I have to make a project for my study exam with using Grizzly server and Jersey. The server is set up and runs perfectly and uses my HTML file to create the website. Now I want to make a button that calls a Java method on click.
Here is the Grizzly server:
public static void main(String[] args) throws IOException {
URI baseUri = URI.create("http://localhost:9998");
final ResourceConfig resourceConfig = new ResourceConfig(Homepage.class);
final HttpServer server = GrizzlyHttpServerFactory.createHttpServer(baseUri, resourceConfig);
System.out.println("Starting grizzly ...");
Homepage hp = new Homepage();
hp.sayHelloInHtml();
JOptionPane.showMessageDialog(null, "Stop Server");
server.shutdownNow();
}
Here is the Homepage.java code:
#Path("")
public class Homepage {
#GET
#Produces("text/html")
public String sayHelloInHtml() throws IOException {
String content = Files.toString(new File("homepage.html"), Charsets.UTF_8);
return content;
}
public void btnClicked(){
System.out.println("Button clicked!");
}
}
And this is the homepage.html code:
<HTML>
<BODY>
<H2>
Hello World
</H2>
<button>
Click Me!
</button>
</BODY>
</HTML>
So when I click the button Click Me! I want to call the method btnClicked() in the class Homepage.
Do I have to make any type of client or something? Never worked with Jersey and we need to do it like that.
Try this in your method. on button click call action with the url /btnClicked
#Path("/btnClicked")
#GET
#Produces("text/html")
public void btnClicked(){
System.out.println("Button clicked!");
}
Related
I want to extend an existing application with a drag and drop file upload feature. The application is built upon Jetty + Wicket. DropzoneJS seems a good way to go. Dropzone provides all front-end work, I just have to wire it up to the back-end.
More easily said than done, as it turns out. First, I created a test application with the Wicket quickstart. I added dropzone to the HomePage:
<!DOCTYPE html>
<html>
<head>
<script src="https://rawgit.com/enyo/dropzone/master/dist/dropzone.js"></script>
<link rel="stylesheet" href="https://rawgit.com/enyo/dropzone/master/dist/dropzone.css">
</head>
<body>
<form action="/upload" class="dropzone"></form>
</body>
</html>
Dropzone is simply included from its repository. On the server, I mounted a resource reference at /upload:
public class FileUploadResourceReference extends ResourceReference
{
public FileUploadResourceReference(String name)
{
super(FileUploadResourceReference.class, name);
}
#Override
public IResource getResource()
{
return new FileUploadResource();
}
}
FileUploadResource will handle processing of uploaded files:
public class FileUploadResource extends AbstractResource
{
#Override
protected ResourceResponse newResourceResponse(Attributes attributes)
{
ServletWebRequest request = (ServletWebRequest) attributes.getRequest();
try
{
MultipartServletWebRequest multipartRequest = request
.newMultipartWebRequest(Bytes.megabytes(100), "ignored");
Map<String, List<FileItem>> files = multipartRequest.getFiles();
List<FileItem> fileItems = files.get("file");
for (FileItem fileItem : fileItems)
{
saveFile(fileItem);
}
}
catch (FileUploadException e)
{
e.printStackTrace();
}
return null;
}
private void saveFile(FileItem fileItem)
{
// not implemented
}
}
Now here's the problem, when uploading files, Dropzone sends a POST-request to my http://localhost:8080/upload. The request is recognized as a multipart request, but the file parameter is absent. A null pointer exception is thrown entering the for-loop:
java.lang.NullPointerException
at com.test.FileUploadResource.newResourceResponse(FileUploadResource.java:31) ~[classes/:?]
at org.apache.wicket.request.resource.AbstractResource.respond(AbstractResource.java:629) ~[wicket-core-7.4.0.jar:7.4.0]
at org.apache.wicket.request.handler.resource.ResourceRequestHandler.respond(ResourceRequestHandler.java:105) ~[wicket-core-7.4.0.jar:7.4.0]
at org.apache.wicket.request.handler.resource.ResourceReferenceRequestHandler.respond(ResourceReferenceRequestHandler.java:108) ~[wicket-core-7.4.0.jar:7.4.0]
I can't figure out what's going on here. According to the Dropzone website, the form declaration should be fine. A bug in Dropzone perhaps? Seems unlikely. Some Jetty configuration parameter that is denying multipart form requests? Seems highly unlikely, at least I've never heard of it.
You can find full source code of my test app on GitHub.
You miss one method call - multipartRequest.parseFileNames().
You need to do it before #getFiles().
See http://wicketinaction.com/2012/11/uploading-files-to-wicket-iresource/
I play NanoHTTPD and WebServer based on it. To update any object in my code (application) I can use GET/POST method. But how can I create dynamic pages? For example I have html page on disc and it should present current temperature:
<html>
<head>
<title>My page</title>
</head>
<body>
<p style="text-align: center">Temperature: [temperature variable] </p>
</body>
</html>
How can I pass "variable temperature" from my application based on NanoHTTPD to html file and present it in browser?
You have to read the template from your disk, and replace the [temperature variable] substring with the value you want to include.
