Date: 2009.05.07
Problem:
(1) Use DWR to implement three-layer cascade: function implementation, but the object in JS cannot be converted to the custom object videocateroy
(2) query JSP pages: How to Use STR returned by Js for SQL statements
1. Use DWR to implement layer-3 Cascade
1. Expected Implementation Structure Analysis
Grade 7
--- Last semester
------- Chinese
------- Mathematics
------- English
--- Next semester
------- Chinese
------- Mathematics
------- English
2. Write a Java class: getchildcategorybyparentid (int id)
Package COM. gslsoft. dao; <br/>/* search for sub-category by parent class ID */<br/> @ suppresswarnings ("finally ") <br/> public list <videocategory> getchildcategorybyparentid (int id) <br/>{< br/> string SQL = "select * From video_category where parentid = '" + ID + "'"; <br/> List <videocategory> List = new arraylist (); <br/> videocategory Category = NULL; <br/> try {<br/> cachedrowset rs = dbconnection. getresultset (SQL); <br/> while (RS. next () {<br/> Category = new videocategory (); <br/> category. setname (RS. getstring ("name"); <br/> category. setremark (RS. getstring ("remark"); <br/> category. setlevel (RS. getint ("level"); <br/> category. setimage (RS. getstring ("image"); <br/> category. setcategoryid (RS. getint ("ID"); <br/> list. add (category); <br/>}< br/> Rs. close (); <br/>}catch (Java. SQL. sqlexception e) {<br/> logger. log (logger. error, <br/> "datarepository_getvideofilebycategoryid: With categoryid =" + id); <br/> logger. log (logger. error, E. tostring (); <br/>}finally {<br/> return list; <br/>}< br/>}
3. Compile the WEB-INF/DWR. xml: The specific configuration instructions are given in the previous chapter.
<? XML version = "1.0" encoding = "GBK"?> <Br/> <DWR> <br/> <allow> <br/> <create creator = "new" javascript = "videocategoryservice"> <br/> <Param name =" class "value =" com. gslsoft. service. videocategoryservice "/> <br/> </create> <br/> </allow> <br/> </DWR> </P> <p>
4. Compile the test. jsp page
<% @ Page Language = "Java" contenttype = "text/html; charset = GBK "pageencoding =" GBK "%> <br/> <% @ taglib uri =" http://java.sun.com/jstl/core "prefix =" C "%> <br/> <% @ page Import = "Java. util. * "%> <br/> <% @ page import =" com. gslsoft. service. * "%> <br/> <% @ page import =" com. gslsoft. model. * "%> <br/> <HTML> <br/> <pead> <br/> <title> File Upload </title> <br/> <LINK rel =" stylesheet "href = ".. /.. /CSS/x_css1.css "mce_href =" CSS/X _ Css1.css "type =" text/CSS "> <br/> <MCE: Script Type = 'text/JavaScript 'src ="/APP/DWR/interface/videocategoryservice. JS "mce_src =" app/DWR/interface/videocategoryservice. JS "> </MCE: SCRIPT> <br/> <MCE: Script Type = 'text/JavaScript 'src ="/APP/DWR/interface/videocategory. JS "mce_src =" app/DWR/interface/videocategory. JS "> </MCE: SCRIPT> <br/> <MCE: Script Type = 'text/JavaScript 'src ="/APP/DWR/engine. JS "mce_src =" app /DWR/engine. JS "> </MCE: SCRIPT> <br/> <MCE: Script Type = 'text/JavaScript 'src ="/APP/DWR/util. JS "mce_src =" app/DWR/util. JS "> </MCE: SCRIPT> <br/> <MCE: Script Type = 'text/JavaScript '> <! -- <Br/> // obtain the last semester Based on the grade id <br/> function queryterm () <br/>{< br/> // var gradeid = $ ("selectgrade "). value; <br/> var gradeid=window.doc ument. getelementbyid ("selectgradea "). value; <br/> // not selected by default <br/> If (gradeid = 0) <br/>{< br/> specify parameter Doc ument. getelementbyid ("selectterma "). options. length = 0; <br/> too many Doc ument. getelementbyid ("selectsubjecta "). options. length = 0; <br/>}< br/> else <br/> {<br/> videocategoryservice. getchildcategorybyparentid (gradeid, termcallback); <br/>}</P> <p> function termcallback (data) <br/>{< br/> Please specify Doc ument. getelementbyid ("selectterma "). options. length = 0; </P> <p> for (VAR I = 0; I <data. length; I ++) {<br/> alert (data. length); <br/> alert (typeof (data [I]); <br/> VaR value = videocategoryservice. convertvideocategory (data [I]). getcategoryid (); <br/> var text = videocategoryservice. convertvideocategory (data [I]). getname (); <br/> var option = New Option (text, value ); <br/> // create an option