Read/Write SD Files on Android

1. Add permission in AndroidManifest.xml

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"></uses-permission>

 

2. Use this class that i implemented

package smswatcher.cn;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStreamWriter;import android.content.Context;import android.os.Environment;import android.util.Log;public class SDFileMan {private String mFolderPath="";private String mFileName="";public SDFileMan(String fileName){File sdCardDir = Environment.getExternalStorageDirectory();mFileName = fileName;try{mFolderPath = sdCardDir.getCanonicalPath() + "/SMSWatcherLogFolder/";Initialize();}catch(Exception e){} }private File Initialize() throws IOException{File folder = new File(mFolderPath);if(!folder.exists()){folder.mkdirs();}File file = new File((GetFileFullPath()));if(!file.exists()){file.createNewFile();}return file;}public boolean Exists(){File file = new File((GetFileFullPath()));return file.exists();}public boolean saveAppend(String content){try{File file = Initialize();FileOutputStream outputStream = new FileOutputStream(file, true);outputStream.write(content.getBytes());outputStream.close();return true;}catch(Exception e){return false;}}public boolean deleteFile(){try{File file = new File((GetFileFullPath()));if(file.exists()){file.delete();}return true;}catch(Exception e){return false;}}public boolean saveAppendLine(String content){byte[] c = new byte[2];c[0]=0x0d;c[1]=0x0a;String c_string = new String(c);return saveAppend(content + c_string);}public String readFile()      {  try{File file = new File(GetFileFullPath());        //获得输入流          FileInputStream inStream = new FileInputStream(file);        //new一个缓冲区          byte[] buffer = new byte[1024];          int len = 0;          //使用ByteArrayOutputStream类来处理输出流          ByteArrayOutputStream outStream = new ByteArrayOutputStream();          while( (len = inStream.read(buffer))!= -1)          {              //写入数据              outStream.write(buffer, 0, len);          }          //得到文件的二进制数据          byte[] data = outStream.toByteArray();          //关闭流          outStream.close();          inStream.close();          return new String(data);}catch(Exception e){return null;}    }public long getFileUpdateTime(){File f = new File(GetFileFullPath());if(f.exists())return f.lastModified();elsereturn -1;}private String GetFileFullPath(){return mFolderPath + mFileName;}}

 

3. Usage:

SDFileMan mFileMan= new SDFileMan("My.log");boolean flag = mFileMan.saveAppendLine("哈哈啊哈哈");