java reflect:打印对象内容 很好的调试工具

备份一个有用的工具类.TypeUtil
它的typeToString(String scope, Object obj)方法,采用java的reflect机制,可以打印出任何对象的内容.
这对调试程序非常有用.
使用方法:
如果你有一个对象(比如testClassObject),想打印它的内容,可用如下方法:
System.out.println(TypeUtil.typeToString("yourClassObjectName",testClassObject));
这个方法,对调试那些对容器依赖的ejb程序很有用,特此备份.
以下为TypeUtil源程序:
/**
* The TypeUtil class static methods for inspecting complex java types.
* The typeToString() method is used to dump the contents of a passed object
* of any type (or collection) to a String. This can be very useful for debugging code that
* manipulates complex structures.
*
*
* @version $Revision : 1.2.6.4 $
*/

import java.util.*;
import java.lang.reflect.*;

public class TypeUtil {

/**
* Returns a string holding the contents
* of the passed object,
* @param scope String
* @param parentObject Object
* @param visitedObjs List
* @return String
*/

private static String complexTypeToString(String scope, Object parentObject,List visitedObjs) {

StringBuffer buffer = new StringBuffer("");

try {
//
// Ok, now we need to reflect into the object and add its child nodes...
//

Class cl = parentObject.getClass();
while ( cl != null ) {

processFields(cl.getDeclaredFields(),
scope,
parentObject,
buffer,
visitedObjs );

cl = cl.getSuperclass();
}
} catch (IllegalAccessException iae) {
buffer.append(iae.toString());
}

return (buffer.toString());
}

/**
* Method processFields
* @param fields Field[]
* @param scope String
* @param parentObject Object
* @param buffer StringBuffer
* @param visitedObjs List
* @throws IllegalAccessException
*/
private static void processFields( Field[] fields,
String scope,
Object parentObject,
StringBuffer buffer,
List visitedObjs ) throws IllegalAccessException {

for (int i = 0; i < fields.length; i++) {

//
// Disregard certain fields for IDL structures
//
if (fields[i].getName().equals("__discriminator")
|| fields[i].getName().equals("__uninitialized")) {
continue;
}

//
// This allows us to see non-public fields. We might need to deal with some
// SecurityManager issues here once it is outside of VAJ...
//
fields[i].setAccessible(true);

if (Modifier.isStatic(fields[i].getModifiers())) {
//
// Ignore all static members. The classes that this dehydrator is
// meant to handle are simple data objects, so static members have no
// bearing....
//
} else {
buffer.append(
typeToString(scope + "." + fields[i].getName(), fields[i].get(parentObject), visitedObjs));
}
}

}

/**
* Method isCollectionType
* @param obj Object
* @return boolean
*/
public static boolean isCollectionType(Object obj) {

return( obj.getClass().isArray()||
(obj instanceof Collection)||
(obj instanceof Hashtable)||
(obj instanceof HashMap)||
(obj instanceof HashSet)||
(obj instanceof List)||
(obj instanceof AbstractMap ) );
}

/**
* Method isComplexType
* @param obj Object
* @return boolean
*/
public static boolean isComplexType(Object obj) {

if ( obj instanceof Boolean ||
obj instanceof Short ||
obj instanceof Byte ||
obj instanceof Integer ||
obj instanceof Long ||
obj instanceof Float ||
obj instanceof Character ||
obj instanceof Double ||
obj instanceof String ) {

return false;
}
else {

Class objectClass = obj.getClass();

if (objectClass == boolean.class
|| objectClass == Boolean.class
|| objectClass == short.class
|| objectClass == Short.class
|| objectClass == byte.class
|| objectClass == Byte.class
|| objectClass == int.class
|| objectClass == Integer.class
|| objectClass == long.class
|| objectClass == Long.class
|| objectClass == float.class
|| objectClass == Float.class
|| objectClass == char.class
|| objectClass == Character.class
|| objectClass == double.class
|| objectClass == Double.class
|| objectClass == String.class ) {

return false;

