如何检查外部存储空间的可用性？

Question

如何检查SD卡是否已满,以便您的应用程序可以决定是否可以继续执行其工作,即写入外部存储器或通知用户存储空间不足.

Answer 1

在新设备上注意StatFs和int溢出

此答案中 的方法在具有大型外部存储的设备上被破坏.例如,在我的Nexus 7上,它实际上返回~2 GB,实际上还剩下大约10 GB的空间.

// DOES NOT WORK CORRECTLY ON DEVICES WITH LARGE STORAGE DUE TO INT OVERFLOW
File externalStorageDir = Environment.getExternalStorageDirectory();
StatFs statFs = new StatFs(externalStorageDirectory.getAbsolutePath());  
int free = (statFs.getAvailableBlocks() * statFs.getBlockSize()) / 1024 / 1024;

的statfs确实有替代方法返回long,getAvailableBlocksLong()和getBlockCountLong(),但问题是,他们是在只增加API等级18.

请改用它

最简单的方法是getFreeSpace()在java.io.File中使用,在API级别9中添加,它返回long:

返回包含此路径的分区上的空闲字节数.如果此路径不存在,则返回0.

因此,要获得外部存储空间("SD卡")的可用空间:

File externalStorageDir = Environment.getExternalStorageDirectory();
long free = externalStorageDir.getFreeSpace() / 1024 / 1024;

或者,如果您确实想使用StatF但需要支持API级别<18,这将修复整数溢出:

File externalStorageDir = Environment.getExternalStorageDirectory();
StatFs statFs = new StatFs(externalStorageDir.getAbsolutePath());  
long blocks = statFs.getAvailableBlocks();
long free = (blocks * statFs.getBlockSize()) / 1024 / 1024;

Answer 2

/******************************************************************************************
Returns size in MegaBytes.

If you need calculate external memory, change this: 
   StatFs statFs = new StatFs(Environment.getRootDirectory().getAbsolutePath());
to this: 
   StatFs statFs = new StatFs(Environment.getExternalStorageDirectory().getAbsolutePath());

******************************************************************************************/
    public long totalMemory()
    {
        StatFs statFs = new StatFs(Environment.getRootDirectory().getAbsolutePath());   
        long   total  = (statFs.getBlockCount() * statFs.getBlockSize()) / 1048576;
        return total;
    }

    public long freeMemory()
    {
        StatFs statFs = new StatFs(Environment.getRootDirectory().getAbsolutePath());
        long   free   = (statFs.getAvailableBlocks() * statFs.getBlockSize()) / 1048576;
        return free;
    }

    public long busyMemory()
    {
        StatFs statFs = new StatFs(Environment.getRootDirectory().getAbsolutePath());   
        long   total  = (statFs.getBlockCount() * statFs.getBlockSize()) / 1048576;
        long   free   = (statFs.getAvailableBlocks() * statFs.getBlockSize()) / 1048576;
        long   busy   = total - free;
        return busy;
    }

Answer 3

使用StatFs和外部存储目录的路径传递给构造函数,你可以调用的功能,如getAvailableBlocks()与getBlockSize()上StatFs对象.