如何在FreeMarker中调用公共Java变量

Question

我试图在我的FreeMarker模板中调用一个Java方法，它使用一个公共静态Java变量作为参数之一。例如，如果test.ftl中的FreeMarker代码是：

${javaClass.getSomething(javaClass.VARIABLE)}

如果类JavaClass是这样的：

public class JavaClass {

    public static final int VARIABLE = 1;

    public String getSomething(int var) {
    ...
    }

我在使用模板时收到如下错误：

[echo] Expression JavaClass is undefined on line 40, column 81 in com/test/template/path/test.ftl. [echo] The problematic instruction: [echo] ---------- [echo] 03:53:01,146 ERROR [main][runtime:96] Template processing error: "Expression JavaClass is undefined on line 40, column 81 in com/test/template/path/test.ftl" [echo] [echo] ==> ${javaClass.getSomething(javaClass.VARIABLE)} [on line 40, column 25 in com/test/template/path/test.ftl] Expression JavaClass is undefined on line 40, column 81 in com/test/template/path/test.ftl. [echo] [echo] ----------The problematic instruction: [echo] [echo] [echo] ---------- [echo] Java backtrace for programmers: [echo] ---------- [echo] ==> ${javaClass.getSomething(javaClass.VARIABLE)} [on line 40, column 25 in com/test/template/path/test.ftl]freemarker.core.InvalidRe ferenceException: Expression JavaClass is undefined on line 40, column 81 in com/test/template/path/test.ftl. ... ...

这个错误抱怨它不喜欢javaClass.VARIABLE并抛出InvalidReferenceException。我尝试过用其他不同的方式指定它，比如JavaClass.VARIABLE、${javaClass.VARIABLE}和${JavaClass.VARIABLE}，但它们都会抛出错误

如何从FreeMarker（.ftl）模板中的Java方法中调用公共Java变量

Answer 1

Freemarker的数据模型不会在自动传入的对象上映射静态字段，因此必须使用BeanRapper http://freemarker.org/docs/pgui_misc_beanwrapper.html

import freemarker.ext.beans.BeansWrapper;

BeansWrapper w = new BeansWrapper(); 
TemplateHashModel statics = w.getStaticModels();
model.addAttribute("myVariable", statics);

然后在模板中使用

${myVariable["fully.qualified.package.ClassName"].FIELD_NAME}