My Java Development-Ajax case: Using ajax to implement automatic completion (below)

Automatic completion using Ajax

Basedao. Java

Package COM. LJ. dao; import Java. SQL. connection; import Java. SQL. drivermanager; import Java. SQL. preparedstatement; import Java. SQL. resultset; import Java. SQL. sqlexception; public class basedao {/*** generates a servletid */Private Static final long serialversionuid =-3005086949118705373l; // define the connection constant Private Static final string driver_name = "com. microsoft. JDBC. sqlserver. sqlserverdriver "; Private Static final stri Ng driver_url = "JDBC: sqlserver: // localhost: 1433; databasename = sellcomputer"; Private Static final string db_user_name = "sa"; Private Static final string db_user_pwd = "sa "; // obtain the public static connection getconn () throws classnotfoundexception, sqlexception {class. forname (driver_name); connection conn = drivermanager. getconnection (driver_url, db_user_name, db_user_pwd); Return conn;} // public static Conne Ction getconn () throws namingexception, sqlexception {// initialize the application context // initialcontext Ic = new initialcontext (); // Java: COMP/ENV is a fixed prefix, JDBC/empdatabase1 is the name of the configured data source // datasource conn = (datasource) IC. lookup ("Java: COMP/ENV/jdbc/News"); // return Conn. getconnection (); //} // release the database resource public static void closeall (connection Conn, preparedstatement ps, resultset RS) {If (RS! = NULL) Try {Rs. Close () ;}catch (sqlexception e) {e. printstacktrace () ;}if (PS! = NULL) Try {ps. Close () ;}catch (sqlexception e) {e. printstacktrace () ;}if (Conn! = NULL) Try {conn. Close () ;}catch (sqlexception e) {e. printstacktrace ();}}}

 

Computerdao. Java

Package COM. LJ. dao; import Java. SQL. connection; import Java. SQL. preparedstatement; import Java. SQL. resultset; import Java. SQL. sqlexception; import Java. util. arraylist; import Java. util. list; import COM. LJ. entity. PC; public class computerdao extends basedao {Private Static connection conn = NULL; // Save the database connection Private Static preparedstatement PS = NULL; // execute the SQL statement Private Static resultset rs = NULL; // used to save the query result set // Add a method to query data from the database and return the public list as a set <Pc> getallpoll (string keyword) {list <Pc> List = new arraylist <Pc> (); try {conn = basedao. getconn (); string SQL = "select * from PC where pcname like '" + keyword + "%'"; PS = Conn. preparestatement (SQL); RS = ps.exe cutequery (); While (RS. next () {PC Pc = new PC (); PC. setid (RS. getint ("ID"); PC. setpcname (RS. getstring ("pcname"); list. add (PC) ;}} catch (classnotfoundexception e) {e. printstacktrace ();} catch (sqlexception e) {e. printstacktrace ();} finally {basedao. closeall (Conn, PS, RS);} return list ;}}

 

PC. Java

package com.LJ.entity;public class PC {private int id;private String pcname;public int getId() {return id;}public void setId(int id) {this.id = id;}public String getPcname() {return pcname;}public void setPcname(String pcname) {this.pcname = pcname;}public PC(int id, String pcname) {super();this.id = id;this.pcname = pcname;}public PC() {super();}}

 

Computerservlet. Java

Package COM. LJ. servlet; import Java. io. ioexception; import Java. io. printwriter; import Java. util. list; import javax. servlet. servletexception; import javax. servlet. HTTP. httpservlet; import javax. servlet. HTTP. httpservletrequest; import javax. servlet. HTTP. httpservletresponse; import COM. LJ. dao. computerdao; import COM. LJ. entity. PC; public class computerservlet extends httpservlet {Private Static final long serialversionuid =-response; @ overrideprotected void doget (httpservletrequest req, httpservletresponse resp) throws servletexception, ioexception {// set the character set req for receiving information. setcharacterencoding ("UTF-8"); // receives information submitted by the browser end // string action = req. getparameter ("action"); string name = req. getparameter ("names"); // sets the format and character resp of the output information. setcontenttype ("text/XML; charset = UTF-8"); resp. setheader ("cache-control", "No-Cache"); // create the output stream printwriter out = resp. getwriter (); // outputs different data information out based on the result. print ("<response>"); computerdao = new computerdao (); List <Pc> List = computerdao. getallpoll (name); For (INT I = 0; I <list. size (); I ++) {PC Pc = List. get (I); out. println ("<res>" + PC. getpcname () + "</RES>");} Out. print ("</response>"); out. close () ;}@ overrideprotected void dopost (httpservletrequest req, httpservletresponse resp) throws servletexception, ioexception {This. doget (req, resp );}}

