使用 DAO 从 Java 类向 jsp 页面传递值
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passing value to a jsp page from a java class using DAO
提问by LaksHmiSekhar
I wanted to pass the value retrieved on a java class to a page.I am using DAO classes. I have retrieved the values from the database and stored them on String variables.Now I want to set them to the text boxes in my view.jsp page.I am new to this area,can anyone help me out??
我想将在 java 类上检索到的值传递给页面。我正在使用 DAO 类。我已经从数据库中检索了值并将它们存储在字符串变量中。现在我想将它们设置到我的 view.jsp 页面中的文本框。我是这个领域的新手，有人能帮我吗？
View.jspis as
View.jsp是这样的
<%@ 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" > <br/><br/>
password: <br/> <input type="text" name="passw" id="passw"><br/><br/>
</form>
</body>
</html>
and My Activity ViewDAO.javais as
和我的活动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();
}
}
}
Thanks...
谢谢...
采纳答案by Gundamaiah
You need to call the DAO method from your servlet like below:
您需要从您的 servlet 调用 DAO 方法，如下所示：
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"));
}
your DAO method should be like the below:
您的 DAO 方法应如下所示：
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;
}
}
Hope this will help you.
希望这会帮助你。
回答by Mightian
If you are using a front controller[spring mvc] then you can pass the data by doing, model.addAttribute("variable_name ", data); and in the jsp you can access it by doing this ${variable_name};
如果您使用的是前端控制器[spring mvc]，那么您可以通过执行 model.addAttribute("variable_name ", data); 来传递数据。在jsp中，您可以通过执行此${variable_name}来访问它；
回答by tarun singh
if you are using simple jsp and servelt, then make one ViewController.java.
如果您使用简单的jsp 和servelt，那么制作一个ViewController.java。
You can two methods one for handling GET and other for POST
您可以使用两种方法，一种用于处理 GET，另一种用于 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
视图.jsp
<%@ 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>
回答by Conquest
The Servlet decides which page must be loaded. So whatever you get from the DAO must go to the Servlet and through that, to the jsp. You can use a bean class to send values from DAO to Servlet. Like this,
Servlet 决定必须加载哪个页面。因此，无论您从 DAO 获得什么，都必须传送到 Servlet，然后再传送到 JSP。您可以使用 bean 类将值从 DAO 发送到 Servlet。像这样，
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;
}
}
And you can make the following changes in DAO after getting the query results in the String. Add these
并且在获取String中的查询结果后，您可以在DAO中进行以下更改。添加这些
Details d = new Details();
d.setEmail(email);
d.setPassword(pass);
return d;
You can pass this object d to the servlet and retrieve the values using the getter methods of the bean. Also, the DAO must be called from the Servlet. And now on the Servlet side.
您可以将此对象 d 传递给 servlet 并使用 bean 的 getter 方法检索值。此外，必须从 Servlet 调用 DAO。现在在 Servlet 端。
On the Servlet you can put your code in the get or post method depending on your need. It may be like
在 Servlet 上，您可以根据需要将代码放入 get 或 post 方法中。它可能像
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
}
}
}
Based on dreturned by the DAO you may redirect to any page you want.
根据dDAO 返回的信息，您可以重定向到您想要的任何页面。
