源码分析之FastJson全局配置日期格式导致@JSONField(format = "yyyy-MM-dd")注解失效

@Configurationpublic class FastJsonConverterConfig { ???@Bean ???public HttpMessageConverters fastJsonHttpMessageConverters() { ???????FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter(); ???????FastJsonConfig fastJsonConfig = new FastJsonConfig(); ???????fastJsonConfig.setSerializerFeatures( ???????????????SerializerFeature.WriteMapNullValue, ???????????????SerializerFeature.WriteNullListAsEmpty, ???????????????SerializerFeature.WriteNullStringAsEmpty, ???????????????SerializerFeature.WriteNullBooleanAsFalse// ???????????????SerializerFeature.WriteDateUseDateFormat ???????); ???????fastConverter.setFastJsonConfig(fastJsonConfig);　　　　　//全局指定了日期格式 ???????fastJsonConfig.setDateFormat("yyyy-MM-dd HH:mm:ss"); ???????//该设置目的，为了兼容jackson ???????fastConverter.setSupportedMediaTypes(Arrays.asList(MediaType.APPLICATION_JSON,MediaType.APPLICATION_JSON_UTF8,MediaType.APPLICATION_OCTET_STREAM)); ???????HttpMessageConverter<?> converter = fastConverter; ???????return new HttpMessageConverters(converter); ???}}

@Datapublic class UserCardInfoResponseModel { ???@JSONField(format = "yyyy-MM-dd") ???private Date validStartDate;}

public class JSONSerializer extends SerializeFilterable {　　
　　/**
　　* format就是@JSONField注解中指定的format值
　　* object就是需要格式化的变量
　　*/
　　public final void writeWithFormat(Object object, String format) { ???????if (object instanceof Date) {
　　　　　　　//从当前类获取一个DateFormat，DateFormat就是用来格式化日期的类，再看看this.getDateFormat();的实现　 ???????????DateFormat dateFormat = this.getDateFormat(); ???????????if (dateFormat == null) {
　　　　　　　//只有当，当前类中的dateFormat为null时，才会使用JSONField注解中的format值初始化一个新的DateFormat
　　　　　　　//那么我们可以肯定@JSONField注解没生效的原因就是,当前类中的dateFormat不为null ???????????????dateFormat = new SimpleDateFormat(format, locale); ???????????????dateFormat.setTimeZone(timeZone); ???????????} ???????????String text = dateFormat.format((Date) object); ???????????out.writeString(text); ???????????return; ???????} ???????if (object instanceof byte[]) { ???????????byte[] bytes = (byte[]) object; ???????????if ("gzip".equals(format) || "gzip,base64".equals(format)) { ???????????????GZIPOutputStream gzipOut = null; ???????????????try {z ???????????????????ByteArrayOutputStream byteOut = new ByteArrayOutputStream(); ???????????????????if (bytes.length < 512) { ???????????????????????gzipOut = new GZIPOutputStream(byteOut, bytes.length); ???????????????????} else { ???????????????????????gzipOut = new GZIPOutputStream(byteOut); ???????????????????} ???????????????????gzipOut.write(bytes); ???????????????????gzipOut.finish(); ???????????????????out.writeByteArray(byteOut.toByteArray()); ???????????????} catch (IOException ex) { ???????????????????throw new JSONException("write gzipBytes error", ex); ???????????????} finally { ???????????????????IOUtils.close(gzipOut); ???????????????} ???????????} else if ("hex".equals(format)) { ???????????????out.writeHex(bytes); ???????????} else { ???????????????out.writeByteArray(bytes); ???????????} ???????????return; ???????} ???????if (object instanceof Collection) { ???????????Collection collection = (Collection) object; ???????????Iterator iterator = collection.iterator(); ???????????out.write(‘[‘); ???????????for (int i = 0; i < collection.size(); i++) { ???????????????Object item = iterator.next(); ???????????????if (i != 0) { ???????????????????out.write(‘,‘); ???????????????} ???????????????writeWithFormat(item, format); ???????????} ???????????out.write(‘]‘); ???????????return; ???????} ???????write(object); ???}　　public DateFormat getDateFormat() {

if (dateFormat == null) { ???????????if (dateFormatPattern != null) {
　　　　　　　//第一次调用该方法时，dateformat为null，满足第一个if条件
　　　　　　　//那么只有当dateFormatPattern有值时，才会初始化一个dateFormat对象，
　　　　　　　//那么问题来了，dateFormatPattern值是从哪里来的呢，答案就是从我们的全局配置中来的，我们继续往下看 ???????????????dateFormat = new SimpleDateFormat(dateFormatPattern, locale); ???????????????dateFormat.setTimeZone(timeZone); ???????????} ???????} ???????return dateFormat; ???}}

