使用struts2的json插件时，自定义日期格式常用的方式是在get属性上添加@JSON注解，这个对于少量Date属性还可以，但是如果date字段多了，总不可能去给每个date get方法添加json注解吧！
发现极大不便后查看了sturts-plugin.xml 中的json-default定义，源码跟踪到json拦截器内部一点发现都没有，自定义
org.apache.struts2.json.JSONPopulator中的dateFormatter属性完全不起效果。但是在同一个包下：org.apache.struts2.json 发现了类：JSONWriter 在这里才找到了一些端倪
将源码中的
/**
* Add date to buffer
*/
protected void date(Date date, Method method) {
JSON json = null;
if (method != null)
json = method.getAnnotation(JSON.class);
if (this.formatter == null)
this.formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
DateFormat formatter = (json != null) && (json.format().length() > 0) ? new SimpleDateFormat(json
.format()) : this.formatter;
this.string(formatter.format(date));
}SimpleDateFormat 格式改成自定义日期格式即可，这样全局json 日期格式就自定义完成了！注意：覆盖时只需要自定义包：org.apache.struts2.json将修改后的JSONWriter放到包下即可，没有必要去修改插件中的源码信息
下面附上整个类的源码：
/*
* $Id$
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.struts2.json;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
import org.apache.struts2.json.annotations.JSON;
import org.apache.struts2.json.annotations.JSONFieldBridge;
import org.apache.struts2.json.annotations.JSONParameter;
import org.apache.struts2.json.bridge.FieldBridge;
import org.apache.struts2.json.bridge.ParameterizedBridge;
import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.text.CharacterIterator;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.text.StringCharacterIterator;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.regex.Pattern;
/**
*
* Serializes an object into JavaScript Object Notation (JSON). If cyclic
* references are detected they will be nulled out.
*
*/
public class JSONWriter {
private static final Logger LOG = LoggerFactory.getLogger(JSONWriter.class);
/**
* By default, enums are serialised as name=value pairs
*/
public static final boolean ENUM_AS_BEAN_DEFAULT = false;
private static char[] hex = "0123456789ABCDEF".toCharArray();
private static final ConcurrentMap, BeanInfo> BEAN_INFO_CACHE_IGNORE_HIERARCHY = new ConcurrentHashMap, BeanInfo>();
private static final ConcurrentMap, BeanInfo> BEAN_INFO_CACHE = new ConcurrentHashMap, BeanInfo>();
private StringBuilder buf = new StringBuilder();
private Stack stack = new Stack();
private boolean ignoreHierarchy = true;
private Object root;
private boolean buildExpr = true;
private String exprStack = "";
private Collection excludeProperties;
private Collection includeProperties;
private DateFormat formatter;
private boolean enumAsBean = ENUM_AS_BEAN_DEFAULT;
private boolean excludeNullProperties;
/**
* @param object Object to be serialized into JSON
* @return JSON string for object
* @throws JSONException
*/
public String write(Object object) throws JSONException {
return this.write(object, null, null, false);
}
/**
* @param object Object to be serialized into JSON
* @return JSON string for object
* @throws JSONException
*/
public String write(Object object, Collection excludeProperties,
Collection includeProperties, boolean excludeNullProperties) throws JSONException {
this.excludeNullProperties = excludeNullProperties;
this.buf.setLength(0);
this.root = object;
this.exprStack = "";
this.buildExpr = ((excludeProperties != null) && !excludeProperties.isEmpty())
|| ((includeProperties != null) && !includeProperties.isEmpty());
this.excludeProperties = excludeProperties;
this.includeProperties = includeProperties;
this.value(object, null);
return this.buf.toString();
}
/**
* Detect cyclic references
*/
protected void value(Object object, Method method) throws JSONException {
if (object == null) {
this.add("null");
return;
}
if (this.stack.contains(object)) {
