Display list of values on JSP using Spring

2019-05-05 18:59发布

站内问答 / Java
1815 3 4

I would like to display my List of values in my jsp view, but i am not able to do this.

Here is my controller class below, which is only add List to the ModelAndView map and than it redirects to my index.jsp page.

EmployeeController

@Controller
public class EmployeeController {

@RequestMapping(value={"/employee"}, method = RequestMethod.GET)
public String listEmployee(){    
    System.out.println("Kontroler EmployeeController");
    LinkedList<String> list = getList();
    ModelAndView map = new ModelAndView("index");
    map.addObject("lists", list);

    return map.getViewName();
}

private LinkedList<String> getList(){
    LinkedList<String> list = new LinkedList<>();

    list.add("Item 1");
    list.add("Item 2");
    list.add("Item 3");

    return list;
}

}

index.jsp

<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Welcome to Spring Web MVC project</title>
</head>

<body>
    <h1>Index page</h1>
    <h1>${msg}</h1>
    <a href="/MavenHello/employee">Zaměstnanci</a>
</body>
    <c:if test="${not empty listEmployee}">

    <ul>
        <c:forEach var="listValue" items="${listEmployee}">
            <li>${listValue}</li>
        </c:forEach>
    </ul>

</c:if>

I am able to access the controller, because every time I hit "Zaměstnanci", the System.out.println("Kontroler EmployeeController") prints "Kontroler EmployeeController" in to Tomcat Log, but the index.jsp page is blank.

Please, can someone give me an advice?

3条回答
一夜七次
2楼-- · 2019-05-05 19:21

Just add Model to your controller method params and then add attribute to this model.

RequestMapping(value={"/employee"}, method = RequestMethod.GET)
public String listEmployee(Model model){    
    System.out.println("Kontroler EmployeeController");
    LinkedList<String> list = getList();
    model.addAttribute("lists", list);

    return "index";
}

One more way to do this, is to return ModelAndView instead of String

@RequestMapping(value={"/employee"}, method = RequestMethod.GET)
public ModelAndView listEmployee(){    
    System.out.println("Kontroler EmployeeController");
    LinkedList<String> list = getList();
    ModelAndView map = new ModelAndView("index");
    map.addObject("lists", list);

    return map;
}

Just choose which way is better for you.

And also change listEmployee in your index page to lists as in the ModelAndView you have an attribute as lists not listEmployee`.

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冷血范
3楼-- · 2019-05-05 19:28

As you are populating ModelAndView return ModelAndView itself and not map.getViewName() which return only name of the name without data as stated in docs:

public String getViewName() Return the view name to be resolved by the DispatcherServlet via a ViewResolver, or null if we are using a View object.

as follows:

@RequestMapping(value = { "/employee" }, method = RequestMethod.GET)
public ModelAndView listEmployee() {
    System.out.println("Kontroler EmployeeController");
    LinkedList<String> list = getList();
    ModelAndView map = new ModelAndView("index");
    map.addObject("lists", list);

    return map;
}

Secondly, you are missing jstl tag <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> on your index page and variable name you given to list is "lists" so iterate over "lists" rather than "listEmployee", as follows:

<html>
<head>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Welcome to Spring Web MVC project</title>
</head>

<body>
    <h1>Index page</h1>
</body>

<c:if test="${not empty lists}">
    <c:forEach items="${lists}" var="lists">
       ${lists}
</c:forEach>
</c:if>

Also, make sure you have JSTL dependency in your classpath:

<dependency>
  <groupId>jstl</groupId>
  <artifactId>jstl</artifactId>
  <version>1.2</version>
</dependency>
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该账号已被封号
4楼-- · 2019-05-05 19:34

Change the key name and try it : listEmployee --> lists as you are setting it as map.addObject("lists", list);

<ul>
    <c:forEach var="listValue" items="${lists}">
        <li>${listValue}</li>
    </c:forEach>
</ul>
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