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：

    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;            }                }