JSP+Servlet+MySQL完成將資料庫中的資料顯示到頁面
阿新 • • 發佈：2019-02-19
步驟：
1 先寫Servlet程式碼，首先匯入mysql-connector-java-5.1.40-bin.jar，在init()方法中載入jdbc驅動，在doGet()方法中獲取資料庫連線物件，然後獲取SQL的操作物件。
程式碼如下：
import java.io.IOException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import bean.User; public class JdbcJspServlet extends HttpServlet { @Override public void init() throws ServletException { try { Class.forName("com.mysql.jdbc.Driver"); } catch (ClassNotFoundException e) { e.printStackTrace(); } } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { Connection conn = null; PreparedStatement ps = null; ResultSet rs = null; try { List<User> userList = new ArrayList<>(); conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/java","root","123456"); ps = conn.prepareStatement("select * from tb_user"); rs = ps.executeQuery(); while(rs.next()){ String name = rs.getString("userName"); String password = rs.getString("userPwd"); User user = new User(name, password); userList.add(user); } req.setAttribute("userList", userList); req.getRequestDispatcher("home.jsp").forward(req, resp); } catch (SQLException e) { e.printStackTrace(); }finally { try { if(rs != null){ rs.close(); } if(ps!=null){ ps.close(); } if(conn!=null){ conn.close(); } } catch (SQLException e) { e.printStackTrace(); } } } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
2 在1中要用到一個實體類User,所以要寫一個User類，把查詢的結果放到一個ArrayList集合中。
程式碼如下：
import java.io.Serializable; public class User implements Serializable { private String name; private String password; public User() { super(); // TODO Auto-generated constructor stub } public User(String name, String password) { super(); this.name = name; this.password = password; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
3 配置web.xml檔案：
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1"> <display-name>Day42_jdbc_jsp_servlet</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>JdbcJspServlet</servlet-name> <servlet-class>com.jdbcjspservlet.JdbcJspServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>JdbcJspServlet</servlet-name> <url-pattern>/jdbcJspServlet.do</url-pattern> </servlet-mapping> </web-app>
4 寫要將資料顯示的jsp頁面
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!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=utf-8">
<title>Insert title here</title>
</head>
<body>
<ul>
<%
Object obj = request.getAttribute("userList");
List<User> userList = null;
if(obj instanceof List){
userList = (List<User>)obj;
}
if(userList!=null){
for(User user:userList){
String userinfo = user.getName()+"---"+user.getPassword();
%>
<li><%=userinfo %></li>
<%
}
}
%>
</ul>
</body>
</html>5 啟動TomCat伺服器，在瀏覽器位址列輸入地址即可將查詢到的資料庫資料顯示到網頁。