Android 文件读写，android文件读写,关于Android文件的

Android 文件读写，android文件读写,关于Android文件的

关于Android文件的读写有两种方式

一种是将txt文件当成资源文件放在res/raw或则res/asset文件夹下，raw的文件可以通过R.raw.fileName获得，asset下的文件可以通过AssetManager am = getAssets();am.open(“FileName”);来打开文件。但是如果把文件当成资源文件存放的话，只能读不能写。如果要想写入数据的话，就使用第二种方法

第二种方法从sd卡中读写文件，这样首先要向AndroidManifest.xml中加入两条权限消息

    <!-- 在SDCard中创建与删除文件权限 -->        <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>        <!-- 往SDCard写入数据权限 -->        <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>    

然后将文件操作封装在一个类中，在这里我把它命名为FileOption，先将代码粘贴如下：```java 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", "无内存卡");          }      }    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());          //换行        raf.write(add.getBytes());          raf.writeChar('\n');          raf.close();          return true;      }      /**返回一共有多少条记录      * @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++;          }          //每三行代表一个数据项          //分别是 id title content data level          return count/5;      }}

```