DWR
: Direct Web remoting, that is, the Java method that can be remotely accessed to the server on the client, is equivalent to a method that can be called to the Java class using JavaScript.
It sounds nice. In fact, this is just the most intuitive feeling. In fact, a dwrservlet is used in the middle to access the server code, while javascript accesses this dwrservlet through Ajax, so it seems that JavaScript directly accesses the Java code.
. DWR encapsulates Ajax and has functions similar to jquery.
To use helloword:
First:
Get the DWR package to DWR. Jar. Download: http://directwebremoting.org/dwr/download.html in the project
Second:
I just mentioned that there is actually a servlet in the middle to connect js to the server, so we need to configure the dwrservlet information in Web. XML, as shown below:
<Servlet>
<Servlet-Name>
DWR</Servlet-Name>
<Servlet-class>
Org. directwebremoting. servlet. dwrservlet
</Servlet-class>
<! -- The init-Param here is only used for debugging -->
<Init-param>
<Param-Name>
Debug
</Param-Name>
<Param-value>
True
</Param-value>
</Init-param>
</Servlet>
<Servlet-mapping>
<Servlet-Name>
DWR
</Servlet-Name>
<URL-pattern>
/DWR /*
</Url-pattern>
</Servlet-mapping>
Write a test class:
Package
Org. LC. DWR;
Public
Class
Dwrtest {
Public
String sayhello (string somebody ){
Return
Somebody + ", hello! ";
}
}
Again (key ):
Create a DWR. xml file under Web-INF of the project:
The content is as follows:
<DWR>
<Allow>
<! -- The information of the test class is configured here -->
<Create javascript ="
HW
"Creator ="
New
"
>
<! -- JavaScript = "HW" indicates that the method of the test class should be called with the HW object in JS, such as HW. sayhello ("China"); creator = "new" indicates to use the new keyword to create an object for the test class .. Spring is not integrated here -->
<Param name ="
Class
"Value ="
Org. LC. DWR. dwrtest
"/>
</Create>
</Allow>
</DWR>
Finally:
Client code
<HTML>
<Head>
<SCRIPT type
= 'Text/JavaScript
'Src
= '/DWR/interface/HW. js
'> </SCRIPT>
<SCRIPT type
= 'Text/JavaScript
'Src
= '/DWR/engine. js
'> </SCRIPT>
<SCRIPT type
= 'Text/JavaScript
'Src
= '/DWR/util. js
'> </SCRIPT>
<SCRIPT>
Function
C (){
HW. sayhello (DWR. util. getvalue ("C
"), Function (RDATA) {<! -- The first parameter is used as the sayhello parameter in the dwrtest class, and the second anonymous function is used to process the return value of sayhello. -->
DWR. util. setvalue ("CC
", RDATA );
});
}
</SCRIPT>
</Head>
<Body>
<
Input
Type
= "Text
"Id =" C
"/> <Input
Type
= "Button" Value
= "Sayhello" onclick
= "C ()
;"/>
<Div
ID
= "Cc"></Div>
</Body>
</Html>
:
Thoughts:
The Return Value of the method here is a string, so there is no problem. What if the return value is a list or a JavaBean object ?,
Or the input parameter is a JavaBean object. How can this problem be solved? If you do not know, add the QQ group: 37983546 and ask a question.
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