情境
有時候你要透過內建的檔案管理器取得照片,
只需要透過內建函式搭配Intent就可以輕鬆辦到。
程式碼說明
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.givemepass.photopickerdemo.MainActivity">
<Button
android:id="@+id/pick_photo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Picker" />
<ImageView
android:layout_below="@id/pick_photo"
android:id="@+id/image"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</RelativeLayout>一開始宣告一個Button跟ImageView,
當Button按下去以後, 就可以開啟檔案總管,
讓使用者去選擇圖片以後,
再透過傳回來的位址將圖片呈現出來在ImageView。
設定Button事件
picker.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent picker = new Intent(Intent.ACTION_GET_CONTENT);
picker.setType("image/*");
picker.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
Intent destIntent = Intent.createChooser(picker, null);
startActivityForResult(destIntent, PICKER);
}
});在Android 6.0的裝置上, 會有權限問題
當Button按下去的時候, 我們可以根據Intent所設定的type,
透過一些已安裝的程式幫我們找到所需要的檔案類型,
這些類別大概分別為
text/*
image/*
application/*
video/*
audio/*因為我們是需要的是圖片, 因此使用
image/jpg
image/bmp
image/png
image/gif但是因為想包含這麼多類型的圖片檔案可以直接用
image/*選完照片會透過startActivityForResult回到Activity的onActivityResult方法內,
所以你必須覆寫onActivityResult來接住回傳回來的資料。
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == PICKER) {
if (resultCode == Activity.RESULT_OK) {
Uri uri = data.getData();
String path = getRealPathFromURI(MainActivity.this, uri);
}
}
}這時候你選完照片以後會發現回來是一個Uri,
所以這時候我們寫一個方法來找到對應的路徑
public static String getRealPathFromURI(Context context, Uri contentUri) {
Cursor cursor = null;
try {
String[] proj = { MediaStore.Images.Media.DATA };
cursor = context.getContentResolver().query(contentUri, proj, null, null, null);
int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
return cursor.getString(column_index);
} finally {
if (cursor != null) {
cursor.close();
}
}
}可是沒想到居然是空的!
查了一下,
原來Android SDK自從4.4以後就採取另外一種方式了。
http://stackoverflow.com/questions/20067508/get-real-path-from-uri-android-kitkat-new-storage-access-framework
/**
* Get a file path from a Uri. This will get the the path for Storage Access
* Framework Documents, as well as the _data field for the MediaStore and
* other file-based ContentProviders.
*
* @param context The context.
* @param uri The Uri to query.
* @author paulburke
*/
@TargetApi(Build.VERSION_CODES.KITKAT)
public static String getPath(final Context context, final Uri uri) {
final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
// DocumentProvider
if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
// ExternalStorageProvider
if (isExternalStorageDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
final String[] split = docId.split(":");
final String type = split[0];
if ("primary".equalsIgnoreCase(type)) {
return Environment.getExternalStorageDirectory() + "/" + split[1];
}
// TODO handle non-primary volumes
}
// DownloadsProvider
else if (isDownloadsDocument(uri)) {
final String id = DocumentsContract.getDocumentId(uri);
final Uri contentUri = ContentUris.withAppendedId(
Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));
return getDataColumn(context, contentUri, null, null);
}
// MediaProvider
else if (isMediaDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
final String[] split = docId.split(":");
final String type = split[0];
Uri contentUri = null;
if ("image".equals(type)) {
contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
} else if ("video".equals(type)) {
contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
} else if ("audio".equals(type)) {
contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
}
final String selection = "_id=?";
final String[] selectionArgs = new String[] {
split[1]
};
return getDataColumn(context, contentUri, selection, selectionArgs);
}
}
// MediaStore (and general)
else if ("content".equalsIgnoreCase(uri.getScheme())) {
return getDataColumn(context, uri, null, null);
}
// File
else if ("file".equalsIgnoreCase(uri.getScheme())) {
return uri.getPath();
}
return null;
}
/**
* Get the value of the data column for this Uri. This is useful for
* MediaStore Uris, and other file-based ContentProviders.
*
* @param context The context.
* @param uri The Uri to query.
* @param selection (Optional) Filter used in the query.
* @param selectionArgs (Optional) Selection arguments used in the query.
* @return The value of the _data column, which is typically a file path.
*/
public static String getDataColumn(Context context, Uri uri, String selection,
String[] selectionArgs) {
Cursor cursor = null;
final String column = "_data";
final String[] projection = {
column
};
try {
cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs,
null);
if (cursor != null && cursor.moveToFirst()) {
final int column_index = cursor.getColumnIndexOrThrow(column);
return cursor.getString(column_index);
}
} finally {
if (cursor != null)
cursor.close();
}
return null;
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is ExternalStorageProvider.
*/
public static boolean isExternalStorageDocument(Uri uri) {
return "com.android.externalstorage.documents".equals(uri.getAuthority());
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is DownloadsProvider.
*/
public static boolean isDownloadsDocument(Uri uri) {
return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is MediaProvider.
*/
public static boolean isMediaDocument(Uri uri) {
return "com.android.providers.media.documents".equals(uri.getAuthority());
}改寫成這樣
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == PICKER) {
if (resultCode == Activity.RESULT_OK) {
Uri uri = data.getData();
String path = getPath(MainActivity.this, uri);
Toast.makeText(MainActivity.this, path, Toast.LENGTH_SHORT).show();
}
}
}就可以拿到路徑了
在6.0的手機上, 會有手機權限的問題,
google設計了一個機制讓使用者決定是否開放權限。
由於會去存取照片, 因此要設定權限在Manifest
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />接著在程式一開始的onCreate加入
int permission = ActivityCompat.checkSelfPermission(this,
Manifest.permission.READ_EXTERNAL_STORAGE);
if (permission != PackageManager.PERMISSION_GRANTED) {
//未取得權限，向使用者要求允許權限
ActivityCompat.requestPermissions(this,
new String[] {Manifest.permission.READ_EXTERNAL_STORAGE},
REQUEST_EXTERNAL_STORAGE
);
} else{
getPermissionAccess();
}就會出現下面的畫面
使用者決定是否賦予app權限結果會回傳至onRequestPermissionsResult
@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case REQUEST_EXTERNAL_STORAGE: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// permission was granted, yay! Do the
// contacts-related task you need to do.
getPermissionAccess();
} else {
finish();
// permission denied, boo! Disable the
// functionality that depends on this permission.
}
return;
}
// other 'case' lines to check for other
// permissions this app might request
}
}如果不給予權限則finish整個app。