流程图解Spring Framework（十二）Spring MVC @InitBinder 原理
文章目录
- 介绍
- 使用
- 全局 WebBinder
- Controller 个性化的Binder
- 原理
- binder 初始化
- binder 使用
介绍
在日常的项目中，经常会遇到页面传参和系统的实体不一致的情况，比如Date类型，页面传入参数是20180112,但是后面接受类型是Date，那么后面的接收不到这个参数，并且会报400错误。
在Spring中可以使用注解@InitBinder来解决这个问题，它可以注册一系列的属性编辑器java.beans.PropertyEditor，这些编辑器向处理器设置一些规则，比如刚才的date类型。就可以注册CustomerDateEditor。详细的类型有如下表示
使用
全局 WebBinder
@ControllerAdvice
public class GlobalWebBinderAdvice {
@InitBinder
protected void initBinder(WebDataBinder binder) {
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
dateFormat.setLenient(false);
// 注册
binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, false));
}
}
Controller 个性化的Binder
@Controller
public class WebBinderTestController {
// 个性化 initBinder
// value 表示只绑定表单的固定key
@InitBinder("date")
protected void initBinder(WebDataBinder binder) {
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd");
dateFormat.setLenient(false);
binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, false));
}
// http://localhost:8080/?date=20180819&date2=2018-09-19
// date 使用个性化binder date2使用全局binder
@RequestMapping("/")
@ResponseBody
private String hello(Date date, Date date2){
System.out.println(date);
return "hello";
}
}
原理
binder 初始化
RequestMappingHandlerAdapter#afterPropertiesSet => RequestMappingHandlerAdapter#initControllerAdviceCache
private void initControllerAdviceCache() {
if (getApplicationContext() == null) {
return;
}
// 获取所有加了 @ControllerAdvice 注解的Controller
List<ControllerAdviceBean> adviceBeans = ControllerAdviceBean.findAnnotatedBeans(getApplicationContext());
AnnotationAwareOrderComparator.sort(adviceBeans);
List<Object> requestResponseBodyAdviceBeans = new ArrayList<>();
for (ControllerAdviceBean adviceBean : adviceBeans) {
Class<?> beanType = adviceBean.getBeanType();
if (beanType == null) {
throw new IllegalStateException("Unresolvable type for ControllerAdviceBean: " + adviceBean);
}
Set<Method> attrMethods = MethodIntrospector.selectMethods(beanType, MODEL_ATTRIBUTE_METHODS);
if (!attrMethods.isEmpty()) {
this.modelAttributeAdviceCache.put(adviceBean, attrMethods);
}
// 搜索所有的@InitBinder注解，说明是用ControllerAdvice实现的InitBinder，这里是全局的InitBinder
Set<Method> binderMethods = MethodIntrospector.selectMethods(beanType, INIT_BINDER_METHODS);
if (!binderMethods.isEmpty()) {
this.initBinderAdviceCache.put(adviceBean, binderMethods);
}
if (RequestBodyAdvice.class.isAssignableFrom(beanType)) {
requestResponseBodyAdviceBeans.add(adviceBean);
}
if (ResponseBodyAdvice.class.isAssignableFrom(beanType)) {
requestResponseBodyAdviceBeans.add(adviceBean);
}
}
if (!requestResponseBodyAdviceBeans.isEmpty()) {
this.requestResponseBodyAdvice.addAll(0, requestResponseBodyAdviceBeans);
}
if (logger.isDebugEnabled()) {
int modelSize = this.modelAttributeAdviceCache.size();
int binderSize = this.initBinderAdviceCache.size();
int reqCount = getBodyAdviceCount(RequestBodyAdvice.class);
int resCount = getBodyAdviceCount(ResponseBodyAdvice.class);
if (modelSize == 0 && binderSize == 0 && reqCount == 0 && resCount == 0) {
logger.debug("ControllerAdvice beans: none");
}
else {
logger.debug("ControllerAdvice beans: " + modelSize + " @ModelAttribute, " + binderSize +
" @InitBinder, " + reqCount + " RequestBodyAdvice, " + resCount + " ResponseBodyAdvice");
}
}
}
binder 使用
请求进入RequestMappingHandlerAdapter之后，请求体进行了一系列的改变
RequestMappingHandlerAdapter#invokeHandlerMethod
protected ModelAndView invokeHandlerMethod(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ServletWebRequest webRequest = new ServletWebRequest(request, response);
try {
// 1. 获取binderFactory
WebDataBinderFactory binderFactory = getDataBinderFactory(handlerMethod);
ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory);
ServletInvocableHandlerMethod invocableMethod = createInvocableHandlerMethod(handlerMethod);
if (this.argumentResolvers != null) {
invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
}
if (this.returnValueHandlers != null) {
invocableMethod.setHandlerMethodReturnValueHandlers(this.returnValueHandlers);
}
invocableMethod.setDataBinderFactory(binderFactory);
invocableMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
ModelAndViewContainer mavContainer = new ModelAndViewContainer();
mavContainer.addAllAttributes(RequestContextUtils.getInputFlashMap(request));
modelFactory.initModel(webRequest, mavContainer, invocableMethod);
mavContainer.setIgnoreDefaultModelOnRedirect(this.ignoreDefaultModelOnRedirect);
AsyncWebRequest asyncWebRequest = WebAsyncUtils.createAsyncWebRequest(request, response);
asyncWebRequest.setTimeout(this.asyncRequestTimeout);
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
asyncManager.setTaskExecutor(this.taskExecutor);
asyncManager.setAsyncWebRequest(asyncWebRequest);
asyncManager.registerCallableInterceptors(this.callableInterceptors);
