JSP中的结果集 [英] Resultset in JSP
本文介绍了JSP中的结果集的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我需要一些帮助将结果集（rs）转发到jsp。我在JAVA中实现了MVC结构（注意：我是新手）。相同的逻辑流程如下：
I need some help with forwarding resultset(rs) to a jsp . I've implemented the MVC structure in JAVA (note: I'm new in this). The logic flow for the same is below :
- 基本形式：用户输入他的选择。
- 提交时，流程将被定向到一个servlet。
- 从servlet流程转到Java文件，在该文件中处理数据库检索和其他逻辑。
- 然后将结果发送回servlet。
- Servlet将结果转发给JSP进行显示。
- basic form : Where user enters his choice .
- On submission the flow get directed to a servlet.
- From servlet the flow goes to a Java file where the data base retrieval and other logic is taken care of.
- Then the result is send back to the servlet .
- Servlet forwards the result to a JSP for display.
Servlet：
package com.example.web;
import com.example.model.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
public class CoffeeSelect extends HttpServlet {
public void doPost( HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
String c = request.getParameter("type");
CoffeeExpert ce = new CoffeeExpert();
List result = ce.getTypes(c);
request.setAttribute("styles", result);
RequestDispatcher view = request.getRequestDispatcher("result.jsp");
view.forward(request, response);
}
}
java文件：
package com.example.model;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.*;
public class CoffeeExpert {
public List<Types> getTypes(String test) {
ResultSet rs = null;
List<Types> list = new ArrayList();
String Name = "na";
String PCANo = "NotFound";
String IP = "NotFound";
Types type=new Types();
if (test.equals("ABC")) {
try{
Connection con = getConnection();
String Query = "select * from Table1";
// System.out.println(Query);
rs = con.createStatement().executeQuery(Query);
while (rs.next()) {
type.setName(rs.getString(1));
type.setPCANo(rs.getString(2));
type.setIP(rs.getString(3));
System.out.println(Name+" "+PCANo+" "+IP);
list.add(type);
}
rs.close();
con.close();
}catch (SQLException e) {
System.out.println("SQLException");
e.printStackTrace();
}
}
else {
System.out.println("Didn't find any data");
}
return(list);
}
public static Connection getConnection() {
Connection con = null;
String Res = "na";
String BusinessUnit = "NotFound";
ResultSet rs = null;
try {
// Load the JDBC driver
String driverName = "oracle.jdbc.driver.OracleDriver";
// String driverName = "oracle.jdbc.OracleDriver";
Class.forName(driverName);
// Create a connection to the database
//Dev
String serverName = "xx.xx.xx.xx";
String portNumber = "1521";
String sid = "SSSS";
String url = "jdbc:oracle:thin:@" + serverName + ":" + portNumber + ":" + sid;
String username = "SSSSS";
String password = "password";
con = DriverManager.getConnection(url, username, password);
return con;
} catch (ClassNotFoundException e) {
System.out.println("ClassNotFoundException");
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return con;
}
}
如下面的解决方案所示，另一个模型类
As suggested in solution below , Another model class
package com.example.model;
public class Types {
private String Name;
private String PCANo;
private String IP;
//constructors //getter-setters
public String setName(String Name){
return this.Name = Name;
}
public String getName() {
return this.Name;
}
public String setPCANo(String PCANo) {
return this.PCANo = PCANo;
}
public String getPCANo() {
return this.PCANo;
}
public String setIP(String IP) {
return this.IP = IP;
}
public String getIP() {
return this.IP;
}
}
最终的JSP显示文件
<%@ page import="java.util.*" %>
<%@ page import="com.example.model.Types" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<body>
<h1 align="center">Final Data JSP View</h1>
<p>
<%
List<Types> styles = (List<Types>) request.getAttribute("styles");
if(styles!=null){
for(Types type: styles){
out.println("<br/>" + type.getName() + " " + type.getPCANo()+ " " + type.getIP());
}
}
%>
</body>
</html>
结果只获取显示的所有行数的最后一行，即数据库表有三行，最后一行显示3次。
The results is fetching only the last line for all the no of rows getting displayed i.e, the database table has three rows, the last row is getting displayed 3 times.
ABC PCA100 XXX.1.0.0
ABC PCA100 XXX.1.0.0
ABC PCA100 XXX.1.0.0
ABC PCA100 XXX.1.0.0
ABC PCA100 XXX.1.0.0
ABC PCA100 XXX.1.0.0
推荐答案
你必须创建一个模型类，它代表名称， PCANo 和 IP 。
You have to create a model class which represent Name, PCANo and IP.
public class Types
{
private String name;
private String pcaNo;
private String ip;
//constructors
//getter-setters
}
和 getTypes 方法返回 List< Types> of CoffeeExpert class 。
and getTypes method returns List<Types> of CoffeeExpert class.
public List<Types> getTypes(String type) {
Connection con = getConnection();
String Query = "select * from ABC";
List<Types> list=new ArrayList();
rs = con.createStatement().executeQuery(Query);
while (rs.next()) {
Types type=new Types();
type.setName(rs.getString(1));
type.setPcaNo(rs.getString(2));
type.setIp(rs.getString(3));
list.add(type);
}
rs.close();
con.close();
return list;
}
显示列表< Types> 在.jsp页面中：
To show the List<Types> in .jsp page:
JSP标签：
<%
List<Types> styles = (List<Types>) request.getAttribute("styles");
if(styles!=null){
for(Types type: styles){
out.println("<br/>" + type.getName() + " " + type.getPcaNo());
}
}
%>
JSTL：
<c:forEach var="type" items="${styles}">
<br/>
<c:out value="${type.name}" />
<c:out value="${type.pcano}" />
<c:out value="${type.ip}" />
</c:forEach>
参考SO主题：
- JSTL常见问题解答 - 使用JSTL 1.2它需要单个 http://download.java.net/maven/1/jstl/jars/jstl-1.2.jar jar文件。
- 如何避免JSP文件中的Java代码？
- JSTL FAQ - Use JSTL 1.2 it requires single http://download.java.net/maven/1/jstl/jars/jstl-1.2.jar jar file.
- How to avoid Java Code in JSP-Files?
这篇关于JSP中的结果集的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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