<!-- 在SDCard 的挂载权限 -->
<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"/>

import java.io.File; 
import android.os.Environment; 
import android.os.StatFs; 
public class SDTool { 
  private static SDTool tool = null; 
  // 检查SD卡是否挂载 
  public boolean SD_EXIST = false; 
  private SDTool() { 
  } 
  public static SDTool instance() { 
    if (tool == null) { 
      synchronized (SDTool.class) { 
        if (tool == null) { 
          tool = new SDTool(); 
          tool.SD_EXIST = Environment.MEDIA_MOUNTED 
              .equals(Environment.getExternalStorageState()); 
        } 
      } 
    } 
    return tool; 
  } 
  public long getSDFreeSize() { 
    // 取得SD卡文件路径 
    File path = Environment.getExternalStorageDirectory(); 
    StatFs sf = new StatFs(path.getPath()); 
    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 
  } 
  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 
  } 
}