asyncManager.registerDeferredResultInterceptors(this.deferredResultInterceptors);
if (asyncManager.hasConcurrentResult()) {
Object result = asyncManager.getConcurrentResult();
mavContainer = (ModelAndViewContainer) asyncManager.getConcurrentResultContext()[0];
asyncManager.clearConcurrentResult();
LogFormatUtils.traceDebug(logger, traceOn -> {
String formatted = LogFormatUtils.formatValue(result, !traceOn);
return "Resume with async result [" + formatted + "]";
});
invocableMethod = invocableMethod.wrapConcurrentResult(result);
}
// 2. 调用WebBinder，convert WebRequest内部的请求参数
invocableMethod.invokeAndHandle(webRequest, mavContainer);
if (asyncManager.isConcurrentHandlingStarted()) {
return null;
}
return getModelAndView(mavContainer, modelFactory, webRequest);
}
finally {
webRequest.requestCompleted();
}
}
- 获取binderFactory
private WebDataBinderFactory getDataBinderFactory(HandlerMethod handlerMethod) throws Exception {
Class<?> handlerType = handlerMethod.getBeanType();
// 从缓存中获取
Set<Method> methods = this.initBinderCache.get(handlerType);
if (methods == null) {
// 查找 当前 Controller 的 InitBinder， 优先级高
methods = MethodIntrospector.selectMethods(handlerType, INIT_BINDER_METHODS);
this.initBinderCache.put(handlerType, methods);
}
// 获取 全局，即ControllerAdvice 下面的 initBinder 的所有方法
List<InvocableHandlerMethod> initBinderMethods = new ArrayList<>();
// 全局的initBinder
this.initBinderAdviceCache.forEach((clazz, methodSet) -> {
// 测试是否匹配
// 匹配条件： controller在Advice所在的包下面同一个包、同一个类型、controller上面有注解
if (clazz.isApplicableToBeanType(handlerType)) {
Object bean = clazz.resolveBean();
for (Method method : methodSet) {
initBinderMethods.add(createInitBinderMethod(bean, method));
}
}
});
for (Method method : methods) {
Object bean = handlerMethod.getBean();
initBinderMethods.add(createInitBinderMethod(bean, method));
}
// 创建一个DataBinderFactory
return createDataBinderFactory(initBinderMethods);
}
private InvocableHandlerMethod createInitBinderMethod(Object bean, Method method) {
InvocableHandlerMethod binderMethod = new InvocableHandlerMethod(bean, method);
if (this.initBinderArgumentResolvers != null) {
binderMethod.setHandlerMethodArgumentResolvers(this.initBinderArgumentResolvers);
}
// 设置 WebBinder ===> this.webBindingInitializer=ConfigurableWebBindingInitializer
binderMethod.setDataBinderFactory(new DefaultDataBinderFactory(this.webBindingInitializer));
binderMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
return binderMethod;
}
protected InitBinderDataBinderFactory createDataBinderFactory(List<InvocableHandlerMethod> binderMethods)
throws Exception {
// 创建一个binder
// getWebBindingInitializer() ==> ConfigurableWebBindingInitializer
return new ServletRequestDataBinderFactory(binderMethods, getWebBindingInitializer());
}
- 使用WebBinder的逻辑
InvocableHandlerMethod#invokeAndHandle
public void invokeAndHandle(ServletWebRequest webRequest, ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
// 执行
Object returnValue = invokeForRequest(webRequest, mavContainer, providedArgs);
setResponseStatus(webRequest);
if (returnValue == null) {
if (isRequestNotModified(webRequest) || getResponseStatus() != null || mavContainer.isRequestHandled()) {
mavContainer.setRequestHandled(true);
return;
}
}
else if (StringUtils.hasText(getResponseStatusReason())) {
mavContainer.setRequestHandled(true);
return;
}
mavContainer.setRequestHandled(false);
Assert.state(this.returnValueHandlers != null, "No return value handlers");
try {
this.returnValueHandlers.handleReturnValue(
returnValue, getReturnValueType(returnValue), mavContainer, webRequest);
}
catch (Exception ex) {
if (logger.isTraceEnabled()) {
logger.trace(formatErrorForReturnValue(returnValue), ex);
}
throw ex;
}
}
InvocableHandlerMethod#invokeForRequest
@Nullable
public Object invokeForRequest(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs);
if (logger.isTraceEnabled()) {
logger.trace("Arguments: " + Arrays.toString(args));
}
return doInvoke(args);
}
InvocableHandlerMethod#getMethodArgumentValues
protected Object[] getMethodArgumentValues(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
if (ObjectUtils.isEmpty(getMethodParameters())) {
return EMPTY_ARGS;
}
MethodParameter[] parameters = getMethodParameters();
Object[] args = new Object[parameters.length];
// 遍历转化参数
for (int i = 0; i < parameters.length; i++) {
MethodParameter parameter = parameters[i];
parameter.initParameterNameDiscovery(this.parameterNameDiscoverer);
args[i] = findProvidedArgument(parameter, providedArgs);
if (args[i] != null) {
continue;
}
if (!this.resolvers.supportsParameter(parameter)) {
throw new IllegalStateException(formatArgumentError(parameter, "No suitable resolver"));
}
try {
args[i] = this.resolvers.resolveArgument(parameter, mavContainer, request, this.dataBinderFactory);
}
catch (Exception ex) {
// Leave stack trace for later, exception may actually be resolved and handled..
