StringBuffer queryBuffer=new StringBuffer("SELECT * FROM "+tableName);
PreparedStatement preparedStatement=getConnection("root", "").prepareStatement(queryBuffer.toString());
ResultSet resultSet=preparedStatement.executeQuery();
ResultSetMetaData resultMetaData=resultSet.getMetaData();
从我得到ResultSetMetaData实例的上层代码中，我可以获得有关表的任何信息。
但我不想像上面那样输入选择查询，而是想获取有关表的信息。
我必须在A和B页面,我想从A到B导航,然后在JSF中从B导航到A. 我在A的托管bean中设置托管属性B,反之亦然,但问题是我得到了像MANAGED BEAN CYCLIC DETECTION这样的错误.
<managed-bean>
<managed-bean-name>viewBulkMetalIssueBean</managed-bean-name>
<managed-bean-class>com.cc.jas.web.manufacturing.bulkmetalissue.ViewBulkMetalIssueBean</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
<managed-property>
<property-name>viewJobcardBean</property-name>
<property-class>com.cc.jas.web.manufacturing.jobcard.ViewJobcardBean</property-class>
<value>#{viewJobcardBean}</value>
</managed-property>
</managed-bean>
<managed-bean>
<managed-bean-name>viewJobcardBean</managed-bean-name>
<managed-bean-class>com.cc.jas.web.manufacturing.jobcard.ViewJobcardBean</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
<managed-property>
<property-name>viewBulkMetalIssueBean</property-name>
<property-class>com.cc.jas.web.manufacturing.bulkmetalissue.ViewBulkMetalIssueBean</property-class>
<value>#{viewBulkMetalIssueBean}</value>
</managed-property>
</managed-bean>
这个问题有解决方案或替代解决方案吗？
我有jspx扩展名的文件,我写的是javascript
function isNumber(inputId){
var value = document.getElementById('mainForm:'+ inputId).value;
var s = value.length;
while(s >= 0){
var c = value.charAt(s);
if(c > "9"){
alert("Value must be digit");
document.getElementById('mainForm:'+ inputId).value = "";
document.getElementById('mainForm:'+ inputId).focus();
return false;
}
s --;
}
return true;
}
这工作完美,但当我检查条件是否如果(c>"9"|| c <"0")它将给出错误像
com.sun.facelets.FaceletException: Error Parsing /WEB-INF/includes/templates/cc-classic-template.jspx: Error Traced[line: 386] The content of elements must consist of well-formed character data or markup.
经过长时间的观察,我发现<(小于)符号会产生问题.JSF不支持<签名吗？
web.xml中的Servlet配置
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>DataEntry</servlet-name>
<servlet-class>com.ctn.origin.connection.DataEntry</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>DataEntry</servlet-name>
<url-pattern>/dataentry</url-pattern>
</servlet-mapping>
Javascript:
<script type="text/javascript">
function unloadEvt() {
document.location.href='/test/dataentry';
}
</script>
但是使用这个javascript无法调用我的servlet.
有什么错误吗？如何调用servlet？
在我的表中有两个字段，一个是姓名，另一个是性别。我想触发查询，以便每个男性都更新为女性，反之亦然。
我不想使用过程、触发器或函数。我只需要通过简单的查询来做到这一点。
我有一个函数将数千条记录插入到表中我希望当时无法使用索引,然后我正在处理该数据数据,所以我想再次重建该索引.
在Oracle可以吗？
当我运行这个演示时，它调用 TestBean 的writeObject私有方法
这怎么可能 ？
这是代码：
import java.io.FileOutputStream;
public class Test {
public static void main(String[] args) {
try {
TestBean testBean = test.new TestBean();
testBean.setSize(23);
testBean.setWidth(167);
FileOutputStream fos =
new FileOutputStream(new File("d:\\serial.txt"));
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(testBean);
oos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
class TestBean implements Serializable {
private static final long serialVersionUID = 1L;
private int size;
private int width;
public int getSize() {
return size;
}
public void setSize(int size) { …当我尝试运行在tomcat内部署的项目时,我得到的错误就像
java.lang.NullPointerException
at org.apache.jsp.index_jsp._jspInit(index_jsp.java:23)
at org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)
at org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:159)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:859)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1555)
at java.lang.Thread.run(Thread.java:619)
我已经搜索过这个并发现它可能是servlet-api.jar和jsp-api.jar的问题,但是我已经从tomcat复制到我的项目的类路径仍然我得到了同样的错误.
Jsp:
<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta …我有一张名为 的表tblm_customer。
firstname它包含名为和 的字段lastname。现在我想从表中删除包含表中已存在的相同名字和姓氏的所有记录。
我用的是mysql数据库，customerid是表中的主键。