If DWR is used, the effect is immediate. Although it may damage the MVC design pattern, its low-coupling programming method is as simple as developing a CS program. In the past, when I used ajax to write a program, the most time spent was the JS part. Now with DWR, I don't have to debug complicated JS and focus on the business logic, this will surely get twice the result! I just learned an entry-level instance. To help you learn, I posted the source code! Don't laugh. I am also a beginner in DWR.
Configure web. XML with the following code:
<? XML version = "1.0" encoding = "UTF-8"?>
<! Doctype web-app
Public "-// Sun Microsystems, Inc. // DTD web application 2.3 // en"
Http://java.sun.com/dtd/web-app_2_3.dtd>
<Web-app>
<Display-Name> SJF </display-Name>
<Description> SJF </description>
<Servlet>
<Servlet-Name> DWR-invoker </servlet-Name>
<Display-Name> DWR servlet </display-Name>
<Description> direct Web remoter servlet </description>
<Servlet-class> UK. Ltd. getahead. DWR. dwrservlet </servlet-class>
<Init-param>
<Param-Name> debug </param-Name>
<Param-value> true </param-value>
</Init-param>
</Servlet>
<Servlet-mapping>
<Servlet-Name> DWR-invoker </servlet-Name>
<URL-pattern>/DWR/* </url-pattern>
</Servlet-mapping>
</Web-app>
DWR. xml file Configuration:
<? XML version = "1.0" encoding = "UTF-8"?>
<! Doctype DWR public "-// getahead limited // DTD direct Web remoting 1.0 //" http://www.getahead.ltd.uk/dwr/dwr10.dtd ">
<DWR>
<! -- Without allow, DWR isn't allowed to do anything -->
<Allow>
<Create scope = "application" creator = "new" javascript = "checklogin">
<Param name = "class" value = "com. Test. Ajax. userlogin"/>
</Create>
</Allow>
</DWR>
Java file (userlogin. Java) code:
Package com. Test. Ajax;
Public class userlogin {
Private string usern;
Private string passwd;
Public userlogin (){
}
Public String checklogin (){
If (usern. Equals ("admin") & passwd. Equals ("admin ")){
Return "Login success! ";
} Else {
Return "Login faild! ";
}
}
Public void setfield (string usern, string passwd ){
This. usern = usern;
This. passwd = passwd;
}
Public static void main (string ARGs []) {
Userlogin ul = new userlogin ();
Ul. setfield ("admin", "admin ");
System. Out. println (UL. checklogin ());
}
}
The code for JSP files (which can be replaced by HTML files) is as follows:
<% @ Page Language = "Java" contenttype = "text/html; charset = UTF-8" pageencoding = "UTF-8" %>
<! Doctype HTML public "-// W3C // dtd xhtml 1.0 transitional // en" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<HTML xmlns = "http://www.w3.org/1999/xhtml">
<Head>
<Meta http-equiv = "Content-Type" content = "text/html; charset = UTF-8"/>
<Title> DWR for user login </title>
<SCRIPT type = "text/JavaScript" src = "<% = request. getcontextpath () %>/DWR/interface/checklogin. js"> </SCRIPT>
<SCRIPT type = "text/JavaScript" src = "<% = request. getcontextpath () %>/DWR/engine. js"> </SCRIPT>
<SCRIPT type = "text/JavaScript" src = "<% = request. getcontextpath () %>/DWR/util. js"> </SCRIPT>
<Script language = "JavaScript">
VaR mycall = function callback (data ){
Alert (data );
}
Function login (){
VaR UN = Document. getelementbyidx ("form_usern ");
VaR Pd = Document. getelementbyidx ("form_passwd ")
Checklogin. setfield (UN. Value, PD. value );
Checklogin. checklogin (mycall );
}
</SCRIPT>
</Head>
<Body>
<H1> User Login <Label for = "form_usern"> User: </label> <input type = "text" id = "form_usern"/> <br/>
<Label for = "form_passwd"> password: </label> <input type = "password" id = "form_passwd"> <br/>
<Input type = "button" value = "login" onclick = "javascript: Login ()">
</Body>
</Html>
Note: Make sure that the DWR. jar file exists in the \ WEB-INF \ Lib folder.
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