object based on the values marked by each set of values and text. <br/> try {<br/> specify parameter Doc ument. getelementbyid ("selectterma "). options. add (option); // Add the option object to the second drop-down box <br/>} catch (E) {<br/>}</P> <p> var termid = too many Doc ument. getelementbyid ("selectterma "). value; <br/> alert (termid); <br/> videocategoryservice. getchildcategorybyparentid (termid, subjectcallback); </P> <p >}</P> <p> function querysubject () <br/>{< br/> var termid = too many Doc ument. getelementbyid ("selectterma "). value; <br/> videocategoryservice. getchildcategorybyparentid (termid, subjectcallback); <br/>}</P> <p> function subjectcallback (videocategory) <br/>{< br/> specify parameter Doc ument. getelementbyid ("selectsubjecta "). options. length = 0; <br/> for (VAR I = 0; I <videocategory. length; I ++) {<br/> // VaR value = videocategory [I]. categoryid; <br/> // var text = videocategory [I]. name; <br/> var option = New Option ("text", "value "); <br/> // create an option object based on the values marked by each set of values and text. <br/> try {<br/> specify parameter Doc ument. getelementbyid ("selectsubjecta "). options. add (option); // Add the option object to the third drop-down box <br/>} catch (E) {<br/>}</P> <p> function Change1 () <br/>{< br/> queryterm (); <br/>}</P> <p> function Change2 () <br/>{< br/> querysubject (); <br/>}< br/> // --> </MCE: SCRIPT> <br/> </pead> <br/> <body> <br/> <p> </P> <br/> <form method = "Post" Action = "uploadm. JSP "enctype =" multipart/form-Data "> <br/> <Table id =" Table1 "bgcolor =" # e1efcb "border =" 0 "cellpadding =" 4 "cellspacing = "0" style = "width: 100% "> <br/> <tbody> <br/> <tr> <br/> <TD bgcolor =" # f7f7f7 "style =" width: 80px "> <br/> category selection: </TD> <br/> <TD colspan = "5"> <br/> <% <br/> List <videocategory> listgrade, listterm, listsubject; <br/> videocategoryservice service1 = new videocategoryservice (); <br/> listgrade = service1.getvideocategorybylevelid (1); <br/> // listterm = service1.w _ getchildcategorybyparentid (integer. parseint (request. getparameter ("selectgrade"); <br/> listsubject = service1.getvideocategorybylevelid (3 ); <br/> %> <br/> <select name = "selectgradea" style = "width: 120px" onchange = "queryterm (); "> <br/> <option selected =" selected "value =" 0 "> <br/> select grade... <br/> </option> <br/> <% <br/> for (INT I = 0; I <listgrade. size (); I ++) <br/>{< br/>%> <br/> <option value = "<% = listgrade. get (I ). getcategoryid () %> "> <% = listgrade. get (I ). getname () %> </option> <br/> <% <br/>}< br/>%> <br/> <% <br/> listterm = service1.getchildcategorybyparentid (3 ); <br/> %> <br/> </SELECT> <br/> <select name = "selectterma" style = "width: 120px" onchange = "querysubject (); "> <br/> <option selected =" selected "value =" 0 "> <br/> select a semester... <br/> </option> <br/> </SELECT> <br/> <select name = "selectsubjecta" style = "width: 120px "onchange =" "> <br/> <option selected =" selected "value =" 0 "> <br/> select a subject... <br/> </option> <br/> </SELECT> <br/> </TD> <br/> </tr> <br/> </tbody> <br/> </table> <br/> </form> <br/> </body> <br/> </ptml>
5. Running Error
6. Problem:
How does one convert the data [I] type object to the custom videocategory type?
7. Solutions
(1) Add in DWR. xml:
// Videocategory indicates the User-Defined type
<Convert converter = "Bean" match = "com. gslsoft. model. videocategory"/>
(2) Use JSP pages directly
Data [I]. ID gets its ID attribute, instead of calling its attribute using the GETID () method.
--------------------------------------------
So far, the problem of using DWR to solve layer-3 cascade has been completely solved.
Ii. jsp Query
1. Use conditions to determine the search keywords
Alert ("the query condition is: where categoryid = '" specified when using Doc ument. getelementbyid ("selectsubject1"). Value + "'");
2. Write Java class:
Public list <videofile> getallvideofileinfowithkey (string key, int start, int limit)
3. Problem:
How can I transmit a search keyword as a parameter to a Java class as a parameter?
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