SpringMVC初始化流程：
初始化流程
- 初始化DispatcherServlet；前端控制器
- initMultipartResolver;分段文件解析器
- initLocaleResolver;本地化解析策略
- initThemeResolver;主题解析器
- initHandlerMappings;处理器映射
- initHandlerAdapters;控制适配器
- initHandlerExceptionResolvers;//如果执行过程中遇到异常将交给HandlerExceptionResolver来解析
- initRequestToViewNameTranslator;//直接解析请求到视图名
- initViewResolvers;视图解析器
- initFlashMapManager;flash映射管理器
源码
1. 继承关系
Servlet------>GenericServlet------->HttpServlet------->HttpServletBean------->FramworkServlet
-------->DispatcherServlet
2. 源码分析
1.Servlet接口：
public void init(ServletConfig config) throws ServletException;
2.GenericServlet ： abstract class抽象类 实现了初始化方法。
public void init(ServletConfig config) throws ServletException {
this.config = config;
this.init();
}
调用了空方法
public void init() throws ServletException {
}
3.HttpServlet 没有对初始化相关的方法进行覆盖
4.HttpServletBean 抽象类HttpServletBean 重写了init()方法。
@Override
public final void init() throws ServletException {
if (logger.isDebugEnabled()) {
logger.debug("Initializing servlet '" + getServletName() + "'");
}
// Set bean properties from init parameters.
try {
PropertyValues pvs = new ServletConfigPropertyValues(getServletConfig(), this.requiredProperties);
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);
ResourceLoader resourceLoader = new ServletContextResourceLoader(getServletContext());
bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader, getEnvironment()));
initBeanWrapper(bw);
bw.setPropertyValues(pvs, true);
}
catch (BeansException ex) {
logger.error("Failed to set bean properties on servlet '" + getServletName() + "'", ex);
throw ex;
}
// Let subclasses do whatever initialization they like.
initServletBean();
if (logger.isDebugEnabled()) {
logger.debug("Servlet '" + getServletName() + "' configured successfully");
}
}
同时调用了
protected void initServletBean() throws ServletException {
}
5.FrameworkServlet
果不其然的重写了上边留空的方法 initServletBean（） 它提供了整合web javabean和spring application context的整合方案
@Override
protected final void initServletBean() throws ServletException {
getServletContext().log("Initializing Spring FrameworkServlet '" + getServletName() + "'");
if (this.logger.isInfoEnabled()) {
this.logger.info("FrameworkServlet '" + getServletName() + "': initialization started");
}
long startTime = System.currentTimeMillis();
try {
this.webApplicationContext = initWebApplicationContext();
initFrameworkServlet();
}
catch (ServletException ex) {
this.logger.error("Context initialization failed", ex);
throw ex;
}
catch (RuntimeException ex) {
this.logger.error("Context initialization failed", ex);
throw ex;
}
if (this.logger.isInfoEnabled()) {
long elapsedTime = System.currentTimeMillis() - startTime;
this.logger.info("FrameworkServlet '" + getServletName() + "': initialization completed in " +
elapsedTime + " ms");
}
}
在这个方法中最重要的就是调用了一个 initWebApplicationContext()
protected WebApplicationContext initWebApplicationContext() {
WebApplicationContext rootContext =
WebApplicationContextUtils.getWebApplicationContext(getServletContext());
WebApplicationContext wac = null;
if (this.webApplicationContext != null) {
// A context instance was injected at construction time -> use it
wac = this.webApplicationContext;
if (wac instanceof ConfigurableWebApplicationContext) {
ConfigurableWebApplicationContext cwac = (ConfigurableWebApplicationContext) wac;
if (!cwac.isActive()) {
// The context has not yet been refreshed -> provide services such as
// setting the parent context, setting the application context id, etc
if (cwac.getParent() == null) {
// The context instance was injected without an explicit parent -> set
// the root application context (if any; may be null) as the parent
cwac.setParent(rootContext);
}
configureAndRefreshWebApplicationContext(cwac);
}
}
}
if (wac == null) {
// No context instance was injected at construction time -> see if one
// has been registered in the servlet context. If one exists, it is assumed
// that the parent context (if any) has already been set and that the
// user has performed any initialization such as setting the context id
wac = findWebApplicationContext();
}
if (wac == null) {
// No context instance is defined for this servlet -> create a local one
wac = createWebApplicationContext(rootContext);
}
if (!this.refreshEventReceived) {
// Either the context is not a ConfigurableApplicationContext with refresh
// support or the context injected at construction time had already been
// refreshed -> trigger initial onRefresh manually here.
onRefresh(wac);
}
if (this.publishContext) {
// Publish the context as a servlet context attribute.
String attrName = getServletContextAttributeName();
getServletContext().setAttribute(attrName, wac);
if (this.logger.isDebugEnabled()) {
this.logger.debug("Published WebApplicationContext of servlet '" + getServletName() +
"' as ServletContext attribute with name [" + attrName + "]");
}
}
return wac;
}
在这里调用了 onRefresh()
protected void onRefresh(ApplicationContext context) {
}
6.DispatcherServlet 重写onRefresh方法
@Override
protected void onRefresh(ApplicationContext context) {
initStrategies(context);
}
调用了 initStrategies(context)
protected void initStrategies(ApplicationContext context) {
initMultipartResolver(context);//分段文件解析器
initLocaleResolver(context);// 本地化解析策略
initThemeResolver(context); // 主题解析器
initHandlerMappings(context); // 处理器映射
initHandlerAdapters(context); //控制适配器
initHandlerExceptionResolvers(context); //如果执行过程中遇到异常将交给HandlerExceptionResolver来解析
initRequestToViewNameTranslator(context); //直接解析请求到视图名
initViewResolvers(context); //视图解析器
initFlashMapManager(context); //flash映射管理器
}
用户请求流程：
用户发送请求-------------》DispatcherServlet(前端控制器)----------------》HandlerMapping（映射处理器返回Handler
将Handler传给映射适配器）------------------>HandlerAdapter(映射适配器)-------------------》
Controller（调用Handler返回ModelAndView）------------>View...ViewResolver(视图解析)---------》Model...View(
视图渲染)---------------》返回响应
- 用户发送请求给DispatcherServlet(前端控制器)
- DispatcherServlet调用HandlerMapping（映射处理器返回Handler）
- DispatcherServlet调用andlerAdapter(映射适配器)（传入Handler）返回（ModelAndView）
- DispatcherServlet调用ViewResolver(视图解析)返回（View）
- DispatcherServlet调用-->Model...View(视图渲染）
- 返回响应