defaultvariableresolver.java

一个很好实用的工作流OSWORKFLOW开发例子.有着非常优秀的灵活性.

/*
 * Copyright (c) 2002-2003 by OpenSymphony
 * All rights reserved.
 */
package com.opensymphony.workflow.util;

import com.opensymphony.module.propertyset.PropertySet;

import com.opensymphony.provider.BeanProvider;
import com.opensymphony.provider.bean.DefaultBeanProvider;

import java.io.Serializable;

import java.util.Map;


/**
 * @author Hani Suleiman ([e-mail])
 * Date: Oct 14, 2003
 * Time: 11:58:12 PM
 */
public class DefaultVariableResolver implements VariableResolver, Serializable {
    //~ Static fields/initializers /////////////////////////////////////////////

    private static final long serialVersionUID = -4819078273560683753L;

    //~ Instance fields ////////////////////////////////////////////////////////

    private transient BeanProvider beanProvider = null;

    //~ Methods ////////////////////////////////////////////////////////////////

    public void setBeanProvider(BeanProvider beanProvider) {
        this.beanProvider = beanProvider;
    }

    public BeanProvider getBeanProvider() {
        return beanProvider;
    }

    public Object getVariableFromMaps(String var, Map transientVars, PropertySet ps) {
        int firstDot = var.indexOf('.');
        String actualVar = var;

        if (firstDot != -1) {
            actualVar = var.substring(0, firstDot);
        }

        Object o = transientVars.get(actualVar);

        if (o == null) {
            o = ps.getAsActualType(actualVar);
        }

        if (firstDot != -1) {
            if (beanProvider == null) {
                beanProvider = new DefaultBeanProvider();
            }

            o = beanProvider.getProperty(o, var.substring(firstDot + 1));
        }

        return o;
    }

    /**
       * Parses a string for instances of "${foo}" and returns a string with all instances replaced
       * with the string value of the foo object (<b>foo.toString()</b>). If the string being passed
       * in only refers to a single variable and contains no other characters (for example: ${foo}),
       * then the actual object is returned instead of converting it to a string.
       */
    public Object translateVariables(String s, Map transientVars, PropertySet ps) {
        String temp = s.trim();

        if (temp.startsWith("${") && temp.endsWith("}") && (temp.indexOf('$', 1) == -1)) {
            // the string is just a variable reference, don't convert it to a string
            String var = temp.substring(2, temp.length() - 1);

            return getVariableFromMaps(var, transientVars, ps);
        } else {
            // the string passed in contains multiple variables (or none!) and should be treated as a string
            while (true) {
                int x = s.indexOf("${");
                int y = s.indexOf("}", x);

                if ((x != -1) && (y != -1)) {
                    String var = s.substring(x + 2, y);
                    String t = null;
                    Object o = getVariableFromMaps(var, transientVars, ps);

                    if (o != null) {
                        t = o.toString();
                    }

                    if (t != null) {
                        s = s.substring(0, x) + t + s.substring(y + 1);
                    } else {
                        // the variable doesn't exist, so don't display anything
                        s = s.substring(0, x) + s.substring(y + 1);
                    }
                } else {
                    break;
                }
            }

            return s;
        }
    }
}