Insert title here

```java コード index.jsp <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ page import=" java.util.ArrayList "%> <%@ page import=" java.util.List"%> <%@ page import=" sample1.UserDto"%> Insert title here <% List list = (List) request.getAttribute("userDto"); for(UserDto a : list){ out.println(a.getid()); out.println(a.getname()); out.println(a.getage()); } %> ``` ```java コード UserDto.java package sample1; public class UserDto { private int id; private String name; private int age; public int getid(){ return id; } public void setid(int id){ this.id = id; } public String getname(){ return name; } public void setname(String name){ this.name = name; } public int getage(){ return age; } public void setage(int age){ this.age = age; } } ``` ```java コード Hello.java package sample1; 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 java.util.List; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * SELECT文を発行・画面に表示するクラス * * @author mori * */ @WebServlet("/Hello") public class Hello extends HttpServlet { private static final long serialVersionUID = 1L; /** * * SELECT文を発行・画面に表示するメソッド * * @param request * サーブレットへのリクエスト * @param response * サーブレットからのレスポンス * @throws ServletException * 処理中に問題が起こったときに、Servlet がスローする可能性がある例外。 * @throws IOException * 入出力処理の失敗、または割り込みの発生によって生成される例外 * */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html; charset=utf-8"); PrintWriter out = response.getWriter(); out.println(""); out.println(""); Connection conn = null; String url = "jdbc:mysql://localhost/training"; String user = "root"; String password = "ryota"; try { Class.forName("com.mysql.jdbc.Driver"); conn = DriverManager.getConnection(url, user, password); Statement stmt = conn.createStatement(); String sql = "SELECT * FROM user"; ResultSet rs = stmt.executeQuery(sql); List users = new ArrayList<>(); while (rs.next()) { UserDto dto = new UserDto(); dto.setid(rs.getInt("id")); dto.setname(rs.getString("name")); dto.setage(rs.getInt("age")); users.add(dto); } request.setAttribute("userDto", users); String jsp = "/WEB-INF/index.jsp"; // ServletContext sc = getServletContext(); RequestDispatcher dispatch = request.getRequestDispatcher(jsp); dispatch.forward(request, response); rs.close(); stmt.close(); } catch (ClassNotFoundException e) { out.println("lassNotFoundException:" + e.getMessage()); } catch (SQLException e) { out.println("SQLException:" + e.getMessage()); } catch (Exception e) { out.println("Exception:" + e.getMessage()); } finally { try { if (conn != null) { conn.close(); } } catch (SQLException e) { out.println("SQLException:" + e.getMessage()); } } out.println(""); out.println(""); } /** * doPostメソッド * */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } } ``` --------------------------------------------------------------------------------------------------- Hello.javaの方から配列を渡してそれを,jsp　側で表示させたいのですが Exception:java.lang.ClassCastException: java.util.ArrayList cannot be cast to sample1.UserDto とエラーが出てしまいます。

	@@ -1 +1 @@
1	- サーブレットからjsp
1	+ サーブレットから配列を渡し、jsp側で表示　エラー

質問編集履歴