＃03:メモ一覧を表示する - Servlet
ここでは、メモ帳のサンプルデータを一覧表示するプログラムを作成します。そのために、データベースに接続して、JSPを呼び出すServletを作成しましょう。
(tomcat/webapps/mymemo/ListServlet.java)import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.sql.*;
public class ListServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
if (request.getAttribute("message") == null) {
request.setAttribute("message", "hello paiza memo");
}
String url = "jdbc:mysql://localhost/memo";
String user = "root";
String password = "";
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (Exception e) {
e.printStackTrace();
}
String sql = "SELECT * FROM posts";
try (Connection connection = DriverManager.getConnection(url, user, password);
PreparedStatement statment = connection.prepareStatement(sql);
ResultSet results = statment.executeQuery()) {
ArrayList<HashMap<String, String>> rows = new ArrayList<HashMap<String, String>>();
while (results.next()) {
HashMap<String, String> columns = new HashMap<String, String>();
String id = results.getString("id");
columns.put("id", id);
String title = results.getString("title");
columns.put("title", title);
String content = results.getString("content");
columns.put("content", content);
rows.add(columns);
}
request.setAttribute("rows", rows);
} catch (Exception e) {
request.setAttribute("message", "Exception:" + e.getMessage());
}
String view = "/WEB-INF/views/list.jsp";
RequestDispatcher dispatcher = request.getRequestDispatcher(view);
dispatcher.forward(request, response);
}
}
- Javaの道＞Servlet・JSP
https://www.javaroad.jp/servletjsp/index.html
- Servletアプリ開発：目次 - Web系開発メモ
http://web-dev.hatenablog.com/entry/java/servlet/dev-restful-app/table-of-contents