Class clazz = object.getClass();
// cyclic reference
if (clazz.isPrimitive() || clazz.equals(String.class)) {
this.process(object, method);
} else {
if (LOG.isDebugEnabled()) {
LOG.debug("Cyclic reference detected on " + object);
}
this.add("null");
}
return;
}
this.process(object, method);
}
/**
* Serialize object into json
*/
protected void process(Object object, Method method) throws JSONException {
this.stack.push(object);
if (object instanceof Class) {
this.string(object);
} else if (object instanceof Boolean) {
this.bool((Boolean) object);
} else if (object instanceof Number) {
this.add(object);
} else if (object instanceof String) {
this.string(object);
} else if (object instanceof Character) {
this.string(object);
} else if (object instanceof Map) {
this.map((Map) object, method);
} else if (object.getClass().isArray()) {
this.array(object, method);
} else if (object instanceof Iterable) {
this.array(((Iterable) object).iterator(), method);
} else if (object instanceof Date) {
this.date((Date) object, method);
} else if (object instanceof Calendar) {
this.date(((Calendar) object).getTime(), method);
} else if (object instanceof Locale) {
this.string(object);
} else if (object instanceof Enum) {
this.enumeration((Enum) object);
} else {
processCustom(object, method);
}
this.stack.pop();
}
/**
* Serialize custom object into json
*/
protected void processCustom(Object object, Method method) throws JSONException {
this.bean(object);
}
/**
* Instrospect bean and serialize its properties
*/
protected void bean(Object object) throws JSONException {
this.add("{");
BeanInfo info;
try {
Class clazz = object.getClass();
info = ((object == this.root) && this.ignoreHierarchy)
? getBeanInfoIgnoreHierarchy(clazz)
: getBeanInfo(clazz);
PropertyDescriptor[] props = info.getPropertyDescriptors();
boolean hasData = false;
for (PropertyDescriptor prop : props) {
String name = prop.getName();
Method accessor = prop.getReadMethod();
Method baseAccessor = findBaseAccessor(clazz, accessor);
if (baseAccessor != null) {
if (baseAccessor.isAnnotationPresent(JSON.class)) {
JSONAnnotationFinder jsonFinder = new JSONAnnotationFinder(baseAccessor).invoke();
if (!jsonFinder.shouldSerialize()) continue;
if (jsonFinder.getName() != null) {
name = jsonFinder.getName();
}
}
// ignore "class" and others
if (this.shouldExcludeProperty(prop)) {
continue;
}
String expr = null;
if (this.buildExpr) {
expr = this.expandExpr(name);
if (this.shouldExcludeProperty(expr)) {
continue;
}
expr = this.setExprStack(expr);
}
Object value = accessor.invoke(object);
if (baseAccessor.isAnnotationPresent(JSONFieldBridge.class)) {
value = getBridgedValue(baseAccessor, value);
}
boolean propertyPrinted = this.add(name, value, accessor, hasData);
hasData = hasData || propertyPrinted;
if (this.buildExpr) {
this.setExprStack(expr);
}
}
}
// special-case handling for an Enumeration - include the name() as
// a property */
if (object instanceof Enum) {
Object value = ((Enum) object).name();
this.add("_name", value, object.getClass().getMethod("name"), hasData);
}
} catch (Exception e) {
throw new JSONException(e);
}
this.add("}");
}
protected BeanInfo getBeanInfoIgnoreHierarchy(final Class clazz) throws IntrospectionException {
BeanInfo beanInfo = BEAN_INFO_CACHE_IGNORE_HIERARCHY.get(clazz);
if (beanInfo != null) {
return beanInfo;
}
beanInfo = Introspector.getBeanInfo(clazz, clazz.getSuperclass());
BEAN_INFO_CACHE_IGNORE_HIERARCHY.put(clazz, beanInfo);
return beanInfo;
}
protected BeanInfo getBeanInfo(final Class clazz) throws IntrospectionException {
BeanInfo beanInfo = BEAN_INFO_CACHE.get(clazz);
