Javascript PluginManager的NullPointer异常-创建自定义Apache Cordova插件Echo.java
我一直在尝试从现有的Echo插件创建一个示例插件。我得到了以下错误:Javascript PluginManager的NullPointer异常-创建自定义Apache Cordova插件Echo.java,javascript,android,apache,cordova,cordova-plugins,Javascript,Android,Apache,Cordova,Cordova Plugins,我一直在尝试从现有的Echo插件创建一个示例插件。我得到了以下错误: W/System.err(1894): java.lang.NullPointerException: cls == null W/System.err(1894): at java.lang.Class.isAssignableFrom(Native Method) W/System.err(1894): at org.apache.cordova.PluginManager.instantiatePlugi
W/System.err(1894): java.lang.NullPointerException: cls == null
W/System.err(1894): at java.lang.Class.isAssignableFrom(Native Method)
W/System.err(1894): at org.apache.cordova.PluginManager.instantiatePlugin(PluginManager.java:489)
W/System.err(1894): at org.apache.cordova.PluginManager.getPlugin(PluginManager.java:167)
W/System.err(1894): at org.apache.cordova.PluginManager.exec(PluginManager.java:120)
W/System.err(1894): at org.apache.cordova.CordovaBridge.jsExec(CordovaBridge.java:59)
W/System.err(1894): at org.apache.cordova.engine.SystemExposedJsApi.exec(SystemExposedJsApi.java:41)
W/System.err(1894): at com.android.org.chromium.base.SystemMessageHandler.nativeDoRunLoopOnce(Native Method)
W/System.err(1894): at com.android.org.chromium.base.SystemMessageHandler.handleMessage(SystemMessageHandler.java:27)
W/System.err(1894): at android.os.Handler.dispatchMessage(Handler.java:102)
W/System.err(1894): at android.os.Looper.loop(Looper.java:136)
W/System.err(1894): at android.os.HandlerThread.run(HandlerThread.java:61)
I/System.out(1894): Error adding plugin .
W/System.err(1894): java.lang.NullPointerException
W/System.err(1894): at org.apache.cordova.PluginManager.getPlugin(PluginManager.java:169)
W/System.err(1894): at org.apache.cordova.PluginManager.exec(PluginManager.java:120)
W/System.err(1894): at org.apache.cordova.CordovaBridge.jsExec(CordovaBridge.java:59)
W/System.err(1894): at org.apache.cordova.engine.SystemExposedJsApi.exec(SystemExposedJsApi.java:41)
W/System.err(1894): at com.android.org.chromium.base.SystemMessageHandler.nativeDoRunLoopOnce(Native Method)
W/System.err(1894): at com.android.org.chromium.base.SystemMessageHandler.handleMessage(SystemMessageHandler.java:27)
W/System.err(1894): at android.os.Handler.dispatchMessage(Handler.java:102)
W/System.err(1894): at android.os.Looper.loop(Looper.java:136)
W/System.err(1894): at android.os.HandlerThread.run(HandlerThread.java:61)
以下是我的档案:
Echo.java
package com.gerald.example.sampleecho;
import org.apache.cordova.CallbackContext;
import org.apache.cordova.CordovaInterface;
import org.apache.cordova.CordovaPlugin;
import org.apache.cordova.CordovaWebView;
import org.json.JSONArray;
import org.json.JSONException;
import android.util.Log;
public class Echo extends CordovaPlugin {
@Override
public void initialize(CordovaInterface cordova, CordovaWebView webView) {
// TODO Auto-generated method stub
super.initialize(cordova, webView);
Log.d("SAMPLE_ECHO", "initializing");
}
@Override
public boolean execute(String action, JSONArray args,
CallbackContext callbackContext) throws JSONException {
Log.d("SAMPLE_ECHO", action);
if(action.equals("echo")){
String message = args.getString(0);
