android Q版本外部存储问题以及获取空间大小问题

Q版本：

1.在manifest 文件中添加权限





2.在application 添加

android:requestLegacyExternalStorage="true"

3.在对应的activity中添加 动态获取权限

private fun applyStoragePermission () {
        val permissionWrite = ContextCompat.checkSelfPermission(applicationContext, WRITE_EXTERNAL_STORAGE)
        val permissionRead = ContextCompat.checkSelfPermission(applicationContext, READ_EXTERNAL_STORAGE)

        if (permissionWrite != PackageManager.PERMISSION_GRANTED || permissionRead != PackageManager.PERMISSION_GRANTED) {
            //Toast.makeText(this, "正在请求权限", Toast.LENGTH_SHORT).show()
            //申请权限，特征码自定义为1，可在回调时进行相关判断
            ActivityCompat.requestPermissions(
                this@MainActivity,
                arrayOf(WRITE_EXTERNAL_STORAGE, READ_EXTERNAL_STORAGE),1)
        }
    }

获取存储空间：Environment.getExternalStorageDirectory();

判断有sd卡存储存在或者加载

Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED

/** 得到SD可用内存 **/
@SuppressLint("NewApi")
private String getSdFree(){
	if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){ 
		StatFs fs = new StatFs(Environment.getExternalStorageDirectory().getPath());
		//Android API18之前：fs.getAvailableBlocks()*fs.getBlockSize()
		return Formatter.formatFileSize(this, (fs.getAvailableBytes()));
	}
	return "未装载";
}

获取手机默认内置存储空间：

/** 得到系统可用内存 **/
@SuppressLint("NewApi")
private String getMemFree(){
    StatFs fs = new StatFs(Environment.getDataDirectory().getPath());
    return Formatter.formatFileSize(this, (fs.getAvailableBytes()));
}