if (beanInfo != null) {
return beanInfo;
}
beanInfo = Introspector.getBeanInfo(clazz);
BEAN_INFO_CACHE.put(clazz, beanInfo);
return beanInfo;
}
protected Object getBridgedValue(Method baseAccessor, Object value) throws InstantiationException, IllegalAccessException {
JSONFieldBridge fieldBridgeAnn = baseAccessor.getAnnotation(JSONFieldBridge.class);
if (fieldBridgeAnn != null) {
Class impl = fieldBridgeAnn.impl();
FieldBridge instance = (FieldBridge) impl.newInstance();
if (fieldBridgeAnn.params().length > 0 && ParameterizedBridge.class.isAssignableFrom(impl)) {
Map params = new HashMap(fieldBridgeAnn.params().length);
for (JSONParameter param : fieldBridgeAnn.params()) {
params.put(param.name(), param.value());
}
((ParameterizedBridge) instance).setParameterValues(params);
}
value = instance.objectToString(value);
}
return value;
}
protected Method findBaseAccessor(Class clazz, Method accessor) {
Method baseAccessor = null;
if (clazz.getName().contains("$$EnhancerByCGLIB$$")) {
try {
baseAccessor = Thread.currentThread().getContextClassLoader().loadClass(
clazz.getName().substring(0, clazz.getName().indexOf("$$"))).getMethod(
accessor.getName(), accessor.getParameterTypes());
} catch (Exception ex) {
LOG.debug(ex.getMessage(), ex);
}
} else if (clazz.getName().contains("$$_javassist")) {
try {
baseAccessor = Class.forName(
clazz.getName().substring(0, clazz.getName().indexOf("_$$")))
.getMethod(accessor.getName(), accessor.getParameterTypes());
} catch (Exception ex) {
LOG.debug(ex.getMessage(), ex);
}
} else {
return accessor;
}
return baseAccessor;
}
/**
* Instrospect an Enum and serialize it as a name/value pair or as a bean
* including all its own properties
*/
protected void enumeration(Enum enumeration) throws JSONException {
if (enumAsBean) {
this.bean(enumeration);
} else {
this.string(enumeration.name());
}
}
protected boolean shouldExcludeProperty(PropertyDescriptor prop) throws SecurityException, NoSuchFieldException {
String name = prop.getName();
return name.equals("class")
|| name.equals("declaringClass")
|| name.equals("cachedSuperClass")
|| name.equals("metaClass");
}
protected String expandExpr(int i) {
return this.exprStack + "[" + i + "]";
}
protected String expandExpr(String property) {
if (this.exprStack.length() == 0) {
return property;
}
return this.exprStack + "." + property;
}
protected String setExprStack(String expr) {
String s = this.exprStack;
this.exprStack = expr;
return s;
}
protected boolean shouldExcludeProperty(String expr) {
if (this.excludeProperties != null) {
for (Pattern pattern : this.excludeProperties) {
if (pattern.matcher(expr).matches()) {
if (LOG.isDebugEnabled()) {
LOG.debug("Ignoring property because of exclude rule: " + expr);
}
return true;
}
}
}
if (this.includeProperties != null) {
for (Pattern pattern : this.includeProperties) {
if (pattern.matcher(expr).matches()) {
return false;
}
}
if (LOG.isDebugEnabled()){
LOG.debug("Ignoring property because of include rule: " + expr);
}
return true;
}
return false;
}
/**
* Add name/value pair to buffer
*/
protected boolean add(String name, Object value, Method method, boolean hasData) throws JSONException {
if (excludeNullProperties && value == null) {
return false;
}
if (hasData) {
this.add(',');
}
this.add('"');
this.add(name);
this.add("\":");
this.value(value, method);
return true;
}
/**
* Add map to buffer
*/
protected void map(Map map, Method method) throws JSONException {
this.add("{");
Iterator it = map.entrySet().iterator();
boolean warnedNonString = false; // one report per map
boolean hasData = false;
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
