如何在FreeMarker中調用公共Java變量

Question

我試圖在我的FreeMarker模板中調用Java方法，該方法使用公共靜態Java變量作爲其參數之一。例如，如果在test.ftl FreeMarker的代碼是這樣的：

${javaClass.getSomething(javaClass.VARIABLE)} 

如果類JavaClass看起來是這樣的：

public class JavaClass { 

    public static final int VARIABLE = 1; 

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

我使用模板時收到錯誤看起來像這樣：

[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. ... ...

這個錯誤是抱怨它不喜歡javaClass.VARIABLE和thro是InvalidReferenceException。我試過用其他不同的方式來指定它，例如JavaClass.VARIABLE,${javaClass.VARIABLE}和${JavaClass.VARIABLE}，但它們都會引發錯誤。

如何從FreeMarker（.ftl）模板中的Java方法中調用公共Java變量？

Answer 1

Freemarker的數據模型不會映射自動傳入的對象上的靜態字段，因此您必須使用beanwrapper 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); 

然後在你的模板，使用

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