1、错误描述

六月 26, 2014 10:44:49 下午 freemarker.log.JDK14LoggerFactory$JDK14Logger error
严重: Template processing error: "The only legal comparisons are between two numbers, two strings, or two dates.\nLeft  hand operand is a freemarker.template.SimpleScalar\nRight hand operand is a freemarker.template.SimpleNumber\n"

The only legal comparisons are between two numbers, two strings, or two dates.
Left  hand operand is a freemarker.template.SimpleScalar
Right hand operand is a freemarker.template.SimpleNumber

The problematic instruction:
----------
==> if-else  [on line 6, column 19 in inc/select.ftl]
 in user-directive items.select [on line 12, column 6 in address.ftl]
----------

Java backtrace for programmers:
----------
freemarker.template.TemplateException: The only legal comparisons are between two numbers, two strings, or two dates.
Left  hand operand is a freemarker.template.SimpleScalar
Right hand operand is a freemarker.template.SimpleNumber

	at freemarker.core.ComparisonExpression.isTrue(ComparisonExpression.java:182)
	at freemarker.core.IfBlock.accept(IfBlock.java:80)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.IfBlock.accept(IfBlock.java:82)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:179)
	at freemarker.core.Environment.visit(Environment.java:428)
	at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.MixedContent.accept(MixedContent.java:92)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.Macro$Context.runMacro(Macro.java:172)
	at freemarker.core.Environment.visit(Environment.java:614)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:106)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.MixedContent.accept(MixedContent.java:92)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.Environment.process(Environment.java:199)
	at freemarker.template.Template.process(Template.java:259)
	at com.you.freemarker.FreemarkerTemplate.printFtl(FreemarkerTemplate.java:77)
	at com.you.test.freemarker.FreemarkerTest.studentPrint(FreemarkerTest.java:267)
	at com.you.test.freemarker.FreemarkerTest.testSelect(FreemarkerTest.java:253)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

<html>
  <head>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <title>freemarker 下拉框</title>

  </head>
  
  <body>
          <select id="city" name="city">
          <option>---请选择---</option>
                 <option value=http://www.mamicode.com/"武汉市">武汉市>
2、错误原因
     比较两边要么是字符串，要么是数字，要么是日期；但是，现在左边是字符串，右边是数字
<#if value =http://www.mamicode.com/= data[key]>

3、解决方法
<#if value =http://www.mamicode.com/= data[key]?string>

     将两边都转换成字符串