beaninfomanager.java

jBpm是一个灵活可扩展的工作流管理系统。作为jBpm运行时server输入的业务流程使用简单强大的语言表达并打包在流程档案中

/*
 * The Apache Software License, Version 1.1
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 * modification, are permitted provided that the following conditions
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 * 1. Redistributions of source code must retain the above copyright
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 *    distribution.
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 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
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package org.jbpm.jpdl.el.impl;

import java.beans.BeanInfo;
import java.beans.EventSetDescriptor;
import java.beans.IndexedPropertyDescriptor;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;

import org.jbpm.jpdl.el.ELException;

/**
 * 
 * <p>
 * Manages the BeanInfo for one class - contains the BeanInfo, and also a
 * mapping from property name to BeanInfoProperty. There are also static methods
 * for accessing the BeanInfoManager for a class - those mappings are cached
 * permanently so that once the BeanInfoManager is calculated, it doesn't have
 * to be calculated again.
 * 
 * @author Nathan Abramson - Art Technology Group
 * @author Tom Baeyens - JBoss
 * @version $Change: 181181 $$DateTime: 2001/06/26 09:55:09 $$Author: tombaeyens $
 */

public class BeanInfoManager {

  // -------------------------------------
  // Properties
  // -------------------------------------
  // property beanClass

  Class mBeanClass;

  public Class getBeanClass() {
    return mBeanClass;
  }

  // -------------------------------------
  // Member variables
  // -------------------------------------

  // The BeanInfo
  BeanInfo mBeanInfo;

  // Mapping from property name to BeanInfoProperty
  Map mPropertyByName;

  // Mapping from property name to BeanInfoIndexedProperty
  Map mIndexedPropertyByName;

  // Mapping from method name to BeanMethod
  Map mMethodByName;

  // Mapping from event set name to event set descriptor
  Map mEventSetByName;

  // Flag if this is initialized
  boolean mInitialized;

  // The global mapping from class to BeanInfoManager
  static Map mBeanInfoManagerByClass = new HashMap();

  // -------------------------------------
  /**
   * 
   * Constructor
   */
  BeanInfoManager(Class pBeanClass) {
    mBeanClass = pBeanClass;
  }

  // -------------------------------------
  /**
   * 
   * Returns the BeanInfoManager for the specified class
   */
  public static BeanInfoManager getBeanInfoManager(Class pClass) {
    BeanInfoManager ret = (BeanInfoManager) mBeanInfoManagerByClass.get(pClass);
    if (ret == null) {
      ret = createBeanInfoManager(pClass);
    }
    return ret;
  }

  // -------------------------------------
  /**
   * 
   * Creates and registers the BeanInfoManager for the given class if it isn't
   * already registered.
   */
  static synchronized BeanInfoManager createBeanInfoManager(Class pClass) {
    // Because this method is synchronized statically, the
    // BeanInfoManager is not initialized at this time (otherwise it
    // could end up being a bottleneck for the entire system). It is
    // put into the map in an uninitialized state. The first time
    // someone tries to use it, it will be initialized (with proper
    // synchronizations in place to make sure it is only initialized
    // once).

    BeanInfoManager ret = (BeanInfoManager) mBeanInfoManagerByClass.get(pClass);
    if (ret == null) {
      ret = new BeanInfoManager(pClass);
      mBeanInfoManagerByClass.put(pClass, ret);
    }
    return ret;
  }

  // -------------------------------------
  /**
   * 
   * Returns the BeanInfoProperty for the specified property in the given class,
   * or null if not found.
   */
  public static BeanInfoProperty getBeanInfoProperty(Class pClass, String pPropertyName, Logger pLogger) throws ELException {
    return getBeanInfoManager(pClass).getProperty(pPropertyName, pLogger);
  }

  // -------------------------------------
  /**
   * 
   * Returns the BeanInfoIndexedProperty for the specified property in the given
   * class, or null if not found.
   */
  public static BeanInfoIndexedProperty getBeanInfoIndexedProperty(Class pClass, String pIndexedPropertyName, Logger pLogger) throws ELException {
    return getBeanInfoManager(pClass).getIndexedProperty(pIndexedPropertyName, pLogger);
  }

  public static BeanMethod getBeanMethod(Class pClass, String indexStr, Logger logger) throws ELException {
    return getBeanInfoManager(pClass).getBeanMethod(indexStr,logger);
  }

  // -------------------------------------
  /**
   * 
   * Makes sure that this class has been initialized, and synchronizes the
   * initialization if it's required.
   */
  void checkInitialized(Logger pLogger) throws ELException {
    if (!mInitialized) {
      synchronized (this) {
        if (!mInitialized) {
          initialize(pLogger);
          mInitialized = true;
        }
      }
    }
  }

  // -------------------------------------
  /**
   * 
   * Initializes by mapping property names to BeanInfoProperties
   */
  void initialize(Logger pLogger) throws ELException {
    try {
      mBeanInfo = Introspector.getBeanInfo(mBeanClass);

      mPropertyByName = new HashMap();
      mIndexedPropertyByName = new HashMap();
      mMethodByName = new HashMap();

