如何在 JSP 文件中以表格格式显示列表内容？

Question

In an Action.java file, am using the following piece of code.

request.setAttribute("TAREWEIGHT", tareWeightList);
    request.setAttribute("BARCODE", barcodeList);
return (mapping.findForward(target));

tareWeightList & barcodeList actually holds few values. After setting the list values to the attributes, the java file forwards the contents to a JSP file.

There in JSP file, I can get the contents using below lines,

<%=request.getAttribute("TAREWEIGHT")%>
<%=request.getAttribute("BARCODE") %>

My requirement is that the contents of that lists should be diplayed in a tabular format.

Barcode values in first column and its corresponding Tareweight values in the second column.

Suggest me an idea for writing the code in JSP file so as the contents are displayed in a tabulated format.

Answer 1

Use HTML <table> element to represent a table in HTML. Use JSTL <c:forEach> to iterate over a list in JSP.

Eg

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
...
<table>
  <c:forEach items="${list}" var="item">
    <tr>
      <td><c:out value="${item}" /></td>
    </tr>
  </c:forEach>
</table>

You've only a design flaw in your code. You've split related data over 2 independent lists. It would make the final approach as ugly as

<table>
  <c:forEach items="${TAREWEIGHT}" var="tareWeight" varStatus="loop">
    <c:set var="barCode" value="${BARCODE[loop.index]}" />
    <tr>
      <td><c:out value="${tareWeight}" /></td>
      <td><c:out value="${barCode}" /></td>
    </tr>
  </c:forEach>
</table>

I suggest to create a custom class to hold the related data together. Eg

public class Product {

    private BigDecimal tareWeight;
    private String barCode;

    // Add/autogenerate getters/setters/equals/hashcode and other boilerplate.
}

so that you end up with a List<Product> which can be represented as follows:

<table>
  <c:forEach items="${products}" var="product">
    <tr>
      <td><c:out value="${product.tareWeight}" /></td>
      <td><c:out value="${product.barCode}" /></td>
    </tr>
  </c:forEach>
</table>

after having put it in the request scope as follows:

request.setAttribute("products", products);

See also:

• Our JSTL wiki page
• How to avoid Java code in JSP files?

Answer 2

Use <c:forEach> and <TABLE>

For Example :

<TABLE>
<c:forEach items="${personList} var="peson">

  <tr>
    <td><c:out value="${person.name}"/></td>
    <td><c:out value="${person.age}"/></td>
  </tr>
</c:forEach>
</TABLE>

Answer 3

我在.jsp页面添加了这个，问题解决了：

<%@ page isELIgnored="false" %>

Answer 4

First of all, you should not use scriptlets in JSP. Use the JSTL, other custom JSP tags, and the expression language.

Second: the point of an MVC framework is to have the action prepare the model for the view, which should stay very simple. You should probably make the action create a single list of objects, each containing the fields from the barcodes and their corresponding tareweight. This way, you would just have one iteration in your JSP.

The code would thus be very simple:

<c:forEach var="barCodeAndTareWeight" items="BARCODE_AND_TAREWEIGHTS">
    <tr>
        <td><c:out value="${barCodeAndTareWeight}.someField"/></td>
        <td><c:out value="${barCodeAndTareWeight}.someOtherField"/></td>
    </tr>
</c:forEach>

Note that there exist specific custom tags to display tables, support sorting, paging etc. I like using the displaytag .