手机的内外存储卡介绍可以参考博客：http://blog.sina.com.cn/s/blog_5da93c8f0102vcam.html
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test_main_layout);
/**设备管理器*/
StorageManager storageManager = (StorageManager) getSystemService(Context.STORAGE_SERVICE);
try {
Class<?>[] paramClasses = {};
/**反射实现*/
Method getVolumePathsMethod = StorageManager.class.getMethod("getVolumePaths", paramClasses);
getVolumePathsMethod.setAccessible(true);
Object[] params = {};
Object invoke = getVolumePathsMethod.invoke(storageManager, params);
for (int i = 0; i < ((String[]) invoke).length; i++) {
/** Android.os下的StatFs类主要用来获取文件系统的状态，能够获取sd卡的大小和剩余空间，获取系统内部空间也就是/system的大小和剩余空间等等。*/
StatFs stat = getStatFs(((String[]) invoke)[i]);
Log.i("ldm", ((String[]) invoke)[i] + ":" + calculateSizeInMB(stat));
}
}
catch (Exception e1) {
e1.printStackTrace();
}
}
private StatFs getStatFs(String path) {
try {
return new StatFs(path);
}
catch (Exception e) {
e.printStackTrace();
}
return null;
}
/**计算存储卡的可用容量（单位:M）*/
private float calculateSizeInMB(StatFs stat) {
if (stat != null)
return stat.getAvailableBlocks() * (stat.getBlockSize() / (1024f * 1024f));
return 0.0f;
}
}