android内存管理工具类

    public class MemoryManager {  
        private static final String TAG = "MemoryManager";  
        private static final int MAXMEMORY=50*1024*1024;//程序运行的最大内存  
        /** 
         * 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 
         */  
        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 
         */  
        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 
         */  
        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 
         */  
        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);  
        }  
    }