 

Computerdaotest. Java

package com.LJ.test;import java.util.List;import com.LJ.dao.ComputerDao;import com.LJ.entity.PC;public class ComputerDaoTest {public static void main(String[] args) {ComputerDao computerDao = new ComputerDao();List<PC> list = computerDao.getAllPoll("H");for(int i = 0;i<list.size();i++){PC pc = list.get(i);System.out.println(pc.getPcname());}}}

 

Ctrf. js

VaR xmlhttpreq; var completediv; var inputfield; var completetable; var completebody; // create the XMLHTTPRequest object function createxmlhttprequest () {// create the XMLHTTPRequest object if (window. XMLHttpRequest) {// IE7, IE8, Firefox, javasillar, and operabrowser xmlhttpreq = new XMLHttpRequest (); // when the header is not set in text/XML format, you need to reset it to text/xmlif (xmlhttpreq. overridemimetype) {xmlhttpreq. overridemimetype ("text/XML") ;}} else if (window. activexobject) {// IE6, Ie5, ie5.5, because all browsers are based on activexobject, it is better to put them behind the scenes to implement var activexname = ["msxml2.xmlhttp. 6.0 "," msxml2.xmlhttp. 5.0 "," msxml2.xmlhttp. 4.0 "," msxml2.xmlhttp. 3.0 "," msxml2.xmlhttp "," miscrosoft. XMLHTTP "]; for (VAR I = 0; I <activexname. length; I ++) {try {xmlhttpreq = new activexobject (activexname [I]); break; // 1. You do not need to judge whether the object is created successfully} catch (E) {// exception does not need to be processed }}// send the function findnames () {inputfield = document. get Elementbyid ("names"); completetable = document. getelementbyid ("complete_table"); completediv = document. getelementbyid ("popup"); completebody = document. getelementbyid ("complete_body"); If (inputfield. value. length> 0) {createxmlhttprequest (); var url = "computerservlet? Names = "+ escape (inputfield. value); // alert (URL); xmlhttpreq. open ("get", URL, true); xmlhttpreq. onreadystatechange = processmatchresponse; xmlhttpreq. send (null) ;}else {clearnames () ;}// function processmatchresponse () {// according to the status // alert ("the current status is: "+ xmlhttpreq. readystate); // determines the object state if (xmlhttpreq. readystate = 4) {// determine whether the response is successful if (xmlhttpreq. status = 200) {// 1. setnames (xmlhttpreq. responsexml. getelementsbytagname ("res"); // 2. Receive the returned data in text format // var respinfomation = xmlhttpreq. responsetext; // alert (respinfomation);} else {alert ("response exception") ;}}// function setnames (names) {clearnames (); var size = names. length; setoffsets (); var row, cell, txtnode; For (VAR I = 0; I <size; I ++) {var nextnode = Names [I]. firstchild. data; ROW = document. createelement ("TR"); cell = document. createelement ("TD"); cell. onmouseout = function () {This. classname = 'mouseover';}; cell. onmouseover = function () {This. classname = 'mouseout';}; cell. setattribute ("bgcolor", "# fffafa"); cell. setattribute ("border", 0); cell. onclick = function () {completefield (this) ;}; txtnode = document. createtextnode (nextnode); cell. appendchild (txtnode); row. appendchild (cell); completebody. appendchild (ROW) ;}/// set the display position function setoffsets () {completetable. style. width = inputfield. offsetwidth; + "PX"; var left = calculateoffset (inputfield, "offsetleft"); var Top = calculateoffset (inputfield, "offsettop") + inputfield. offsetheight; completediv. style. border = "Black 1px solid"; completediv. style. left = left + "PX"; completediv. style. top = Top + "PX" ;}// calculate the display position function calculateoffset (field, ATTR) {var offset = 0; while (field) {Offset + = field [ATTR]; field = field. offsetparent;} return offset;} // enter the input box function completefield (cell) {inputfield. value = cell. firstchild. nodevalue; clernames ();} // clear the automatically completed row function clearnames () {var ind = completebody. childnodes. length; For (vari = ind-1; I> = 0; I ++) {completebody. removechild (completebody. childnodes [I]);} completediv. style. border = "NONE ";}

Web. xml

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"><servlet><servlet-name>computerServlet</servlet-name><servlet-class>com.LJ.servlet.ComputerServlet</servlet-class></servlet><servlet-mapping><servlet-name>computerServlet</servlet-name><url-pattern>/computerServlet</url-pattern></servlet-mapping>  <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list></web-app>

 

Index. jsp

<% @ Page Language = "Java" Import = "Java. util. * "pageencoding =" UTF-8 "%> <HTML>