Android 文件讀寫

關於Android文件的讀寫有兩種方式

一種是將txt文件當成資源文件放在res/raw或則res/asset文件夾下，raw的文件可以通過R.raw.fileName獲得，asset下的文件可以通過AssetManager am = getAssets();am.open(“FileName”);來打開文件。但是如果把文件當成資源文件存放的話，只能讀不能寫。如果要想寫入數據的話，就使用第二種方法

第二種方法從sd卡中讀寫文件，這樣首先要向AndroidManifest.xml中加入兩條權限消息

 

然後將文件操作封裝在一個類中，在這裡我把它命名為FileOption，先將代碼粘貼如下：

 

 

package com.example.littleapplication;

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 java.util.Vector;

import android.os.Environment;
import android.util.Log;

public class FileOption {
	private String fileName;
	private File targetFile;
	private File sdCardDir;
	
	public FileOption(String fileName) throws IOException {
		// TODO Auto-generated constructor stub
		boolean mark = Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
		if(mark)
		{
			this.fileName = fileName;
			this.sdCardDir = Environment.getExternalStorageDirectory();
			this.targetFile = new File(this.sdCardDir.getCanonicalPath()+this.fileName);	
			if(this.targetFile.exists()==false)
			{
				this.targetFile.createNewFile();
			}
		}
		else{
			Log.e(SDK, 無內存卡);
		}
	}

		
		
		
	

	public Vector read() throws FileNotFoundException, IOException {
		
		FileInputStream fis = new FileInputStream(this.sdCardDir.getCanonicalPath()+this.fileName);
		BufferedReader br = new BufferedReader(new InputStreamReader(fis));
		Vector res = new Vector();
		String line = null;
		while((line = br.readLine())!=null)
		{
			res.add(line);
		}
		br.close();
		return res;
		// TODO Auto-generated method stub
	}
	public boolean write(String add) throws IOException
	{
		RandomAccessFile raf = new RandomAccessFile(this.targetFile,rw);
		raf.seek(targetFile.length());
		//換行
		
		raf.write(add.getBytes());
		raf.writeChar('
');
		raf.close();
		return true;
	}
	/**返回一共有多少條記錄
	 * @throws IOException 
	 * @throws FileNotFoundException */
	public int size() throws FileNotFoundException, IOException
	{
		FileInputStream fis = new FileInputStream(this.sdCardDir.getCanonicalPath()+this.fileName);
		BufferedReader br = new BufferedReader(new InputStreamReader(fis));
		String line = null;
		int count = 0;
		while((line = br.readLine())!=null)
		{
			count++;
		}
		//每三行代表一個數據項
		//分別是 id title content data level
		return count/5;
	}

}