src/java.management/share/classes/javax/management/MBeanConstructorInfo.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * accompanied this code).
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package javax.management;

import com.sun.jmx.mbeanserver.Introspector;
import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.util.Arrays;
import java.util.Objects;

/**
 * Describes a constructor exposed by an MBean.  Instances of this
 * class are immutable.  Subclasses may be mutable but this is not
 * recommended.
 *
 * @since 1.5
 */
public class MBeanConstructorInfo extends MBeanFeatureInfo implements Cloneable {

    /* Serial version */
    static final long serialVersionUID = 4433990064191844427L;

    static final MBeanConstructorInfo[] NO_CONSTRUCTORS =
        new MBeanConstructorInfo[0];

    /** @see MBeanInfo#arrayGettersSafe */
    private final transient boolean arrayGettersSafe;

    /**
     * @serial The signature of the method, that is, the class names of the arguments.
     */
    private final MBeanParameterInfo[] signature;

    /**
     * Constructs an {@code MBeanConstructorInfo} object.  The
     * {@link Descriptor} of the constructed object will include
     * fields contributed by any annotations on the {@code
     * Constructor} object that contain the {@link DescriptorKey}
     * meta-annotation.
     *
     * @param description A human readable description of the operation.
     * @param constructor The {@code java.lang.reflect.Constructor}
     * object describing the MBean constructor.
     */
    public MBeanConstructorInfo(String description, Constructor<?> constructor) {
        this(constructor.getName(), description,
             constructorSignature(constructor),
             Introspector.descriptorForElement(constructor));
    }

    /**
     * Constructs an {@code MBeanConstructorInfo} object.
     *
     * @param name The name of the constructor.
     * @param description A human readable description of the constructor.
     * @param signature {@code MBeanParameterInfo} objects
     * describing the parameters(arguments) of the constructor.  This
     * may be null with the same effect as a zero-length array.
     */
    public MBeanConstructorInfo(String name,
                                String description,
                                MBeanParameterInfo[] signature) {
        this(name, description, signature, null);
    }

    /**
     * Constructs an {@code MBeanConstructorInfo} object.
     *
     * @param name The name of the constructor.
     * @param description A human readable description of the constructor.
     * @param signature {@code MBeanParameterInfo} objects
     * describing the parameters(arguments) of the constructor.  This
     * may be null with the same effect as a zero-length array.
     * @param descriptor The descriptor for the constructor.  This may be null
     * which is equivalent to an empty descriptor.
     *
     * @since 1.6
     */
    public MBeanConstructorInfo(String name,
                                String description,
                                MBeanParameterInfo[] signature,
                                Descriptor descriptor) {
        super(name, description, descriptor);

        if (signature == null || signature.length == 0)
            signature = MBeanParameterInfo.NO_PARAMS;
        else
            signature = signature.clone();
        this.signature = signature;
        this.arrayGettersSafe =
            MBeanInfo.arrayGettersSafe(this.getClass(),
                                       MBeanConstructorInfo.class);
    }


    /**
     * <p>Returns a shallow clone of this instance.  The clone is
     * obtained by simply calling {@code super.clone()}, thus calling
     * the default native shallow cloning mechanism implemented by
     * {@code Object.clone()}.  No deeper cloning of any internal
     * field is made.</p>
     *
     * <p>Since this class is immutable, cloning is chiefly of
     * interest to subclasses.</p>
     */
     public Object clone () {
         try {
             return super.clone() ;
         } catch (CloneNotSupportedException e) {
             // should not happen as this class is cloneable
             return null;
         }
     }

    /**
     * <p>Returns the list of parameters for this constructor.  Each
     * parameter is described by an {@code MBeanParameterInfo}
     * object.</p>
     *
     * <p>The returned array is a shallow copy of the internal array,
     * which means that it is a copy of the internal array of
     * references to the {@code MBeanParameterInfo} objects but
     * that each referenced {@code MBeanParameterInfo} object is
     * not copied.</p>
     *
     * @return  An array of {@code MBeanParameterInfo} objects.
     */
    public MBeanParameterInfo[] getSignature() {
        if (signature.length == 0)
            return signature;
        else
            return signature.clone();
    }

    private MBeanParameterInfo[] fastGetSignature() {
        if (arrayGettersSafe)
            return signature;
        else
            return getSignature();
    }

    public String toString() {
        return
            getClass().getName() + "[" +
            "description=" + getDescription() + ", " +
            "name=" + getName() + ", " +
            "signature=" + Arrays.asList(fastGetSignature()) + ", " +
            "descriptor=" + getDescriptor() +
            "]";
    }

    /**
     * Compare this MBeanConstructorInfo to another.
     *
     * @param o the object to compare to.
     *
     * @return true if and only if {@code o} is an MBeanConstructorInfo such
     * that its {@link #getName()}, {@link #getDescription()},
     * {@link #getSignature()}, and {@link #getDescriptor()}
     * values are equal (not necessarily
     * identical) to those of this MBeanConstructorInfo.  Two
     * signature arrays are equal if their elements are pairwise
     * equal.
     */
    public boolean equals(Object o) {
        if (o == this)
            return true;
        if (!(o instanceof MBeanConstructorInfo))
            return false;
        MBeanConstructorInfo p = (MBeanConstructorInfo) o;
        return (Objects.equals(p.getName(), getName()) &&
                Objects.equals(p.getDescription(), getDescription()) &&
                Arrays.equals(p.fastGetSignature(), fastGetSignature()) &&
                Objects.equals(p.getDescriptor(), getDescriptor()));
    }

    /* Unlike attributes and operations, it's quite likely we'll have
       more than one constructor with the same name and even
       description, so we include the parameter array in the hashcode.
       We don't include the description, though, because it could be
       quite long and yet the same between constructors.  Likewise for
       the descriptor.  */
    public int hashCode() {
        return Objects.hash(getName()) ^ Arrays.hashCode(fastGetSignature());
    }

    private static MBeanParameterInfo[] constructorSignature(Constructor<?> cn) {
        final Class<?>[] classes = cn.getParameterTypes();
        final Annotation[][] annots = cn.getParameterAnnotations();
        return MBeanOperationInfo.parameters(classes, annots);
    }
}