使用 DAO 從 Java 類向 jsp 頁面傳遞值
[英]passing value to a jsp page from a java class using DAO
問題描述
我想將在 java 類上檢索到的值傳遞給頁面。我正在使用 DAO 類。 我已經從數據庫中檢索了值並將它們存儲在字符串變量中。現在我想將它們設置到我的 view.jsp 頁面中的文本框。我是這個領域的新手，有人能幫我嗎？
View.jsp是
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!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>
<form action="process.jsp">
Enter Name <br/> <br> <input type="text" name="uname" onclick="this.value=''"/><br/><br/>
<input type="submit" value="view details"/><br/><br/>
Email id: <br/> <input type="text" name="email" id="email" > <br/><br/>
password: <br/> <input type="text" name="passw" id="passw"><br/><br/>
</form>
</body>
</html>
和我的活動ViewDAO.java是
public static void view(user u) {
Connection con=ConnectionProvider.getCon();
String uname=u.getUname();
try {
PreparedStatement ps=con.prepareStatement("select email,pass from S1.USER432 where name='"+uname+"'");
ResultSet rs = ps.executeQuery();
while (rs.next()) {
String email = rs.getString("EMAIL");
String pass = rs.getString("PASS");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
謝謝...
6 個解決方案
解決方案1
1 2014-05-05 05:03:44
如果您使用的是前端控制器[spring mvc]，則可以通過執行model.addAttribute（“ variable_name”，data）;來傳遞數據。 在jsp中，您可以通過執行此$ {variable_name}來訪問它；
解決方案2
0 2014-05-05 05:22:14
如果您使用的是簡單的jsp和servelt，則創建一個ViewController.java。
您可以使用兩種方法來處理GET，另一種用於POST。
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
String email = request.getParameter("email");
String password = request.getParameter("password");
request.setAttribute("email", email);
request.setAttribute("password", password);
request.getRequestDispatcher("view.jsp").forward(request, response);
}
catch(Exception e){
}
view.jsp的
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!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>
<form action="process.jsp">
Enter Name <br/> <br> <input type="text" name="uname" onclick="this.value=''"/><br/><br/>
<input type="submit" value="view details"/><br/><br/>
Email id: <br/> <input type="text" name="email" id="email" value="<%=email%>" > <br/><br/>
password: <br/> <input type="text" name="passw" id="passw" value="<%=password%>"><br/><br/>
</form>
</body>
</html>
解決方案3
0 2014-05-06 05:04:37
Servlet決定必須加載哪個頁面。 因此，無論您從DAO獲得什么，都必須轉到Servlet並通過它到達jsp。 您可以使用bean類將值從DAO發送到Servlet。 像這樣，
public class Details{
private String email;
private String password;
public void setEmail(String email){
this.email = email;
}
public void setPassword(String password){
this.password= password;
}
public String getEmail(){
return this.email;
}
public String getPassword(){
return this.password;
}
}
在字符串中獲取查詢結果后，可以在DAO中進行以下更改。 添加這些
Details d = new Details();
d.setEmail(email);
d.setPassword(pass);
return d;
您可以將此對象d傳遞給servlet，並使用bean的getter方法檢索值。 另外，必須從Servlet調用DAO。 現在在Servlet端。
在Servlet上，您可以根據需要將代碼放入get或post方法中。 可能像
public class ExampleServlet extends HttpServlet{
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
String email = request.getParameter("email"); //got from the jsp where "email" is the name attribute of the input field
Details d = new Details();
d = ViewDao.view(user_object); //the bean sent by DAO. "user_object" is parameter that your DAO method is taking in your code
if(d.getEmail()!=null){ //just an example
// your code that redirects desired page
}
}
}
根據DAO返回的d ，您可以重定向到所需的任何頁面。
解決方案4
0 已采納 2014-05-06 05:12:11
您需要像下面這樣從servlet調用DAO方法：
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// call DAO method to get the email and password
HashMap<String,String> map=ViewDAO.getDetails();
//from the map you will get the email and password.then you need to set them in the attributes and get them in your jsp
request.setAttribute("email", map.get("email"));
request.setAttribute("password", map.get("password"));
}
您的DAO方法應如下所示：
public static HashMap<String,String> getDetails(user u) {
Connection con=ConnectionProvider.getCon();
String uname=u.getUname();
Map<String,String> map=new HashMap<>();
try {
PreparedStatement ps=con.prepareStatement("select email,pass from S1.USER432 where name='"+uname+"'");
ResultSet rs = ps.executeQuery();
while (rs.next()) {
String email = rs.getString("EMAIL");
String pass = rs.getString("PASS");
}
map.put("email",email);
map.put("password",pass);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return map;
}
}
希望這會幫助你。
解決方案5
0 2021-12-17 20:42:02
類似的東西
觀察這個導入 dao.UserDao,bean.*,
- dao 是包
- UserDao 是類
- bean 是您想要的方法，或者可以是來自 dao 的屬性
記住
jsp
<body>
<%@page import="dao.UserDao,bean.*,java.util.*"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<h1>Users List</h1>
<%
List<User> list=UserDao.getAllRecords();
request.setAttribute("list",list);
%>