public class FastJsonHttpMessageConverter extends AbstractHttpMessageConverter<Object>// ???????implements GenericHttpMessageConverter<Object> {@Override ???protected void writeInternal(Object object, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException { ???????ByteArrayOutputStream outnew = new ByteArrayOutputStream(); ???????try { ???????????HttpHeaders headers = outputMessage.getHeaders(); ???????????//获取全局配置的filter ???????????SerializeFilter[] globalFilters = fastJsonConfig.getSerializeFilters(); ???????????List<SerializeFilter> allFilters = new ArrayList<SerializeFilter>(Arrays.asList(globalFilters)); ???????????boolean isJsonp = false; ???????????//不知道为什么会有这行代码， 但是为了保持和原来的行为一致，还是保留下来 ???????????Object value = strangeCodeForJackson(object); ???????????if (value instanceof FastJsonContainer) { ???????????????FastJsonContainer fastJsonContainer = (FastJsonContainer) value; ???????????????PropertyPreFilters filters = fastJsonContainer.getFilters(); ???????????????allFilters.addAll(filters.getFilters()); ???????????????value = fastJsonContainer.getValue(); ???????????} ???????????//revise 2017-10-23 , ???????????// 保持原有的MappingFastJsonValue对象的contentType不做修改 保持旧版兼容。 ???????????// 但是新的JSONPObject将返回标准的contentType：application/javascript ，不对是否有function进行判断 ???????????if (value instanceof MappingFastJsonValue) { ???????????????if(!StringUtils.isEmpty(((MappingFastJsonValue) value).getJsonpFunction())){ ???????????????????isJsonp = true; ???????????????} ???????????} else if (value instanceof JSONPObject) { ???????????????isJsonp = true; ???????????}　　　　　　　//我们看这里，fastJsonConfig就是我们全局配置的配置类，
　　　　　　　//fastJsonConfig.getDateFormat()获取的就是我们全局配置的时间格式yyyy-MM-dd HH:mm:ss，然后我们看看JSON.writeJSONString方法 ???????????int len = JSON.writeJSONString(outnew, // ???????????????????fastJsonConfig.getCharset(), // ???????????????????value, // ???????????????????fastJsonConfig.getSerializeConfig(), // ???????????????????//fastJsonConfig.getSerializeFilters(), // ???????????????????allFilters.toArray(new SerializeFilter[allFilters.size()]), ???????????????????fastJsonConfig.getDateFormat(), // ???????????????????JSON.DEFAULT_GENERATE_FEATURE, // ???????????????????fastJsonConfig.getSerializerFeatures()); ???????????if (isJsonp) { ???????????????headers.setContentType(APPLICATION_JAVASCRIPT); ???????????} ???????????if (fastJsonConfig.isWriteContentLength()) { ???????????????headers.setContentLength(len); ???????????} ???????????outnew.writeTo(outputMessage.getBody()); ???????} catch (JSONException ex) { ???????????throw new HttpMessageNotWritableException("Could not write JSON: " + ex.getMessage(), ex); ???????} finally { ???????????outnew.close(); ???????} ???}}

public abstract class JSON implements JSONStreamAware, JSONAware {public static final int writeJSONString(OutputStream os, // ?????????????????????????????????????????????Charset charset, // ?????????????????????????????????????????????Object object, // ?????????????????????????????????????????????SerializeConfig config, // ????????????????????????????????????????????SerializeFilter[] filters, // ????????????????????????????????????????????String dateFormat, // ????????????????????????????????????????????int defaultFeatures, // ????????????????????????????????????????????SerializerFeature... features) throws IOException { ???????SerializeWriter writer = new SerializeWriter(null, defaultFeatures, features); ???????try {
　　　　　　//看这里,就是用来初始化JSONSerializer对象 ???????????JSONSerializer serializer = new JSONSerializer(writer, config); ???????????????????????if (dateFormat != null && dateFormat.length() != 0) {
　　　　　　　//然后在这里，将全局配置的日期格式dateFormat，设置到JSONSerializer中的
　　　　　　　//到这里我们就应该很清楚整个的逻辑了 ???????????????serializer.setDateFormat(dateFormat); ???????????????serializer.config(SerializerFeature.WriteDateUseDateFormat, true); ???????????} ???????????if (filters != null) { ???????????????for (SerializeFilter filter : filters) { ???????????????????serializer.addFilter(filter); ???????????????} ???????????} ???????????????????????serializer.write(object); ???????????????????????int len = writer.writeToEx(os, charset); ???????????return len; ???????} finally { ???????????writer.close(); ???????} ???}}

WebMvcMetricsFilter\doFilterInternalWebMvcMetricsFilter\filterAndRecordMetricsApplicationFilterChain\internalDoFilterWsFilter\doFilterApplicationFilterChain\doFilterApplicationFilterChain\internalDoFilterFrameworkServlet\serviceFrameworkServlet\doGetFrameworkServlet\processRequestDispatcherServlet\doService()DispatcherServlet\doDispatch\mv = ha.handle(processedRequest, response, mappedHandler.getHandler());AbstractHandlerMethodAdapter\handle(84)RequestMappingHandlerAdapter\handleInternal(761)\mav = invokeHandlerMethod(request, response, handlerMethod);RequestMappingHandlerAdapter\invokeHandlerMethod(835)ServletInvocableHandlerMethod\invokeAndHandle(99)HandlerMethodReturnValueHandlerComposite\handleReturnValue(75)RequestResponseBodyMethodProcessor\handleReturnValue(171)AbstractMessageConverterMethodProcessor\genericConverter.write(outputValue, declaredType, selectedMediaType, outputMessage);(272)FastJsonHttpMessageConverter\super.write(o, contentType, outputMessage);(184)AbstractHttpMessageConverter\writeInternal(t, outputMessage);(224)FastJsonHttpMessageConverter\writeInternal(246)**** ?JSON\writeJSONString(821)===>JSONSerializer\writeWithFieldName===>MapSerializer\write()===>JavaBeanSerializer\fieldSerializer.writeValue(serializer, propertyValue);===>FieldSerializer\serializer.writeWithFormat(propertyValue, format);===>**** JSONSerializer\public final void writeWithFormat(Object object, String format) {}