Is there an easy way to send HTML from a servlet to a JSP, using AJAX.
I've already figured out how to make AJAX work with servlets dynamically, but now I want to press a button on a form and generate HTML based on text-input.
Is it possible, and if so, how, to send just pieces of HTML to an existing HTML page?
Example,
I have a basic form where you can input your age, and based on the age the text has a different size/color. So, you send for example, 25 as your age to the servlet, and it send back a piece of HTML like this <p STYLE="font-size: age;"> to the page.
Through ajax call you can get the output result either a string, html or a Json object that will be parsed and results can be displayed over JSP/HTML. So for sure you can send html code segment from servlet to jsp through ajax call.
For example you can use this approach--
1. Take a string variable in your servlet.
2. Put appropriate html string as per your conditions in this string variable
3. send this string as a response from servlet like:
response.setCharacterEncoding("UTF-8");
response.getWriter().write("your string variable here");
4. In your ajax call do like this:
success : function(dataString) {
document.getElementById("containerId").innerHTML=dataString;
},
where containerId is the id of html element (like div or span) where you want to display output html.
The easiest approach, without client-side javascript libraries, would be to point an HTML form to an iframe, just like
<iframe name="myIframe"...>
<form target="myIframe"...>
And submit your form as many times as necessary. The HTML returned by the servlet would load itself in the iframe element.
If you like AJAX and client-side javascript libraries, you can find very easy programmatical ways to do this in jQuery and similar libraries.
Basically your servlet can generate any kind of content, e.g. JSON, HTML etc.
You'd then send that content back to the client and integrate it into the page.
How that is done depends on the type of content.
Example:
You issue an AJX request (e.g. by using jQuery's ajax functionality) and your servlet generates plain html. When your JavaScript receives the anser you just replace the relevant part, e.g. by replacing the content of some defined element.
If you used JSON instead, your servlet might send data only instead, e.g. a font size based on the age as in your example. You'd then use JavaScript to access that JSON data and perform relevant operations, e.g. by changing the style of the paragraph.
Related
I hope you get my problem.
out.println("<li class='has-sub'><a href='#'>" + k1.getKName() + "</a>\n");
I have a JSP and inside this java code. The result is a navigation on the left side with several categories and subcategories. So this is one category element. As you can see, I didn't put anything in the href. What I want to do is, that when I click on this category, I will get the articles of this category in the content space on the right side.
So, what do I have to do with servlets or JSPs in order to give a result to the content space. I can't just call a servlet there of course, because that means that I get the result of the servlet inside the href obviously.
I am sorry if this is a silly question, but I really don't know how to solve this :(
Further to previous comments you do not need web services. You can do this using ajax and a normal Servlet. You might want to look at using JQuery to help with the Ajax part. Here's some JQuery documentation around the load() function which will:
Load data from the server and place the returned HTML into the matched
element.
https://api.jquery.com/load/
Your link will look something like (if k1 is a bean in some scope then you can use EL rather than scriptlets):
<a href='javascript:loadData(${k1.id});'>${k1.name}</a>
Your Javascript will look something like:
function loadData(id){
var url = "/pathToMyServlet?id=" + id;
$( "#result" ).load( url );
}
which will call your Servlet and insert the HTML returned to an element on your page with the ID 'result'.
Your Servlet then needs to generate the data and forward to a simple JSP which returns the results (and only the results) i.e. it does not need to be a fully formed HTML page but should only contain the table of results or whatever.
And stop using scriptlets:
How to avoid Java code in JSP files?
I need to call small part of JSP page(like only div load) when a method is invoked? I know we can load whole JSP page from Servlet. Is this possible or any other solution for this?
know we can load whole JSP page from Servlet. Is this possible
Yes it is possible, you forward your request to jsp from servlet and it will render that jsp, here is an exact same example
1) Set some session or request variable equal to some value, say boolean myVar = true.
2) Redirect from your jsp page from your servlet.
3) In the jsp page, check for particular condition for the variable myVar. If condition is fulfilled, using scriptlets or JSTL display only the relevant part of you jsp.
You can use AJAX(Asynchronous Javascript and XML) for this purpose
For example, Suggestions, that appear without any refresh for auto-complete in google search, are using Ajax. JSP code will contain the Ajax code and will send the information to the servlet in form of XmlHttpRequest object and then takes the response from servlet as xmlhttp.responseText. The result can be written at JSP page by using DOM.
To initiate this process, you need to use the onkeyup in input tag like this:
<input type="text" onkeyup="methodName(this.value)"
Learn more about Ajax
To use AJAX with Java, try this
Ajax for Java Web Applications
$('#myDiv').load('serverPage.jsp #server_div_id');
OR
$.ajax({
url: 'serverPage.jsp',
success: function(data) {
data=$(data).find('div#id');
$('#mydiv').html(data);
}
});
I have two different divisions in a JSP page. One contains a menu of links, when clicked the div2 (id-content) loads different pages accordingly. I am doing something like -
<div id="menu">
<ul class="navbar">
<li><a name="login" href="Login.jsp" onclick="changeContent()">Login</a>
</li></div>
and in the script I have something as -
<script language="JavaScript">
function changeContent() {
document.getElementById('content').load('Login.jsp');
}
</script>
I also tried -
document.getElementById('content').innerHTML=
"<jsp:include page="Login.jsp">";
None of the ways worked. Please suggest how should I
Try jquery..
function changeContent() {
$('#content').load('Login.jsp');
}
The solution is to use Ajax, which will asynchronously retrieve your page content that can be pasted in with the innerHTML method. See my answer to a similar question of how an Ajax call works and some introductory links.
As to why your examples in your answer don't work, in the first case there is no load() method on an Element object (unless you've defined one yourself and not shown it). In the second example, as one of the question comments says, there is probably something causing a syntax error in the javascript.
As an FYI, when there is a syntax error in some javascript in a web page, the current expression being parsed and the rest of the <script></script> block will be ignored. Since this is inside a function declaration, that function will never get defined.
For instance, an embedded quote in the included page will end the string for the innerHTML assignment. Then the javascript parser will try to parse the remainder of the HTML causing a syntax error as the HTML will not be valid javascript.
We use jquery. Add a click event handler to the anchor elements. In the click handler call $('#content').load(your_url);. You might want to use the load(url, function() { ...}) version. More info here http://api.jquery.com/load/
Your initial page comes down from the server. It's displayed by the browser. When you click on a link (or a button) in the browser, you want to fill the second div with new HTML. This is is a perfect job for an AJAX request. What the AJAX object in the browser does, is to send a POST (or whatever) string to the server. And then the Ajax object receives the HTML response back from the server. And then you can display that response data which the AJAX object contains, anywhere you want.
In my JSP page I have DIV.
<div id="100">
ALI
</div>
When I click on this DIV...
$("#100").click(function(){
});
...I need to send the value of the id 100, to a servlet, so that the servlet makes some database java codes, and returns for example, either 1 or 0. How can I do that? and is this the proper way?
Using Ajax, you should call your server using a URL similar to this:
http://localhot:8080/youAppContext/yourServer?id=100
Then, in the servler side, you should retrieve the value that will be in the request with the name "id"
There are out there many tool as jQuery that can help you to do the Ajax petition.
Edited
Well, here you can find a very simple Ajax example using jQuery. In the example, instead call a file (test1.txt) you should invoke a URL (as I described above). Of course, you will need to write some JS code to build your URL (where id be a variable). Once task is done in servlet side, you can return whatever, for example: "done" and display or not this information the HTML as it is done in the example.
Take a look to this Web, there are many links that can help you.
get the value using
var value = $("#100").html();
and pass it to servlet using AJAX
I know this question is similar to my previous question. I am making a AJAX request sending form values to a servlet which processes and sends me a JSON object as string. I am want to use that JSON object in my custom tag. How do I achieve this ? If its not possible with AJAX, what other alternatives have I got which prevents user from page refresh.
Custom tags are evaluated server-side, while ajax-requests are initiated from the browser. So you can't get a response from the server and use it in the tag evaluation.
Either add some javascript to the tag output which will handle the ajax response, or don't use JSON at all - since the tag is handled on the server you can get what you want without any serialization.