IndexedPropertyDescriptor.java

/* IndexedPropertyDescriptor.java --
   Copyright (C) 1998, 2003 Free Software Foundation, Inc.

This file is part of GNU Classpath.

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package java.beans;

import java.lang.reflect.Array;
import java.lang.reflect.Method;

/**
 * IndexedPropertyDescriptor describes information about a JavaBean
 * indexed property, by which we mean an array-like property that
 * has been exposed via a pair of get and set methods and another
 * pair that allows you to get to the property by an index.<P>
 *
 * An example property would have four methods like this:<P>
 * <CODE>FooBar[] getFoo()</CODE><BR>
 * <CODE>void setFoo(FooBar[])</CODE><BR>
 * <CODE>FooBar getFoo(int)</CODE><BR>
 * <CODE>void setFoo(int,FooBar)</CODE><P>
 *
 * The constraints put on get and set methods are:<P>
 * <OL>
 * <LI>There must be at least a get(int) or a set(int,...) method.
 * Nothing else is required.  <B>Spec note:</B>One nice restriction
 * would be that if there is a get() there must be a get(int), same
 * with set, but that is not in the spec and is fairly harmless.)</LI>
 * <LI>A get array method must have signature
 *     <CODE>&lt;propertyType&gt;[] &lt;getMethodName&gt;()</CODE></LI>
 * <LI>A set array method must have signature
 *     <CODE>void &lt;setMethodName&gt;(&lt;propertyType&gt;[])</CODE></LI>
 * <LI>A get index method must have signature
 *     <CODE>&lt;propertyType&gt; &lt;getMethodName&gt;(int)</CODE></LI>
 * <LI>A set index method must have signature
 *     <CODE>void &lt;setMethodName&gt;(int,&lt;propertyType&gt;)</CODE></LI>
 * <LI>All these methods may throw any exception.</LI>
 * <LI>All these methods must be public.</LI>
 * </OL>
 *
 * @author John Keiser
 * @since JDK1.1
 */
public class IndexedPropertyDescriptor extends PropertyDescriptor
{
  private Class<?> indexedPropertyType;
  private Method setIndex;
  private Method getIndex;

  /**
   * Create a new IndexedPropertyDescriptor by introspection.
   * This form of constructor creates the PropertyDescriptor by
   * looking for getter methods named <CODE>get&lt;name&gt;()</CODE>
   * and setter methods named
   * <CODE>set&lt;name&gt;()</CODE> in class
   * <CODE>&lt;beanClass&gt;</CODE>, where &lt;name&gt; has its
   * first letter capitalized by the constructor.<P>
   *
   * <B>Implementation note:</B> If there is a get(int) method,
   * then the return type of that method is used to find the
   * remaining methods.  If there is no get method, then the
   * set(int) method is searched for exhaustively and that type
   * is used to find the others.<P>
   *
   * <B>Spec note:</B>
   * If there is no get(int) method and multiple set(int) methods with
   * the same name and the correct parameters (different type of course),
   * then an IntrospectionException is thrown.  While Sun's spec
   * does not state this, it can make Bean behavior different on
   * different systems (since method order is not guaranteed) and as
   * such, can be treated as a bug in the spec.  I am not aware of
   * whether Sun's implementation catches this.
   *
   * @param name the programmatic name of the property, usually
   *             starting with a lowercase letter (e.g. fooManChu
   *             instead of FooManChu).
   * @param beanClass the class the get and set methods live in.
   *
   * @exception IntrospectionException if the methods are not found or
   *            invalid.
   */
  public IndexedPropertyDescriptor(String name, Class<?> beanClass)
    throws IntrospectionException
  {
    super(name);
    String capitalized;
    try
      {
        capitalized = Character.toUpperCase(name.charAt(0))
          + name.substring(1);
      }
    catch(StringIndexOutOfBoundsException e)
      {
        capitalized = "";
      }
    findMethods(beanClass, "get" + capitalized, "set" + capitalized,
                "get" + capitalized, "set" + capitalized);
  }