this.echo(message, callbackContext);
return true;
}
return false;
}
private void echo(String message, CallbackContext callbackContext){
Log.d("SAMPLE_ECHO", "Echoing...");
if(message != null && message.length()>0){
callbackContext.success(message);
}else{
callbackContext.error("Expected one non-empty string argument.");
}
}
}
plugin.xml如下所示
plugin.xml
<?xml version="1.0" encoding="UTF-8"?>
<plugin xmlns="http://www.phonegap.com/ns/plugins/1.0"
xmlns:android="http://schemas.android.com/apk/res/android"
id="com.gerald.example.sampleecho.echo"
version="1.2.2">
<name>SampleEcho</name>
<description>Echoes stuff</description>
<author>Oyudo Gerald</author>
<js-module src="www/echo.js" name="echo" >
<clobbers target="myEcho"/>
</js-module>
<engines>
<engine name="cordova" version="4.0.2"/>
</engines>
<!-- android -->
<platform name="android">
<config-file target="res/xml/config.xml" parent="/*">
<feature name="Echo"
value="com.gerald.example.sampleecho.Echo"/>
</config-file>
<source-file src="src/com/gerald/example/sampleecho/Echo.java"
target-dir="src/com/gerald/example/sampleecho" />
</platform>
</plugin>
样本回波
回声
奥尤多·杰拉尔德
还有HTML代码
index.html
<html>
<head>
<title>HelloWorld!</title>
<meta charset="UTF-8">
<meta http-equiv="Content-Security-Policy" content="default-src *; style-src 'self' 'unsafe-inline'; script-src 'self' 'unsafe-inline' 'unsafe-eval'">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<script type="text/javascript" src="cordova.js"></script>
<script type="text/javascript">
function onBodyLoad(){
document.addEventListener("deviceready",onDeviceReady, false);
}
function onDeviceReady(){
br = "<br />";
//Get the appInfo DOM element
var element = document.getElementById("appInfo");
////Replace it with specific information about the device
////running the application
element.innerHTML = 'Cordova Version: ' +
device.cordova + br +
'Platform: ' + device.platform + br +
'Model: ' + device.model + br +
'OS Version: ' + device.version;
}
function doEcho(){
myEcho.echo("Plugin installed successfully", function(message){
alert(message);
});
}
</script>
</head>
<body onload="onBodyLoad()">
<h1>Hello World</h1>
<p>This is a sample Cordova application</p>
<p id ="appInfo">
waiting for cordova initialization to complete
</p>
<button onclick="doEcho();">Please Echo</button>
</body>
</html>
地狱世界!
函数onBodyLoad(){
文件。添加的监听器(“deviceready”,OnDeviceraddy,false);
}
函数ondevicerady(){
br=“
”;
//获取appInfo DOM元素
var元素=document.getElementById(“appInfo”);
////将其替换为有关设备的特定信息
////运行应用程序
element.innerHTML='Cordova版本:'+
device.cordova+br+
'平台:'+device.Platform+br+
“型号:”+device.Model+br+
“操作系统版本:”+device.Version;
}
函数doEcho(){
echo(“插件安装成功”,函数(消息){
警报(信息);
});
}
你好,世界
这是一个示例Cordova应用程序
正在等待cordova初始化完成
请回音
我使用的是cordova版本4.0.2和JDK 8。
stacktrace没有引用我的代码的部分,所以我甚至不知道从哪里开始。我哪里出错了
我在eclipse调试模式下运行android项目,我注意到我的插件类的一个字符串表示被传递给了null,然后传递给了CordovaWebViewImpl,最后传递给了PluginManager,我想这就是错误产生的原因。新的问题是,当通过init()方法从CordovaInterface传递到CordovaWebViewImpl时,为什么我的插件的pluginEntry为空?和。。。经过一整天的尝试,通过研究ConfigXMLParser,我终于发现下面插件的特性格式无法读取
<feature name="Echo"
value="com.gerald.example.sampleecho.Echo"/>
相反,请使用以下命令:
<feature name="Echo">
<param name="android-package" value="com.gerald.example.sampleecho.Echo" />
</feature>