Android：StatFs类 获取系统/sdcard存储空间信息

在存储文件时，为了保证有充足的存储空间大小，通常需要知道系统内部或者sdcard的剩余存储空间大小，这里就需要用到StatFs类。

1. 判断 SDCard 是否存在,并且是否具有可读写权限 

/** 
* 外部存储是否可用 (存在且具有读写权限) 
* @return 
*/ 
staticpublicboolean isExternalStorageAvailable() {  
 return Environment.getExternalStorageState().equals(  
            Environment.MEDIA_MOUNTED);  
}  

     /**
     * 外部存储是否可用 (存在且具有读写权限)
     * @return
     */
    static public boolean isExternalStorageAvailable() {
        return Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED);
    }

2.获取手机系统可用空间大小

/** 
* 获取手机内部可用空间大小 
* @return 
*/ 
staticpubliclong getAvailableInternalMemorySize() {  
    File path = Environment.getDataDirectory();  
    StatFs stat = new StatFs(path.getPath());  
 long blockSize = stat.getBlockSize();  
 long availableBlocks = stat.getAvailableBlocks();  
 return availableBlocks * blockSize;  
}  

    /**
     * 获取手机内部可用空间大小
     * @return
     */
    static public long getAvailableInternalMemorySize() {
        File path = Environment.getDataDirectory();
        StatFs stat = new StatFs(path.getPath());
        long blockSize = stat.getBlockSize();
        long availableBlocks = stat.getAvailableBlocks();
        return availableBlocks * blockSize;
    }

3.获取手机内部总空间大小

/** 
* 获取手机内部空间大小 
* @return 
*/ 
staticpubliclong getTotalInternalMemorySize() {  
    File path = Environment.getDataDirectory();//Gets the Android data directory 
    StatFs stat = new StatFs(path.getPath());  
 long blockSize = stat.getBlockSize();      //每个block 占字节数 
 long totalBlocks = stat.getBlockCount();   //block总数 
 return totalBlocks * blockSize;  
}  

    /**
     * 获取手机内部空间大小
     * @return
     */
    static public long getTotalInternalMemorySize() {
        File path = Environment.getDataDirectory();//Gets the Android data directory
        StatFs stat = new StatFs(path.getPath());
        long blockSize = stat.getBlockSize();      //每个block 占字节数
        long totalBlocks = stat.getBlockCount();   //block总数
        return totalBlocks * blockSize;
    }

4.获取手机外部可用空间大小、获取手机外部总空间大小

/** 
    * 获取手机外部可用空间大小 
    * @return 
    */ 
 staticpubliclong getAvailableExternalMemorySize() {  
 if (isExternalStorageAvailable()) {  
           File path = Environment.getExternalStorageDirectory();//获取SDCard根目录 
           StatFs stat = new StatFs(path.getPath());  
 long blockSize = stat.getBlockSize();  
 long availableBlocks = stat.getAvailableBlocks();  
 return availableBlocks * blockSize;  
       } else {  
 return -1;  
       }  
   }  
 /** 
    * 获取手机外部总空间大小 
    * @return 
    */ 
 staticpubliclong getTotalExternalMemorySize() {  
 if (isExternalStorageAvailable()) {  
           File path = Environment.getExternalStorageDirectory(); //获取SDCard根目录 
           StatFs stat = new StatFs(path.getPath());  
 long blockSize = stat.getBlockSize();  
 long totalBlocks = stat.getBlockCount();  
 return totalBlocks * blockSize;  
       } else {  
 return -1;  
       }  
   }  

 /**
     * 获取手机外部可用空间大小
     * @return
     */
    static public long getAvailableExternalMemorySize() {
        if (isExternalStorageAvailable()) {
            File path = Environment.getExternalStorageDirectory();//获取SDCard根目录
            StatFs stat = new StatFs(path.getPath());
            long blockSize = stat.getBlockSize();
            long availableBlocks = stat.getAvailableBlocks();
            return availableBlocks * blockSize;
        } else {
            return -1;
        }
    }

    /**
     * 获取手机外部总空间大小
     * @return
     */
    static public long getTotalExternalMemorySize() {
        if (isExternalStorageAvailable()) {
            File path = Environment.getExternalStorageDirectory(); //获取SDCard根目录
            StatFs stat = new StatFs(path.getPath());
            long blockSize = stat.getBlockSize();
            long totalBlocks = stat.getBlockCount();
            return totalBlocks * blockSize;
        } else {
            return -1;
        }
    }

注意： 访问SDCard进行文件读写时：

在AndroidManifest.xml中加入访问SDCard的权限如下:

<!-- 在SDCard中创建与删除文件权限 -->

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>

<!-- 往SDCard写入数据权限 -->

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

接着我们在使用SDcard进行读写的时候 会用到Environment类下面的几个静态方法：

1:getDataDirectory() 获取到Android中的data数据目录

2:getDownloadCacheDirectory() 获取到下载的缓存目录

3:getExternalStorageDirectory()     获取到外部存储的目录 一般指SDcard

4:getExternalStorageState()           获取外部设置的当前状态 一般指SDcard,

android系统中对于外部设置的状态，比较常用的是 MEDIA_MOUNTED（SDcard存在且可以进行读写） MEDIA_MOUNTED_READ_ONLY (SDcard存在，只可以进行读操作) 当然还有其他的一些状态，可以在文档中进行查找到。

5:getRootDirectory()                   获取到Android Root路径

6:isExternalStorageEmulated()    返回Boolean值判断外部设置是否有效

7:isExternalStorageRemovable() 返回Boolean值，判断外部设置是否可以移除