Android中如何用Parse Server查询更新应用？实时展示表内容到ListView求助

Hey there! Let's tackle your two requirements one by one—getting real-time data from your Parse Server table into an Android ListView, and implementing app updates using Parse queries. I'll walk you through practical, working code examples and best practices.

1. Displaying Parse Server Data in ListView (Real-time) #

Step 1: Ensure Parse SDK is Properly Initialized #

First, make sure you've set up the Parse SDK in your Android project. In your Application class or main activity's onCreate():

Parse.initialize(new Parse.Configuration.Builder(context)
        .applicationId("YOUR_APP_ID")
        .clientKey("YOUR_CLIENT_KEY")
        .server("YOUR_PARSE_SERVER_URL/parse/")
        .build());

// Initialize LiveQuery for real-time updates
ParseLiveQueryClient parseLiveQueryClient = ParseLiveQueryClient.Factory.getClient();

Step 2: Create a Parse Data Model #

Define a model class for your table (replace YourTableName with your actual table name):

@ParseClassName("YourTableName")
public class YourDataModel extends ParseObject {
    // Define getter/setter for your columns
    public String getTitle() {
        return getString("title");
    }

    public void setTitle(String title) {
        put("title", title);
    }

    // Add other fields as per your table
}

Don't forget to register this model in your Application class:

ParseObject.registerSubclass(YourDataModel.class);

Step 3: Set Up ListView and Adapter #

Use a ListAdapter (or a custom adapter for complex layouts) to bind data to your ListView. Let's use a basic ArrayAdapter for simplicity:

// In your Activity/Fragment
private ListView listView;
private ArrayAdapter<YourDataModel> adapter;
private List<YourDataModel> dataList = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    listView = findViewById(R.id.list_view);
    adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, dataList);
    listView.setAdapter(adapter);

    // Load initial data and set up real-time updates
    loadInitialData();
    setupLiveQuery();
}

Step 4: Load Initial Data (One-time Query) #

Fetch existing data from Parse Server asynchronously:

private void loadInitialData() {
    ParseQuery<YourDataModel> query = ParseQuery.getQuery(YourDataModel.class);
    query.findInBackground(new FindCallback<YourDataModel>() {
        @Override
        public void done(List<YourDataModel> objects, ParseException e) {
            if (e == null) {
                dataList.clear();
                dataList.addAll(objects);
                adapter.notifyDataSetChanged();
            } else {
                // Handle error
                Toast.makeText(MainActivity.this, "Failed to load data: " + e.getMessage(), Toast.LENGTH_SHORT).show();
            }
        }
    });
}

Step 5: Implement Real-time Updates with LiveQuery #

Subscribe to your Parse table to get real-time notifications when data is created, updated, or deleted:

private void setupLiveQuery() {
    ParseLiveQueryClient client = ParseLiveQueryClient.Factory.getClient();
    ParseQuery<YourDataModel> query = ParseQuery.getQuery(YourDataModel.class);

    // Subscribe to the query
    SubscriptionHandling<YourDataModel> subscriptionHandling = client.subscribe(query);

    // Handle new objects added
    subscriptionHandling.handleEvent(SubscriptionHandling.Event.CREATE, (query1, object) -> {
        runOnUiThread(() -> {
            dataList.add(object);
            adapter.notifyDataSetChanged();
        });
    });

    // Handle updated objects
    subscriptionHandling.handleEvent(SubscriptionHandling.Event.UPDATE, (query1, object) -> {
        runOnUiThread(() -> {
            int index = findIndexById(object.getObjectId());
            if (index != -1) {
                dataList.set(index, object);
                adapter.notifyDataSetChanged();
            }
        });
    });

    // Handle deleted objects
    subscriptionHandling.handleEvent(SubscriptionHandling.Event.DELETE, (query1, object) -> {
        runOnUiThread(() -> {
            int index = findIndexById(object.getObjectId());
            if (index != -1) {
                dataList.remove(index);
                adapter.notifyDataSetChanged();
            }
        });
    });
}

// Helper method to find index of an object by its ObjectId
private int findIndexById(String objectId) {
    for (int i = 0; i < dataList.size(); i++) {
        if (dataList.get(i).getObjectId().equals(objectId)) {
            return i;
        }
    }
    return -1;
}

2. Implement App Updates via Parse Queries #

Step 1: Create an "AppUpdate" Table in Parse Server #

First, create a new table in your Parse dashboard with these fields:

• latestVersionCode (Number, int): The version code of the latest app version
• latestVersionName (String): The version name (e.g., "1.1.0")
• updateUrl (String): Download link for the APK (or Play Store URL)
• isMandatory (Boolean): Whether the update is required

Step 2: Check for Updates on App Launch #

Add this logic to your splash screen or main activity's onCreate():

private void checkForAppUpdate() {
    ParseQuery<ParseObject> query = ParseQuery.getQuery("AppUpdate");
    query.orderByDescending("createdAt"); // Get the latest update record
    query.setLimit(1);

    query.getFirstInBackground(new GetCallback<ParseObject>() {
        @Override
        public void done(ParseObject updateObject, ParseException e) {
            if (e == null && updateObject != null) {
                int latestVersionCode = updateObject.getInt("latestVersionCode");
                String updateUrl = updateObject.getString("updateUrl");
                boolean isMandatory = updateObject.getBoolean("isMandatory");

                // Get current app version code
                int currentVersionCode = getCurrentVersionCode();

                if (latestVersionCode > currentVersionCode) {
                    // Show update dialog
                    showUpdateDialog(updateUrl, isMandatory);
                }
            } else {
                // Handle error or no update found
            }
        }
    });
}

// Helper to get current app version code
private int getCurrentVersionCode() {
    try {
        PackageInfo packageInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.P ? (int) packageInfo.getLongVersionCode() : packageInfo.versionCode;
    } catch (PackageManager.NameNotFoundException e) {
        e.printStackTrace();
        return 0;
    }
}

// Show update prompt dialog
private void showUpdateDialog(String updateUrl, boolean isMandatory) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("New Update Available")
            .setMessage("A newer version of the app is ready. Please update to continue.")
            .setPositiveButton("Update", (dialog, which) -> {
                // Open update URL
                Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(updateUrl));
                startActivity(intent);
            });

    if (!isMandatory) {
        builder.setNegativeButton("Later", (dialog, which) -> dialog.dismiss());
    }

    AlertDialog dialog = builder.create();
    dialog.setCancelable(!isMandatory); // Prevent closing if mandatory
    dialog.show();
}

Pro Tips #

• Permissions: Don't forget to add INTERNET permission in your AndroidManifest.xml:

  <uses-permission android:name="android.permission.INTERNET" />
  

• Background Threads: All Parse queries are asynchronous by default, so you don't have to worry about blocking the main thread—but always update UI elements on the main thread (we used runOnUiThread() in the LiveQuery handlers for this).
• LiveQuery Connection: Make sure your Parse Server has LiveQuery enabled (check your server configuration for liveQuery settings).

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