FileProvider.getUriForFile返回NullPointerException [英] FileProvider.getUriForFile returns NullPointerException
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问题描述
我正在尝试编写我的第一个android应用，该应用将涉及拍照并对其进行处理。
I'm trying to write my first android app, which will involve taking a picture and doing stuff with it.
我在看了几本在线教程后整理了一些代码，但是每当单击按钮时都会得到以下NullPointerException：
I've put together some code after looking at several tutorials online but am getting the following NullPointerException whenever the button is clicked:
10-03 14:48:00.284 26310-26310/org.broadinstitute.jsnap E/MainActivity: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.XmlResourceParser android.content.pm.ProviderInfo.loadXmlMetaData(android.content.pm.PackageManager, java.lang.String)' on a null object reference
10-03 14:48:00.293 26310-26310/org.broadinstitute.jsnap E/MYAPP: exception
java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.XmlResourceParser android.content.pm.ProviderInfo.loadXmlMetaData(android.content.pm.PackageManager, java.lang.String)' on a null object reference
at android.support.v4.content.FileProvider.parsePathStrategy(FileProvider.java:583)
at android.support.v4.content.FileProvider.getPathStrategy(FileProvider.java:557)
at android.support.v4.content.FileProvider.getUriForFile(FileProvider.java:399)
at org.broadinstitute.jsnap.MainActivity.takePhoto(MainActivity.java:54)
at org.broadinstitute.jsnap.MainActivity.access$000(MainActivity.java:24)
at org.broadinstitute.jsnap.MainActivity$1.onClick(MainActivity.java:43)
at android.view.View.performClick(View.java:6205)
at android.widget.TextView.performClick(TextView.java:11103)
at android.view.View$PerformClick.run(View.java:23653)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6682)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1520)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1410)
I'我不太确定如何解决。这是我的相关代码：
I'm not quite sure how to resolve. Here's my relevant code:
清单：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="org.broadinstitute.jsnap">
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" android:required="true"/>
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-feature android:name="android.hardware.camera.flash" android:required="false"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
>
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="${applicationId}.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/file_paths"></meta-data>
</provider>
</application>
</manifest>
file_paths.xml
file_paths.xml
<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<external-path name="jsnap_images" path="Android/data/org.broadinstitute.jsnap/files/Pictures" />
</paths>
和MainActivity：
And MainActivity:
package org.broadinstitute.jsnap;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.Intent;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Build;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v4.content.FileProvider;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.io.IOException;
import java.util.jar.Manifest;
public class MainActivity extends Activity {
private static String logtag = "MainActivity";
private static int TAKE_PICTURE = 1;
private static final String AUTHORITY = "org.broadinstitute.jsnap.provider";
private static final String PHOTOS="photos";
private static final String FILENAME="jsnap_test.jpeg";
Uri imageURI;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button cameraButton = (Button)(findViewById(R.id.cam_button));
cameraButton.setOnClickListener(cameraListener);
}
private View.OnClickListener cameraListener = new View.OnClickListener() {
public void onClick(View v) {
try {
takePhoto(v);
} catch (Exception e) {
Log.e(logtag, e.toString());
}
}
};
private void takePhoto(View v){
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
File photo = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), FILENAME);
imageURI=FileProvider.getUriForFile(this, AUTHORITY, photo);
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageURI);
// TAKE_PICTURE is a request code saying we want to use the rear-facing camera.
startActivityForResult(intent, TAKE_PICTURE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
super.onActivityResult(requestCode, resultCode, intent);
if(resultCode == Activity.RESULT_OK) {
Uri selectedImage = imageURI;
getContentResolver().notifyChange(selectedImage, null);
ImageView imageView = (ImageView)findViewById(R.id.image_camera);
ContentResolver cr = getContentResolver();
Bitmap bitmap;
try {
bitmap = MediaStore.Images.Media.getBitmap(cr, selectedImage);
imageView.setImageBitmap(bitmap);
Toast.makeText(MainActivity.this, selectedImage.toString(), Toast.LENGTH_SHORT).show();
} catch(Exception e) {
Log.e(logtag, e.toString());
}
}
}
}
任何非常感谢您的帮助。
Any help is greatly appreciated.
推荐答案
首先，这是
android:authorities="${applicationId}.fileprovider"
与此不匹配：
private static final String AUTHORITY = "org.broadinstitute.jsnap.provider";
在两个地方使用相同的算法。因此，将第二行替换为：
Use the same algorithm in both places. So, replace the second line with:
private static final String AUTHORITY = BuildConfig.APPLICATION_ID+".fileprovider";
这将使您通过 NullPointerException 。
第二个，
File photo = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), FILENAME);
与此不匹配：
<external-path name="jsnap_images" path="Android/data/org.broadinstitute.jsnap/files/Pictures" />
由于我不知道您真正想要的是哪个，因此我无法提出解决方案。
Since I don't know which of those is what you really want, I cannot suggest a fix.
这篇关于FileProvider.getUriForFile返回NullPointerException的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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