在 Jsp 中打印字符串数组的 Arraylist 最有效的方法是什么？

Question

There is an ArrayList which contains String arrays . Each string array contains values of each row. I want to print this in JSP. I tried printing it directly from servlet,its working but it is very slow since there is a lot of data.How to do this in JSP EL ?

public void printTableData(List<String[]> dataTable, PrintWriter out) {
        System.out.println(dataTable);
        out.println("<table border='1'>");
        out.println("<tr>");
        for (int j = 0; j < dataTable.get(0).length; j++) {
            out.println("<th>" + dataTable.get(0)[j] + "</th>");
        }
        out.println("</tr>");
        if (dataTable.size() > 1)
            for (int i = 1; i < dataTable.size(); i++) {
                out.println("<tr>");
                for (int j = 1; j < dataTable.get(i).length; j++) {
                    out.println("<td>" + dataTable.get(i)[j] + "</td>");

                }
                out.println("</tr>");
            }
        out.println("</table>");
    }

}

Answer 1

Maybe if you use a StringBuilder to concatenate the Strings will improve your performance.

public void printTableData(List<String[]> dataTable, PrintWriter out) {
    System.out.println(dataTable);
    StringBuilder sb = new StringBuilder();
    sb.append("<table border='1'>\n");
    sb.append("<tr>\n");
    for (int j = 0; j < dataTable.get(0).length; j++) {
        sb.append("<th>");
        sb.append(dataTable.get(0)[j]);
        sb.append("</th>\n");
    }
    sb.append("</tr>\n");
    if (dataTable.size() > 1)
        for (int i = 1; i < dataTable.size(); i++) {
            sb.append("<tr>\n");
            for (int j = 1; j < dataTable.get(i).length; j++) {
                sb.append("<td>");
                sb.append(dataTable.get(i)[j]);
                sb.append("</td>\n");

            }
            sb.append("</tr>\n");
        }
    sb.append("</table>\n");
    out.println(sb.toString());
    }

}

Answer 2

First pass the data to your request. Create a table header after:

<table class="your_class">
    <thead>
        <tr>
            <th>Title</th>
            <th>More</th>
            <th>Other</th>
        </tr>
    </thead>

then iterate over elements with <for:each> :

    <tbody>
        <c:forEach items="${list}" var="data">
            <tr class="your_class">
                <td>${data.attribute1}</td>
                <td>${data.attribute2}</td>
                <td>${data.attribute3}</td>
            </tr>
        </c:forEach>
    </tbody>
</table>

Answer 3

The question was how to iterate in JSP...So...

• First you need to add list into request attribute:

   request.setAttribute("list", dataTable)

• Then you can iterate in jsp using c:forEach tag

  <c:forEach items="${list}" var="entry"> <!-- iterate here using ${entry} --> </c:forEach>

You can also use varStatus="loop" , if you're using JSP 2.0

Answer 4

I go with Bazz answer. The below code should work fine. You need to add the listName model in request attribute.

<c:forEach var="listVar" items="${listName}">
<option value ="10"><c:out value="${listVar.attribute}"/></option>