如何在eclipse环境中使用struts2从jsp中的mysql获取数据条目？答案

【问题标题】：How to fetch data entries from mysql in jsp using struts2 in eclipse environment?如何在eclipse环境中使用struts2从jsp中的mysql获取数据条目？
【发布时间】：2014-07-07 15:57:59
【问题描述】：

EventDropDown.java //第1页

package com.tutorialspoint.struts2;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
//import java.util.List;


import com.mysql.jdbc.ResultSetMetaData;
import com.opensymphony.xwork2.ActionSupport;

@SuppressWarnings("serial")`enter code here`
public class EventDropdownAction extends ActionSupport {

    ArrayList<Event> eventList=new ArrayList<Event>();

    public ArrayList<Event> getList() {
        return eventList;
    }


    public void setList(ArrayList<Event> eventList) {
        this.eventList = eventList;
    }
     private String eventName;
     public String execute()
     {
        logger.info("Message-execute");
        return ""; 
     }
    public String getEventList() 
    {
Connection conn = null;
 try {
             String URL = "jdbc:mysql://localhost:3306/bookmyshow_dates";
             Class.forName("com.mysql.jdbc.Driver");
             conn = DriverManager.getConnection(URL, "dra2", "dr@2");
        "CASE \r\n" + 
                    "   WHEN DATEDIFF(DATE,NOW()) = 0 THEN CONCAT('Today',',',DAY(DATE),' ',MONTHNAME(DATE))\r\n" + 
                    "   WHEN DATEDIFF(DATE,NOW()) = 1 THEN CONCAT('Tomorrow',',',DAY(DATE),' ',MONTHNAME(DATE))\r\n" + 
                    "   WHEN DATEDIFF(DATE,NOW()) > 1 THEN CONCAT(DAYNAME(DATE),',',DAY(DATE),' ',MONTHNAME(DATE))\r\n" + 
                    "END AS EventDay\r\n" + 
                    "FROM EVENTS\r\n" + 
                    "WHERE DATE_FORMAT(DATE,'%d/%m/%Y') >= DATE_FORMAT(NOW(),'%d/%m/%Y')";
 String sql ="SELECT * FROM user3333";
             PreparedStatement ps = conn.prepareStatement(sql);

             ResultSet rs = ps.executeQuery();
             ResultSetMetaData rsmd = (ResultSetMetaData) rs.getMetaData();
             int numberOfColumns = rsmd.getColumnCount();
             int rowCount=0;
             if(rs.last()){
                 rowCount= rs.getRow();
              } else {
                  rowCount= 0; //just cus I like to always do some kind else statement.
              }
              while (rs.next()) {
Event objEvent=new Event();
                 objEvent.setEventId(rs.getInt("EventId"));
                 objEvent.setEventName(rs.getString("EventName"));
                 objEvent.setEventDay(rs.getString("EventDay"));

                 Event objEvent=new Event(rs.getInt(1),rs.getString(2));
                 eventList.add(objEvent);
                ret = SUCCESS;
 }
          } catch (Exception e) 
{
  ret = ERROR;
 return "error";
          } 
          finally {
             if (conn != null) {
                try {
                   conn.close();
                } catch (Exception e) {
                }
             }
          }
          return "eventDropdown";
    }
}

Event.java //第2页

package com.tutorialspoint.struts2;

public class Event {
    public int EventId;
    public String EventName,EventDay;

    Event()
    {
        this.EventId = 0;
        this.EventName = "";
    }
    Event(int eventId, String eventName)
    {
        this.EventId = eventId;
        this.EventName = eventName;
    }

    public int getEventId() {
        return EventId;
    }
    public void setEventId(int id) {
        this.EventId = id;
    }
    public String getEventName() {
        return EventName;
    }
    public void setEventName(String name) {
        this.EventName = name;
    }
    public String getEventDay() {
        return EventDay;
    }
    public void setEventDay(String eventDay) {
        this.EventDay = eventDay;
    }
}

Error.jsp //第3页

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
error page.
</body>
</html>

**Success.jsp** //Page 3

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
success page.

</body>
</html>

EventDayDropdown.jsp //第4页

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
    <%@ taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
     <s:select name="username" label="Username" list="{'Mike','John','Smith'}" />
     <br>
     <s:select label="Select Event" name="ddlEvent" headerKey="0" headerValue="--Select--" list="{eventList}" listKey="{EventId}" listValue="{EventName}"/>
<%-- <s:select label="Select Event" name="ddlEvent" headerKey="0" headerValue="--Select--" list="{eventList}" /> --%>
<%-- <s:select name="event" list="eventList" listKey="eventId" listValue="eventName" headerKey="0" headerValue="--Event--" label="Select a event" /> --%>
</body>
</html>

Struts.xml //第5页

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
   "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
   "http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>

   <package name="helloworld" extends="struts-default">
      <action name="event" class="com.tutorialspoint.struts2.EventDropdownAction" 
            method="getEventList">
            <result name="success">/success.jsp</result>
            <result name="failure">/error.jsp</result>
            <result name="eventDropdown">/EventDayDropdown.jsp</result>
      </action>
     </package>

</struts>

这些是在 Eclipse IDE 中使用 struts 2 完成的文件。

我的数据库包含

具有属性的3列

Event_Id  1, 2, 3, 4 
EventName 2 states, Hobbit, Gravity,Gladiator.
Dates 20/5/2014, 21/5/2014, 21/5/2014, 23/5/2014

像这样。请帮我。我是初学者。

【问题讨论】：

标签： java mysql eclipse jsp struts2

【解决方案1】：

尝试通过使用日志框架或简单的 System.out.println 语句来跟踪您的代码块，但它们在 db 获取期间的 db 调用之后和从方法返回之前的开始中间，然后查看究竟是什么你的问题？它是在数据库中还是来自 struts2 或来自 Java 代码。

另一种解决方案是创建单独的应用程序，创建一个独立项目以从 mysql 数据库中获取数据并在控制台中对其进行测试，并创建一个带有静态的 struts2 项目内容而不是尝试从数据库中获取数据并查看 Web 应用程序是否提供你所需要的。最后加入这两个项目。所以如果发生任何错误，你可以解决分开。

【讨论】：

感谢您的回复。我成功连接了 MySQL。