我想在ajax调用期间在表上显示sql查询结果。我编写了在ajax调用期间执行查询的代码但是当我试图在表中显示这些值时，它在div标记上显示空值。这是什么是什么？如何以表格格式显示结果集值。
mycode的：
ViewQuery.jsp
<%--
Document : ViewQuery
Created on : Nov 10, 2014, 10:23:48 AM
Author : user
--%>
<%@page import="java.util.ArrayList"%>
<%@page import="querywork.ReadXml"%>
<%@page import="java.sql.ResultSet"%>
<%@page import="querywork.DBConnection"%>
<!--
To change this template, choose Tools | Templates
and open the template in the editor.
-->
<!DOCTYPE html>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="UTF-8">
<title>Zerotype Website Template</title>
<link rel="stylesheet" href="css/style.css" type="text/css">
<script lang="javascript">
try
{
var request;
function myfunction(str)
{
try
{
var url="queryview.jsp"
url=url+"?query="+str
url=url+"&sid="+Math.random()
if(window.XMLHttpRequest){
request=new XMLHttpRequest();
}
else if(window.ActiveXObject){
request=new ActiveXObject("Microsoft.XMLHTTP");
}
try
{
request.onreadystatechange=getInfo;
request.open("GET",url,true);
request.send();
}
catch(e)
{
alert("Unable to connect to server");
}
// alert(textboxes2)
// alert(select)
}
catch(err)
{
alert(err)
}
}
function getInfo(){
if(request.readyState==4){
var val=request.responseText;
document.getElementById('amit').innerHTML=val;
}
}
}
catch(err)
{}
</script>
</head>
<body>
</body>
<body>
<form method="POST" action="ViewQuery.jsp">
<%
ReadXml rxml = new ReadXml();
ArrayList al = rxml.readXML(0);
%>
<font color="white"> Choose query</font></label>
</label>
<select id="c" name="Chooser" style="width:800px; height:50px" onchange="myfunction(this.value)">
<% for (int i = 0; i < al.size(); i++) {
%><option><font color="white"><%=al.get(i)%></font></option>
<% }%>
</select>
<p> </p>
<p> </p>
<p><font color="white"> Result:</font> <font color="white"> <div id="amit"> </div></font></p>
</form>
</body>
</html>
queryview.jsp
<%--
Document : queryview
Created on : Nov 16, 2014, 7:15:09 PM
Author : user
--%>
<%@page import="querywork.getObject"%>
<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.DatabaseMetaData"%>
<%@page import="querywork.Query"%>
<%@page import="querywork.Parser"%>
<%@page import="gudusoft.gsqlparser.EDbVendor"%>
<%@page import="querywork.gettablecolumns"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%@page import="querywork.DBConnection"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
<%
String responseText = new String("");
boolean flg = false;
String query1 = (String) request.getParameter("query");
String[] colname=new String[100];
EDbVendor dbVendor = EDbVendor.dbvmysql;
try {
getObject g = new getObject(dbVendor);
Parser parser1 = new Parser();
Parser.Node parsedNode1 = parser1.parse(query1);
g.setSqltext(query1);
System.out.println(query1);
String table = g.run();
String[] splitstring = table.split("Columns:");
String newval = splitstring[1].replaceAll("\\([^\\)]*\\)", "");
String[] inputSplitNewLine = newval.split("\\\n");
int i1=0;
String[] firstval = splitstring[0].split("\\\n");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/", "root", "");
DatabaseMetaData dbmd = conn.getMetaData();
responseText= "<table border=1 cellpadding =2 cellspacing=3><tr>";
for(int p=0;p<inputSplitNewLine.length;p++)
{
String col=inputSplitNewLine[p];
responseText=responseText+" <td> "+col+" </td>";
}
responseText="</tr>";
ResultSet ctlgs = dbmd.getCatalogs();
for (int i = 1; i < firstval.length; i++) {
while (ctlgs.next()) {
String dbname = ctlgs.getString(1);
DBConnection dbc = new DBConnection(dbname);
ResultSet rs = dbc.SelectTable();
while (rs.next()) {
String columnName = "";
String tableName = rs.getString("TABLE_NAME");
if (tableName.equalsIgnoreCase(firstval[i])) {
DBConnection dbc1 = new DBConnection(dbname);
ResultSet rs1 = dbc1.execute(query1);
while(rs1.next()) {
out.println(rs1.getString(1));
responseText=responseText +"<tr><td> "+rs1.getString(1)+"</td></tr>";
}
}
}
}
}
out.print(responseText);
} catch (Exception e) {
out.print(e);
}
%>
</head>
<body>
</body>
</html>
答案 0 :(得分：0)
检查获取数据是否为空。 在将数据打印到表格单元格之前，用于验证获取数据是否有效或不为空的条件，空值在单元格中添加空格。
示例代码： -
while(rs.next())
{
%>
<tr>
<td><%= (rs.getString(1) !='')?rs.getString(1):"-" %></td>
<td><%= (rs.getString(2) !='')?rs.getString(2):"-" %></td>
<%
}
您的代码： - 仅代码编写
<%--
Document : queryview
Created on : Nov 16, 2014, 7:15:09 PM
Author : user
--%>
<%@page import="querywork.getObject"%>
<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.DatabaseMetaData"%>
<%@page import="querywork.Query"%>
<%@page import="querywork.Parser"%>
<%@page import="gudusoft.gsqlparser.EDbVendor"%>
<%@page import="querywork.gettablecolumns"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%@page import="querywork.DBConnection"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%
String responseText = new String("");
boolean flg = false;
String query1 = (String) request.getParameter("query");
String[] colname=new String[100];
EDbVendor dbVendor = EDbVendor.dbvmysql;
try {
getObject g = new getObject(dbVendor);
Parser parser1 = new Parser();
Parser.Node parsedNode1 = parser1.parse(query1);
g.setSqltext(query1);
System.out.println(query1);
String table = g.run();
String[] splitstring = table.split("Columns:");
String newval = splitstring[1].replaceAll("\\([^\\)]*\\)", "");
String[] inputSplitNewLine = newval.split("\\\n");
int i1=0;
String[] firstval = splitstring[0].split("\\\n");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/", "root", "");
DatabaseMetaData dbmd = conn.getMetaData();
responseText= "<table border=1 cellpadding =2 cellspacing=3><tr>";
for(int p=0;p<inputSplitNewLine.length;p++)
{
String col=inputSplitNewLine[p];
responseText=responseText+" <td> "+col+" </td>";
}
responseText="</tr>";
ResultSet ctlgs = dbmd.getCatalogs();
for (int i = 1; i < firstval.length; i++) {
while (ctlgs.next()) {
String dbname = ctlgs.getString(1);
DBConnection dbc = new DBConnection(dbname);
ResultSet rs = dbc.SelectTable();
while (rs.next()) {
String columnName = "";
String tableName = rs.getString("TABLE_NAME");
if (tableName.equalsIgnoreCase(firstval[i])) {
DBConnection dbc1 = new DBConnection(dbname);
ResultSet rs1 = dbc1.execute(query1);
while(rs1.next()) {
out.println(rs1.getString(1));
responseText=responseText +"<tr><td> "+rs1.getString(1)+"</td></tr>";
}
}
}
}
}
out.print(responseText);
} catch (Exception e) {
out.print(e);
}
%>