判断SD卡是否存在及容量查询的简单方法如下：

首先要在AndroidManifest.xml中增加SD卡访问权限

<!-- 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();
     //空闲的数据块的数量
     long freeBlocks = sf.getAvailableBlocks();
     //返回SD卡空闲大小
     //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

[java]

      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();
     //获取所有数据块数
     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
   }