一.搭建项目
1.新建项目 选中Spring ->Spring MVC 模块 点击next 和 Finish
注意：将生产的lib文件移动到WEB-INF目录下
2.配置 web.xml和SpringMVCxml文件
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0">
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">
3.添加index.jsp文件 在WEB-INF/views目录下
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
${message}
4.添加handler处理器
@Controller
class HelloController {
@RequestMapping("/hello")
public ModelAndView handleRequest(javax.servlet.http.HttpServletRequest httpServletRequest, javax.servlet.http.HttpServletResponse httpServletResponse) throws Exception {
ModelAndView mav = new ModelAndView("index");
mav.addObject("message", "Hello Spring MVC");
return mav;
}
@RequestMapping("/helloRes")
@ResponseBody
public String helloResponse() {
return "hello SpringMVC";
}
}
5.添加本地tomcat启动项目
1.edit configration中选中local tomcat
2.选中项目war包
注意 application context 可以理解是项目的对外名称，端口后必须和配置的一致
6.启动tomcat
二执行流程
1.时序图
2.执行流程
1、前端请求到前端控制器DispatcherServlet
2、DispatcherServlet收到请求调用处理映射器HandlerMapping
3、处理映射器根据请求url找到具体的处理器（ApplicationContext初始化时用Map保存所有的url和controller对应关系），生成处理器执行链HandlerExecutionChain（包含处理器对象和处理器拦截器）返回给DispatcherServlet
4、DispatcherServlet根据处理器Handler获取对应的适配器
5、HandlerAdapter调用处理器Handler找到具体的Controller
6、Controller 执行完成后返回ModelAndView
7、HandlerAdapter返回ModelAndView
8、DispatcherServlet统一将返回的ModelAndView派送到ViewResolve（视图解析器）解析
9，视图解析器解析之后返回 View
10、对View进行渲染
11、回显页面
3.容器的初始化
1.DispatcherServlet的父类HttpServletBean中找到初始化的init()方法；
2.在init()方法中又会调用FrameworkServlet类的initServletBean()方法，最终会调用refresh()方法；
3.IOC容器初始化完成之后会调用DispatcherServlet类的onRefresh()方法，完成SpringMVC九大组件的初始化。
三.源码分析（5.2.3）
一.将请求和url与Controller绑定
1.在spring容器启动时，在实例化Controller bean后，调用afterPropertiesSet() ->initHandlerMethods()->
processCandidateBean() ->detectHandlerMethods 解析bean的方法
```java
protected void detectHandlerMethods(Object handler) {
Class handlerType = handler instanceof String ? this.obtainApplicationContext().getType((String)handler) : handler.getClass();
if (handlerType != null) {
Class userType = ClassUtils.getUserClass(handlerType);
Map
try {
return this.getMappingForMethod(method, userType);
} catch (Throwable var4) {
throw new IllegalStateException("Invalid mapping on handler class [" + userType.getName() + "]: " + method, var4);
}
});
if (this.logger.isTraceEnabled()) {
this.logger.trace(this.formatMappings(userType, methods));
}
methods.forEach((method, mapping) -> {
Method invocableMethod = AopUtils.selectInvocableMethod(method, userType);
// 为每个方法绑定url
this.registerHandlerMethod(handler, invocableMethod, mapping);
});
}
}
```
给每个controller中的方法绑定url
```java
public void register(T mapping, Object handler, Method method) {
if (KotlinDetector.isKotlinType(method.getDeclaringClass()) && AbstractHandlerMethodMapping.KotlinDelegate.isSuspend(method)) {
throw new IllegalStateException("Unsupported suspending handler method detected: " + method);
} else {
this.readWriteLock.writeLock().lock();
try {
HandlerMethod handlerMethod = AbstractHandlerMethodMapping.this.createHandlerMethod(handler, method);
this.validateMethodMapping(handlerMethod, mapping);
// 映射关系放入map中
this.mappingLookup.put(mapping, handlerMethod);
List
Iterator var6 = directUrls.iterator();
while(var6.hasNext()) {
String url = (String)var6.next();
this.urlLookup.add(url, mapping);
}
String name = null;
if (AbstractHandlerMethodMapping.this.getNamingStrategy() != null) {
name = AbstractHandlerMethodMapping.this.getNamingStrategy().getName(handlerMethod, mapping);
this.addMappingName(name, handlerMethod);
}
CorsConfiguration corsConfig = AbstractHandlerMethodMapping.this.initCorsConfiguration(handler, method, mapping);
if (corsConfig != null) {
this.corsLookup.put(handlerMethod, corsConfig);
}
this.registry.put(mapping, new AbstractHandlerMethodMapping.MappingRegistration(mapping, handlerMethod, directUrls, name));
} finally {
this.readWriteLock.writeLock().unlock();
}
}
```
二.前端请求找到对应的Controller
根据servlet的 service()方法->doService()->doDispatch()
```java
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpServletRequest processedRequest = request;
HandlerExecutionChain mappedHandler = null;
boolean multipartRequestParsed = false;
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
try {
try {
ModelAndView mv = null;
Object dispatchException = null;
try {
processedRequest = this.checkMultipart(request);
multipartRequestParsed = processedRequest != request;
// 获取handle
mappedHandler = this.getHandler(processedRequest);
if (mappedHandler == null) {
this.noHandlerFound(processedRequest, response);
return;
}
// 获取adapter
HandlerAdapter ha = this.getHandlerAdapter(mappedHandler.getHandler());
String method = request.getMethod();
boolean isGet = "GET".equals(method);
if (isGet || "HEAD".equals(method)) {
long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
if ((new ServletWebRequest(request, response)).checkNotModified(lastModified) && isGet) {
return;
}
}
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}
// 调用handler的具体方法
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
if (asyncManager.isConcurrentHandlingStarted()) {
return;
}
this.applyDefaultViewName(processedRequest, mv);