  /**
   * Create a new IndexedPropertyDescriptor by introspection.
   * This form of constructor allows you to specify the
   * names of the get and set methods to search for.<P>
   *
   * <B>Implementation note:</B> If there is a get(int) method,
   * then the return type of that method is used to find the
   * remaining methods.  If there is no get method, then the
   * set(int) method is searched for exhaustively and that type
   * is used to find the others.<P>
   *
   * <B>Spec note:</B>
   * If there is no get(int) method and multiple set(int) methods with
   * the same name and the correct parameters (different type of course),
   * then an IntrospectionException is thrown.  While Sun's spec
   * does not state this, it can make Bean behavior different on
   * different systems (since method order is not guaranteed) and as
   * such, can be treated as a bug in the spec.  I am not aware of
   * whether Sun's implementation catches this.
   *
   * @param name the programmatic name of the property, usually
   *             starting with a lowercase letter (e.g. fooManChu
   *             instead of FooManChu).
   * @param beanClass the class the get and set methods live in.
   * @param getMethodName the name of the get array method.
   * @param setMethodName the name of the set array method.
   * @param getIndexName the name of the get index method.
   * @param setIndexName the name of the set index method.
   *
   * @exception IntrospectionException if the methods are not found or invalid.
   */
  public IndexedPropertyDescriptor(String name, Class<?> beanClass,
                                   String getMethodName, String setMethodName,
                                   String getIndexName, String setIndexName)
    throws IntrospectionException
  {
    super(name);
    findMethods(beanClass, getMethodName, setMethodName, getIndexName,
                setIndexName);
  }

  /**
   * Create a new PropertyDescriptor using explicit Methods.
   * Note that the methods will be checked for conformance to standard
   * Property method rules, as described above at the top of this class.
   *
   * @param name the programmatic name of the property, usually
   *             starting with a lowercase letter (e.g. fooManChu
   *             instead of FooManChu).
   * @param getMethod the get array method.
   * @param setMethod the set array method.
   * @param getIndex the get index method.
   * @param setIndex the set index method.
   *
   * @exception IntrospectionException if the methods are not found or invalid.
   */
  public IndexedPropertyDescriptor(String name, Method getMethod,
                                   Method setMethod, Method getIndex,
                                   Method setIndex)
    throws IntrospectionException
  {
    super(name);
    if(getMethod != null && getMethod.getParameterTypes().length > 0)
      throw new IntrospectionException("get method has parameters");
    if(getMethod != null && setMethod.getParameterTypes().length != 1)
      throw new IntrospectionException("set method does not have exactly one parameter");
    if(getMethod != null && setMethod != null)
      {
        if(!getMethod.getReturnType().equals(setMethod.getParameterTypes()[0]))
          {
            throw new IntrospectionException("set and get methods do not "
                                             + "share the same type");
          }
        if(!getMethod.getDeclaringClass().isAssignableFrom
           (setMethod.getDeclaringClass())
           && !setMethod.getDeclaringClass().isAssignableFrom
           (getMethod.getDeclaringClass()))
          {
            throw new IntrospectionException("set and get methods are not in "
                                             + "the same class.");
          }
      }

    if (getIndex != null
        && (getIndex.getParameterTypes().length != 1
         || !(getIndex.getParameterTypes()[0]).equals(java.lang.Integer.TYPE)))
      {
        throw new IntrospectionException("get index method has wrong "
                                         + "parameters");
      }
    if (setIndex != null
       && (setIndex.getParameterTypes().length != 2
         || !(setIndex.getParameterTypes()[0]).equals(java.lang.Integer.TYPE)))
      {
        throw new IntrospectionException("set index method has wrong "
                                         + "parameters");
      }
    if (getIndex != null && setIndex != null)
      {
        if(!getIndex.getReturnType().equals(setIndex.getParameterTypes()[1]))
          {
            throw new IntrospectionException("set index methods do not share "
                                             + "the same type");
          }
        if(!getIndex.getDeclaringClass().isAssignableFrom
           (setIndex.getDeclaringClass())
           && !setIndex.getDeclaringClass().isAssignableFrom
           (getIndex.getDeclaringClass()))
          {
            throw new IntrospectionException("get and set index methods are "
                                             + "not in the same class.");
          }
      }

    if (getIndex != null && getMethod != null
        && !getIndex.getDeclaringClass().isAssignableFrom
        (getMethod.getDeclaringClass())
        && !getMethod.getDeclaringClass().isAssignableFrom
        (getIndex.getDeclaringClass()))
      {
        throw new IntrospectionException("methods are not in the same class.");
      }