<div class="table-responsive">
<table class="table">
<thread class="bg-info">
<th>Id</th><th>Name</th><th>Password</th><th>Edit</th><th>Delete</th>
</thread>
<c:forEach items="${list}" var="u">
<tr>
<td>${u.getId()}</td><td>${u.getUsername()}</td><td>${u.getPassword()}</td>
<td><a href="editform.jsp?id=${u.getId()}">Edit</a></td>
<td><a href="deleteuser.jsp?id=${u.getId()}">Delete</a></td>
</tr>
</c:forEach>
</table>
</div>
<br/><a href="adduserform.jsp">Add New User</a>
<br>
<br>
<form action="index.jsp">
<button type="submit">IndexUsers</button>
</form>
</body>
豆子或模型
包豆；
// 將 para 分類為表格
public class User {
private int id;
private String username,password;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
道
public class UserDao {
public static Connection getConnection(){
Connection con=null;
try{
Class.forName("com.mysql.cj.jdbc.Driver");
con=DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql_database","root","14570");
}catch(Exception e){System.out.println(e);}
return con;
}
public static int save(User u){
int status=0;
try{
Connection con=getConnection();
PreparedStatement ps=con.prepareStatement(
"insert into login(username,password) values(?,?)");
ps.setString(1,u.getUsername());
ps.setString(2,u.getPassword());
status=ps.executeUpdate();
}catch(Exception e){System.out.println(e);}
return status;
}
public static int update(User u){
int status=0;
try{
Connection con=getConnection();
PreparedStatement ps=con.prepareStatement(
"update login set username=?,password=? where id=?");
ps.setString(1,u.getUsername());
ps.setString(2,u.getPassword());
ps.setInt(3,u.getId());
status=ps.executeUpdate();
}catch(Exception e){System.out.println(e);}
return status;
}
public static int delete(User u){
int status=0;
try{
Connection con=getConnection();
PreparedStatement ps=con.prepareStatement("delete from login where id=?");
ps.setInt(1,u.getId());
status=ps.executeUpdate();
}catch(Exception e){System.out.println(e);}
return status;
}
public static List<User> getAllRecords(){
List<User> list=new ArrayList<User>();
try{
Connection con=getConnection();
PreparedStatement ps=con.prepareStatement("select * from login");
ResultSet rs=ps.executeQuery();
while(rs.next()){
User u=new User();
u.setId(rs.getInt("id"));
u.setUsername(rs.getString("username"));
u.setPassword(rs.getString("password"));
list.add(u);
}
}catch(Exception e){System.out.println(e);}
return list;
}
public static User getRecordById(int id){
User u=null;
try{
Connection con=getConnection();
PreparedStatement ps=con.prepareStatement("select * from login where id=?");
ps.setInt(1,id);
ResultSet rs=ps.executeQuery();
while(rs.next()){
u=new User();
u.setId(rs.getInt("id"));
u.setUsername(rs.getString("username"));
u.setPassword(rs.getString("password"));
}
}catch(Exception e){System.out.println(e);}
return u;
}
}
解決方案6
0 2021-12-17 23:55:03
另一個例子這個 import import="dao.*"% 使包 dao 中的任何方法可用，下面您將看到如何獲取 dao 中方法 countid() 的結果。
<%@page import="dao.*"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.Connection"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<% int id = 0; %>
<%
DaoEvento daoEvento = new DaoEvento();
id = daoEvento.countId();
%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.1/dist/css/bootstrap.min.css" integrity="sha384-zCbKRCUGaJDkqS1kPbPd7TveP5iyJE0EjAuZQTgFLD2ylzuqKfdKlfG/eSrtxUkn" crossorigin="anonymous">
<body>
<br><br>
<form action="add_event_servletnew" method="POST">
<div class="form-group">
<td>
<font color='green' face = "Arial" size = "4">
<%= request.getParameter("message") %>
</font>
<a href="view_event.jsp">view</a>
<td>
</div>
<div class="form-group">
<label>id</label>
<input type="text" name="id" value="<%= id%>" readonly="readonly" class="form-control"/>
</div>
<div class="form-group">
<label>Title</label>
<input type="text" name="title" value="" class="form-control" />
</div>
<div class="form-group">
<label>Start</label>
<input type="date" name="start" value="" class="form-control"/>
</div>
<div class="form-group">
<label>End</label>
<input type="date" name="end" value="" class="form-control" />
</div>
<div class="form-group">
<td><input type="submit" value="submit" class="btn btn-success btn-block"/></td>
</div>
</form>
</body>
<script src="https://cdn.jsdelivr.net/npm/jquery@3.5.1/dist/jquery.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.6.1/dist/js/bootstrap.bundle.min.js" integrity="sha384-fQybjgWLrvvRgtW6bFlB7jaZrFsaBXjsOMm/tB9LTS58ONXgqbR9W8oWht/amnpF" crossorigin="anonymous"></script>
<script src="jquery.mask.min.js"> </script>
</html>
從jsp頁面調用java dao類方法是否明智？
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