SD卡操作（1）

（1）首先要获取SD卡信息，必须先对SD卡有访问权限。
<uses-permission
android:name="android.permission.WRITE_EXTERNAL_STORAGE">
</uses-permission>
（2）然后判断SD卡是否插好，有SD卡才能获取信息,用if语句做判断。
Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
取得SD卡文件的路径：
File path = Environment.getExternalStorageDirectory();
StatFs statfs = new StatFs(path.getPaht());
获取block的Size：
long blockSize = statfs.getBlockSize();
获取block数量：
long totalBlocks = statfs.getBlockCount();
获取空闲的block的数量：
long availBlock = statfs.getAvailableBlocks();
计算总空间的大小和空闲空间的大小：


取得空闲空间大小：
public long getAvailableSize(){
File path = Environment.getExternalStorageDirectory();//取得SD卡文件的路径
StatFs statfs = new StatFs(path.getPaht());
long blockSize = statfs.getBlockSize();
long availBlock = statfs.getAvailableBlocks();
//返回bit大小值
return availBlock * blockSize / 1024 / 1024;
}


获取SD卡大小:
public long getAllSize(){
File path = Environment.getExternalStorageDirectory();//取得SD卡文件的路径
StatFs statfs = new StatFs(path.getPaht());
long blockSize = statfs.getBlockSize();
long totalBlocks = statfs.getBlockCount();
//返回bit大小值
return totalBlocks * blockSize / 1024 / 1024;
}