小编给大家分享一下SpringBoot与springMVC中参数传递的示例分析,相信大部分人都还不怎么了解,因此分享这篇文章给大家参考一下,希望大家阅读完这篇文章后大有收获,下面让我们一起去了解一下吧!一:普通参数与基本注解HandlerM
小编给大家分享一下SpringBoot与springMVC中参数传递的示例分析,相信大部分人都还不怎么了解,因此分享这篇文章给大家参考一下,希望大家阅读完这篇文章后大有收获,下面让我们一起去了解一下吧!
HandlerMapping中找到能处理请求的Handler(Controller,method())
为当前Handler找一个适配器HandlerAdapter:RequestMappingHandlerAdapter
HandlerAdapter
0-支持方法上标注@RequestMapping
1-支持函数式编程的
xxxx
执行目标方法
参数解析器:确定要执行的目标方法每一个参数的值是什么
boolean supportsParameter(MethodParameter parameter);
Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
先判断是否支持该参数类型, 如果支持, 就调用resolveArgument解析方法
返回值处理器
挨个判断所有参数解析器哪个支持这个参数:HandlerMethodArgumentResolver: 把控着支持的方法参数类型
请求进来后, 首先从handlerMapping中查找是否有对应的映射处理, 得到映射适配器Adapter,再通过适配器,查找有哪些方法匹配请求,首先判断方法名,以及参数类型是否匹配,首先获得方法中声明的参数名字, 放到数组里,循环遍历27种解析器判断是否有支持处理对应参数名字类型的解析器,如果有的话,根据名字进行解析参数,根据名字获得域数据中的参数, 循环每个参数名字进行判断, 从而为每个参数进行赋值.
对于自定义的POJO类参数:
ServletRequestMethodArgumentResolver 这个解析器用来解析: 是通过主要是通过判断是否是简单类型得到的
@Overridepublic boolean supportsParameter(MethodParameter parameter) {return (parameter.hasParameterAnnotation(ModelAttribute.class) ||(this.annotationNotRequired && !BeanUtils.isSimpleProperty(parameter.getParameterType())));}public static boolean isSimpleValueType(Class<?> type) {return (Void.class != type && void.class != type &&(ClassUtils.isPrimitiveOrWrapper(type) ||Enum.class.isAssignableFrom(type) ||CharSequence.class.isAssignableFrom(type) ||Number.class.isAssignableFrom(type) ||Date.class.isAssignableFrom(type) ||Temporal.class.isAssignableFrom(type) ||URI.class == type ||URL.class == type ||Locale.class == type ||Class.class == type));}public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,NativeWEBRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {Assert.state(mavContainer != null, "ModelAttributeMethodProcessor requires ModelAndViewContainer");Assert.state(binderFactory != null, "ModelAttributeMethodProcessor requires WebDataBinderFactory");String name = ModelFactory.getNameForParameter(parameter);ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);if (ann != null) {mavContainer.setBinding(name, ann.binding());}Object attribute = null;BindingResult bindingResult = null;if (mavContainer.containsAttribute(name)) {attribute = mavContainer.getModel().get(name);}else {// Create attribute instancetry {attribute = createAttribute(name, parameter, binderFactory, webRequest);}catch (BindException ex) {if (isBindExceptionRequired(parameter)) {// No BindingResult parameter -> fail with BindExceptionthrow ex;}// Otherwise, expose null/empty value and associated BindingResultif (parameter.getParameterType() == Optional.class) {attribute = Optional.empty();}else {attribute = ex.getTarget();}bindingResult = ex.getBindingResult();}}if (bindingResult == null) {// Bean property binding and validation;// skipped in case of binding failure on construction.WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name);if (binder.getTarget() != null) {if (!mavContainer.isBindingDisabled(name)) {bindRequestParameters(binder, webRequest);}validateIfApplicable(binder, parameter);if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {throw new BindException(binder.getBindingResult());}}// Value type adaptation, also covering java.util.Optionalif (!parameter.getParameterType().isInstance(attribute)) {attribute = binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType(), parameter);}bindingResult = binder.getBindingResult();}// Add resolved attribute and BindingResult at the end of the modelMap<String, Object> bindingResultModel = bindingResult.getModel();mavContainer.removeAttributes(bindingResultModel);mavContainer.addAllAttributes(bindingResultModel);return attribute;}
