android - 从 Firebase 数据库获取和 ID 的 Intent 问题
问题描述
正如您在 Firebase 数据库图像中看到的那样,我对发送带有 Course_ID 的额外字符串的类的 Intent 有疑问。有时在 UploadFile.class 类中,使用额外字符串(包含 Course_ID)获取意图的字符串会获得空值。如果您能向我推荐一种从 Firebase 申请获取此 Course_ID 的新方法,我将不胜感激。在此文本下方附加了 Firebase 数据库的屏幕、我有时在 UploadFile.class 中遇到的错误以及 UploadFile.class 的代码以及我的类中的一部分代码,该类使用额外的字符串发送此意图。
上传文件.class
public class UploadFile extends AppCompatActivity {
EditText denumire_material;
Button selectare_material;
ImageView adaugare_material;
DatabaseReference databaseReference;
FirebaseAuth mFirebaseAuth;
FirebaseDatabase reference;
private FirebaseStorage storage;
private StorageReference storageReference;
private Uri pdfUri;
String url;
String generatedFilePath;
Uri downloadUri;
TeacherCoursesFragment teacherCoursesFragment = new TeacherCoursesFragment();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_upload_file);
denumire_material = findViewById(R.id.editBoxDenumireMaterial);
selectare_material = findViewById(R.id.btnSelectareMaterial);
adaugare_material = findViewById(R.id.imgAddMaterial);
mFirebaseAuth = FirebaseAuth.getInstance();
storageReference = FirebaseStorage.getInstance().getReference();
reference = FirebaseDatabase.getInstance();
databaseReference = FirebaseDatabase.getInstance().getReference().child("Materials").child(mFirebaseAuth.getCurrentUser().getUid());
selectare_material.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(ContextCompat.checkSelfPermission(UploadFile.this, Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED){
selectPDF();
} else{
ActivityCompat.requestPermissions(UploadFile.this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},9);
}
}
});
adaugare_material.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(pdfUri!=null){
uploadFile(pdfUri);
adaugareDateInFirebase();
} else{}
}
});
}
private void adaugareDateInFirebase(){
DatabaseReference reference1 = FirebaseDatabase.getInstance().getReference();
Query query = reference1.child(mFirebaseAuth.getCurrentUser().getUid());
DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");
Date date = new Date();
String datee = dateFormat.format(date).toString();
String course_id = getIntent().getExtras().getString("course id").toString();
HashMap<String, Object> firebase = new HashMap<>();
firebase.put("Denumire_material", denumire_material.getText().toString());
firebase.put("Locatie_material", generatedFilePath);
firebase.put("Teacher_ID", mFirebaseAuth.getCurrentUser().getUid());
firebase.put("Course_ID", course_id);
firebase.put("Data_adaugarii", datee);
databaseReference.push().setValue(firebase).addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
if(task.isSuccessful()){
}
}
});
}
private void uploadFile(Uri pdfUri) {
final String fileName = System.currentTimeMillis()+"";
StorageReference storageReference = storage.getInstance().getReference();
final StorageReference storageReference1 = storageReference.child("Materiale/" + mFirebaseAuth.getCurrentUser().getUid()+"/"+denumire_material.getText().toString());
storageReference1.putFile(pdfUri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
taskSnapshot.getStorage().getDownloadUrl().addOnCompleteListener(new OnCompleteListener<Uri>() {
@Override
public void onComplete(@NonNull Task<Uri> task) {
generatedFilePath = task.getResult().toString();
}
});
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Toast.makeText(UploadFile.this, "File not succesfully uploaded", Toast.LENGTH_SHORT).show();
}
}).addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
@Override
public void onProgress(@NonNull UploadTask.TaskSnapshot taskSnapshot) {
}
});
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if(requestCode == 9 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
