SpringMVC核心组件完全自定义实现

概述通过Spring定义请求接口是非常容器化的，可以通过几个注解来完成，如下：@RestController@RequestMapping("/demos")publicclassDemoController{@GetMapping("/index")publicObjectindex(){return"index";}}通过上面的@RestController，@RequestMapping完成了一个简单的接口定义。其实SpringWeb的底层做了很多工作，其核心组件包括HandlerMapping、HandlerAdapter、ViewResolver等组件。HandlerMapping根据当前请求的URI找到对应的Handler，如：HandlerExecutionChain，封装后的HandlerMethodHandlerAdapter根据上面确定的HandlerMethod找到可以处理Handler的Adapter，调用ViewResolver。如果返回的ModelAndView对象是通过对应的ViewResolverOutput渲染的了解了以上核心组件后，接下来就是自定义以上核心类的实现，完成接口的请求处理。CustomizeEndpoint自定义注解来标记Controller类和请求参数：@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documentedpublic@interfacePackEndpoint{}参数标记，用于注解接口参数。@Target(ElementType.PARAMETER)@Retention(RetentionPolicy.RUNTIME)@Documentedpublic@interfacePackParam{}Endpoint接口参数封装对象该对象用于保存记录，方法参数为@PackParam注解的参数。publicclassPackMethodParameter{//用于解析接口参数的名称privateParameterNameDiscovererparameterNameDiscoverer=newLocalVariableTableParameterNameDiscoverer();私有字符串名称；私有可执行文件可执行文件；私有int参数索引；私有类类型；publicPackMethodParameter(Stringname,intparameterIndex,Executableexecutable){this.name=name;this.parameterIndex=parameterIndex;this.executable=executable;}publicPackMethodParameter(intparameterIndex,Executableexecutable,Classtype){this.parameterIndex=parameterIndex;this.executable=executable;this.type=类型;}publicbooleanhasParameterAnnotation(Classclazz){Methodmethod=(Method)this.executable;参数[]参数=方法.getParameters();返回参数[this.parameterIndex].isAnnotationPresent(clazz);}publicStringgetParameterName(){String[]parameterNames=parameterNameDiscoverer.getParameterNames((Method)this.executable);返回参数名[this.parameterIndex];}}CustomHandlerMapping自定义实现SpringMVC标准的HandlerMapping，使其在DispatcherServlet中能够被识别公共类PackHandlerMapping实现HandlerMapping、InitializingBean、ApplicationContextAware{privateApplicationContext上下文；privateMapmapping=newHashMap<>();@OverridepublicHandlerExecutionChaingetHandler(HttpServletRequestrequest)抛出异常{StringrequestPath=request.getRequestURI();可选opt=mapping.entrySet().stream().filter(entry->entry.getKey().equals(requestPath)).findFirst().map(Map.Entry::getValue);if(opt.isPresent()){HandlerExecutionChainexecutionChain=newHandlerExecutionChain(opt.get());返回执行链；}返回空值；}//Bean初始化时，从容器中查找所有符合条件的Bean对象，即Bean对象上有@PackEndpoint注解@OverridepublicvoidafterPropertiesSet()throwsException{String[]beanNames=context.getBeanNamesForType(Object.class);for(StringbeanName:beanNames){对象bean=this.context.getBean(豆名);类clazz=bean.getClass();//判断当前Bean上是否有PackEndpoint注解，只处理有这个注解的类if(clazz.getAnnotation(PackEndpoint.class)!=null){StringrootPath=clazzMapping.value()[0];if(clazzMapping!=null){ReflectionUtils.doWithMethods(clazz,method->{RequestMappingnestMapping=AnnotatedElementUtils.findMergedAnnotation(method,RequestMapping.class);if(nestMapping!=null){StringnestPath=nestMapping.value()[0];Stringpath=rootPath+nestPath;PackMethodHandlerhandler=newPackMethodHandler(method,bean);mapping.put(path,handler);}});}}}}@OverridepublicvoidsetApplicationContext(ApplicationContextapplicationContext)throwsBeansException{this.context=应用上下文；}//该类的作用：用来记录接口对应的信息，方法，对应的实例，参数信息publicstaticclassPackMethodHandler{privateMethodmethod;私有对象实例；私有PackMethodParameter[]参数；publicMethodgetMethod(){返回方法；}publicvoidsetMethod(Methodmethod){this.method=method;}publicObjectgetInstance(){返回实例；}publicvoidsetInstance(Objectinstance){this.instance=instance;}publicPackMethodHandler(方法方法，对象实例){super();this.method=方法；this.instance=实例；参数[]params=method.getParameters();this.parameters=newPackMethodParameter[params.length];for(inti=0;i