WebDataBinder binder =binderFactory.createBinder(webRequest,attribute,name)
WebDataBinder:web数据绑定器,将请求参数的值绑定到指定的javaBean里面
WebDataBinder 利用它里面的Converters将请求数据转成指定的数据类型,通过反射一系列操作,再次封装到javabean中
GenericConversionService:在设置每一个值的时候,找它里面所有的converter哪个可以将这个数据类型(request带来参数的字符串)转换到指定的类型(javabean—某一个类型)
未来我们可以给WebDataBinder里面放自己的Converter
private static final class StringToNumber implements Converter<String, T> {converter总接口:@FunctionalInterfacepublic interface Converter<S, T> {
//自定义转换器:实现按照自己的规则给相应对象赋值
@Override public void addFORMatters(FormatterReGIStry registry) { registry.addConverter(new Converter<String, Pet>() { @Override public Pet convert(String source) { if (!StringUtils.isEmpty(source)){ Pet pet = new Pet(); String[] split = source.split(","); pet.setName(split[0]); pet.setAge(split[1]); return pet; } return null; } }); }
Map/Model(map/model里面的数据会被放在request的请求域 相当于request.setAttribute)/Errors/BindingResult/RedirectAttributes(重定向携带数据)/ServletRespons().SessionStaus.UriComponentsBuilder
在上面第五步目标方法执行完成后:
将所有的数据都放在ModelAdnViewContainer;包含要去的页面地址View,还包含Model数据
处理派发结果
processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
在页面进行响应前, 进行视图渲染的时候:
exposeModelAsRequestAttributes(model, request); 该方法将model中所有参数都放在请求域数据中
protected void renderMergedOutputModel(Map<String, Object> model, httpservletRequest request, HttpServletResponse response) throws Exception {// Expose the model object as request attributes.exposeModelAsRequestAttributes(model, request);// Expose helpers as request attributes, if any.exposeHelpers(request);// Determine the path for the request dispatcher.String dispatcherPath = prepareForRendering(request, response);// Obtain a RequestDispatcher for the target resource (typically a jsP).RequestDispatcher rd = getRequestDispatcher(request, dispatcherPath);if (rd == null) {throw new ServletException("Could not get RequestDispatcher for [" + getUrl() +"]: Check that the corresponding file exists within your web application arcHive!");}// If already included or response already committed, perform include, else forward.if (useInclude(request, response)) {response.setContentType(getContentType());if (logger.isDebugEnabled()) {logger.debug("Including [" + getUrl() + "]");}rd.include(request, response);}else {// Note: The forwarded resource is supposed to determine the content type itself.if (logger.isDebugEnabled()) {logger.debug("Forwarding to [" + getUrl() + "]");}rd.forward(request, response);}}
通过循环遍历model中的所有数据放在请求域中
protected void exposeModelAsRequestAttributes(Map<String, Object> model,HttpServletRequest request) throws Exception {model.forEach((name, value) -> {if (value != null) {request.setAttribute(name, value);}else {request.removeAttribute(name);}});}
不管我们在方法形参位置放 Map集合或者Molde 最终在底层源码都是同一个对象在mvcContainer容器中进行保存
以上是“springBoot与SpringMVC中参数传递的示例分析”这篇文章的所有内容,感谢各位的阅读!相信大家都有了一定的了解,希望分享的内容对大家有所帮助,如果还想学习更多知识,欢迎关注编程网精选频道!
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