It's been a long time since I've studied new technology. As a programmer, I feel very ashamed. I've been wanting to see the technology about XMLHTTP, and today I have a little time to do a first experience. fell in love with it at once.
XMLHTTP technology is a good choice if you want to interact with the background data without refreshing the page, or exchange data between heterogeneous systems.
Below is a very small experience of my program, referring to the csdn netizen S_phoenix () to the person's reply.
Start by building a Tomcat Web project.
1:-------index.htm The contents of the document are as follows:
<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 transitional//en" >
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<meta name= "generator" content= "EditPlus" >
<meta name= "Author" content= "" >
<meta name= "Keywords" content= "" >
<meta name= "Description" content= "" >
</HEAD>
<BODY>
<script language= "JavaScript" >
var xml= "<root><test> Li Chunlei </test><test> Mao Zedong </test></root>"
var xmlHttp = new ActiveXObject ("Msxml2.xmlhttp");
var xmldoc=new activexobject ("msxml2.domdocument");
function test () {//Client XML parsing
Xmldoc.loadxml (XML);
if (xmldoc.parseerror.line>0) {
Throw XmlDoc.parseError.reason;
}
var nodes= xmldoc.selectnodes ("/root/test");
for (Var i=0;i<nodes.length;i++) {
Alert (Nodes.item (i). text);
}
}
function action () {//client and server-side communication
Xmlhttp.open ("Post", "Http://127.0.0.1:8888/xmlhttpTest/UrlTestServlet", false);
Xmlhttp.setrequestheader ("Context-type", "text/xml;charset=utf-8");
Xmlhttp.send (XML);
var Showstr=xmlhttp.responsetext;
alert (SHOWSTR);
}
</script>
<button > View the xml</button><br/> that will be transferred
<button > sends XML to server and receives server response </button>
</BODY>
</HTML>
2:------------Write a Servlet:UrlTestServlet.java
/*
* Date Created 2005-4-7
*
* TODO to change the template for this generated file, go to the
* Windows-Preferences-Java-code styles-code templates
*/
Package COM.LCL;
Import javax.servlet.*;
Import javax.servlet.http.*;
Import java.io.*;
Import java.util.*;
Import org.dom4j.io.*;
Import org.dom4j.*;
/**
* @author LCL
*
* TODO to change the template for this generated type annotation, go to the
* Windows-Preferences-Java-code styles-code templates
*/
public class Urltestservlet extends HttpServlet {
private static final String Content_Type = "Text/xml;charset=utf-8";
Initialize Global Variables
public void Init () throws Servletexception {
}
Process the HTTP GET request
public void doget (HttpServletRequest request, httpservletresponse response)
Throws Servletexception, IOException {
Response.setcontenttype (Content_Type);
Request.setcharacterencoding ("Utf-8");
PrintWriter out = Response.getwriter ();
InputStream Is=request.getinputstream ();
Saxreader reader=new Saxreader ();
Document Doc=null;
try{
Doc=reader.read (IS);
catch (Exception ex) {
System.out.println (ex);
}
String[] s= getelementtexts (doc, "Test");
OUT.PRINTLN ("Data exchange success: Return" + s[0] + s[1]);
}
public void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {
Doget (Request,response);
}
Private String Getelementtext (Document doc,string name) {
Return doc.getrootelement (). Element (name). GetText ();
}
Private string[] Getelementtexts (Document doc,string name) {
List l=doc.getrootelement (). elements (name);
Iterator It=l.iterator ();
List l1=new LinkedList ();
while (It.hasnext ()) {
Element e= (Element) It.next ();
L1.add (E.gettext ());
}
Return (string[]) L1.toarray (new string[]{});
}
Clean up resources
public void Destroy () {
}
}
3:--------Web.xml changes as follows (plus servlet mapping):
<?xml version= "1.0" encoding= "Iso-8859-1"?>
<! 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>welcome to Tomcat</display-name>
<description>
Welcome to Tomcat
</description>
<!--jspc servlet mappings Start-->
<servlet>
<servlet-name>UrlTestServlet</servlet-name>
<servlet-class>com.lcl.UrlTestServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UrlTestServlet</servlet-name>
<url-pattern>/UrlTestServlet</url-pattern>
</servlet-mapping>
<!--jspc servlet mappings End-->
<welcome-file-list>
<welcome-file>index.htm</welcome-file>
</welcome-file-list>
</web-app>
Okay, start tomcat, Access: http://127.0.0.1:8888/xmlhttpTest/work/(if your tomcat port is 8080, change it)
See the results, it's really good. Do not refresh the page, let the HTM foreground page and background for a data exchange.
You can even exchange data between different servers, such as a mis system, and a GIS system, to integrate into a system, we used a frame, the left is MIS, the right is a GIS, Exchange data between two systems via JavaScript. If you use XMLHTTP technology, there is absolutely no need to do so.
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