android - 导出 Room 数据库并附加到电子邮件 Android Kotlin
问题描述
我有以下代码用于导出房间数据库,然后将其附加到电子邮件中。目前,用户首先必须选择他们想要保存数据的位置,然后才能附加数据。
有没有一种方法可以做到这一点,而无需先询问用户将数据库保存在哪里?
这是我的代码:
fun exportDatabase() {
val intent = Intent(Intent.ACTION_CREATE_DOCUMENT)
intent.type = "*/*" // this line is a must when using ACTION_CREATE_DOCUMENT
startActivityForResult(
intent,
DATABASE_EXPORT_CODE
)
}
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data)
when (requestCode) {
DATABASE_EXPORT_CODE -> {
val userChosenUri = data?.data
val inStream = getDatabasePath("app_database").inputStream()
val outStream = userChosenUri?.let { contentResolver.openOutputStream(it) }
inStream.use { input ->
outStream.use { output ->
output?.let { input.copyTo(it) }
Toast.makeText(this, "Data exported successfully", Toast.LENGTH_LONG).show()
val emailIntent = Intent(Intent.ACTION_SEND)
//Set type to email
emailIntent.type = "vnd.android.cursor.dir/email"
var toEmail: String = "whatever@gmail.com"
emailIntent.putExtra(Intent.EXTRA_EMAIL, toEmail)
emailIntent.putExtra(Intent.EXTRA_STREAM, userChosenUri)
emailIntent.putExtra(Intent.EXTRA_SUBJECT, "Data for Training Log")
startActivity(Intent.createChooser(emailIntent, "Send Email"))
}
}
}
else ->
Log.d("D001", "onActivityResult: unknown request code")
}
}
解决方案
您需要使用FileProvider。但FileProvider
不支持直接传输数据库文件(在此处查看)。
这可以通过以下方式处理:
解决方案1:
创建一个FileProvider
支持复制数据库文件的自定义类:
class DBFileProvider : FileProvider {
fun getDatabaseURI(c: Context, dbName: String?): Uri? {
val file: File = c.getDatabasePath(dbName)
return getFileUri(c, file)
}
private fun getFileUri(context: Context, file: File): Uri? {
return getUriForFile(context, "com.android.example.provider", file)
}
}
并请求FileProvider
清单:
<application>
....
<provider
android:name="androidx.core.content.FileProvider"
android:authorities="com.android.example.provider"
android:exported="false"
android:enabled="true"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/provider_paths" />
</provider>
</application>
并provider_paths
在下创建res\xml
<?xml version="1.0" encoding="utf-8"?>
<paths>
<files-path
name="databases"
path="../" />
</paths>
然后通过电子邮件发送此数据库文件:
public static void backupDatabase(AppCompatActivity activity) {
Uri uri = new DBFileProvider().getDatabaseURI(activity, "app_database.db");
sendEmail(activity, uri);
}
private fun sendEmail(activity: AppCompatActivity, attachment: Uri) {
val emailIntent = Intent(Intent.ACTION_SEND)
//Set type to email
emailIntent.type = "vnd.android.cursor.dir/email"
val toEmail = "whatever@gmail.com"
emailIntent.putExtra(Intent.EXTRA_EMAIL, toEmail)
emailIntent.putExtra(Intent.EXTRA_STREAM, attachment)
emailIntent.putExtra(Intent.EXTRA_SUBJECT, "Data for Training Log")
activity.startActivity(Intent.createChooser(emailIntent, "Send Email"))
}
解决方案2:
将数据库文件复制到一个临时文件到一个受FileProvider
like支持的目录filesDir
:
- 使用获取数据库文件
getDatabasePath
- 将数据库文件复制到受支持的存储目录
FileProvider
- 使用
FileProvider
fun backupDatabase(activity: AppCompatActivity) {
// Get the database file
val dbFile = activity.getDatabasePath("app_database.db")
try {
// Copy database file to a temp file in (filesDir)
val parent = File(activity.filesDir, "databases_temp")
val file = File(parent, "myDatabase")
dbFile.copyTo(file)
// Get Uri of the copied database file from filesDir to be used in email intent
val uri = getUri(activity.applicationContext, file)
// Send an email
sendEmail(activity, uri)
} catch (e: IOException) {
e.printStackTrace()
}
}
private fun getUri(context: Context, file: File): Uri {
var uri = Uri.fromFile(file)
// Using FileProvider for API >= 24
if (Build.VERSION.SDK_INT >= 24) {
uri = FileProvider.getUriForFile(
context,
"com.android.example.provider", file
)
}
return uri
}
使用与解决方案 1 相同的清单。并使用创建的临时目录进行provider_paths
调整:res\xml
<?xml version="1.0" encoding="utf-8"?>
<paths>
<files-path
name="databases_temp"
path="/" />
</paths>
注意:在这两种解决方案中,将包名称调整为您的。