selectPDF();
} else{
Toast.makeText(UploadFile.this, "Permission denied", Toast.LENGTH_SHORT).show();
}
}
}
TeacherCoursesFragments.class - 我发送带有附加字符串的意图的类(它当然包含 id)。
public class TeacherCoursesFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
v = inflater.inflate(R.layout.fragment_teacher_courses, container, false);
ImageView addCourseBtn = (ImageView) v.findViewById(R.id.btnAddCourse);
recyclerView = v.findViewById(R.id.recyclerView_fragmentCourses);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
mAuth = FirebaseAuth.getInstance();
FirebaseUser user = mAuth.getCurrentUser();
String uid = user.getUid();
createCourse = new CreateCourse();
reference = FirebaseDatabase.getInstance().getReference().child("Courses").child("Teacher-Courses").child(uid);
intent = new Intent(getActivity(), CreateCourse.class);
addCourseBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(intent);
}
});
return v;
}
@Override
public void onStart() {
super.onStart();
options = new FirebaseRecyclerOptions.Builder<Course>().setQuery(reference, Course.class).build();
adapter = new FirebaseRecyclerAdapter<Course, CourseViewHolder>(options) {
@Override
protected void onBindViewHolder(@NonNull final CourseViewHolder courseViewHolder, int i, @NonNull final Course course) {
courseViewHolder.courseRealName.setText(course.getCourse_name());
String numberOfStudents = String.valueOf(course.getCourse_students());
courseViewHolder.realNumberOfStudents.setText(numberOfStudents);
courseViewHolder.detailsButtonCourse2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), CourseMaterial.class);
intent.putExtra("course id", course.getCourse_ID());
intent.putExtra("teacher id", course.getTeacher_ID());
startActivity(intent);
}
});
courseViewHolder.course_chenar.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), CourseOperations.class);
intent.putExtra("course name", course.getCourse_name());
intent.putExtra("course description", course.getCourse_description());
intent.putExtra("course points", String.valueOf(course.getCourse_points()));
intent.putExtra("course students", String.valueOf(course.getCourse_students()));
startActivity(intent);
}
});
courseViewHolder.detailsButtonCourse.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), UploadFile.class);
intent.putExtra("course id", course.getCourse_ID());
startActivity(intent);
}
});
}
我应该制作 2 个 DatabaseReference,一个用于教师课程,一个用于材料吗?我已经尝试过了,但如果没有意图,我无法从教师课程中获取 Course_ID。我已经在 stackoverflow 和 Google 上进行了搜索,但我根本没有找到任何解决方案。等待您的回复、建议或解决方案,如果您能给我一些。谢谢!
附加说明:课程名称和学生人数(第二个标题)是使用 RecyclerViewAdapter 和 RecyclerViewOptions 从 Firebase 数据库中提取的,您可以在 TeacherCoursesFragment.class 中看到。第一个按钮重定向到 UploadFile.class,我在其中上传文件并为它建立一个名称以存储在 Firebase Storage 中。第二个按钮将用户发送到另一个页面,用户可以在其中从多个选项中进行选择(删除等)。
解决方案
也许改变这个UploadFile
:
String course_id = getIntent().getExtras().getString("course id").toString();
对此:
String course_id = getIntent().getStringExtra("course id");
更新:
我想你应该打电话getIntent()
来onCreate()
:
在你的UploadFile
public class UploadFile extends AppCompatActivity {
........
//declare as member variable
private String course_id;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_upload_file);
//get it here
course_id = getIntent().getStringExtra("course id");
.......
.......
.......
}
}
删除您正在使用的这一行:
String course_id = getIntent().getExtras().getString("course id").toString();
推荐阅读
- c - 使用 strsep 读取 csv 文件的分段错误
- c# - 获取目标总和的数字组合 - C#
- gnupg - gpg:错误读取符号链接'/proc/curproc/file':没有这样的文件或目录
- typescript - 在下一个js中临时存储数据
- css - 在 VS Code 中使用 Google 字体
- ipad - Whatsapp Web Beta 无法在 iPadOS 上运行,反复获取 QR 码
- python - 尝试下载 THOR 跟踪器时,Conda 环境缺少依赖项
- php - dompdf getTextWidth() 获取自定义字体的正确字符串宽度
- python - 如何替换熊猫数据框中的值
- windows - 我的批处理代码做错了什么?