Picasso加载Firestore存储图片仅重启后可见、onActivityResult无回调求助

• 跳转逻辑错误：你在AddJourney中调用startActivityForResult启动HomePage，所以onActivityResult只会回调到AddJourney，不会回到HomePage，完全用反了启动逻辑
• 列表数据仅加载一次：HomePage的列表数据只在onCreate中执行了一次一次性拉取，从AddJourney返回后没有触发重新拉取，也没有监听Firestore的数据变更，自然拿不到最新上传的图片URL
• 异步时序问题：你在添加行程后直接跳转，此时图片上传、URL写入Firestore的异步操作还没执行完，就算立刻拉取也拿不到最新的图片地址
• Picasso未做异常处理：空URL或者地址无效时没有占位兜底，也没有错误提示

1. 修正跳转逻辑 #

修改HomePage.java #

修改添加按钮的点击事件，用startActivityForResult启动AddJourney：

case R.id.add_journey:
    Intent intent_add = new Intent(HomePage.this, AddJourney.class);
    startActivityForResult(intent_add, 1001); // 自定义请求码
    break;

在HomePage中重写onActivityResult，返回时触发列表刷新：

@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == 1001 && resultCode == RESULT_OK) {
        loadDataInListView(); // 返回时刷新列表
    }
}

修改loadDataInListView方法，支持重复调用刷新 #

private void loadDataInListView() {
    db.collection("users").document(userID).collection("journeys").get()
            .addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
                @Override
                public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
                    dataArrayList.clear(); // 先清空旧数据
                    if(!queryDocumentSnapshots.isEmpty()){
                        List<DocumentSnapshot> list = queryDocumentSnapshots.getDocuments();
                        for(DocumentSnapshot d : list){
                            Data data = d.toObject(Data.class);
                            dataArrayList.add(data);
                        }
                        // 不要每次新建Adapter，改为更新数据后通知刷新
                        if(listView.getAdapter() == null){
                            Adapter adapter = new Adapter(HomePage.this, dataArrayList);
                            listView.setAdapter(adapter);
                        }else{
                            ((Adapter)listView.getAdapter()).notifyDataSetChanged();
                        }
                    } else {
                        Toast.makeText(HomePage.this, "No data found in database", Toast.LENGTH_SHORT).show();
                        // 空数据也要刷新Adapter
                        if(listView.getAdapter() != null){
                            ((Adapter)listView.getAdapter()).notifyDataSetChanged();
                        }
                    }
                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Toast.makeText(HomePage.this, "Fail to load data..", Toast.LENGTH_SHORT).show();
                }
            });
}

2. 修正AddJourney的返回逻辑 #

删除原有跳转HomePage的代码，等所有异步操作完成后再返回：

case R.id.add:
    addJourney();
    // 删掉下面这两行错误代码
    // Intent intent = new Intent(AddJourney.this, HomePage.class);
    // intent.setFlags(0);
    // startActivityForResult(intent, 78);
    break;

修改addJourney方法，等图片URL写入Firestore成功后再返回：

private void addJourney() {
    jTitle = title.getText().toString();
    jDescription = description.getText().toString();

    Map<String, String> data = new HashMap<>();
    data.put("title", jTitle);
    data.put("description", jDescription);
    data.put("journeyID", null);
    data.put("imgUrl", null);

    fStore.collection("users").document(userID).collection("journeys").add(data)
            .addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
                @Override
                public void onSuccess(DocumentReference documentReference) {
                    Toast.makeText(AddJourney.this, "Successfully added journey!", Toast.LENGTH_SHORT).show();
                    // 先更新journeyID
                    documentReference.update("journeyID", documentReference.getId())
                            .addOnSuccessListener(new OnSuccessListener<Void>() {
                                @Override
                                public void onSuccess(Void unused) {
                                    // 上传图片
                                    filepath.putFile(uri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                                        @Override
                                        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
                                            filepath.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                                                @Override
                                                public void onSuccess(Uri uri) {
                                                    // 写入图片URL成功后再返回
                                                    documentReference.update("imgUrl", uri.toString())
                                                            .addOnSuccessListener(new OnSuccessListener<Void>() {
                                                                @Override
                                                                public void onSuccess(Void unused) {
                                                                    setResult(RESULT_OK);
                                                                    finish(); // 关闭当前页回到HomePage
                                                                }
                                                            });
                                                }
                                            });
                                        }
                                    });
                                }
                            });
                }
            }).addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception e) {
            Toast.makeText(AddJourney.this, "Failed to add data", Toast.LENGTH_SHORT).show();
        }
    });
}

3. 优化Picasso加载逻辑 #

修改Adapter的getView方法，添加占位和错误处理：

if(data.getImgUrl() != null && !data.getImgUrl().isEmpty()){
    Picasso.get()
            .load(data.getImgUrl())
            .placeholder(R.drawable.ic_default_image) // 替换为你自己的占位图
            .error(R.drawable.ic_error_image) // 替换为你自己的错误图
            .into(imageView);
}else{
    imageView.setImageResource(R.drawable.ic_default_image);
}

可选优化：使用Firestore实时监听替代手动刷新 #

如果不需要手动触发刷新，可以把get()改为addSnapshotListener，Firestore数据变化时自动更新列表，不用每次返回都拉取：

// 在onCreate中调用一次即可
private void listenToJourneyData() {
    db.collection("users").document(userID).collection("journeys")
            .addSnapshotListener(new EventListener<QuerySnapshot>() {
                @Override
                public void onEvent(@Nullable QuerySnapshot value, @Nullable FirebaseFirestoreException error) {
                    if(error != null){
                        Toast.makeText(HomePage.this, "数据监听失败", Toast.LENGTH_SHORT).show();
                        return;
                    }
                    dataArrayList.clear();
                    for(DocumentSnapshot d : value.getDocuments()){
                        Data data = d.toObject(Data.class);
                        dataArrayList.add(data);
                    }
                    if(listView.getAdapter() == null){
                        Adapter adapter = new Adapter(HomePage.this, dataArrayList);
                        listView.setAdapter(adapter);
                    }else{
                        ((Adapter)listView.getAdapter()).notifyDataSetChanged();
                    }
                }
            });
}

内容的提问来源于stack exchange，提问作者EnCoder2000