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script value (ScriptEngine)

Posted on 2009-07-01
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Last Modified: 2012-05-07
I try to get some information in my script from my java program by using ScriptEngineManager.  Why values of the variables I would love to get were null?  How can I get a variable's value from the script?
My script...
function googleMapCal(lat, lng, city, region, country)
{
	var ClientLoc = google.loader.ClientLocation;
	drawMap(ClientLoc);
	lat = ClientLoc.latitude;
	lng = ClientLoc.Longitude;
	city = ClientLoc.address.city;
	region = ClientLoc.address.region;
	country = ClientLoc.address.country;
}
 
function drawMap(ClientLoc) {
    if (google.loader.ClientLocation) {
        var cl = google.loader.ClientLocation;
        var location = [cl.address.city, cl.address.region, cl.address.country].join(', ');
        ClientLoc = cl;
    } else {
        document.getElementById('cantfindyou').innerHTML = "Crap, I don't know. Good hiding!";
    }
}
 
Where I try to get values....
		ScriptEngineManager manager = new ScriptEngineManager();
		ScriptEngine engine = manager.getEngineByName("JavaScript");
		Bindings vars = new SimpleBindings();
 
		// Run Javascript
		try{
			engine.eval("function googleMapCal(lat, lng, city, region, country)" +
			"{" +
				"var ClientLoc = google.loader.ClientLocation;" +
				"drawMap(ClientLoc);" +
				"lat = ClientLoc.latitude;" +
				"lng = ClientLoc.Longitude;" +
				"city = ClientLoc.address.city;" +
				"region = ClientLoc.address.region;" +
				"country = ClientLoc.address.country;" +
			"}", vars);
		} catch (ScriptException ex){
			ex.printStackTrace();
		}
		
		// Get JavaScript Variables
		lat = (String)vars.get("lat");
		lng = (String)vars.get("lng");
		city = (String)vars.get("city");
		country = (String)vars.get("country");
		region = (String)vars.get("region");
		System.out.println("You are from " + lat + "/" + lng + "/" + city + "/" + country + "/" + region);

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Question by:xenia27
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6 Comments
 

Author Comment

by:xenia27
ID: 24760803
What's wrong with my code?
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LVL 10

Accepted Solution

by:
mahome earned 1500 total points
ID: 24761156
You're just defining a function. You must call the function, that the values will be set. Here an example:

Bindings vars = new SimpleBindings();
                
        // Run Javascript
        try{
                engine.eval("function mytest(param1)" +
                "{" +
                        "value = param1;" +
                "}" +
                "mytest('test it');"
                        
                        , vars);
        } catch (ScriptException ex){
                ex.printStackTrace();
        }
        
        // Get JavaScript Variables
        String value = vars.get("value").toString();
        System.out.println("My Value: " + value);

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Author Comment

by:xenia27
ID: 24761226
I got an error message "Source  not found"...
What should I do?  Did I define something wrong?
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LVL 10

Expert Comment

by:mahome
ID: 24761234
Can you post your complete Java-main-Funktion and the complete error message.
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Author Comment

by:xenia27
ID: 24761263
When I tried to run in debug mode, I got an error message pops up said I missed ";" somewhere in my file.  Then, I tried to run the function where calls javascript function and I got..

2009/7/2
H 08:12:23 com.google.appengine.tools.development.ApiProxyLocalImpl log
SEVERE: [1246522343671000] javax.servlet.ServletContext log: Exception while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract java.lang.String com.unet.googleproject.client.GreetingService.greetServer(java.lang.String)' threw an unexpected exception: java.lang.NullPointerException
      at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:360)
      at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:546)
      at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:166)
      at com.google.gwt.user.server.rpc.RemoteServiceServlet.doPost(RemoteServiceServlet.java:86)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:713)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:806)
      at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
      at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1093)
      at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
      at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
      at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:360)
      at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
      at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
      at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:712)
      at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
      at com.google.apphosting.utils.jetty.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:54)
      at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
      at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:306)
      at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
      at org.mortbay.jetty.Server.handle(Server.java:313)
      at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:506)
      at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:844)
      at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:644)
      at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:205)
      at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:381)
      at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:396)
      at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:442)
Caused by: java.lang.NullPointerException
      at com.unet.googleproject.server.GreetingServiceImpl.GetClient(GreetingServiceImpl.java:48)
      at com.unet.googleproject.server.GreetingServiceImpl.greetServer(GreetingServiceImpl.java:28)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
      at java.lang.reflect.Method.invoke(Unknown Source)
      at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:527)
      ... 25 more
this is where I try to call the javascript function...
public class GreetingServiceImpl extends RemoteServiceServlet implements
		GreetingService {
 
	public String greetServer(String input) {
		
		String serverInfo = getServletContext().getServerInfo();
		String userAgent = getThreadLocalRequest().getHeader("User-Agent");
		Locale clientRequest = getThreadLocalRequest().getLocale();
		String clientHostAddr = getThreadLocalRequest().getRemoteAddr();
		String lat = new String();
		String lng = new String();
		String city = new String();
		String country = new String();
		String region = new String();
		
