ConverterTag.java

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package com.sun.faces.taglib.jsf_core;

import com.sun.faces.util.MessageUtils;

import javax.el.ValueExpression;
import javax.faces.component.StateHolder;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.ConverterException;
import javax.servlet.jsp.JspException;

/**
 * Basic implementation of <code>ConverterELTag</code>.
 */
public class ConverterTag extends AbstractConverterTag {

    // --------------------------------------------- Methods from ConverterELTag


    private static final long serialVersionUID = -7044710401705704550L;

    @Override
    protected Converter createConverter() throws JspException {

        if (converterId != null && converterId.isLiteralText()) {
            return createConverter(converterId,
                                   binding,
                                   FacesContext.getCurrentInstance());
        } else {
            return new BindingConverter(converterId, binding);
        }

    }

    // ----------------------------------------------------------- Inner Classes


    public static class BindingConverter implements Converter, StateHolder {

        ValueExpression converterId;
        ValueExpression binding;       

        // -------------------------------------------------------- Constructors


        /**
         * <p>This is only used during state restoration.</p>
         */
        public BindingConverter() {
        }


        public BindingConverter(ValueExpression converterId,
                                ValueExpression binding) {

            this.converterId = converterId;
            this.binding = binding;

        }

        // ---------------------------------------------- Methods From Converter


        @Override
        public Object getAsObject(FacesContext context, UIComponent component, String value) {
            Converter delegate = getDelegate(context);
            if (delegate != null) {
                return delegate.getAsObject(context, component, value);
            } else {
                throw new ConverterException(
                     MessageUtils.getExceptionMessage(
                          MessageUtils.CANNOT_CONVERT_ID,
                          converterId != null ? converterId.getExpressionString() : "",
                          binding != null ? binding.getExpressionString() : ""));
            }
        }

        @Override
        public String getAsString(FacesContext context, UIComponent component, Object value) {
            Converter delegate = getDelegate(context);
            if (delegate != null) {
                return delegate.getAsString(context, component, value);
            } else {
                throw new ConverterException(
                     MessageUtils.getExceptionMessage(
                          MessageUtils.CANNOT_CONVERT_ID,
                          converterId != null ? converterId.getExpressionString() : "",
                          binding != null ? binding.getExpressionString() : "")); 
            }
        }

        // -------------------------------------------- Methods from StateHolder


        private Object[] state;
        @Override
        public Object saveState(FacesContext context) {

            if (context == null) {
                throw new NullPointerException();
            }
            if (state == null) {
                state = new Object[2];
            }
            state[0] = converterId;
            state[1] = binding;

            return state;

        }

        @Override
        public void restoreState(FacesContext context, Object state) {

            if (context == null) {
                throw new NullPointerException();
            }

            this.state = (Object[]) state;
            if (this.state != null) {
                this.converterId = (ValueExpression) this.state[0];
                this.binding = (ValueExpression) this.state[1];
            }

        }

        @Override
        public boolean isTransient() {

            return false;

        }

        @Override
        public void setTransient(boolean newTransientValue) {
            //no-op
        }

        // ----------------------------------------------------- Private Methods


        private Converter getDelegate(FacesContext context) {

            return createConverter(converterId, binding, context);

        }

    }
    
}