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分享如何用jsp+javaBean+servlet写一个数据库查询并显示
连接数据库并查询 我都会 就是不知道怎么将查询的东西显示出来
求大神
求大神
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qq_37471217 2017-05-10
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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">
<display-name></display-name>
<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>yonghuzhuce</servlet-name>
<servlet-class>Conntroller_servlet.yonghuzhuce</servlet-class>
</servlet>
<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>chaxunMP</servlet-name>
<servlet-class>Conntroller_servlet.chaxunMP</servlet-class>
</servlet>
<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>yonghuSC</servlet-name>
<servlet-class>Conntroller_servlet.yonghuSC</servlet-class>
</servlet>
<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>zengjiaMP</servlet-name>
<servlet-class>Conntroller_servlet.zengjiaMP</servlet-class>
</servlet>
<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>changeMP</servlet-name>
<servlet-class>Conntroller_servlet.changeMP</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>yonghuzhuce</servlet-name>
<url-pattern>/yonghuzhuce</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>chaxunMP</servlet-name>
<url-pattern>/chaxunMP</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>yonghuSC</servlet-name>
<url-pattern>/yonghuSC</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>zengjiaMP</servlet-name>
<url-pattern>/zengjiaMP</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>changeMP</servlet-name>
<url-pattern>/changeMP</url-pattern>
</servlet-mapping>
</web-app>
Dbutil:
还有当我输入数据查询的时候console：
五月 10, 2017 1:05:15 下午 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet [chaxunMP] in context with path [/qimo] threw exception
java.lang.NullPointerException
at Conntroller_servlet.chaxunMP.doGet(chaxunMP.java:52)
at Conntroller_servlet.chaxunMP.doPost(chaxunMP.java:88)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:218)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:506)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:962)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:452)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1087)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
qq_37471217 2017-05-09
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110成成 2017-05-09
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CXresult.jsp在哪一级目录，你把项目整个结构截图看下。
110成成 2017-05-09
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web.xml贴出来，然后跳转的utl贴出来
qq_37471217 2017-05-08
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得到的是一个集合rs 怎么把name拿出来[/quote]
String name=null;
try {
while(rs.next()){
name=rs.getString("userName");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
request.setAttribute( "name",name)；
[/quote]
另一个页面：
当我输入名字电话的时候点击按钮就是这样
我觉得没有错误啊...
qq_37471217 2017-05-08
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得到的是一个集合rs 怎么把name拿出来[/quote]
String name=null;
try {
while(rs.next()){
name=rs.getString("userName");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
request.setAttribute( "name",name)；
[/quote]
好的 明白了
110成成 2017-05-08
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得到的是一个集合rs 怎么把name拿出来[/quote]
String name=null;
try {
while(rs.next()){
name=rs.getString("userName");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
request.setAttribute( "name",name)；
qq_37471217 2017-05-08
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得到的是一个集合rs 怎么把name拿出来
110成成 2017-05-08
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给一个 request.setAttribute( "name",name)；
jsp上取
<%
String name =(String)request.getAttribute( "name");
%>
最好是servlet中封装成对象，在界面去取
qq_37471217 2017-05-08
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Dbutil代码在这：
package model_db;
import java.sql.*;
public class DbUtil {
private Connection con=null;
private PreparedStatement pstm=null;
private ResultSet rs=null;
public int updateSQL(String sql){
int n=-1;
try{
con=DBConnection.getDBconnection();
pstm=con.prepareStatement(sql);
n=pstm.executeUpdate();
}catch(SQLException e){e.printStackTrace();}
DBConnection.closeDB(con,pstm,rs);
return n;
}
public ResultSet QuerySQL(String sql){
try{
con=DBConnection.getDBconnection();
pstm=con.prepareStatement(sql);
rs=pstm.executeQuery();
return rs;
}catch(SQLException e){
e.printStackTrace();
}return null;
}
}
qq_37471217 2017-05-08
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我是这么写的 但是什么都不显示 可以帮我看下哪儿错了么
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("GB2312");
String nameM=request.getParameter("nameM");
String callM=request.getParameter("callM");
String sql="SELECT * from mingpian where userName='"+nameM+"' and userCall='"+callM+"'";
DbUtil run=new DbUtil();
ResultSet rs=run.QuerySQL(sql);
try {
while(rs.next()){
String name=rs.getString("userName");
String sex=rs.getString("userSex");
int age=rs.getInt("userAge");
String call=rs.getString("userCall");
String add=rs.getString("userAdd");
System.out.println(name+"\t"+sex+"\t"+age+"\t"+call+"\t"+add);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
千杯不醉476 2017-05-08
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<% User user = (User)request.getAttribute("User") %>
要写在jsp的头部顶部，el表达式为
${user.name}，小写u，跟对象名统一。
千杯不醉476 2017-05-08
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在控制层或者是你的servlet方法里，将查询的结果用request.setAttribute方法存入
如：
User user = userDao.getUser();
request.setAttribute("User",user);
在jsp页面，使用el表达式
${User.name}可以取值
或者用jsp自带的<% User user = (User)request.getAttribute("User") %>
然后在标签里，如<input type = "text" value="<%=user.getusername() %>" />
两种常用简答取值方式，
再往后也就是使用ajax请求，返回值就用ajax的success回调函数，使用javascript给页面修改值了。
qq_37471217 2017-05-08
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额 你说的这个我还没学..
李德胜1995 2017-05-06
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把数据放在request域对象里然后转发过去。。。或者使用ajax返回json
