java reflect:打印对象内容 很好的调试工具（转载收藏）

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:

java 代码

/**
 * 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 + ": \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");
  }
 }
}

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• 2007-03-06 11:59
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1 楼 ming500 2007-03-06  

非常好的工具。我也曾经写过了一个。当时对 数组的数据值出来太麻烦，实现的不好。
学习了。