/***********************************************
 * 內存管理工具
 *
 * @author chen.lin
 * @version 1.0
 ************************************************/
public class MemoryManager {
  private static final String TAG = "MemoryManager";
  private static final int MAXMEMORY=300*1024*1024;//程序運行的最大內存 模擬器(0-16m)
  /**
   * 判斷系統是否在低內存下運行
   * @param context
   * @return
   */
  public static boolean hasAcailMemory() {
    // 獲取手機內部空間大小
    long memory = getAvailableInternalMemorySize();
    Log.i(TAG, memory+"");
    if (memory < MAXMEMORY) {
      //應用將處于低內存狀態下運行
      return false;
    } else {
      return true;
    }
  }
  /**
   * 獲取手機內部可用空間大小
   *
   * @return
   */
  @SuppressWarnings("deprecation")
  public static long getAvailableInternalMemorySize() {
    File path = Environment.getDataDirectory();// 獲取 Android 數據目錄
    StatFs stat = new StatFs(path.getPath());// 一個模擬linux的df命令的一個類,獲得SD卡和手機內存的使用情況
    long blockSize = stat.getBlockSize();// 返回 Int ，大小，以字節為單位，一個文件系統
    long availableBlocks = stat.getAvailableBlocks();// 返回 Int ，獲取當前可用的存儲空間
    return availableBlocks * blockSize;
  }
  /**
   * 獲取手機內部空間大小
   *
   * @return
   */
  @SuppressWarnings("deprecation")
  public static long getTotalInternalMemorySize() {
    File path = Environment.getDataDirectory();
    StatFs stat = new StatFs(path.getPath());
    long blockSize = stat.getBlockSize();
    long totalBlocks = stat.getBlockCount();// 獲取該區域可用的文件系統數
    return totalBlocks * blockSize;
  }
  /**
   * 獲取手機外部可用空間大小
   *
   * @return
   */
  @SuppressWarnings("deprecation")
  public static long getAvailableExternalMemorySize() {
    if (externalMemoryAvailable()) {
      File path = Environment.getExternalStorageDirectory();
      StatFs stat = new StatFs(path.getPath());
      long blockSize = stat.getBlockSize();
      long availableBlocks = stat.getAvailableBlocks();
      return availableBlocks * blockSize;
    } else {
      throw new RuntimeException("Don't have sdcard.");
    }
  }
  /**
   * 獲取手機外部空間大小
   *
   * @return
   */
  @SuppressWarnings("deprecation")
  public static long getTotalExternalMemorySize() {
    if (externalMemoryAvailable()) {
      File path = Environment.getExternalStorageDirectory();// 獲取外部存儲目錄即 SDCard
      StatFs stat = new StatFs(path.getPath());
      long blockSize = stat.getBlockSize();
      long totalBlocks = stat.getBlockCount();
      return totalBlocks * blockSize;
    } else {
      throw new RuntimeException("Don't have sdcard.");
    }
  }
  /**
   * 外部存儲是否可用
   *
   * @return
   */
  public static boolean externalMemoryAvailable() {
    return android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);
  }
}