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/*
* Copyright 2002-2005 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.lang.builder;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.HashSet;
import java.util.Set;
import org.apache.commons.lang.ClassUtils;
/**
*
* Assists in implementing {@link Object#toString()} methods using reflection.
*
*
*
* This class uses reflection to determine the fields to append. Because these
* fields are usually private, the class uses
* {@link java.lang.reflect.AccessibleObject#setAccessible(java.lang.reflect.AccessibleObject[], boolean)}
* to change the visibility of the fields. This will fail under a security
* manager, unless the appropriate permissions are set up correctly.
*
*
*
* A typical invocation for this method would look like:
*
*
*
* public String toString() {
* return ReflectionToStringBuilder.toString(this);
* }
*
*
*
*
* You can also use the builder to debug 3rd party objects:
*
*
*
* System.out.println("An object: " + ReflectionToStringBuilder.toString(anObject));
*
*
*
*
* A subclass can control field output by overriding the methods:
*
* - {@link #accept(java.lang.reflect.Field)}
* - {@link #getValue(java.lang.reflect.Field)}
*
*
*
* For example, this method does not include the password
* field in the returned String:
*
*
*
* public String toString() {
* return (new ReflectionToStringBuilder(this) {
* protected boolean accept(Field f) {
* return super.accept(f) && !f.getName().equals("password");
* }
* }).toString();
* }
*
*
*
*
* The exact format of the toString is determined by the
* {@link ToStringStyle} passed into the constructor.
*
*
* @author Gary Gregory
* @author Stephen Colebourne
* @author Pete Gieser
* @since 2.0
* @version $Id: ReflectionToStringBuilder.java,v 1.15 2003/12/02 19:11:58
* ggregory Exp $
*/
public class ReflectionToStringBuilder extends ToStringBuilder {
/**
*
* A registry of objects used by reflectionToString methods
* to detect cyclical object references and avoid infinite loops.
*
*/
private static ThreadLocal registry = new ThreadLocal() {
protected synchronized Object initialValue() {
// The HashSet implementation is not synchronized,
// which is just what we need here.
return new HashSet();
}
};
/**
*
* Returns the registry of objects being traversed by the reflectionToString
* methods in the current thread.
*
*
* @return Set the registry of objects being traversed
*/
static Set getRegistry() {
return (Set) registry.get();
}
/**
*
* Returns true if the registry contains the given object.
* Used by the reflection methods to avoid infinite loops.
*
*
* @param value
* The object to lookup in the registry.
* @return boolean true if the registry contains the given
* object.
*/
static boolean isRegistered(Object value) {
return getRegistry().contains(value);
}
/**
*
* Registers the given object. Used by the reflection methods to avoid
* infinite loops.
*
*
* @param value
* The object to register.
*/
static void register(Object value) {
getRegistry().add(value);
}
/**
*
* This method uses reflection to build a suitable toString
* using the default ToStringStyle.
*
*
* It uses AccessibleObject.setAccessible to gain access to
* private fields. This means that it will throw a security exception if
* run under a security manager, if the permissions are not set up
* correctly. It is also not as efficient as testing explicitly.
*
*
*
* Transient members will be not be included, as they are likely derived.
* Static fields will not be included. Superclass fields will be appended.
*
*
* @param object
* the Object to be output
* @return the String result
* @throws IllegalArgumentException
* if the Object is null
*/
public static String toString(Object object) {
return toString(object, null, false, false, null);
}
/**
*
* This method uses reflection to build a suitable toString.
*
*
*
* It uses AccessibleObject.setAccessible to gain access to
* private fields. This means that it will throw a security exception if
* run under a security manager, if the permissions are not set up
* correctly. It is also not as efficient as testing explicitly.
*
*
*
* Transient members will be not be included, as they are likely derived.
* Static fields will not be included. Superclass fields will be appended.
*
*
*
* If the style is null, the default ToStringStyle
* is used.
*
*
* @param object
* the Object to be output
* @param style
* the style of the toString to create, may be
* null
* @return the String result
* @throws IllegalArgumentException
* if the Object or ToStringStyle is null
*/
public static String toString(Object object, ToStringStyle style) {
return toString(object, style, false, false, null);
}
/**
*
* This method uses reflection to build a suitable toString.
*
*
*
* It uses AccessibleObject.setAccessible to gain access to
* private fields. This means that it will throw a security exception if
* run under a security manager, if the permissions are not set up
* correctly. It is also not as efficient as testing explicitly.