if (logger.isDebugEnabled()) {
String error = ex.getMessage();
if (error != null && !error.contains(parameter.getExecutable().toGenericString())) {
logger.debug(formatArgumentError(parameter, error));
}
}
throw ex;
}
}
return args;
}
真正逻辑在下面
AbstractNamedValueMethodArgumentResolver
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
NamedValueInfo namedValueInfo = getNamedValueInfo(parameter);
MethodParameter nestedParameter = parameter.nestedIfOptional();
Object resolvedName = resolveStringValue(namedValueInfo.name);
if (resolvedName == null) {
throw new IllegalArgumentException(
"Specified name must not resolve to null: [" + namedValueInfo.name + "]");
}
Object arg = resolveName(resolvedName.toString(), nestedParameter, webRequest);
if (arg == null) {
if (namedValueInfo.defaultValue != null) {
arg = resolveStringValue(namedValueInfo.defaultValue);
}
else if (namedValueInfo.required && !nestedParameter.isOptional()) {
handleMissingValue(namedValueInfo.name, nestedParameter, webRequest);
}
arg = handleNullValue(namedValueInfo.name, arg, nestedParameter.getNestedParameterType());
}
else if ("".equals(arg) && namedValueInfo.defaultValue != null) {
arg = resolveStringValue(namedValueInfo.defaultValue);
}
if (binderFactory != null) {
WebDataBinder binder = binderFactory.createBinder(webRequest, null, namedValueInfo.name);
try {
// 使用webBinder 转换
arg = binder.convertIfNecessary(arg, parameter.getParameterType(), parameter);
}
catch (ConversionNotSupportedException ex) {
throw new MethodArgumentConversionNotSupportedException(arg, ex.getRequiredType(),
namedValueInfo.name, parameter, ex.getCause());
}
catch (TypeMismatchException ex) {
throw new MethodArgumentTypeMismatchException(arg, ex.getRequiredType(),
namedValueInfo.name, parameter, ex.getCause());
}
}
handleResolvedValue(arg, namedValueInfo.name, parameter, mavContainer, webRequest);
return arg;
}
- 使用webBinder 转换
DataBinder#convertIfNecessary
public <T> T convertIfNecessary(@Nullable Object value, @Nullable Class<T> requiredType,
@Nullable MethodParameter methodParam) throws TypeMismatchException {
return getTypeConverter().convertIfNecessary(value, requiredType, methodParam);
}
TypeConverterSupport#convertIfNecessary
@Override
@Nullable
public <T> T convertIfNecessary(@Nullable Object value, @Nullable Class<T> requiredType) throws TypeMismatchException {
return doConvert(value, requiredType, null, null);
}
@Nullable
private <T> T doConvert(@Nullable Object value,@Nullable Class<T> requiredType,
@Nullable MethodParameter methodParam, @Nullable Field field) throws TypeMismatchException {
Assert.state(this.typeConverterDelegate != null, "No TypeConverterDelegate");
try {
if (field != null) {
return this.typeConverterDelegate.convertIfNecessary(value, requiredType, field);
}
else {
return this.typeConverterDelegate.convertIfNecessary(value, requiredType, methodParam);
}
}
catch (ConverterNotFoundException | IllegalStateException ex) {
throw new ConversionNotSupportedException(value, requiredType, ex);
}
catch (ConversionException | IllegalArgumentException ex) {
throw new TypeMismatchException(value, requiredType, ex);
}
}