To read the file, you can use the Files class:
byte[] data = Files.readAllBytes(Paths.get("mytemplpate.html"));
String templ = new String(data, StandardCharsets.UTF_8);
To insert your temperature:
double temperature = 22.3;
String html = templ.replace("[temperature variable]", Double.toString(temperature));
And finally to send this as the response with NanoHTTPD:
return new NanoHTTPD.Response(html);
The complete program:
Foreword: Exceptions are not handled, this is just for demonstration purposes.
public class TemperatureServer extends NanoHTTPD {
// Loaded and cached html template
private static String templ;
// Value of this variable will be included and sent in the response
private static double temperature;
public TemperatureServer () {
super(8080);
}
#Override
public Response serve(IHTTPSession session) {
String html = templ.replace("[temperature variable]",
Double.toString(temperature));
return new NanoHTTPD.Response(html);
}
public static void main(String[] args) throws Exception {
byte[] data = Files.readAllBytes(Paths.get("mytemplpate.html"));
templ = new String(data, StandardCharsets.UTF_8);
ServerRunner.run(TemperatureServer.class);
}
}
For more advanced examples check out the Samples package of the NanoHttpd Github site.
HTML Code:
Dummy Text
Script Code:
$('#test').editable({
url: '<%=resourceURL.toString() %>',
send: 'always'
});
Java Class Code:
public void serveResource(ResourceRequest resourceRequest, ResourceResponse resourceResponse) {
String test = ParamUtil.getString(resourceRequest, "test");
System.out.println(test);
}
What happened everytime I change the editable value, there's no data sent from editable ajax.
By the way I'm using Liferay for development.
I am having a very wierd issue and I'm hoping you can help me out
At work, we use a web application made with the framework GWT, and all the sales reports have an option to export the data to excel. It usually works fine, but the days that the report has more than about 15-20 thousand rows, the excel file only opens with the word "null" on the first cell.
Within the code, we use a JSP to send the data as html and a StringBuffer object to append all the text of the html. Here es the method that sends the html:
public void export(final String psFormat) {
manageStartOfCall();
String lsFileName = "resources/system/excel_file.jsp";
final DynamicForm loForm = new DynamicForm();
loForm.setAction(lsFileName);
loForm.setMethod(FormMethod.POST);
loForm.setCanSubmit(true);
final TextAreaItem loDataToExport = new TextAreaItem("psExcelData");
final Window loExcelWindow = new Window();
loExcelWindow.setWidth(5);
loExcelWindow.setHeight(5);
loExcelWindow.addItem(loForm);
addChild(loExcelWindow);
new Timer() {
public void run() {
cancel();
loDataToExport.setValue(moHeader.getHeaderAsExcel() + "<br><br>" + moReportGrid.getDataAsHTML());
loForm.setFields(loDataToExport);
new Timer() {
public void run() {
cancel();
manageEndOfCall();
loForm.submit();
loExcelWindow.destroy();
}
}.schedule(200);
}
}.schedule(200);
}
I've already debugged the getDataAsHTML method and the string that it returns is fine, it contains the correct HTML, however when I call the method getParameter in the JSP y returns a null value. Here the code of the JSP:
<%
response.setContentType("application/vnd.ms-excel");
response.setHeader("Content-Disposition", "attachment;filename=eYumReport.xls");
String msDataToExcel = request.getParameter("psExcelData");
%>
<html>
<head>
<title>Data to excel</title>
</head>
<body>
<%=msDataToExcel %>
</body>
</html>
I may have to mention I am using this on Firefox 26, GWT 2.1, smartGWT 2.4, Windows 7 Professional and the Web application is on Windows Server 2008, mounted on Apache 6.
Any ideas why this is happening??
I've tried this question before with little success but that's probably my fault so I'll be as specific as possible!
Part A)
I have a compiled java class which returns a hello world string. The source code for this file is below. After configuring the web.xml setting I am able to get good results from a browser pointing at localhost. This is working exactly as planned.
Part B)
I have an HTML landing page with a single link in it which, when pressed will read a local text file and replace content within it. This is also working exactly as planned.
Part A means I am able to have a client call a server-side java class file and get outputs. Part B means I am able to replace one part of a webpage after a button has been pressed.
My question, from this point is quite straight forward. I would like to merge the two concepts so that when the link from part B is pressed the text updated will reflect the 'hello world' result set from Part A.
Thanks in advance.
Part A Code:
package mypkg;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class HelloServlet extends HttpServlet {
#Override
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
out.println("<!DOCTYPE html>");
out.println("<html><head>");
out.println("<meta http-equiv='Content-Type' content='text/html; charset=UTF-8'>");
out.println("<title>Hello, World</title></head>");
out.println("<body>");
out.println("<h1>Hello, world!</h1>");
out.println("</body>");
out.println("</html>");
} finally {
out.close();
}
}
}
Part B Code
<p id="mySentence">
Click here to update the page.
When you click the link, this content will be replaced.</p>
<script type="text/javascript">
var http = createRequestObject();
function createRequestObject() {
var objAjax;
var browser = navigator.appName;
if(browser == "Microsoft Internet Explorer"){
objAjax = new ActiveXObject("Microsoft.XMLHTTP");
}else{
objAjax = new XMLHttpRequest();
}
return objAjax;
}
function getNewContent(){
http.open('get','newcontent.txt');
http.onreadystatechange = updateNewContent;
http.send(null);
return false;
}
function updateNewContent(){
if(http.readyState == 4){
document.getElementById('mySentence').innerHTML = http.responseText;
}
}
</script>