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Extensions to the SLF4J API
/**
* Copyright (c) 2004-2011 QOS.ch
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
package org.slf4j.instrumentation;
import java.util.Map;
import java.util.WeakHashMap;
public class ToStringHelper {
/**
* Prefix to use at the start of the representation. Always used.
*/
private static final String ARRAY_PREFIX = "[";
/**
* Suffix to use at the end of the representation. Always used.
*/
private static final char ARRAY_SUFFIX = ']';
/**
* String separating each element when rendering an array. To be compatible
* with lists comma-space is used.
*/
private static final char[] ELEMENT_SEPARATOR = ", ".toCharArray();
/**
* unrenderableClasses is essentially a Set of Class objects which has for
* some reason failed to render properly when invoked through a toString
* method call. To avoid memory leaks a data structure using weak references
* is needed, but unfortunately the runtime library does not contain a
* WeakHashSet class, so the behavior is emulated with a WeakHashmap with
* the class as the key, and a Long containing the value of
* System.currentTimeMillis when an instance of the class failed to render.
*/
final static Map, Object> unrenderableClasses = new WeakHashMap<>();
/**
* Returns o.toString() unless it throws an exception (which causes it to be
* stored in unrenderableClasses) or already was present in
* unrenderableClasses. If so, the same string is returned as would have
* been returned by Object.toString(). Arrays get special treatment as they
* don't have usable toString methods.
*
* @param o
* incoming object to render.
* @return
*/
public static String render(Object o) {
if (o == null) {
return String.valueOf(o);
}
Class objectClass = o.getClass();
if (unrenderableClasses.containsKey(objectClass) == false) {
try {
if (objectClass.isArray()) {
return renderArray(o, objectClass).toString();
} else {
return o.toString();
}
} catch (Exception e) {
Long now = Long.valueOf(System.currentTimeMillis());
System.err.println("Disabling exception throwing class " + objectClass.getName() + ", " + e.getMessage());
unrenderableClasses.put(objectClass, now);
}
}
String name = o.getClass().getName();
return name + "@" + Integer.toHexString(o.hashCode());
}
/**
* renderArray returns an array similar to a List. If the array type is an
* object they are rendered with "render(object)" for each. If the array
* type is a primitive each element is added directly to the string buffer
* collecting the result.
*
* @param o
* @param objectClass
* @return
*/
private static StringBuilder renderArray(Object o, Class objectClass) {
Class componentType = objectClass.getComponentType();
StringBuilder sb = new StringBuilder(ARRAY_PREFIX);
if (componentType.isPrimitive() == false) {
Object[] oa = (Object[]) o;
for (int i = 0; i < oa.length; i++) {
if (i > 0) {
sb.append(ELEMENT_SEPARATOR);
}
sb.append(render(oa[i]));
}
} else {
if (Boolean.TYPE.equals(componentType)) {
boolean[] ba = (boolean[]) o;
for (int i = 0; i < ba.length; i++) {
if (i > 0) {
sb.append(ELEMENT_SEPARATOR);
}
sb.append(ba[i]);
}
} else if (Integer.TYPE.equals(componentType)) {
int[] ia = (int[]) o;
for (int i = 0; i < ia.length; i++) {
if (i > 0) {
sb.append(ELEMENT_SEPARATOR);
}
sb.append(ia[i]);
}
} else if (Long.TYPE.equals(componentType)) {
long[] ia = (long[]) o;
for (int i = 0; i < ia.length; i++) {
if (i > 0) {
sb.append(ELEMENT_SEPARATOR);
}
sb.append(ia[i]);
}
} else if (Double.TYPE.equals(componentType)) {
double[] ia = (double[]) o;
for (int i = 0; i < ia.length; i++) {
if (i > 0) {
sb.append(ELEMENT_SEPARATOR);
}
sb.append(ia[i]);
}
} else if (Float.TYPE.equals(componentType)) {
float[] ia = (float[]) o;
for (int i = 0; i < ia.length; i++) {
if (i > 0) {
sb.append(ELEMENT_SEPARATOR);
}
sb.append(ia[i]);
}
} else if (Character.TYPE.equals(componentType)) {
char[] ia = (char[]) o;
for (int i = 0; i < ia.length; i++) {
if (i > 0) {
sb.append(ELEMENT_SEPARATOR);
}
sb.append(ia[i]);
}
} else if (Short.TYPE.equals(componentType)) {
short[] ia = (short[]) o;
for (int i = 0; i < ia.length; i++) {
if (i > 0) {
sb.append(ELEMENT_SEPARATOR);
}
sb.append(ia[i]);
}
} else if (Byte.TYPE.equals(componentType)) {
byte[] ia = (byte[]) o;
for (int i = 0; i < ia.length; i++) {
if (i > 0) {
sb.append(ELEMENT_SEPARATOR);
}
sb.append(ia[i]);
}
}
}
sb.append(ARRAY_SUFFIX);
return sb;
}
}