Javascript 和 Phonegap 插件之间的异步通信 [英] Asynchronous communication between Javascript and Phonegap Plugin

问题描述

所以，每个人都知道我们创建了一个扩展 CordovaPlugin 的类并覆盖了 execute()，然后在 JS 和原生 Java(对于 Android)之间创建了一座桥梁.此外，我们使用 PluginResult 将结果返回给 JS.

因此，所有这些都发生在从 JS 向 Java 插件发出请求时.我的问题是，如何将结果发送回 JS(并因此发送回 HTML)异步?

我不知道 异步 就在这里.问题是我想突然将一些东西发送回 JS(例如，当 wifi 启用/禁用时).

我已经对此进行了研究，但没有任何适合我的情况.

我试过的事情是 -

So, everybody knows that we make a Class extending CordovaPlugin and override the execute() and then creates a bridge between the JS and native Java (for Android). Further we use PluginResult to return the result back to the JS.

So, all of this happens when there is a request fired from the JS to the Java Plugin. My question is, how to send a result back to JS (and therefore to HTML) asynchronously ?

I don't know if the word asynchronous is right here. The thing is I want to send something back to the JS out of the blue (say, when wifi becomes enable/disable).

I have already researched on this but haven't got anything which suits to my case.

The thing I've tried is -

• 使用 WifiManager 类创建了一个 BroadcastReceiver 来监听 WiFi 事件.
• 注册接收者.
• 最后，当 WiFi 启用/禁用时弹出一个 Toast，并使用 CallbackContext
  
  <代码>callbackContext.sendPluginResult(new PluginResult(PluginResult.Status.OK, "Wifi已连接")) 和断开与不同的消息.
  
  

• Created a BroadcastReceiver listening to the WiFi events using the WifiManager class.
• Registered the receiver.
• And finally, popping a Toast when WiFi is enabled/disabled, and sending the result using CallbackContext

callbackContext.sendPluginResult(new PluginResult(PluginResult.Status.OK, "Wifi Connected")) and for disconnected with a different message.
  
  

MyPlugin.java

import org.apache.cordova.CallbackContext;
import org.apache.cordova.CordovaPlugin;
import org.apache.cordova.PluginResult;
import org.json.JSONArray;

...

public class MyPlugin extends CordovaPlugin {
private WifiReceiver wifiBroadcastReceiver = null;
private CallbackContext callbackContext = null;

...

    public MyPlugin() {     
        wifiBroadcastReceiver = new WifiReceiver();
    ...
    }
    ...
    public boolean execute(String action, final JSONArray args,
            final CallbackContext callbackId) throws JSONException {
        IntentFilter wifiFilter = new IntentFilter(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION);
        cordova.getActivity().registerReceiver(wifiBroadcastReceiver, wifiFilter);
        this.callbackContext = callbackId;

    ...
    }
    public class WifiReceiver extends BroadcastReceiver{

        @Override
        public void onReceive(Context context, Intent intent) {
            final String action = intent.getAction();
            if (action.equals(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION)) {
                if (intent.getBooleanExtra(WifiManager.EXTRA_SUPPLICANT_CONNECTED, false)) {
                    Toast.makeText(cordova.getActivity(), "Wifi Connected", Toast.LENGTH_SHORT).show();
                    callbackContext.sendPluginResult(new PluginResult(PluginResult.Status.OK, "Wifi Connected"));
                } else {
                    Toast.makeText(cordova.getActivity(), "Wifi Disconnected", Toast.LENGTH_SHORT).show();
                    callbackContext.sendPluginResult(new PluginResult(PluginResult.Status.ERROR, "Wifi Disconnected"));
                }
            }           
        }

}

Toast 弹出，但 PluginResult 没有发送到 JS.

The Toast pops but the PluginResult isn't sent to the JS.

PS:监听 WiFi 事件不是我的实际问题，我想在 Phonegap 中复制 Android 蓝牙聊天 应用程序.因此，它本质上必须是异步的.

PS : Listening to WiFi events isn't my actual problem, I want to replicate the Android Bluetooth Chat app in Phonegap. So, it has to be asynchronous in nature.

推荐答案

您已经快完成了，但是您需要在您的 PluginResult 上将KeepCallback 设置为 true.如果不这样做，Java 端的后续结果将不会在 JavaScript 端有回调.此类编码的最佳示例是 Cordova 核心中的网络插件.以下是来源链接:

You are almost there but you need to setKeepCallback to true on your PluginResult. If you don't the subsequent results from the Java side will not have a callback on the JavaScript side. The best example of this type of coding is the Network plugin in Cordova core. Here is a link to the source:

https://git-wip-us.apache.org/repos/asf?p=cordova-plugin-network-information.git;a=blob;f=src/android/NetworkManager.java;h=e2ac500ccc885db641d5df6dab8eae23026a5828;hb=HEAD

因此您应该将代码更新为:

So you should update your code to:

public boolean execute(String action, final JSONArray args,
        final CallbackContext callbackId) throws JSONException {
    IntentFilter wifiFilter = new IntentFilter(
            WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION);
    cordova.getActivity().registerReceiver(wifiBroadcastReceiver,
            wifiFilter);
    this.callbackContext = callbackId;
    PluginResult result = new PluginResult(PluginResult.Status.NO_RESULT);
    result.setKeepCallback(true);
    this.callbackContext.sendPluginResult(result);
    return true;
}

public class WifiReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        final String action = intent.getAction();
        if (action.equals(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION)) {
            PluginResult result;
            if (intent.getBooleanExtra(
                    WifiManager.EXTRA_SUPPLICANT_CONNECTED, false)) {
                Toast.makeText(cordova.getActivity(), "Wifi Connected",
                        Toast.LENGTH_SHORT).show();
                result = new PluginResult(PluginResult.Status.OK,
                        "Wifi Connected");
            } else {
                Toast.makeText(cordova.getActivity(), "Wifi Disconnected",
                        Toast.LENGTH_SHORT).show();
                result = new PluginResult(PluginResult.Status.ERROR,
                        "Wifi Disconnected");
            }

            result.setKeepCallback(false);
            if (callbackContext != null) {
                callbackContext.sendPluginResult(result);
                callbackContext = null;
            }
        }
    }
}

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