mappedHandler.applyPostHandle(processedRequest, response, mv);
} catch (Exception var20) {
dispatchException = var20;
} catch (Throwable var21) {
dispatchException = new NestedServletException("Handler dispatch failed", var21);
}
this.processDispatchResult(processedRequest, response, mappedHandler, mv, (Exception)dispatchException);
} catch (Exception var22) {
this.triggerAfterCompletion(processedRequest, response, mappedHandler, var22);
} catch (Throwable var23) {
this.triggerAfterCompletion(processedRequest, response, mappedHandler, new NestedServletException("Handler processing failed", var23));
}
} finally {
if (asyncManager.isConcurrentHandlingStarted()) {
if (mappedHandler != null) {
mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
}
} else if (multipartRequestParsed) {
this.cleanupMultipart(processedRequest);
}
}
}
```
handleInternal
```java
protected ModelAndView handleInternal(HttpServletRequest request, HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
this.checkRequest(request);
ModelAndView mav;
if (this.synchronizeOnSession) {
HttpSession session = request.getSession(false);
if (session != null) {
Object mutex = WebUtils.getSessionMutex(session);
synchronized(mutex) {
mav = this.invokeHandlerMethod(request, response, handlerMethod);
}
} else {
mav = this.invokeHandlerMethod(request, response, handlerMethod);
}
} else {
mav = this.invokeHandlerMethod(request, response, handlerMethod);
}
if (!response.containsHeader("Cache-Control")) {
if (this.getSessionAttributesHandler(handlerMethod).hasSessionAttributes()) {
this.applyCacheSeconds(response, this.cacheSecondsForSessionAttributeHandlers);
} else {
this.prepareResponse(response);
}
}
return mav;
}
```
invokeHandlerMethod
```java
protected ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ServletWebRequest webRequest = new ServletWebRequest(request, response);
ModelAndView var15;
try {
WebDataBinderFactory binderFactory = this.getDataBinderFactory(handlerMethod);
ModelFactory modelFactory = this.getModelFactory(handlerMethod, binderFactory);
ServletInvocableHandlerMethod invocableMethod = this.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);
Object result;
if (asyncManager.hasConcurrentResult()) {
result = asyncManager.getConcurrentResult();
mavContainer = (ModelAndViewContainer)asyncManager.getConcurrentResultContext()[0];
asyncManager.clearConcurrentResult();
LogFormatUtils.traceDebug(this.logger, (traceOn) -> {
String formatted = LogFormatUtils.formatValue(result, !traceOn);
return "Resume with async result [" + formatted + "]";
});
invocableMethod = invocableMethod.wrapConcurrentResult(result);
}
invocableMethod.invokeAndHandle(webRequest, mavContainer, new Object[0]);
if (asyncManager.isConcurrentHandlingStarted()) {
result = null;
return (ModelAndView)result;
}
var15 = this.getModelAndView(mavContainer, modelFactory, webRequest);
} finally {
webRequest.requestCompleted();
}
return var15;
}
```
invokeAndHandle 反射调用方法
```java
public void invokeAndHandle(ServletWebRequest webRequest, ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception {
// 反射调用Controller中的具体方法
Object returnValue = this.invokeForRequest(webRequest, mavContainer, providedArgs);
this.setResponseStatus(webRequest);
if (returnValue == null) {
if (this.isRequestNotModified(webRequest) || this.getResponseStatus() != null || mavContainer.isRequestHandled()) {
this.disableContentCachingIfNecessary(webRequest);
mavContainer.setRequestHandled(true);
return;
}
} else if (StringUtils.hasText(this.getResponseStatusReason())) {
mavContainer.setRequestHandled(true);
return;
}
mavContainer.setRequestHandled(false);
Assert.state(this.returnValueHandlers != null, "No return value handlers");
try {
this.returnValueHandlers.handleReturnValue(returnValue, this.getReturnValueType(returnValue), mavContainer, webRequest);
} catch (Exception var6) {
if (this.logger.isTraceEnabled()) {
this.logger.trace(this.formatErrorForReturnValue(returnValue), var6);
}
throw var6;
}
}
```
解析结果，渲染视图
```java
private void processDispatchResult(HttpServletRequest request, HttpServletResponse response, @Nullable HandlerExecutionChain mappedHandler, @Nullable ModelAndView mv, @Nullable Exception exception) throws Exception {
boolean errorView = false;
if (exception != null) {
if (exception instanceof ModelAndViewDefiningException) {
this.logger.debug("ModelAndViewDefiningException encountered", exception);
mv = ((ModelAndViewDefiningException)exception).getModelAndView();
} else {
Object handler = mappedHandler != null ? mappedHandler.getHandler() : null;
mv = this.processHandlerException(request, response, handler, exception);
errorView = mv != null;
}
}
if (mv != null && !mv.wasCleared()) {
// 渲染视图
this.render(mv, request, response);
if (errorView) {
WebUtils.clearErrorRequestAttributes(request);
}
} else if (this.logger.isTraceEnabled()) {
this.logger.trace("No view rendering, null ModelAndView returned.");
}
if (!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {
if (mappedHandler != null) {
mappedHandler.triggerAfterCompletion(request, response, (Exception)null);
}
}
}
```