append(line);
    }
    return sb.toString();
   }
  }catch (Exception e)
   {
   
    e.printStackTrace();
   }
  return null;
 }
 
 private void write(String content)
 {
  try
  {
   if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))
   {
    File sdCardDir=Environment.getExternalStorageDirectory();
    File targetFile=new File(sdCardDir.getCanonicalPath()+FILE_NAME);
                //以指定文件創建RandomAccessFile對象
    RandomAccessFile raf=new RandomAccessFile(targetFile,"rw");
    //將文件記錄指針移動到最後
    raf.seek(targetFile.length());
    //輸出文件內容
    raf.write(content.getBytes());
    raf.close();
   }
  }catch(Exception e)
  {
   e.printStackTrace();
  }
 }

}