首先要在AndroidManifest.xml中添加SD卡訪问权限

<!-- 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"/>   

SD卡是否存在

private boolean ExistSDCard() {

  if (android.os.Environment.getExternalStorageState().equals(

    android.os.Environment.MEDIA_MOUNTED)) {

   return true;

  } else

   return false;

 }  

SD卡剩余空间

public long getSDFreeSize(){

     //取得SD卡文件路径

     File path = Environment.getExternalStorageDirectory();

     StatFs sf = new StatFs(path.getPath());

     //获取单个数据块的大小(Byte)

     long blockSize = sf.getBlockSize();

     //空暇的数据块的数量

     long freeBlocks = sf.getAvailableBlocks();

     //返回SD卡空暇大小

     //return freeBlocks * blockSize;  //单位Byte

     //return (freeBlocks * blockSize)/1024;   //单位KB

     return (freeBlocks * blockSize)/1024 /1024; //单位MB

   }   

SD卡总容量

public long getSDAllSize(){

     //取得SD卡文件路径

     File path = Environment.getExternalStorageDirectory();

     StatFs sf = new StatFs(path.getPath());

     //获取单个数据块的大小(Byte)

     long blockSize = sf.getBlockSize();

     //获取全部数据块数

     long allBlocks = sf.getBlockCount();

     //返回SD卡大小

     //return allBlocks * blockSize; //单位Byte

     //return (allBlocks * blockSize)/1024; //单位KB

     return (allBlocks * blockSize)/1024/1024; //单位MB

   }