使用Java EL 2.2 / JSF2是否可以进行字段访问而不是getter / setter？ [英] With Java EL 2.2 / JSF2 Is it possible to do field access rather than getters/setters?

问题描述

当我不需要控制对对象内部状态的访问时，我非常厌倦了getter / setter堵塞我的代码。我必须仍然生成getter / setter的唯一真正原因是因为JSF2.0 / EL 2.2通过定位方法而不是字段来工作： $ {myBean.fieldName} 。其中 fieldName 是指函数 getFieldName（）。是否有可能扩展EL解析器只返回公共字段值，除非找到了getter？

I'm serious tired of getters/setters clogging my code, when I don't need to control access to the internal state of an object. The only real reason I have to still generate getters/setters is because JSF2.0 / EL 2.2 works by locating methods, not fields: ${myBean.fieldName}. where fieldName refers to the function getFieldName(). Would it be possible to extend an EL Resolver to just return the public field value unless a getter was found?

编辑：
我希望这可以帮助其他人。注意我是如何明确地检查我只在Form或Lead对象上使用这个elresolver，它们是我的域对象。

I hope this helps someone else. Notice how I explicitly check that I only use this elresolver on Form or Lead objects, which are my domain objects.

public class PublicFieldSupportingELResolver extends ELResolver {
    @Override
    public Class<?> getCommonPropertyType(ELContext context, Object base) {
        if (base instanceof Form || base instanceof Lead) {
            try {
                context.setPropertyResolved(true);
                return base.getClass();
            } catch (Exception e) {
                context.setPropertyResolved(false);
                return null;
            }
        } else {
            context.setPropertyResolved(false);
            return null;
        }
    }

    @Override
    public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {
        return null;
    }

    @Override
    public Class<?> getType(ELContext context, Object base, Object property) {
        if (base instanceof Form || base instanceof Lead) {
            try {
                Field field = base.getClass().getField((String) property);
                context.setPropertyResolved(true);
                return field.getType();
            } catch (Exception e) {
                context.setPropertyResolved(false);
                return null;
            }
        } else {
            context.setPropertyResolved(false);
            return null;
        }
    }

    @Override
    public Object getValue(ELContext context, Object base, Object property) {
        if (base instanceof Form || base instanceof Lead) {
            try {
                Field field = base.getClass().getField((String) property);
                Object value = field.get(base);
                context.setPropertyResolved(true);
                return value;
            } catch (Exception e) {
                context.setPropertyResolved(false);
                return null;
            }
        } else {
            context.setPropertyResolved(false);
            return null;
        }
    }

    @Override
    public boolean isReadOnly(ELContext context, Object base, Object property) {
        if (base instanceof Form || base instanceof Lead) {
            try {
                base.getClass().getField((String) property);
                context.setPropertyResolved(true);
                return true;
            } catch (Exception e) {
                context.setPropertyResolved(false);
                return false;
            }
        } else {
            context.setPropertyResolved(false);
            return false;
        }
    }

    @Override
    public void setValue(ELContext context, Object base, Object property, Object value) {
        if (base instanceof Form || base instanceof Lead) {
            try {
                Field field = base.getClass().getField((String) property);
                field.set(base, value);
                context.setPropertyResolved(true);
            } catch (Exception e) {
                context.setPropertyResolved(false);
            }
        } else {
            context.setPropertyResolved(false);
        }
    }
}

推荐答案

是。 Jsf是非常可扩展的，几乎所有东西都可以扩展或替换。

Yes. Jsf is very extensible, pretty much everything can be extended or replaced.

自定义解析器的一个很好的例子是这里

A great example of custom resolvers is here

这家伙用它来填充数据库查询的下拉列表。我确信您可以使用类似的技术来解析基于公共字段而不是公共get / set方法。

The guy was using it to populate dropdown lists from database queries. I'm certain you could use similar techniques to resolve based on public fields rather than public get/set methods.

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