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A simple Ajax login example

Source: Internet
Author: User
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1. View (loginajax. jsp)

Code:
  1. <% @ Page contenttype = "text/html; charset = UTF-8" Language = "Java" %>
  2. <Head>
  3. <Meta http-equiv = Content-Type content = "text/html; charset = UTF-8">
  4. </Head>
  5. <Script language = "JavaScript">
  6. VaR xmlhttpreq = false;
  7. // Create an XMLHTTPRequest object
  8. Function createxmlhttprequest (){
  9. If (window. XMLHttpRequest) {// Mozilla Browser
  10. Xmlhttpreq = new XMLHttpRequest ();
  11. } Else if (window. activexobject) {// IE browser
  12. Try {
  13. Xmlhttpreq = new activexobject ("msxml2.xmlhttp ");
  14. } Catch (e ){
  15. Try {
  16. Xmlhttpreq = new activexobject ("Microsoft. XMLHTTP ");
  17. } Catch (e ){
  18. }
  19. }
  20. }
  21. }
  22. // Send the request Function
  23. Function sendrequest (URL ){
  24. Createxmlhttprequest ();
  25. Xmlhttpreq. Open ("get", URL, true );
  26. Xmlhttpreq. onreadystatechange = processresponse; // specify the response function.
  27. Xmlhttpreq. Send (null); // send the request
  28. }
  29. // Function for processing returned information
  30. Function processresponse (){
  31. If (xmlhttpreq. readystate = 4) {// judge the object status
  32. // Window. Alert (xmlhttpreq. status); Test
  33. If (xmlhttpreq. Status = 200) {// The information has been returned successfully. Start to process the information.
  34. VaR res = xmlhttpreq. responsexml. getelementsbytagname ("res") [0]. firstchild. Data;
  35. Window. Alert (RES );
  36. } Else {// The page is abnormal.
  37. Window. Alert ("the page you requested has an exception. ");
  38. }
  39. }
  40. }
  41. // Identity verification function
  42. Function usercheck (){
  43. VaR uname = Document. myform. uname. value;
  44. VaR psw = Document. myform. psw. value;
  45. If (uname = ""){
  46. Window. Alert ("the user name cannot be blank. ");
  47. Document. myform. uname. Focus ();
  48. Return false;
  49. } Else {
  50. Sendrequest ('loginajax? Uname = '+ uname +' & psw = '+ psw );
  51. }
  52. }
  53. </SCRIPT>
  55. <Body vlink = "#006666" link = "#003366" bgcolor = "# e0f0f8">
  56. /images/enter.gif"
  57. Width = "148">
  59. <Form action = "" method = "Post" name = "myform">
  60. Username: <input size = "15" name = "uname">
  61. <P> password: <input type = "password" size = "15" name = "psw">
  62. <P> <input type = "button" value = "log on to Ajax" onclick = usercheck ();>
  63. </Form>

2. p21.loginaction. Java

Code:
  1. Package p21;
  3. Import java. Io. ioexception;
  4. Import java. Io. printwriter;
  5. Import javax. servlet. servletconfig;
  6. Import javax. servlet. servletexception;
  7. Import javax. servlet. http. httpservlet;
  8. Import javax. servlet. http. httpservletrequest;
  9. Import javax. servlet. http. httpservletresponse;
  12. Public class loginaction extends httpservlet {
  14. Private Static final long serialversionuid = 1l;
  15. Public void Init (servletconfig config) throws servletexception {
  16. }
  18. /*
  19. * Process the <get> request method.
  20. */
  21. Protected void doget (httpservletrequest request, httpservletresponse response)
  22. Throws servletexception, ioexception {
  23. // Set the character set for receiving information
  24. Request. setcharacterencoding ("UTF-8 ");
  25. // Receives information submitted by the browser.
  26. String uname = request. getparameter ("uname ");
  27. String psw = request. getparameter ("psw ");
  28. // Set the format and Character Set of output information
  29. Response. setcontenttype ("text/XML; charset = UTF-8 ");
  30. Response. setheader ("cache-control", "No-Cache ");
  31. // Create an output stream object
  32. Printwriter out = response. getwriter ();
  33. // Output different data information based on the verification result
  34. Out. println ("<response> ");
  35. System. Out. println ("coming to servlet ");
  36. If (uname. Equals ("nothing") & psw. Equals ("123 ")){
  37. Out. println ("<res>" + "Welcome! "+" </RES> ");
  38. } Else {
  39. Out. println ("<res>" + "sorry, Logon Failed! "+" </RES> ");
  40. }
  41. Out. println ("</response> ");
  42. Out. Close ();
  43. }
  44. /*
  45. * Process the <post> request method.
  46. */
  47. Protected void dopost (httpservletrequest request, httpservletresponse response)
  48. Throws servletexception, ioexception {
  49. Doget (request, response );
  50. }
  51. }

3. Web. xml configuration

Code:
  1. <Servlet>
  2. <Servlet-Name> loginajax </servlet-Name>
  3. <Servlet-class> p21.loginaction </servlet-class>
  4. </Servlet>
  5. <Servlet-mapping>
  6. <Servlet-Name> loginajax </servlet-Name>
  7. <URL-pattern>/loginajax </url-pattern>
  8. </Servlet-mapping>

 

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Related Keywords:
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