-1
MainServ.java无法使用JSTL
package servs.com;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import serv.com.Users;
@WebServlet(name="mainServ",urlPatterns={"/mainServ"})
public class haha extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
// JDBC driver name and database URL
final String DB_URL="jdbc:mysql://localhost/test";
// Database credentials
final String USER = "root";
final String PASS = "root";
Connection conn = null;
Statement stmt = null;
ArrayList<Users> usersArr = new ArrayList<Users>();
// Set response content type
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Database Result";
String docType =
"<!doctype html public \"-//w3c//dtd html 4.0 " +
"transitional//en\">\n";
out.println(docType +
"<html>\n" +
"<head><title>" + title + "</title></head>\n" +
"<body bgcolor=\"#f0f0f0\">\n" +
"<h1 align=\"center\">" + title + "</h1>\n");
try{
// Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");
// Open a connection
conn = DriverManager.getConnection(DB_URL, USER, PASS);
// Execute SQL query
stmt = conn.createStatement();
String sql;
sql = "SELECT id, first, last, age FROM Employees";
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()){
//Retrieve by column name
int id = rs.getInt("id");
int age = rs.getInt("age");
String first = rs.getString("first");
String last = rs.getString("last");
Users u = new Users();
u.setAge(age);
u.setId(id);
u.setFirst(first);
u.setLast(last);
usersArr.add(u);
}
rs.close();
stmt.close();
conn.close();
}catch(SQLException se){
//Handle errors for JDBC
se.printStackTrace();
}catch(Exception e){
//Handle errors for Class.forName
e.printStackTrace();
}finally{
//finally block used to close resources
try{
if(stmt!=null)
stmt.close();
}catch(SQLException se2){
}// nothing we can do
try{
if(conn!=null)
conn.close();
}catch(SQLException se){
se.printStackTrace();
}//end finally try
} //end try
request.setAttribute("users", usersArr);
request.getRequestDispatcher("NewFile.jsp").forward(request,response);
System.out.println(usersArr.size());
}
}
NewFile.JSP
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!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>
<c:forEach items="${users}" var="rowss">
<c:forEach items="${rowss}" var="item">
<c:out value="${item}"/>
</c:forEach>
</c:forEach>
<!--
<c:forEach var="user" items="${users}">
<c:out value="${users.first}"/>
<c:out value="${users.last}"/>
<c:out value="${users.ageIp}"/>
<c:out value="${users.id}"/>
</c:forEach>
-->
</body>
</html>
Users.java
package servs.com;
final public class Users {
private int id;
private int age;
private String first;
private String last;
public void setId(int i){
this.id=i;
}
public void setAge(int i){
this.age=i;
}
public void setFirst(String i){
this.first=i;
}
public void setLast(String i){
this.last=i;
}
}
当我试图在NEWFILE以打印对象的ArrayList打印.jsp我收到以下错误。
javax.servlet.jsp.JspTagException：不知道如何遍历在<的forEach超过 提供的“项目” >
我不知道错误是在打印或我在将对象放入Arraylist（userArr）时做错了什么。我正在从数据库中成功地获取数据，因为我先打印了它。
请让我知道我可以修改什么来打印数据。我会开放如果有相同的任何不同的方法。