      PropertyDescriptor[] pds = mBeanInfo.getPropertyDescriptors();
      for (int i = 0; pds != null && i < pds.length; i++) {
        // Treat as both an indexed property and a normal property
        PropertyDescriptor pd = pds[i];
        if (pd instanceof IndexedPropertyDescriptor) {
          IndexedPropertyDescriptor ipd = (IndexedPropertyDescriptor) pd;
          Method readMethod = getPublicMethod(ipd.getIndexedReadMethod());
          Method writeMethod = getPublicMethod(ipd.getIndexedWriteMethod());
          BeanInfoIndexedProperty property = new BeanInfoIndexedProperty(readMethod, writeMethod, ipd);

          mIndexedPropertyByName.put(ipd.getName(), property);
        }

        Method readMethod = getPublicMethod(pd.getReadMethod());
        Method writeMethod = getPublicMethod(pd.getWriteMethod());
        BeanInfoProperty property = new BeanInfoProperty(readMethod, writeMethod, pd);

        mPropertyByName.put(pd.getName(), property);
      }

      mEventSetByName = new HashMap();
      EventSetDescriptor[] esds = mBeanInfo.getEventSetDescriptors();
      for (int i = 0; esds != null && i < esds.length; i++) {
        EventSetDescriptor esd = esds[i];
        mEventSetByName.put(esd.getName(), esd);
      }
    } catch (IntrospectionException exc) {
      if (pLogger.isLoggingWarning()) {
        pLogger.logWarning(Constants.EXCEPTION_GETTING_BEANINFO, exc, mBeanClass.getName());
      }
    }

    // parsing the bean methods
    Method[] methods = mBeanClass.getDeclaredMethods();
    for (int i=0; i<methods.length; i++) {
      Method method = methods[i];
      if ( (method.getParameterTypes()==null)
           || (method.getParameterTypes().length==0)
         ) {
        mMethodByName.put(method.getName(), new BeanMethod(method));
      }
    }
  }

  // -------------------------------------
  /**
   * 
   * Returns the BeanInfo for the class
   */
  BeanInfo getBeanInfo(Logger pLogger) throws ELException {
    checkInitialized(pLogger);
    return mBeanInfo;
  }

  // -------------------------------------
  /**
   * 
   * Returns the BeanInfoProperty for the given property name, or null if not
   * found.
   */
  public BeanInfoProperty getProperty(String pPropertyName, Logger pLogger) throws ELException {
    checkInitialized(pLogger);
    return (BeanInfoProperty) mPropertyByName.get(pPropertyName);
  }

  // -------------------------------------
  /**
   * 
   * Returns the BeanInfoIndexedProperty for the given property name, or null if
   * not found.
   */
  public BeanInfoIndexedProperty getIndexedProperty(String pIndexedPropertyName, Logger pLogger) throws ELException {
    checkInitialized(pLogger);
    return (BeanInfoIndexedProperty) mIndexedPropertyByName.get(pIndexedPropertyName);
  }

  public BeanMethod getBeanMethod(String pMethodName, Logger pLogger) throws ELException {
    checkInitialized(pLogger);
    return (BeanMethod) mMethodByName.get(pMethodName);
  }

  // -------------------------------------
  /**
   * 
   * Returns the EventSetDescriptor for the given event set name, or null if not
   * found.
   */
  public EventSetDescriptor getEventSet(String pEventSetName, Logger pLogger) throws ELException {
    checkInitialized(pLogger);
    return (EventSetDescriptor) mEventSetByName.get(pEventSetName);
  }

  // -------------------------------------
  // Finding the public version of a method - if a PropertyDescriptor
  // is obtained for a non-public class that implements a public
  // interface, the read/write methods will be for the class, and
  // therefore inaccessible. To correct this, a version of the same
  // method must be found in a superclass or interface.
  // -------------------------------------
  /**
   * 
   * Returns a publicly-accessible version of the given method, by searching for
   * a public declaring class.
   */
  static Method getPublicMethod(Method pMethod) {
    if (pMethod == null) {
      return null;
    }

    // See if the method is already available from a public class
    Class cl = pMethod.getDeclaringClass();
    if (Modifier.isPublic(cl.getModifiers())) {
      return pMethod;
    }

    // Otherwise, try to find a public class that declares the method
    Method ret = getPublicMethod(cl, pMethod);
    if (ret != null) {
      return ret;
    } else {
      return pMethod;
    }
  }

  // -------------------------------------
  /**
   * 
   * If the given class is public and has a Method that declares the same name
   * and arguments as the given method, then that method is returned. Otherwise
   * the superclass and interfaces are searched recursively.
   */
  static Method getPublicMethod(Class pClass, Method pMethod) {
    // See if this is a public class declaring the method
    if (Modifier.isPublic(pClass.getModifiers())) {
      try {
        Method m;
        try {
          m = pClass.getDeclaredMethod(pMethod.getName(), pMethod.getParameterTypes());
        } catch (java.security.AccessControlException ex) {
          // kludge to accommodate J2EE RI's default settings
          // TODO: see if we can simply replace
          // getDeclaredMethod() with getMethod() ...?
          m = pClass.getMethod(pMethod.getName(), pMethod.getParameterTypes());
        }
        if (Modifier.isPublic(m.getModifiers())) {
          return m;
        }
      } catch (NoSuchMethodException exc) {
      }
    }

    // Search the interfaces
    {
      Class[] interfaces = pClass.getInterfaces();
      if (interfaces != null) {
        for (int i = 0; i < interfaces.length; i++) {
          Method m = getPublicMethod(interfaces[i], pMethod);
          if (m != null) {
            return m;
          }
        }
      }
    }

    // Search the superclass
    {
      Class superclass = pClass.getSuperclass();
      if (superclass != null) {
        Method m = getPublicMethod(superclass, pMethod);
        if (m != null) {
          return m;
        }
      }
    }

    return null;
  }

  // -------------------------------------
}