我需要取到根元素root -->List<Map<String, Object>> 的一些数据进行数学运算:
准备一些原始数据:
List<Map<String, Object>> queryForListTest=new ArrayList<Map<String, Object>>();
Map<String, Object> mapForTest1 =new HashMap<String, Object>();
mapForTest1.put("TNUM", 1);
mapForTest1.put("TEST_VALUE1", 5.70);
queryForListTest.add(mapForTest1);
Map<String, Object> mapForTest2 =new HashMap<String, Object>();
mapForTest2.put("TNUM", 2);
mapForTest2.put("TEST_VALUE1", 5.72);
queryForListTest.add(mapForTest2);
Map<String, Object> mapForTest3 =new HashMap<String, Object>();
mapForTest3.put("TNUM", 3);
mapForTest3.put("TEST_VALUE1", 5.69);
queryForListTest.add(mapForTest3);
Map<String, Object> mapForTest4 =new HashMap<String, Object>();
mapForTest4.put("TNUM", 4);
mapForTest4.put("TEST_VALUE1", 5.72);
queryForListTest.add(mapForTest4);
Map<String, Object> mapForTest5 =new HashMap<String, Object>();
mapForTest5.put("TNUM", 5);
mapForTest5.put("TEST_VALUE1", 5.70);
queryForListTest.add(mapForTest5);
freemarker模板获取数据:
//获取第一个数据
<#list queryForListTest as m>
<#assign tsampName = m['TNUM']/>
<#if tsampName == 1>
<#assign tn1 = m['TEST_VALUE1']/>
</#if>
</#list>
//获取第二个数据
<#list queryForListTest as m>
<#assign tsampName = m['TNUM']/>
<#if tsampName == 2>
<#assign tn2 = m['TEST_VALUE1']/>
</#if>
</#list>
//获取第三个数据
<#list queryForListTest as m>
<#assign tsampName = m['TNUM']/>
<#if tsampName == 3>
<#assign tn3 = m['TEST_VALUE1']/>
</#if>
</#list>
//获取第四个数据
<#list queryForListTest as m>
<#assign tsampName = m['TNUM']/>
<#if tsampName == 4>
<#assign tn4 = m['TEST_VALUE1']/>
</#if>
</#list>
//获取第五个数据
<#list queryForListTest as m>
<#assign tsampName = m['TNUM']/>
<#if tsampName == 5>
<#assign tn5 = m['TEST_VALUE1']/>
</#if>
</#list>
${((tn1+tn2+tn3+tn4+tn5)/5)?string["0.##"]}
遇到问题如下:
1. <#if tsampName == 1> <#if tsampName == "1"> -->会报格式不匹配的异常
因为存的是数字类型,所以比较的时候也必须是数字类型.
数字-->字符串 ${x?string}
字符串-->数字 ${x?number}
2.平均值的求法
<#assign sum = 0 />
<#assign count = 0 />
<#list queryForTestList as m>
<#assign itemName = m['ITEM_NAME']/>
<#if itemName == '标准燃速发动机'>
<#if m['TEST_VALUE']??>
<#assign tempVal = m['TEST_VALUE']?number/>
<#assign sum="${sum?number + tempVal?number}">
<#assign count="${count?number + 1?number}">
</#if>
</#if>
</#list>
${sum}--${count}--${sum?number/count?number}
3.我计算的值需要保留两位小数
数字格式化:
<#assign x = 1.234>
${x?string["0"]} -->1
${x?string["0.#"]} -->1.2
${x?string["0.##"]} -->1.23
${x?string["0.###"]} -->1.234
${x?string["0.####"]} -->1.234
${1?string["000.00"]} -->001.00
${12.1?string["000.00"]} -->012.10
${123.456?string["000.00"]} -->123.46
${1.2?string["0"]} -->1
${1.8?string["0"]} -->2
${1.5?string["0"]} -->2
${2.5?string["0"]} -->2
${12345?string["0.##E0"]} -->1.23E4
以及其他数字格式的处理: