已解决 - 从Java调用javascript函数 [英] Resolved - Call javascript function from Java

问题描述

我开发使用PhoneGap的应用程序。我有一个服务，这是在背景为codeD本身（服务和手机应用的差距是在同一个项目）。不幸的是，我想打电话从这项服务中一个JavaScript函数。所以，我在网上搜索并成立一些有趣的事情：创建扩展插件类，并在其中做一些治疗。然后我发现这一点：

I develop an app using PhoneGap. I got a service which is in background and is coded natively (the service and the phone gap app is in the same project). Unfortunatly, I want to call a javascript function from this service. So I searched on the Web and founded something interesting : create a class extending Plugin and do some treatment in it. Then I found this :

this.ctx.sendJavascript("myJavascriptFunction");

我这个code测试，但蹊跷的事情发生了：

I tested with this code, but something wrong happened :

java.lang.NullPointerException

下面是我的测试：

class c = new class();
c.execute("myFunction",null,null);

在C类，执行方法是这样的：

In the class c, the execute method is like this :

public PluginResult execute(String action, JSONArray args, String callbackId) {
if (action.equals("myFunction")){
    Log.d(TAG,"start actions to do");
    this.ctx.sendJavascript("nameOfFunctionToLaunch");
    Log.d(TAG,"end actions to do");
    return new PluginResult(PluginResult.Status.OK);
}
}

在应用程序启动，我第一个

When the app start, I have the first

Log.d(TAG,"start actions to do");

我该如何解决这个问题呢？

How can I solve this problem ?

推荐答案

我终于找到了解决办法：其实在 NullPointerException异常是在 CTX 。
为了解决这个问题，我安装在上下文我对象的值 C 是这样的：

Finally I found the solution : in fact the NullPointerException was on ctx. To fix it, I setup the Context value of my object c like this :

c.setContext(use_An_Object_Of_Type_PhonegapActivity);

要获得对象，我抓住它从AppActivity在此方法：

To get the object, I grab it from the AppActivity in this method :

public class CloudPhoneAppActivity extends DroidGap {
private class NoScaleWebViewClient extends GapViewClient {

    public NoScaleWebViewClient(DroidGap ctx) {
        super(ctx);
        myApp.ctx = ctx;
    }

    public void onScaleChanged(WebView view, float oldScale, float newScale) {
        Log.d("NoScaleWebViewClient", "Scale changed: " + String.valueOf(oldScale) + " => " + String.valueOf(newScale));
    }
}
/** other stuff after**/ 
}

所以，终于在这里是解决方案：

So finally here is the solution :

class c = new class();
c.setContext(myApp.ctx);
c.execute("myFunction",null,null);

有没有变化在执行方式是之前描述的事情。但要小心你是如何调用JavaScript函数。

There is no change to do in the execute method which is describe before. But be careful of how you call the javascript function.

二万

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