Android获取手机内存

public boolean externalMemoryAvailable(){  

     return android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);  

    }

    public 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/(1024*1024);//返回单位 M  

           }  

           else{  

               return -1;  

           }  

    }