Question

任何人都知道如何扩展百里香的表达？（我需要百里香的“多样性”功能）克隆“数字”表达式有效，但是......
当我自己表达时，我有错误：

SEVERE：带有路径[]的servlet [appServlet]的Servlet.service（）抛出异常

  [Request processing failed;
   nested exception is   org.thymeleaf.exceptions.TemplateProcessingException: 
   Exception evaluating SpringEL expression:
   "Variety.Variety(review.usefulScore, 'osoba', 'osoby', 'osób')"
   (static:/cms/fragments/reviews:49)] with root cause
   org.springframework.expression.spel.SpelEvaluationException:
   EL1011E:(pos 8): Method call: 
  Attempted to call method  Variety(java.lang.Integer,java.lang.String,java.lang.String,java.lang.String) on null context object

有什么建议吗？

编辑（我的代码）：包org.springframework.expression;

import org.springframework.expression.spel.support.StandardEvaluationContext;

public abstract class Variety extends StandardEvaluationContext {

    private boolean in_array(int needle, int[] haystack) {

        for(int i = 0; i < haystack.length; i++) {
            if(haystack[i] == needle) return true;
        }
        return false;
    }

    public String Variety(int number, String varietyFor1, String varietyFor234,  String varietyForOthers) {
        if(number == 1)
            return varietyFor1;
        if(number % 100 >= 10 && number % 100 <= 20)
            return varietyForOthers;
        if(in_array(number%10, new int[] {2,3,4}))
            return varietyFor234;
        return varietyForOthers;
    }
}

编辑（忘了，像所有人一样）：我想使用它：$ {utils.Variety（...）}

Answer 1

以下异常表明上下文中没有Variety个对象。

Attempted to call method  Variety(java.lang.Integer,java.lang.String,java.lang.String,java.lang.String) on null context object

必须通过方言添加表达式对象。如果您已将方言添加到模板引擎，则可以使用#utils.variety(...)。

public class UtilsDialect implements IExpressionEnhancingDialect {

    public static final String UTILS_EXPRESSION_OBJECT_NAME = "utils";

    private final Variety utils;

    public UtilsDialect (final Variety utils){
        this.utils = utils;
    }

    @Override
    public Map<String, Object> getAdditionalExpressionObjects(final IProcessingContext processingContext) {
        final Map<String, Object> objects = new HashMap<>();
        objects.put(UTILS_EXPRESSION_OBJECT_NAME, variety);
        return objects;
    }
}

还要确保以大小写混合的方式编写方法：

public abstract class Variety extends StandardEvaluationContext {

    private boolean inArray(...){
        ...
    }

    public String variety(...){
        ...      
    }
}

如何创建一个与Thymeleaf和Spring一起使用的新表达式？

1 个答案: