如何将一个ArrayList分解并显示为多个表列 [英] How to break and display one ArrayList into multiple table columns
问题描述
我有一个servlet，它加载一个属性文件，并在ArrayList对象中包含100个测试用例名称的列表。将servlet加载到JSP后，该JSP在表中显示列表。列表很长，所以我想要一些优雅的方式在表中显示它，以便它分成例如JSP上的三列或四列。
I have a servlet which loads a properties file and contains a list of 100 test case names into an ArrayList object. After loading the servlet forwards to a JSP which displays the list in a table. The list is long so I would like some elegant way to display it in a table so that it breaks up into, for example, three or four columns on the JSP.
我现在所做的是将列表分成servlet中的三个子列表：
What I do now is break up the list into three sublists in the servlet:
//load properties
Properties props = new Properties();
ArrayList<String> tests = new ArrayList<String>();
props.load(getServletContext().getResourceAsStream("/WEB-INF/sailcertifier.properties"));
Pattern pattern = Pattern.compile("[A-Z]{3}-[0-9]{2}");
for (Enumeration<Object> e = props.keys(); e.hasMoreElements();) {
String key = (String) e.nextElement();
Matcher m = pattern.matcher(key);
if (m.find())
tests.add(key);
}
Collections.sort(tests, new TestOrderComparator());
confBean.setPossibleTests(tests.toArray(new String[tests.size()]));
int third = tests.size() / 3;
List<String> testSubset1 = tests.subList(0, third);
List<String> testSubset2 = tests.subList(third, third * 2);
List<String> testSubset3 = tests.subList(third * 2, tests.size());
//store the bean as a request attribute
request.setAttribute("testSet1", testSubset1.toArray(new String[testSubset1.size()]));
request.setAttribute("testSet2", testSubset2.toArray(new String[testSubset2.size()]));
request.setAttribute("testSet3", testSubset3.toArray(new String[testSubset3.size()]));
request.setAttribute("testsConf", confBean);
request.setAttribute("certProps", props);
//forward to tests selection page
String url = "/sailcertifier/jsp/testsSelection.jsp";
RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(url);
response.setContentType("application/javascript");
try {
dispatcher.forward(request, response);
} catch (ServletException e) {
e.printStackTrace();
}
在JSP中，我像这样迭代子列表（添加一些html元素每种情况）：
In the JSP I iterate through the sublists like so (adding some html elements for each case):
<table>
<tr>
<td style="width: 33%">
<table>
<tr>
<td>
<c:forEach var="testName" items="${testSet1}">
<tr>
<td><label for="${testName}" id=${testName}Label>${testName}</label></td>
<td><input id=${testName} type="checkbox" value=${testName} name="selTest"></input></td>
<td><input id=${testName}Run type="button" value="Run Test" name="runButtons" /></td>
<td><input id=${testName}ManPass type="button" value="Manual Pass" name="manPassButtons"/></td>
<td><div id=${testName}Status style="width:100px"></td>
<td></td>
<td></td>
</tr>
</c:forEach>
<tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr>
</td>
</tr>
</table>
</td>
<td style="width: 33%">
<table>
<tr>
<td>
<c:forEach var="testName" items="${testSet2}">
<tr>
<td><label for="${testName}" id=${testName}Label>${testName}</label></td>
<td><input id=${testName} type="checkbox" value=${testName} name="selTest"></input></td>
<td><input id=${testName}Run type="button" value="Run Test" name="runButtons" /></td>
<td><input id=${testName}ManPass type="button" value="Manual Pass" name="manPassButtons"/></td>
<td><div id=${testName}Status style="width:100px"></td>
<td></td>
<td></td>
</tr>
</c:forEach>
<tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr>
</td>
</tr>
</table>
</td>
<td style="width: 33%">
<table>
<tr>
<td>
<c:forEach var="testName" items="${testSet3}">
<tr>
<td><label for="${testName}" id=${testName}Label>${testName}</label></td>
<td><input id=${testName} type="checkbox" value=${testName} name="selTest"></input></td>
<td><input id=${testName}Run type="button" value="Run Test" name="runButtons" /></td>
<td><input id=${testName}ManPass type="button" value="Manual Pass" name="manPassButtons"/></td>
<td><div id=${testName}Status style="width:100px"></td>
<td></td>
</tr>
</c:forEach>
</td>
</tr>
</table>
</td>
</tr>
</table>
我承认使用三个JSTL for循环有点难看（还没弄明白使用完整原版列表）。有没有更清晰的方法来处理这个，通过使用一些jquery插件（如 jquery grid plugin ）或其他图书馆（ displaytag ？）为我们平均分配行？
I admit using three JSTL for loops is kind of ugly (haven't figured out use the full original list yet). Is there a cleaner way to handle this, by using some jquery plugin (like jquery grid plugin) or other library (displaytag?) to handle the breaking up into rows evenly for me?
推荐答案
打印< tr> ，然后遍历数组列表，然后打印每个项目在< td> 中打印< / tr>< tr> 每 n items，然后结束数组列表上的循环，最后打印< / tr> 。
Print a <tr>, then loop over the array list, then print each item in a <td> and print a </tr><tr> every n items, then end the loop over the array list and finally print a </tr> afterwards.
EG每隔3个项目换一个新行：
E.g. a new row every 3rd item:
<table>
<tr>
<c:forEach items="${items}" var="item" varStatus="loop">
<c:if test="${not loop.first and loop.index % 3 == 0}">
</tr><tr>
</c:if>
<td>${item}</td>
</c:forEach>
</tr>
</table>
$ {loop.index} 返回当前迭代轮次的索引。 ％3 只返回 0 ，如果它可以被3分割而没有余数（因此，当索引为0时） ，3,6,9,12等）。
The ${loop.index} returns the index of the current iteration round. The % 3 would only return 0 if it is dividable by 3 without a remainder (thus, when the index is 0, 3, 6, 9, 12, etc).
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