java - 在 FreeMarker 中对表列使用多个序列的最佳方法

Question

我有两个单独的数据列表(集)，我想用它们来创建表格

ColumnA      ColumnB
Value1       Value1
Value2       Value2
Value3       Value3
Value4       Value4
             Value5
             Value6

我知道我可以通过 POJO 来做到这一点，其中我的集合将是 POJO(例如 a 和 b)字段，我可以在模板中调用它们，例如:

<table>
<tr>
<th>ColumnA</th>
<th>ColumnB</th>
</tr>
<tr>
<#list object as c>
<td>${c.a}</td>
<td>${c.b}</td>
</#list>
</tr>
</table>

但是我想使用单独的集合并分别填充 ColumnA 和 ColumnsB

您能建议最好的方法吗？

例如:

data.put("set1", SET1)

data.put("set2", SET2)

模板:

<table>
<tr>
<th>ColumnA</th>
<th>ColumnB</th>
</tr>
<#list set1 as c>
<tr><td>${c}</td></tr>
</#list>
<#list set2 as d>
<tr><td>${d}</td></tr>
</#list>
</table>

因此它将合并 ColumnA 的两个集合

Answer 1

参见https://freemarker.apache.org/docs/dgui_template_exp.html#dgui_template_exp_var_sequence

Retrieving data from a sequence

This is the same as for hashes, but you can use the square bracket syntax only, and the expression in the brackets must evaluate to a number, not a string. For example to get the name of the first animal of the example data-model (remember that the number of the first item is 0, not 1): animals[0].name

和内置序列大小:https://freemarker.apache.org/docs/ref_builtins_sequence.html#ref_builtin_size

size

The number of sub variables in sequence (as a numerical value). The highest possible index in sequence s is s?size - 1 (since the index of the first subvariable is 0) assuming that the sequence has at least one subvariable.

如果你想找到最大的尺寸，请使用 https://freemarker.apache.org/docs/ref_builtins_sequence.html#ref_builtin_min_max

min, max

Returns the smaller (min) or greatest (max) item of the sequence (or collection). The items must be either all numbers, or all date/time values of the same kind (date-only, time-only, date-time), or else a comparison error will occur

这允许您执行以下操作:

<#list 0..<[sequenceA?size, sequenceB?size]?max as i>
  <tr>
  <td>${sequenceA[i]!""}</td>
  <td>${sequenceB[i]!""}</td>
  </tr>
</#list>

另请参阅:

• Handling null values in Freemarker