/***********************************************
 * 内存管理工具
 *
 * @author chen.lin
 * @version 1.0
 ************************************************/
public class MemoryManager {
  private static final String TAG = "MemoryManager";
  private static final int MAXMEMORY=300*1024*1024;//程序运行的最大内存 模拟器(0-16m)
  /**
   * 判断系统是否在低内存下运行
   * @param context
   * @return
   */
  public static boolean hasAcailMemory() {
    // 获取手机内部空间大小
    long memory = getAvailableInternalMemorySize();
    Log.i(TAG, memory+"");
    if (memory < MAXMEMORY) {
      //应用将处于低内存状态下运行
      return false;
    } else {
      return true;
    }
  }
  /**
   * 获取手机内部可用空间大小
   *
   * @return
   */
  @SuppressWarnings("deprecation")
  public static long getAvailableInternalMemorySize() {
    File path = Environment.getDataDirectory();// 获取 Android 数据目录
    StatFs stat = new StatFs(path.getPath());// 一个模拟linux的df命令的一个类,获得SD卡和手机内存的使用情况
    long blockSize = stat.getBlockSize();// 返回 Int ，大小，以字节为单位，一个文件系统
    long availableBlocks = stat.getAvailableBlocks();// 返回 Int ，获取当前可用的存储空间
    return availableBlocks * blockSize;
  }
  /**
   * 获取手机内部空间大小
   *
   * @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();// 获取该区域可用的文件系统数
    return totalBlocks * blockSize;
  }
  /**
   * 获取手机外部可用空间大小
   *
   * @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.");
    }
  }
  /**
   * 获取手机外部空间大小
   *
   * @return
   */
  @SuppressWarnings("deprecation")
  public static long getTotalExternalMemorySize() {
    if (externalMemoryAvailable()) {
      File path = Environment.getExternalStorageDirectory();// 获取外部存储目录即 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.");
    }
  }
  /**
   * 外部存储是否可用
   *
   * @return
   */
  public static boolean externalMemoryAvailable() {
    return android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);
  }
}