public class MainActivity extends AppCompatActivity {
      String TAG = MainActivity.class.getCanonicalName();     @Override     protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);         String storageState = Environment.getExternalStorageState();         //sd卡的状态         Log.e(TAG, "onCreate: "+storageState );         Log.e(TAG, "onCreate: "+Environment.MEDIA_MOUNTED );         //判断是否有sd卡         boolean equals = Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState());         Log.e(TAG, "onCreate: "+equals);         //得到sd卡的路径         String absolutePath = Environment.getExternalStorageDirectory().getAbsolutePath();         Log.e(TAG, "onCreate: "+absolutePath );         //得到内置sd卡内所有的文件         File file = Environment.getExternalStorageDirectory();         File[] files = file.listFiles();         for (int i = 0; i < files.length; i++) {
              Log.e(TAG, "onCreate: "+files[i] );         }         long freeSpace = Environment.getExternalStorageDirectory().getFreeSpace();         long usableSpace = Environment.getExternalStorageDirectory().getUsableSpace();         long totalSpace = Environment.getExternalStorageDirectory().getTotalSpace();         Log.e(TAG, "onCreate: 剩余空间大小："+freeSpace/1024/1024+" 可用大小:"+usableSpace/1024/1024+" 总空间大小:"+totalSpace/1024/1024 );     } } demo下载地址：https://github.com/renjiemei1225/ExtraTest