如何使用JSTL迭代字符串映射和对象列表中的列表? [英] How to iterate a List in a Map of String and List of object using JSTL?
问题描述
我正在研究Spring MVC项目，在该项目中，我需要将一个对象从Controller传递到JSP，然后需要迭代该对象并将其显示在jsp页面的表中.
I am working on Spring MVC project in which I need to pass an object from my Controller to JSP and then I need to iterate that object and show them in a table in jsp page.
下面是我的类，其中包含数据-
Below is my class which holds the data -
public class DatacenterMachineMapping {
private Map<String, List<MachineMetrics>> datacenterMachines;
// getters and setters
}
public class MachineMetrics {
private String machineName;
private String t2_95;
private String t2_99;
private String syncs;
private String syncsBehind;
private String average;
// getters and setters
}
下面是我在Controller中的方法，我需要从中将一个对象传递给JSP，然后在JSP中迭代该对象以在表中显示数据-
And below is my method in my Controller from which I need to pass an object to JSP and then iterate that object in JSP to show the data in a table -
@RequestMapping(value = "testOperation", method = RequestMethod.GET)
public Map<String, String> testData() {
final Map<String, String> model = new LinkedHashMap<String, String>();
// for datacenter 1
MachineMetrics metrics1 = new MachineMetrics();
metrics1.setAvg("10");
metrics1.setT2_95("100");
metrics1.setT2_99("200");
metrics1.setMachineName("machineA");
metrics1.setSyncs("100");
metrics1.setSyncsBehind("1000");
MachineMetrics metrics2 = new MachineMetrics();
metrics2.setAvg("20");
metrics2.setT2_95("200");
metrics2.setT2_99("300");
metrics2.setMachineName("machineB");
metrics2.setSyncs("200");
metrics2.setSyncsBehind("2000");
List<MachineMetrics> metrics = new LinkedList<MachineMetrics>();
metrics.add(metrics1);
metrics.add(metrics2);
DatacenterMachineMapping mappings = new DatacenterMachineMapping();
Map<String, List<MachineMetrics>> holder = new LinkedHashMap<String, List<MachineMetrics>>();
holder.put("dc1", metrics);
mappings.setDatacenterMachines(holder);
model.put("testing", mappings);
return model;
}
下面是我的JSP页面.我不确定如何在JSP页面中以上述方式使用上面的mappings对象，以便我可以对其进行迭代并在表中显示结果.
And below is my JSP page.. And I am not sure how to use the above mappings object in such a way in the JSP page so that I can iterate it and show the result in a table.
<body>
<table>
<thead>
<tr>
<th>Machine Name</th>
<th>T2_95</th>
<th>T2_99</th>
<th>Syncs</th>
<th>Syncs Behind</th>
<th>Average</th>
</tr>
</thead>
<tbody>
<!-- this gives me exception -->
<c:forEach items="${testing.value}" var="m">
<tr>
<td>${m.machineName}</td>
<td>${m.t2_95}</td>
<td>${m.t2_99}</td>
<td>${m.syncs}</td>
<td>${m.syncsBehind}</td>
<td>${m.average}</td>
</tr>
</c:forEach>
</tbody>
</table>
</body>
如上所述，我尝试使用JSTL，并且尝试在从Controller传递到JSP的映射中迭代list，但是不知何故，它给了我一个例外--
I have tried using JSTL as shown above and I was trying to iterate the list in a map which I have passed from Controller to JSP but somehow it is giving me an exception as -
'${testing.value}' Property 'value' not found
在迭代Map-中的列表后，我的数据在Datacenter 1的表中应如下所示
My data should look like this in the table for Datacenter 1 after iterating the list in the Map-
Machine Name T2_95 T2_99 Syncs Syncs Behind Average
machineA 100 200 100 1000 10
machineB 200 300 200 2000 20
我在这里做错什么了吗?
Anything wrong I am doing here?
I am following up on my previous question here. In this question response object is different as I have Map of string and list here.
推荐答案
我认为这应该可行.
<c:set var="entry" value="${testing.datacenterMachines}"></c:set>
<c:forEachn var="m" items="${entry.value}">
<tr>
<td>${m.machineName}</td>
<td>${m.t2_95}</td>
<td>${m.t2_99}</td>
<td>${m.syncs}</td>
<td>${m.syncsBehind}</td>
<td>${m.average}</td>
</tr>
</c:forEach>
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