Linkage drop-down selection box, dynamically get the next level, displays the next level according to the previous level, this kind of benefit is that it does not read the drop-down box from the database, causing too much content, not very good choice. The first level link knows how to achieve it, and the multi-level linkage is also true. The examples listed here give you a reference and study.
Linkage drop-down box, just a Java file, a JSP file.
Table Structure A, Table ID VARCHAR2 (10), Name VARCHAR2 (10)
B Table ID VARCHAR2, NAME VARCHAR2 (10)
A Table content: 1 computer, 2 air conditioning 3 appliances
B Table Content: 1 Lenovo, 1 Foundation, 2 Haier, 2 Chunlan, 3 LG, 3 TCL
Mydbbean.java
. Import java.sql *; public class MyDbBean {Connection con = null; public First () {Class.forName ( "oracle.jdbc.driver.OracleDriver") newInstance (); con = DriverManager .getConnection ( "jdbc:. Oracle : @ 127.0.0.1: 1521: Test "," DD "," DD ");} Public ResultSet ExecuteQuery (String SQL) {PreparedStatement PSTM = NULL; ResultSet RS = NULL; TRY {PSTM = Con.PrepareStatement (SQL Rs = pstm.executeQuery (); return}} catch (sqlexception e) {E.PrintStackTrace (); return null;} catch (exception e) {E.PrintStackTrace (); return null;} finally {TRY NULL; {IF (rs! = Null) {} catch (exception e) {}}}}
Test.jsp
<% @ Page ContentType = "Text / HTML; Charset = GBK"%> <% @ page import = "Database. *"%> <% @ page import = "java.sql. *"%> <%! mydbbean bean = New mydbbean ();%>
test </ title> </ head> <body bgcolor = "# fffff"> <form method = "post"> <select name = "dl" Onchange = "JavaScript: window.location = (this.Options [this.selected"> <% string id = request.getParameter ("ID");</p>
<p>String csql = "select * from a"; resultset SQLRST = bean.executeQuery (csql); try {while (sqlrst.next ()) {string i = sqlrst.getstring ("id"); string name = Sqlrst.getstring "name"); if (id == null) ID = "1"; IF (id.equals (i)) {string Temp = "./ Test.jsp? id =" i "& name =" Name; OUT.PRINTLN ("<option value =" i "value1 =" TEMP "SELECTED>" Name "</ option>");} else {string temp = "./ Test.jsp? id =" i "& name =" name; out.println ("<option value =" "value1 =" TEMP "> Name " </ option> ");}}} catch (exception E) {}%> </ select> <select name = "dl"> <% string csql = null; if (id == null) {csql = "select * from b where id = 1";} else {csql = "SELECT * FROM B WHERE ID = " ID;} SQLRST = bean.executeQuery (csql); try {while (sqlrst.next ()) {string i = sqlrst.getstring (" id "); string name = sq Lrst.getstring ("name"); IF (id.equals (i)) {string temp = "./ Test.jsp? id =" i "& name =" name; out.println ("<option value = " i " Value1 = " TEMP " SELECTED> " Name " </ option> ");</p>
<p>} Else {string temp = "./ Test.jsp? Id =" i "& name =" name; out.println ("<option value = i " value1 = " temp "> name "< / option> ");}}} catch (exception e) {}%> </ select> </ form> </ body> </ html></p></div><div class="text-center mt-3 text-grey">
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var debug = DEBUG = 0;
var url_rewrite_on = 1;
var url_path = './';
var forumarr = {"1":"Tech"};
var fid = 1;
var uid = 0;
var gid = 0;
xn.options.water_image_url = 'view/img/water-small.png';
</script><script src="view/js/wellcms.js?2.2.0"></script><a class="scroll-to-top rounded" href="javascript:void(0);"><i class="icon-angle-up"></i></a><a class="scroll-to-bottom rounded" href="javascript:void(0);" style="display: inline;"><i class="icon-angle-down"></i></a></body></html><script>
var forum_url = 'list-1.html';
var safe_token = 'aFOLTwoU3lEGu0_2F7qJz5tc_2BURh6CmLpcSoT7kBm_2BFlsyQ9EdVNYmlhgazgN_2FMsX1ZS2fYW3fZ68Y4Kkx6AR5Kw_3D_3D';
var body = $('body');
body.on('submit', '#form', function() {
var jthis = $(this);
var jsubmit = jthis.find('#submit');
jthis.reset();
jsubmit.button('loading');
var postdata = jthis.serializeObject();
$.xpost(jthis.attr('action'), postdata, function(code, message) {
if(code == 0) {
location.reload();
} else {
$.alert(message);
jsubmit.button('reset');
}
});
return false;
});
function resize_image() {
var jmessagelist = $('div.message');
var first_width = jmessagelist.width();
jmessagelist.each(function() {
var jdiv = $(this);
var maxwidth = jdiv.attr('isfirst') ? first_width : jdiv.width();
var jmessage_width = Math.min(jdiv.width(), maxwidth);
jdiv.find('img, embed, iframe, video').each(function() {
var jimg = $(this);
var img_width = this.org_width;
var img_height = this.org_height;
if(!img_width) {
var img_width = jimg.attr('width');
var img_height = jimg.attr('height');
this.org_width = img_width;
this.org_height = img_height;
}
if(img_width > jmessage_width) {
if(this.tagName == 'IMG') {
jimg.width(jmessage_width);
jimg.css('height', 'auto');
jimg.css('cursor', 'pointer');
jimg.on('click', function() {
});
} else {
jimg.width(jmessage_width);
var height = (img_height / img_width) * jimg.width();
jimg.height(height);
}
}
});
});
}
function resize_table() {
$('div.message').each(function() {
var jdiv = $(this);
jdiv.find('table').addClass('table').wrap('<div class="table-responsive"></div>');
});
}
$(function() {
resize_image();
resize_table();
$(window).on('resize', resize_image);
});
var jmessage = $('#message');
jmessage.on('focus', function() {if(jmessage.t) { clearTimeout(jmessage.t); jmessage.t = null; } jmessage.css('height', '6rem'); });
jmessage.on('blur', function() {jmessage.t = setTimeout(function() { jmessage.css('height', '2.5rem');}, 1000); });
$('#nav li[data-active="fid-1"]').addClass('active');
</script>
