error-handling - 如何在XPages中的自定义控件中处理设计错误？

Question

在自定义控件中，有一个重复控件，它引用文件夹中的一列(不是 View )。结合自定义控件，可以及时更改文件夹的默认设计。因此，可能发生的情况是，自定义控件的代码比文件夹的设计新，因此设计不匹配并且XPage错误消失了。

我特别想要的是自定义控件处理与缺少 View /文件夹列有关的错误或类似的设计错误。该错误将在某处报告，通知用户他/她可以激活某些可以修复这种情况的东西。

我知道如何捕获JavaScript错误，不幸的是所有列值都在表达式语言中。我当然可以重新编码，但是我想知道是否有更好的方法。

简而言之:如何捕获表达式语言错误？

Answer 1

您可以通过添加自己的EL和自己的VariableResolver来捕获PropertyResolver语言错误。为此，您必须创建两个Java类:

变量解析器

package ch.hasselba.xpages.demo;

import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
import javax.faces.el.EvaluationException;
import javax.faces.el.VariableResolver;

public class ELErrVariableResolver extends VariableResolver {

  private final VariableResolver delegate;

  public ELErrVariableResolver(VariableResolver resolver) {
    delegate = resolver;
  }

  @Override
  public Object resolveVariable(FacesContext context, String name) throws EvaluationException {
      Object variable = null;
      try{
          variable = delegate.resolveVariable(context, name);
      }catch( EvaluationException ee ){
          addResolveErrMessage( context, name );
      }

     return variable;
  }

  public void addResolveErrMessage( FacesContext context , String name ){
      FacesMessage msg = new FacesMessage();
      msg.setSummary( "BAD EL! Variable '" + name + "' not found." );
      msg.setSeverity( FacesMessage.SEVERITY_FATAL );
      context.addMessage("BAD EL!", msg);
  }
}

属性解析器

package ch.hasselba.xpages.demo;

import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
import javax.faces.el.EvaluationException;
import javax.faces.el.PropertyNotFoundException;
import javax.faces.el.PropertyResolver;

public class ELErrPropertyResolver extends PropertyResolver{

    private final PropertyResolver delegate;

      public ELErrPropertyResolver(PropertyResolver resolver) {
        delegate = resolver;
      }


    @Override
    public Class getType(Object paramObject1, Object paramObject2)
            throws EvaluationException, PropertyNotFoundException {
        Class c = null;
        try{
            c = delegate.getType(paramObject1, paramObject2);
        }catch(Exception e){
            addResolveErrMessage( FacesContext.getCurrentInstance(), paramObject1.toString() + "." + paramObject2.toString() );
        }
        return c;
    }

    @Override
    public Class getType(Object paramObject, int paramInt)
            throws EvaluationException, PropertyNotFoundException {
        Class c = null;
        try{
            c = delegate.getType(paramObject, paramInt);
        }catch(Exception e){
            addResolveErrMessage( FacesContext.getCurrentInstance(), paramObject.toString() + "." + paramInt );
        }
        return c;
    }

    @Override
    public Object getValue(Object paramObject1, Object paramObject2)
            throws EvaluationException, PropertyNotFoundException {
        Object c = null;

        try{
            c = delegate.getValue(paramObject1, paramObject2);
        }catch(Exception e){
            addResolveErrMessage( FacesContext.getCurrentInstance(), paramObject1.toString() + "."  + paramObject2.toString() );
        }
        return c;
    }

    @Override
    public Object getValue(Object paramObject, int paramInt)
            throws EvaluationException, PropertyNotFoundException {
        Object c = null;
        try{
            c = delegate.getValue(paramObject, paramInt);
        }catch(Exception e){
            addResolveErrMessage( FacesContext.getCurrentInstance(), paramObject.toString() + "." + paramInt );
        }
        return c;
    }

    @Override
    public boolean isReadOnly(Object paramObject1, Object paramObject2)
            throws EvaluationException, PropertyNotFoundException {
        boolean c = false;
        try{
            c = delegate.isReadOnly(paramObject1, paramObject2);
        }catch(Exception e){
            addResolveErrMessage( FacesContext.getCurrentInstance(), paramObject1.toString() + "." + paramObject2.toString() );
        }
        return c;
    }

    @Override
    public boolean isReadOnly(Object paramObject, int paramInt)
            throws EvaluationException, PropertyNotFoundException {
        boolean c = false;
        try{
            c = delegate.isReadOnly(paramObject, paramInt);
        }catch(Exception e){
            addResolveErrMessage( FacesContext.getCurrentInstance(), paramObject.toString() + "." + paramInt );
        }
        return c;
    }

    @Override
    public void setValue(Object paramObject1, Object paramObject2,
            Object paramObject3) throws EvaluationException,
            PropertyNotFoundException {
        try{
            delegate.setValue(paramObject1, paramObject2, paramObject3);
        }catch(Exception e){
            addResolveErrMessage( FacesContext.getCurrentInstance(), paramObject1.toString() + "." + paramObject2.toString() );
        }

    }

    @Override
    public void setValue(Object paramObject1, int paramInt, Object paramObject2)
            throws EvaluationException, PropertyNotFoundException {

        try{
            delegate.setValue(paramObject1, paramInt, paramObject2);
        }catch(Exception e){
            addResolveErrMessage( FacesContext.getCurrentInstance(), paramObject1.toString() + "." + paramInt );
        }

    }

    public void addResolveErrMessage( FacesContext context , String name ){
          FacesMessage msg = new FacesMessage();
          msg.setSummary( "BAD EL! Property '" + name + "' not found." );
          msg.setSeverity( FacesMessage.SEVERITY_FATAL );
          context.addMessage("BAD EL!", msg);
      }
}

将新的解析器添加到您的faces-config.xml中:

<?xml version="1.0" encoding="UTF-8"?>
<faces-config>
   <application>
        <variable-resolver>ch.hasselba.xpages.demo.ELErrVariableResolver
        </variable-resolver>
        <property-resolver>ch.hasselba.xpages.demo.ELErrPropertyResolver
        </property-resolver>
    </application>
</faces-config>

在CC上添加一个xp:messages组件以显示消息(或更改类中的错误例程以添加所需的任何内容。)