java reflect:打印对象属性内容 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));
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"); } } }