		GetClient(lat, lng, city, country, region);
		
		return "Hello, " + input + "!<br><br>I am running " + serverInfo
				+ ".<br><br>It looks like you are using:<br>" + userAgent
				+ ".<br><br>You are from:<br>" + city + "/" + country + " " + region
				+ ".<br><br>Your Lat/Lng:<br>" + lat + "/" + lng;
	}
	
	public void GetClient(String lat, String lng, String city, String country, String region)
	{
		ScriptEngineManager manager = new ScriptEngineManager();
		ScriptEngine engine = manager.getEngineByName("javascript");
		Bindings vars = new SimpleBindings();
		Invocable invocableEngine = (Invocable)engine; 
 
		// Run Javascript
		try{
			engine.eval("function getInfo(Lat){"
					+ "  getLat(Lat); } ", vars
        		);
			lat = vars.get("Lat").toString();
			System.out.println("Lat: " + lat);
		} catch (ScriptException ex){
			ex.printStackTrace();
		} 
 
	}
}
 
this is where I have my javascript...in a html file...
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
        "http://www.w3.org/TR/html4/loose.dtd">
<!-- The HTML 4.01 Transitional DOCTYPE declaration-->
<!-- above set at the top of the file will set     -->
<!-- the browser's rendering engine into           -->
<!-- "Quirks Mode". Replacing this declaration     -->
<!-- with a "Standards Mode" doctype is supported, -->
<!-- but may lead to some differences in layout.   -->
 
<html>
  <head>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
 
    <!--                                                               -->
    <!-- Consider inlining CSS to reduce the number of requested files -->
    <!--                                                               -->
    <link type="text/css" rel="stylesheet" href="xxx.css">
 
    <!--                                           -->
    <!-- Any title is fine                         -->
    <!--                                           -->
    <title>Web Application Starter Project</title>
    
    <!--                                           -->
    <!-- This script loads your compiled module.   -->
    <!-- If you add any GWT meta tags, they must   -->
    <!-- be added before this line.                -->
    <!--                                           -->
    <script type="text/javascript" language="javascript" src="xxx/xxxt.nocache.js"></script>
      <style type="text/css">
  body {
    padding: 0;
    margin: 0;
    background-color: #4f4e45;
    font-family: Tahoma, Arial, sans-serif;
  }
  
  #header {
    height: 30px;
    background-color: #111;
    color: #EEE;
    font-size: 10pt;
    padding-top: 4px;
    border-bottom: 1px solid #333;
  }
  
  #main {
    margin: 20px auto;  
    width: 610px;
  }
  
  #main h2 {
    font-weight: normal;
    margin: 0;
    color: #ff9600;
    font-size: 16pt;
    font-family: Tahoma, Arial, sans-serif;
    padding-bottom: 1em;
  }
  
  a {
    color: #fff;
  }
 
  #cantfindyou {
      font-size: 18pt;
  }
  
  #map {
      display: none;
      height: 300px;
      border: 1px solid black;
      margin: 10px 4px;
  }
  </style>
    
  </head>
 
  <!--                                           -->
  <!-- The body can have arbitrary html, or      -->
  <!-- you can leave the body empty if you want  -->
  <!-- to create a completely dynamic UI.        -->
  <!--                                           -->
<body>
 
    <!-- OPTIONAL: include this if you want history support -->
    <iframe src="javascript:''" id="__gwt_historyFrame" tabIndex='-1' style="position:absolute;width:0;height:0;border:0"></iframe>
 
    <h1>Web Application Starter Project</h1>
 
    <table align="center">
      <tr>
        <td colspan="2" style="font-weight:bold;">Please enter your name:</td>        
      </tr>
      <tr>
        <td id="nameFieldContainer"></td>
        <td id="sendButtonContainer"></td>
      </tr>
    </table>
    
	<script type="text/javascript" src="http://www.google.com/jsapi?key=ABQIAAAAJjoQAkGmq5qsa0PKk9Y6nxQdF2TG78juI7gyCxAZXlcasg4lQxTlaYHDB6IKUESWIPTqiJvXPeiwhg"></script>
	<script type="text/javascript">
 
	functionn getInfo(Lat)
	{
		getLat(Lat);
	}
 
	function getLat(Lat)
	{
	    if (google.loader.ClientLocation) {
	        var cl = google.loader.ClientLocation;
	        var location = [cl.address.city, cl.address.region, cl.address.country].join(', ');
	    }
	    Lat = cl.latitude;
	}
 
	</script>
 
</body>
 
</html>

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Author Comment

by:xenia27
ID: 24769645
Any help?
Is there any example which contains both javascript and java examples?  All I can find is examples in java about how I can use ScriptEngineManager.

By the way, I try to create a web application with google wizard and eclipse.  Please help me~
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