*
*
*
* If the outputTransients is true,
* transient members will be output, otherwise they are ignored, as they
* are likely derived fields, and not part of the value of the Object.
*
*
*
* Static fields will not be included. Superclass fields will be appended.
*
*
*
* If the style is null, the default ToStringStyle
* is used.
*
*
* @param object
* the Object to be output
* @param style
* the style of the toString to create, may be
* null
* @param outputTransients
* whether to include transient fields
* @return the String result
* @throws IllegalArgumentException
* if the Object is null
*/
public static String toString(Object object, ToStringStyle style, boolean outputTransients) {
return toString(object, style, outputTransients, false, null);
}
/**
*
* This method uses reflection to build a suitable toString.
*
*
*
* It uses AccessibleObject.setAccessible to gain access to
* private fields. This means that it will throw a security exception if
* run under a security manager, if the permissions are not set up
* correctly. It is also not as efficient as testing explicitly.
*
*
*
* If the outputTransients is true,
* transient fields will be output, otherwise they are ignored, as they are
* likely derived fields, and not part of the value of the Object.
*
*
*
* If the outputStatics is true, static
* fields will be output, otherwise they are ignored.
*
*
*
* Static fields will not be included. Superclass fields will be appended.
*
*
*
* If the style is null, the default ToStringStyle
* is used.
*
*
* @param object
* the Object to be output
* @param style
* the style of the toString to create, may be
* null
* @param outputTransients
* whether to include transient fields
* @param outputStatics
* whether to include transient fields
* @return the String result
* @throws IllegalArgumentException
* if the Object is null
* @since 2.1
*/
public static String toString(Object object, ToStringStyle style, boolean outputTransients, boolean outputStatics) {
return toString(object, style, outputTransients, outputStatics, null);
}
/**
*
* This method uses reflection to build a suitable toString.
*
*
*
* It uses AccessibleObject.setAccessible to gain access to
* private fields. This means that it will throw a security exception if
* run under a security manager, if the permissions are not set up
* correctly. It is also not as efficient as testing explicitly.
*
*
*
* If the outputTransients is true,
* transient fields will be output, otherwise they are ignored, as they are
* likely derived fields, and not part of the value of the Object.
*
*
*
* If the outputStatics is true, static
* fields will be output, otherwise they are ignored.
*
*
*
* Superclass fields will be appended up to and including the specified
* superclass. A null superclass is treated as java.lang.Object.
*
*
*
* If the style is null, the default ToStringStyle
* is used.
*
*
* @param object
* the Object to be output
* @param style
* the style of the toString to create, may be
* null
* @param outputTransients
* whether to include transient fields
* @param outputStatics
* whether to include static fields
* @param reflectUpToClass
* the superclass to reflect up to (inclusive), may be null
* @return the String result
* @throws IllegalArgumentException
* if the Object is null
* @since 2.1
*/
public static String toString(Object object, ToStringStyle style, boolean outputTransients, boolean outputStatics,
Class reflectUpToClass) {
return new ReflectionToStringBuilder(object, style, null, reflectUpToClass, outputTransients, outputStatics)
.toString();
}
/**
*
* This method uses reflection to build a suitable toString.
*
*
*
* It uses AccessibleObject.setAccessible to gain access to
* private fields. This means that it will throw a security exception if
* run under a security manager, if the permissions are not set up
* correctly. It is also not as efficient as testing explicitly.
*
*
*
* If the outputTransients is true,
* transient members will be output, otherwise they are ignored, as they
* are likely derived fields, and not part of the value of the Object.
*
*
*
* Static fields will not be included. Superclass fields will be appended
* up to and including the specified superclass. A null superclass is
* treated as java.lang.Object.
*
*
*
* If the style is null, the default ToStringStyle
* is used.
*
*
* @deprecated Use
* {@link #toString(Object,ToStringStyle,boolean,boolean,Class)}
*
* @param object
* the Object to be output
* @param style
* the style of the toString to create, may be
* null
* @param outputTransients
* whether to include transient fields
* @param reflectUpToClass
* the superclass to reflect up to (inclusive), may be null
* @return the String result
* @throws IllegalArgumentException
* if the Object is null
* @since 2.0
*/
public static String toString(Object object, ToStringStyle style, boolean outputTransients,
Class reflectUpToClass) {
return new ReflectionToStringBuilder(object, style, null, reflectUpToClass, outputTransients).toString();
}
/**
*
* Unregisters the given object.