}

else {
return true;
}
}
}
/**
* Returns a string holding the contents
* of the passed object,
* @param scope String
* @param obj Object
* @param visitedObjs List
* @return String
*/

private static String collectionTypeToString(String scope, Object obj, List visitedObjs) {

StringBuffer buffer = new StringBuffer("");

if (obj.getClass().isArray()) {
if (Array.getLength(obj) > 0) {

for (int j = 0; j < Array.getLength(obj); j++) {

Object x = Array.get(obj, j);

buffer.append(typeToString(scope + "[" + j + "]", x, visitedObjs));
}

} else {
buffer.append(scope + "[]: empty\n");
}
} else {
boolean isCollection = (obj instanceof Collection);
boolean isHashTable = (obj instanceof Hashtable);
boolean isHashMap = (obj instanceof HashMap);
boolean isHashSet = (obj instanceof HashSet);
boolean isAbstractMap = (obj instanceof AbstractMap);
boolean isMap = isAbstractMap || isHashMap || isHashTable;

if (isMap) {
Set keySet = ((Map) obj).keySet();
Iterator iterator = keySet.iterator();
int size = keySet.size();

if (size > 0) {

for (int j = 0; iterator.hasNext(); j++) {

Object key = iterator.next();
Object x = ((Map) obj).get(key);

buffer.append(typeToString(scope + "[\"" + key + "\"]", x, visitedObjs));
}
} else {
buffer.append(scope + "[]: empty\n");
}
} else
if (/*isHashTable || */
isCollection || isHashSet /* || isHashMap */
) {

Iterator iterator = null;
int size = 0;

if (obj != null) {

if (isCollection) {
iterator = ((Collection) obj).iterator();
size = ((Collection) obj).size();
} else
if (isHashTable) {
iterator = ((Hashtable) obj).values().iterator();
size = ((Hashtable) obj).size();
} else
if (isHashSet) {
iterator = ((HashSet) obj).iterator();
size = ((HashSet) obj).size();
} else
if (isHashMap) {
iterator = ((HashMap) obj).values().iterator();
size = ((HashMap) obj).size();
}

if (size > 0) {

for (int j = 0; iterator.hasNext(); j++) {

Object x = iterator.next();
buffer.append(typeToString(scope + "[" + j + "]", x, visitedObjs));
}
} else {
buffer.append(scope + "[]: empty\n");
}
} else {
//
// theObject is null
buffer.append(scope + "[]: null\n");
}
}
}

return (buffer.toString());

}
/**
* Method typeToString
* @param scope String
* @param obj Object
* @param visitedObjs List
* @return String
*/
private static String typeToString(String scope, Object obj, List visitedObjs) {

if (obj == null) {
return (scope + ": null\n");
}
else if (isCollectionType( obj ) ) {
return collectionTypeToString( scope, obj, visitedObjs );
}
else if (isComplexType( obj ) ) {
if( ! visitedObjs.contains(obj)) {
visitedObjs.add(obj);
return complexTypeToString( scope, obj, visitedObjs ) ;
}
else {
return(scope + ": <already visited>\n" );
}
}
else {
return ( scope + ": " + obj.toString() + "\n");
}
}
/**
* The typeToString() method is used to dump the contents of a passed object
* of any type (or collection) to a String. This can be very useful for debugging code that
* manipulates complex structures.
*
* @param scope
* @param obj
*
* @return String
*
*/

public static String typeToString(String scope, Object obj) {

if (obj == null) {
return (scope + ": null\n");
}
else if (isCollectionType( obj ) ) {
return collectionTypeToString( scope, obj, new ArrayList());
}
else if (isComplexType( obj ) ) {
return complexTypeToString( scope, obj, new ArrayList() ) ;
}
else {
return ( scope + ": " + obj.toString() + "\n");
}
}
}