Learn Spring - Spring MVC

摘要：例如，将请求信息中的字符串格式参数转换为对应方法中的类类型入参可通过的属性注册自定义转换器。

请求提交给DispatchServlet

查找HandlerMapping

调用由HandlerAdapter封装后的Handler

返回ModelAndView到DispatcherServlet

借由ViewResolver完成逻辑视图到真实视图的转换

返回响应

web.xml

    
    
        contextConfigLocation
        
            /WEB-INF/applicationServlet.xml,
        
    
    
        org.springframework.web.context.ContextLoaderListener
    

    
    
        app
        org.springframework.web.servlet.DispatcherServlet
        
            logLevel
            FINE
        
        1
    

    
    
        app
        /api/*
    

子容器可以访问父容器的bean，父容器不能访问子容器的bean

默认采用org.springframework.web.context.ContextLoaderListener

默认使用/WEB-INF/{servlet-name}-*.xml加载子容器

DispatcherServlet初始化

protected void initStrategies(ApplicationContext context) {
    initMultipartResolver(context);
    initLocaleResolver(context);
    initThemeResolver(context);
    initHandlerMappings(context);
    initHandlerAdapters(context);
    initHandlerExceptionResolvers(context);
    initRequestToViewNameTranslator(context);
    initViewResolvers(context);
    initFlashMapManager(context);
}

默认配置: DispatcherServlet.properties

# Default implementation classes for DispatcherServlet"s strategy interfaces.
# Used as fallback when no matching beans are found in the DispatcherServlet context.
# Not meant to be customized by application developers.

org.springframework.web.servlet.LocaleResolver=org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver

org.springframework.web.servlet.ThemeResolver=org.springframework.web.servlet.theme.FixedThemeResolver

org.springframework.web.servlet.HandlerMapping=org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping,
    org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping

org.springframework.web.servlet.HandlerAdapter=org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter,
    org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter,
    org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter

org.springframework.web.servlet.HandlerExceptionResolver=org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver,
    org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver,
    org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver

org.springframework.web.servlet.RequestToViewNameTranslator=org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator

org.springframework.web.servlet.ViewResolver=org.springframework.web.servlet.view.InternalResourceViewResolver

org.springframework.web.servlet.FlashMapManager=org.springframework.web.servlet.support.SessionFlashMapManager

@Controller(由Spring识别Handler实例)

@RequestMapping(value=, method=, params=)

@RequestMapping(value=, method=, params=)

@PathVariable，配合占位符{parameter}

@RequestParam(value=, required=, defaultValue=)

@CookieValue(value=, required=, defaultValue=)

@RequestHeader(value=, required=, defaultValue=)

HttpServletRequest, WebRequest, ServletRequest的InputStream / Reader

HttpServeltResponse, ServletResponse的OutputStream / Writer

HttpMessageConverter

使用@RequestBody / @ResponseBody；使用HttpEntity / ResponseEntity

Spring根据HTTP报文头部的Accept指定的MIME类型，查找匹配的HttpMessageConverter

Spring MVC默认装配AnnotationMethodHandlerAdapter，调用HttpMessageConverter

mvc命名空间的标签会创建并注册一个默认的DefaultAnnotationHandlerMapping和一个AnnotationMethodHandlerAdapter实例，如果上下文中存在自定义的对应组件bean，则覆盖默认配置

app-servlet.xml

Spring MVC在调用方法前会创建一个隐含的模型对象

ModelAndView：返回值类型为ModelAndView时，方法体通过该对象添加模型数据

@ModelAttribute：入参对象添加到数据模型中

Map和Model：入参为org.springframework.ui.Model、org.springframework.ui.ModelMap或java.util.Map时，处理方法返回时，Map中的数据会自动添加到模型中

@SessionAttributes：将模型中的某个属性暂存到HttpSession中，以便多个请求共享

Spring MVC将ServletRequest对象及处理方法的入参实例传递给DataBinder；

DataBinder调用ConversionService组件进行数据类型转换、数据格式化等工作，将ServletRequest中的消息填充到入参对象中；

然后再调用Validator组件对已经绑定了请求消息数据的入参对象进行数据合法性校验，并最终生成绑定结果BindingResult对象，其中还包含相应的校验错误对象

抽取BindingResult中的入参对象及校验错误对象，赋给处理方法的相应入参

例如：将请求信息中A类型参数转换并绑定到Controller对应的处理方法的B类型入参中

基于ConversionService接口，Spring将自动识别其实现类，用于入参类型转换，类似于C++中的自定义类型转换。例如，将http请求信息中的字符串格式参数转换为Controller对应方法中的类类型入参

可通过ConversionServiceFactoryBean的converters属性注册自定义转换器。可接受Converter，ConverterFacotory，GenericConverter或ConditionalConverterFactory的实现类，并统一封装到一个ConversionService的实例（即GenericConversionService）中

标签还会注册一个默认的ConversionService，即FormattingConversionServiceFactoryBean

例如：将请求信息中字符串类型参数转换并绑定到Controller对应的处理方法入参中的Date类型属性中

格式化框架定义了Formatter接口，扩展于Printer和Parser接口

Srping提供AnnotationFormatterFactory接口及两个实现类：NumberFormatAnnotationFormatterFactory和JodaDateTimeFormatAnnotationFormatterFactory

public Class User {
    private String userId;

    @Pattern(regexp="w{4,30}")
    private String userName;

    @Length(min=2, max=100)
    private String nickName;

    @Past
    @DateTimeFormat(pattern = "yyyy-MM-dd")
    private Date birthday;

    @DecimalMin(value = "1000.00")
    @DecimalMax(value = "10000.00")
    @NumberFormat(pattern = "#,###.##")
    pirvate Long salary;
}


@RequestMapping(value = "/handle")
public void handle(@Valid User uer, BindingResult bindingResult) {
    //do something
}

    






    
    
    
    
        text/html; charset=UTF-8
    
    



    
    
        
            UTF-8
            UTF-8
            
            true
            loopCursor
            0
        
    

public interface HandlerInterceptor {

  boolean preHandle (HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception;

  void postHandle (HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception;

  void afterCompletion (HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception;
}

public interface HandlerExceptionResolver {
  ModelAndView resolveException (HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex);
}

    
    
        404
        /error
    
    
        403
        /error
    
    
        java.lang.Throwable
        /error