今回は、「データベースアプリケーションの作成(9)―UPDATEを使ってデータを更新する―」です。
UPDATEのSQLを使って、データを更新してみましょう。
■動画はこちら
■動画で使用しているソースコード
サーブレット(Sv5.java)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | package yurufuwa.prog.sample; import java.io.IOException; import jakarta.servlet.RequestDispatcher; import jakarta.servlet.ServletContext; import jakarta.servlet.ServletException; import jakarta.servlet.http.HttpServlet; import jakarta.servlet.http.HttpServletRequest; import jakarta.servlet.http.HttpServletResponse; public class Sv5 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //データ更新ページを表示 ServletContext sc = getServletContext(); RequestDispatcher rd = sc.getRequestDispatcher("/WEB-INF/jsp/in.jsp"); rd.forward(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //入力パラメーターを取得 String kenCode = req.getParameter("txtKenCode"); String kenName = req.getParameter("txtKenName"); //データの更新 Koushin t = new Koushin(); t.execute(kenCode, kenName); int updateRows = t.getUpdateRows(); //結果をリクエストにセット req.setAttribute("ken_code", kenCode); req.setAttribute("ken_name", kenName); req.setAttribute("update_rows", updateRows); //結果を表示 ServletContext sc = getServletContext(); RequestDispatcher rd = sc.getRequestDispatcher("/WEB-INF/jsp/out.jsp"); rd.forward(req, resp); } } |
更新処理(Koushin.java)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | package yurufuwa.prog.sample; import java.sql.Connection; import java.sql.Statement; import javax.naming.InitialContext; import javax.sql.DataSource; public class Koushin { private int updateRows = -1; public void execute(String kenCode, String kenName) { Connection conn = null; try { //DBに接続 InitialContext ctx = new InitialContext(); DataSource ds = (DataSource)ctx.lookup("java:comp/env/jdbc/mysql"); conn = ds.getConnection(); //SQLを発行 Statement stmt = conn.createStatement(); updateRows = stmt.executeUpdate( "UPDATE todofuken " + "SET ken_name = '" + kenName + "'" + "WHERE ken_code = '" + kenCode + "'" ); stmt.close(); } catch(Exception e) { e.printStackTrace(); } finally { try { //接続を閉じる conn.close(); } catch(Exception e) { } } } public int getUpdateRows() { return updateRows; } } |
JSP1(in.jsp)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>都道府県データ更新</title> </head> <body> <h2>更新するデータを入力してください</h2> <form action="./sv5" method="post"> <table> <tr><td>都道府県コード</td><td><input type="text" name="txtKenCode" /></td></tr> <tr><td>都道府県名</td><td><input type="text" name="txtKenName" /></td></tr> </table> <input type="submit" value="更新" /> </form> </body> </html> |
JSP2(out.jsp)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <% String kenCode = (String)request.getAttribute("ken_code"); String kenName = (String)request.getAttribute("ken_name"); int updateRows = (int)request.getAttribute("update_rows"); %> <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>都道府県データ更新</title> <style>table, th, td { border-collapse: collapse; border: 1px black solid; }</style> </head> <body> <h2>データの更新結果</h2> <h3>入力内容</h3> <table> <tr><td>都道府県コード</td><td><%= kenCode %></td></tr> <tr><td>都道府県名</td><td><%= kenName %></td></tr> </table> <h3>更新の件数</h3> <%= updateRows %>件 </body> </html> |
web.xml
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | <?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="https://jakarta.ee/xml/ns/jakartaee" xmlns:web="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd" id="WebApp_ID" version="5.0"> <display-name>testWeb</display-name> <servlet> <description></description> <display-name>Sv5</display-name> <servlet-name>Sv5</servlet-name> <servlet-class>yurufuwa.prog.sample.Sv5</servlet-class> </servlet> <servlet-mapping> <servlet-name>Sv5</servlet-name> <url-pattern>/sv5</url-pattern> </servlet-mapping> </web-app> |
context.xml
1 2 3 4 5 6 7 8 9 10 11 12 | <?xml version="1.0" encoding="UTF-8"?> <Context> <Resource name="jdbc/mysql" auth="Container" type="javax.sql.DataSource" factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" maxActive="5" maxIdle="5" initialSize="5" username="yuruku" password="fuwatto" driverClassName="com.mysql.cj.jdbc.Driver" url="jdbc:mysql://localhost/yuruku"/> </Context> |
