我正在学校开展项目，我需要捕获图片并将其保存到Firebase。这是我的代码
package com.example.akoni.conread;
import android.app.ProgressDialog;
import android.content.Intent;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Spinner;
import android.widget.Toast;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.StorageReference;
import com.google.firebase.storage.UploadTask;
import static android.app.Activity.RESULT_OK;
/**
* Created by Akoni on 12/2/2017.
*/
public class WaterConsumptionPage extends Fragment {
Spinner month, date, year;
ImageView imageView;
Button upload, consumption;
static final int CAM_REQUEST = 1;
private StorageReference mStorageRef;
private FirebaseAuth mAuth;
private DatabaseReference dbRef;
private ProgressDialog mProgress;
private Uri uri = null;
private Bitmap photo;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.water_consumption_page, container, false);
mStorageRef = FirebaseStorage.getInstance().getReference();
mAuth = FirebaseAuth.getInstance();
dbRef = FirebaseDatabase.getInstance().getReference();
month = rootView.findViewById(R.id.wtr_month);
date = rootView.findViewById(R.id.wtr_date);
year = rootView.findViewById(R.id.wtr_year);
imageView = rootView.findViewById(R.id.water_image);
upload = rootView.findViewById(R.id.water_upload);
consumption = rootView.findViewById(R.id.water_consumption);
upload.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent cam_intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cam_intent, CAM_REQUEST);
}
});
mProgress = new ProgressDialog(getContext());
consumption.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mProgress.setMessage("Uploading Image...");
mProgress.show();
StorageReference filepath = mStorageRef.child("Water").child(uri.getLastPathSegment());
filepath.putFile(uri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
mProgress.dismiss();
Toast.makeText(getContext(), "Upload Finished...", Toast.LENGTH_LONG).show();
Intent i = new Intent(getContext(), WaterConsumption.class);
startActivity(i);
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
mProgress.dismiss();
Toast.makeText(getContext(), "Upload has stopped.", Toast.LENGTH_LONG).show();
}
});
}
});
return rootView;
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if(requestCode == CAM_REQUEST && resultCode == RESULT_OK){
uri = data.getData();
Bundle extras = data.getExtras();
photo = (Bitmap) extras.get("data");
imageView.setImageBitmap(photo);
}
}
}
我的依赖
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:26.1.0'
implementation 'com.android.support.constraint:constraint-layout:1.0.2'
implementation 'com.android.support:support-v4:26.1.0'
implementation 'com.android.support:design:26.1.0'
implementation 'com.google.firebase:firebase-auth:11.0.4'
implementation 'com.google.firebase:firebase-database:11.0.4'
implementation 'com.google.firebase:firebase-storage:11.0.4'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.1'
androidTestImplementation 'com.android.support.test.espresso:espresso-
core:3.0.1'
}
apply plugin: 'com.google.gms.google-services'
的AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.akoni.conread">
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature
android:name="android.hardware.camera2"
android:required="true" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity
android:name=".SignIn"
android:screenOrientation="portrait">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".ForgotPassword"
android:screenOrientation="portrait" />
<activity
android:name=".TabMenu"
android:label="@string/title_activity_tab_menu"
android:screenOrientation="portrait"
android:theme="@style/AppTheme.NoActionBar" />
<activity android:name=".WaterConsumption" />
<activity android:name=".ElectricConsumption"></activity>
</application>
</manifest>
logcat的（应用）
12-12 18:20:20.209 31023-31023/com.example.akoni.conread E/MultiWindowProxy: getServiceInstance failed!
12-12 18:20:22.832 31023-31078/com.example.akoni.conread E/NativeCrypto: ssl=0xb9393e78 cert_verify_callback x509_store_ctx=0xa297e21c arg=0x0
12-12 18:20:22.832 31023-31078/com.example.akoni.conread E/NativeCrypto: ssl=0xb9393e78 cert_verify_callback calling verifyCertificateChain authMethod=ECDHE_RSA
12-12 18:20:43.498 31023-31023/com.example.akoni.conread E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.akoni.conread, PID: 31023
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.net.Uri.getLastPathSegment()' on a null object reference
at com.example.akoni.conread.WaterConsumptionPage$2.onClick(WaterConsumptionPage.java:78)
at android.view.View.performClick(View.java:5265)
at android.view.View$PerformClick.run(View.java:21534)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5728)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)
在我的firebase.google.com中，我的存储空间等于空，仅用于保存图片。
我的问题是，每次运行程序时，当我按下消耗按钮将捕获的图像保存到firebase时，应用程序最终会停止。
答案 0 :(得分：0)
应用程序崩溃的原因是：
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.net.Uri.getLastPathSegment()' on a null object reference
变量uri未初始化，因此当您执行此操作时：
StorageReference filepath = mStorageRef.child("Water").child(uri.getLastPathSegment());
您正试图访问getLastPathSegment()个null个对象的uri。
您应该设置一些断点来检查变量uri是否正确初始化;查看代码onActivityResult在{{1}}中设置一次，因此您应该检查方法是否被触发以及变量是否已初始化。
修改：
This answer可能有助于解决您的问题。