*
*
*
* Used by the reflection methods to avoid infinite loops.
*
*
* @param value
* The object to unregister.
*/
static void unregister(Object value) {
getRegistry().remove(value);
}
/**
* Whether or not to append static fields.
*/
private boolean appendStatics = false;
/**
* Whether or not to append transient fields.
*/
private boolean appendTransients = false;
/**
* The last super class to stop appending fields for.
*/
private Class upToClass = null;
/**
*
* Constructor.
*
*
*
* This constructor outputs using the default style set with setDefaultStyle.
*
*
* @param object
* the Object to build a toString for, must not
* be null
* @throws IllegalArgumentException
* if the Object passed in is null
*/
public ReflectionToStringBuilder(Object object) {
super(object);
}
/**
*
* Constructor.
*
*
*
* If the style is null, the default style is used.
*
*
* @param object
* the Object to build a toString for, must not
* be null
* @param style
* the style of the toString to create, may be
* null
* @throws IllegalArgumentException
* if the Object passed in is null
*/
public ReflectionToStringBuilder(Object object, ToStringStyle style) {
super(object, style);
}
/**
*
* Constructor.
*
*
*
* If the style is null, the default style is used.
*
*
*
* If the buffer is null, a new one is created.
*
*
* @param object
* the Object to build a toString for
* @param style
* the style of the toString to create, may be
* null
* @param buffer
* the StringBuffer to populate, may be null
* @throws IllegalArgumentException
* if the Object passed in is null
*/
public ReflectionToStringBuilder(Object object, ToStringStyle style, StringBuffer buffer) {
super(object, style, buffer);
}
/**
* Constructor.
*
* @deprecated Use
* {@link #ReflectionToStringBuilder(Object,ToStringStyle,StringBuffer,Class,boolean,boolean)}.
*
* @param object
* the Object to build a toString for
* @param style
* the style of the toString to create, may be
* null
* @param buffer
* the StringBuffer to populate, may be null
* @param reflectUpToClass
* the superclass to reflect up to (inclusive), may be null
* @param outputTransients
* whether to include transient fields
*/
public ReflectionToStringBuilder(Object object, ToStringStyle style, StringBuffer buffer, Class reflectUpToClass,
boolean outputTransients) {
super(object, style, buffer);
this.setUpToClass(reflectUpToClass);
this.setAppendTransients(outputTransients);
}
/**
* Constructor.
*
* @param object
* the Object to build a toString for
* @param style
* the style of the toString to create, may be
* null
* @param buffer
* the StringBuffer to populate, may be null
* @param reflectUpToClass
* the superclass to reflect up to (inclusive), may be null
* @param outputTransients
* whether to include transient fields
* @param outputStatics
* whether to include static fields
* @since 2.1
*/
public ReflectionToStringBuilder(Object object, ToStringStyle style, StringBuffer buffer, Class reflectUpToClass,
boolean outputTransients, boolean outputStatics) {
super(object, style, buffer);
this.setUpToClass(reflectUpToClass);
this.setAppendTransients(outputTransients);
this.setAppendStatics(outputStatics);
}
/**
* Returns whether or not to append the given Field.
*
* - Transient fields are appended only if {@link #isAppendTransients()}
* returns
true.
* - Static fields are appended only if {@link #isAppendStatics()}
* returns
true.
* - Inner class fields are not appened.
*
*
* @param field
* The Field to test.
* @return Whether or not to append the given Field.
*/
protected boolean accept(Field field) {
if (field.getName().indexOf(ClassUtils.INNER_CLASS_SEPARATOR_CHAR) != -1) {
// Reject field from inner class.
return false;
}
if (Modifier.isTransient(field.getModifiers()) && !this.isAppendTransients()) {
// transients.
return false;
}
if (Modifier.isStatic(field.getModifiers()) && !this.isAppendStatics()) {
// transients.
return false;
}
return true;
}
/**
*
* Appends the fields and values defined by the given object of the given
* Class.
*
*
*
* If a cycle is detected as an object is "toString()'ed", such
* an object is rendered as if Object.toString() had been
* called and not implemented by the object.
*
*
* @param clazz
* The class of object parameter
*/
protected void appendFieldsIn(Class clazz) {
if (isRegistered(this.getObject())) {
// The object has already been appended, therefore we have an
// object cycle.
