在groovy中使用追加节点操作列表

Question

我正在尝试将一个xml文件解析为一个列表。然后在列表中使用嵌套循环并追加新节点。

这是我写的代码

    import java.util.HashMap;
    import groovy.xml.*;

    def scresp        = '''
    <root>
    <Customer>
    <CustomerID>100</CustomerID>
    </Customer>
    <Customer>
    <CustomerID>101</CustomerID>
    </Customer>
    <Customer>
    <CustomerID>102</CustomerID>
    </Customer>
    </root>'''

          def reslist       = new XmlSlurper().parseText(scresp)
          def str = ''
          reslist.each
          {line ->
              line.Customer.eachWithIndex { cust, idx ->
                  str = "Count: " + idx
                  println str
                  cust.appendNode{
                      Count(idx)
                      Sample(str)}
                } }

        def updatedPayload = new StreamingMarkupBuilder().bind { mkp.yield reslist }.toString()
        println updatedPayload 

我得到的输出是

Count: 0
Count: 1
Count: 2
<root>
    <Customer>
        <CustomerID>100</CustomerID>
        <Sample>Count: 2</Sample>
    </Customer>
    <Customer>
        <CustomerID>101</CustomerID>
        <Sample>Count: 2</Sample>
    </Customer>
    <Customer>
        <CustomerID>102</CustomerID>
        <Sample>Count: 2</Sample>
    </Customer>
</root>

我的问题是为什么只有最后一个值'Count: 2‘被添加到xml中，尽管println返回正确的值Count: 0，Count: 1& Count: 2？

Answer 1

您正在使用流生成器，这是懒惰的。这意味着，在执行过程中，它获得全局变量str的实际(最近)值。

为了使其正确，您必须缩小变量的范围：

          // def str = '' // << delete this line
          reslist.each
          {line ->
              line.Customer.eachWithIndex { cust, idx ->
                  String str = "Count: " + idx // declare the variable here
                  println str
                  cust.appendNode{
                      Count(idx)
                      Sample(str)}
                } }

然后打印出来：

<root>
<Customer><CustomerID>100</CustomerID><Count>0</Count><Sample>Count: 0</Sample></Customer>
<Customer><CustomerID>101</CustomerID><Count>1</Count><Sample>Count: 1</Sample></Customer>
<Customer><CustomerID>102</CustomerID><Count>2</Count><Sample>Count: 2</Sample></Customer>
</root>