    if (getIndex != null && getMethod != null
        && !Array.newInstance(getIndex.getReturnType(),0)
        .getClass().equals(getMethod.getReturnType()))
      {
        throw new IntrospectionException("array methods do not match index "
                                         + "methods.");
      }

    this.getMethod = getMethod;
    this.setMethod = setMethod;
    this.getIndex = getIndex;
    this.setIndex = setIndex;
    this.indexedPropertyType = getIndex != null ? getIndex.getReturnType()
                                             : setIndex.getParameterTypes()[1];
    this.propertyType = getMethod != null ? getMethod.getReturnType()
      : (setMethod != null ? setMethod.getParameterTypes()[0]
         : Array.newInstance(this.indexedPropertyType,0).getClass());
  }

  public Class<?> getIndexedPropertyType()
  {
    return indexedPropertyType;
  }

  public Method getIndexedReadMethod()
  {
    return getIndex;
  }

  /**
   * Sets the method that is used to read an indexed property.
   *
   * @param m the method to set
   */
  public void setIndexedReadMethod(Method m) throws IntrospectionException
  {
    getIndex = m;
  }

  public Method getIndexedWriteMethod()
  {
    return setIndex;
  }

  /**
   * Sets the method that is used to write an indexed property.
   *
   * @param m the method to set
   */
  public void setIndexedWriteMethod(Method m) throws IntrospectionException
  {
    setIndex = m;
  }

  private void findMethods(Class beanClass, String getMethodName,
                           String setMethodName, String getIndexName,
                           String setIndexName)
    throws IntrospectionException
  {
    try
      {
        if(getIndexName != null)
          {
            try
              {
                Class[] getArgs = new Class[1];
                getArgs[0] = java.lang.Integer.TYPE;
                getIndex = beanClass.getMethod(getIndexName,getArgs);
                indexedPropertyType = getIndex.getReturnType();
              }
            catch(NoSuchMethodException E)
              {
              }
          }
        if(getIndex != null)
          {
            if(setIndexName != null)
              {
                try
                  {
                    Class[] setArgs = new Class[2];
                    setArgs[0] = java.lang.Integer.TYPE;
                    setArgs[1] = indexedPropertyType;
                    setIndex = beanClass.getMethod(setIndexName,setArgs);
                    if(!setIndex.getReturnType().equals(java.lang.Void.TYPE))
                      {
                        throw new IntrospectionException(setIndexName
                                                + " has non-void return type");
                      }
                  }
                catch(NoSuchMethodException E)
                  {
                  }
              }
          }
        else if(setIndexName != null)
          {
            Method[] m = beanClass.getMethods();
            for(int i=0;i<m.length;i++)
              {
                Method current = m[i];
                if(current.getName().equals(setIndexName)
                   && current.getParameterTypes().length == 2
                   && (current.getParameterTypes()[0])
                   .equals(java.lang.Integer.TYPE)
                   && current.getReturnType().equals(java.lang.Void.TYPE))
                  {
                    if(setIndex != null)
                      {
                        throw new IntrospectionException("Multiple, different "
                                     + "set methods found that fit the bill!");
                      }
                    else
                      {
                        setIndex = current;
                        indexedPropertyType = current.getParameterTypes()[1];
                      }
                  }
              }
            if(setIndex == null)
              {
                throw new IntrospectionException("Cannot find get or set "
                                                 + "methods.");
              }
          }
        else
          {
           throw new IntrospectionException("Cannot find get or set methods.");
          }

        Class arrayType = Array.newInstance(indexedPropertyType,0).getClass();

        Class[] setArgs = new Class[1];
        setArgs[0] = arrayType;
        try
          {
            setMethod = beanClass.getMethod(setMethodName,setArgs);
            if (!setMethod.getReturnType().equals(java.lang.Void.TYPE))
              {
                setMethod = null;
              }
          }
        catch(NoSuchMethodException E)
          {
          }

        Class[] getArgs = new Class[0];
        try
          {
            getMethod = beanClass.getMethod(getMethodName,getArgs);
            if (!getMethod.getReturnType().equals(arrayType))
              {
                getMethod = null;
              }
          }
        catch(NoSuchMethodException E)
          {
          }
      }
    catch(SecurityException E)
      {
        throw new IntrospectionException("SecurityException while trying to "
                                         + "find methods.");
      }
  }
}