// Append a simple Object.toString style string. The field name is
// already appended at this point.
this.appendAsObjectToString(this.getObject());
return;
}
try {
this.registerObject();
if (clazz.isArray()) {
this.reflectionAppendArray(this.getObject());
return;
}
Field[] fields = clazz.getDeclaredFields();
AccessibleObject.setAccessible(fields, true);
for (int i = 0; i < fields.length; i++) {
Field field = fields[i];
String fieldName = field.getName();
if (this.accept(field)) {
try {
// Warning: Field.get(Object) creates wrappers objects
// for primitive types.
Object fieldValue = this.getValue(field);
if (isRegistered(fieldValue) && !field.getType().isPrimitive()) {
// A known field value has already been appended,
// therefore we have an object cycle,
// append a simple Object.toString style string.
this.getStyle().appendFieldStart(this.getStringBuffer(), fieldName);
this.appendAsObjectToString(fieldValue);
this.getStyle().appendFieldEnd(this.getStringBuffer(), fieldName);
// The recursion out of
// builder.append(fieldName, fieldValue);
// below will append the field
// end marker.
} else {
try {
this.registerObject();
this.append(fieldName, fieldValue);
} finally {
this.unregisterObject();
}
}
} catch (IllegalAccessException ex) {
//this can't happen. Would get a Security exception
// instead
//throw a runtime exception in case the impossible
// happens.
throw new InternalError("Unexpected IllegalAccessException: " + ex.getMessage());
}
}
}
} finally {
this.unregisterObject();
}
}
/**
*
* Gets the last super class to stop appending fields for.
*
*
* @return The last super class to stop appending fields for.
*/
public Class getUpToClass() {
return this.upToClass;
}
/**
*
* Calls java.lang.reflect.Field.get(Object).
*
*
* @param field
* The Field to query.
* @return The Object from the given Field.
*
* @throws IllegalArgumentException
* see {@link java.lang.reflect.Field#get(Object)}
* @throws IllegalAccessException
* see {@link java.lang.reflect.Field#get(Object)}
*
* @see java.lang.reflect.Field#get(Object)
*/
protected Object getValue(Field field) throws IllegalArgumentException, IllegalAccessException {
return field.get(this.getObject());
}
/**
*
* Gets whether or not to append static fields.
*
*
* @return Whether or not to append static fields.
* @since 2.1
*/
public boolean isAppendStatics() {
return this.appendStatics;
}
/**
*
* Gets whether or not to append transient fields.
*
*
* @return Whether or not to append transient fields.
*/
public boolean isAppendTransients() {
return this.appendTransients;
}
/**
*
* Append to the toString an Object array.
*
*
* @param array
* the array to add to the toString
* @return this
*/
public ToStringBuilder reflectionAppendArray(Object array) {
this.getStyle().reflectionAppendArrayDetail(this.getStringBuffer(), null, array);
return this;
}
/**
*
* Registers this builder's source object to avoid infinite loops when
* processing circular object references.
*
*/
void registerObject() {
register(this.getObject());
}
/**
*
* Sets whether or not to append static fields.
*
*
* @param appendStatics
* Whether or not to append static fields.
* @since 2.1
*/
public void setAppendStatics(boolean appendStatics) {
this.appendStatics = appendStatics;
}
/**
*
* Sets whether or not to append transient fields.
*
*
* @param appendTransients
* Whether or not to append transient fields.
*/
public void setAppendTransients(boolean appendTransients) {
this.appendTransients = appendTransients;
}
/**
*
* Sets the last super class to stop appending fields for.
*
*
* @param clazz
* The last super class to stop appending fields for.
*/
public void setUpToClass(Class clazz) {
this.upToClass = clazz;
}
/**
*
* Gets the String built by this builder.
*
*
* @return the built string
*/
public String toString() {
if (this.getObject() == null) {
return this.getStyle().getNullText();
}
Class clazz = this.getObject().getClass();
this.appendFieldsIn(clazz);
while (clazz.getSuperclass() != null && clazz != this.getUpToClass()) {
clazz = clazz.getSuperclass();
this.appendFieldsIn(clazz);
}
return super.toString();
}
/**
*
* Unregisters this builder's source object to avoid infinite loops when
* processing circular object references.
*
*/
void unregisterObject() {
unregister(this.getObject());
}
}