if (excludeNullProperties && entry.getValue() == null) {
continue;
}
Object key = entry.getKey();
if (key == null) {
LOG.error("Cannot build expression for null key in #0", exprStack);
continue;
}
String expr = null;
if (this.buildExpr) {
expr = this.expandExpr(key.toString());
if (this.shouldExcludeProperty(expr)) {
continue;
}
expr = this.setExprStack(expr);
}
if (hasData) {
this.add(',');
}
hasData = true;
if (!warnedNonString && !(key instanceof String)) {
if (LOG.isWarnEnabled()) {
LOG.warn("JavaScript doesn't support non-String keys, using toString() on #0", key.getClass().getName());
}
warnedNonString = true;
}
this.value(key.toString(), method);
this.add(":");
this.value(entry.getValue(), method);
if (this.buildExpr) {
this.setExprStack(expr);
}
}
this.add("}");
}
/**
* Add date to buffer
*/
protected void date(Date date, Method method) {
JSON json = null;
if (method != null)
json = method.getAnnotation(JSON.class);
if (this.formatter == null)
this.formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
DateFormat formatter = (json != null) && (json.format().length() > 0) ? new SimpleDateFormat(json
.format()) : this.formatter;
this.string(formatter.format(date));
}
/**
* Add array to buffer
*/
protected void array(Iterator it, Method method) throws JSONException {
this.add("[");
boolean hasData = false;
for (int i = 0; it.hasNext(); i++) {
String expr = null;
if (this.buildExpr) {
expr = this.expandExpr(i);
if (this.shouldExcludeProperty(expr)) {
it.next();
continue;
}
expr = this.setExprStack(expr);
}
if (hasData) {
this.add(',');
}
hasData = true;
this.value(it.next(), method);
if (this.buildExpr) {
this.setExprStack(expr);
}
}
this.add("]");
}
/**
* Add array to buffer
*/
protected void array(Object object, Method method) throws JSONException {
this.add("[");
int length = Array.getLength(object);
boolean hasData = false;
for (int i = 0; i < length; ++i) {
String expr = null;
if (this.buildExpr) {
expr = this.expandExpr(i);
if (this.shouldExcludeProperty(expr)) {
continue;
}
expr = this.setExprStack(expr);
}
if (hasData) {
this.add(',');
}
hasData = true;
this.value(Array.get(object, i), method);
if (this.buildExpr) {
this.setExprStack(expr);
}
}
this.add("]");
}
/**
* Add boolean to buffer
*/
protected void bool(boolean b) {
this.add(b ? "true" : "false");
}
/**
* escape characters
*/
protected void string(Object obj) {
this.add('"');
CharacterIterator it = new StringCharacterIterator(obj.toString());
for (char c = it.first(); c != CharacterIterator.DONE; c = it.next()) {
if (c == '"') {
this.add("\\\"");
} else if (c == '\\') {
this.add("\\\\");
} else if (c == '/') {
this.add("\\/");
} else if (c == '\b') {
this.add("\\b");
} else if (c == '\f') {
this.add("\\f");
} else if (c == '\n') {
this.add("\\n");
} else if (c == '\r') {
this.add("\\r");
} else if (c == '\t') {
this.add("\\t");
} else if (Character.isISOControl(c)) {
this.unicode(c);
} else {
this.add(c);
}
}
this.add('"');
}
/**
* Add object to buffer
*/
protected void add(Object obj) {
this.buf.append(obj);
}
/**
* Add char to buffer
*/
protected void add(char c) {
this.buf.append(c);
}
/**
* Represent as unicode
*
* @param c character to be encoded
*/
protected void unicode(char c) {
this.add("\\u");
int n = c;
for (int i = 0; i < 4; ++i) {
int digit = (n & 0xf000) >> 12;
this.add(hex[digit]);
n <<= 4;
}
}
public void setIgnoreHierarchy(boolean ignoreHierarchy) {
this.ignoreHierarchy = ignoreHierarchy;
}
/**
* If true, an Enum is serialized as a bean with a special property
* _name=name() as all as all other properties defined within the enum.
