blocks|key|311615|text|DispatcherServlet是Spring+MVC对front+controller+pattern的实现。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|311616|请参阅Spring+docs+here中的描述。|311617|本质上，它是一个servlet，它接受传入的请求，并将该请求的处理委托给许多处理程序中的一个处理程序，这些处理程序的映射在DispatcherServlet配置中是特定的。|311618|entityMap|0|LINK|mutability|MUTABLE|url|http://www.oracle.com/technetwork/java/frontcontroller-135648.html|1|http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-servlet^0|0|H|T|O|0|0|F|4|1|0|1P|H|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@$9|W|A|X|1|Y]]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@$9|10|A|11|1|12]]|E|$]]|$1|H|3|I|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]|R|$5|M|N|O|E|$P|S]]]]

<code>DispatcherServlet</code> is Spring MVC's implementation of the <a href="http://www.oracle.com/technetwork/java/frontcontroller-135648.html" rel="noreferrer">front controller pattern</a>.

See description in the Spring docs <a href="http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-servlet" rel="noreferrer">here</a>.

Essentially, it's a servlet that takes the incoming request, and delegates processing of that request to one of a number of handlers, the mapping of which is specific in the <code>DispatcherServlet</code> configuration.

blocks|key|3046038|text|DispatcherServlet的工作是接收传入的URI，并找到处理程序(通常是控制器类上的方法)和视图(通常是JSP)的正确组合，这些组合形成了应该在该位置找到的页面或资源。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3046039|我可能有过|3046040|在类上使用/WEB-INF/jsp/pages/Home.jsp|offset|length|style|CODE|3046041|and+a|unordered-list-item|3046042|
|3046043|a+|3046044|a+file|3046045|3046046|3046047|@RequestMapping(value="/pages/Home.html")私有页面buildHome()+{+ModelMap+buildHome；}|3046048|Dispatcher+servlet是在浏览器请求页面时调用该方法，并将其结果与匹配的JSP文件组合以生成html文档的部分。|3046049|它如何实现这一点因配置和Spring版本的不同而有很大不同。|3046050|也没有理由最终结果必须是网页。它可以做同样的事情来定位RMI端点，处理SOAP请求，以及任何可以进入servlet的东西。|3046051|entityMap^0|0|0|5|R|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|16|8|@$F|17|G|18|H|I]]|9|@]|A|$]]|$1|J|3|K|5|L|7|19|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|1A|8|@]|9|@]|A|$]]|$1|O|3|P|5|L|7|1B|8|@]|9|@]|A|$]]|$1|Q|3|R|5|L|7|1C|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1F|8|@]|9|@]|A|$]]|$1|W|3|X|5|6|7|1G|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1H|8|@]|9|@]|A|$]]|$1|10|3|11|5|6|7|1I|8|@]|9|@]|A|$]]|$1|12|3|-4|5|6|7|1J|8|@]|9|@]|A|$]]]|13|$]]

The job of the DispatcherServlet is to take an incoming URI and find the right combination of handlers (generally methods on Controller classes) and views (generally JSPs) that combine to form the page or resource that's supposed to be found at that location.

I might have

<ul>
<li>a file <code>/WEB-INF/jsp/pages/Home.jsp</code></li>
<li>and a method on a class

<pre><code>@RequestMapping(value="/pages/Home.html")
private ModelMap buildHome() {
 return somestuff;
}
</code></pre></li>
</ul>

The Dispatcher servlet is the bit that "knows" to call that method when a browser requests the page, and to combine its results with the matching JSP file to make an html document.

How it accomplishes this varies widely with configuration and Spring version.

There's also no reason the end result has to be web pages. It can do the same thing to locate RMI end points, handle SOAP requests, anything that can come into a servlet.

blocks|key|308504|text|我们可以说，就像DispatcherServlet处理Spring+MVC中的一切一样。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|308505|在web容器启动时：|308506|308507|DispatcherServlet将通过调用init()来加载和初始化，DispatcherServlet的method|ordered-list-item|308508|init()将尝试使用类似于"servlet_name-servlet.xml"的命名约定来标识init()配置文档，然后可以标识所有bean。|308509|308510|示例：|308511|public+class+DispatcherServlet+extends+HttpServlet+{

++++ApplicationContext+ctx+=+null;

++++public+void+init(ServletConfig+cfg){
++++++++//+1.+try+to+get+the+spring+configuration+document+with+default+naming+conventions
++++++++String+xml+=+"servlet_name"+%2B+"-servlet.xml";

++++++++//if+it+was+found+then+creates+the+ApplicationContext+object
++++++++ctx+=+new+XmlWebApplicationContext(xml);
++++}
++++...
}|code-block|syntax|javascript|308512|因此，在一般情况下，DispatcherServlet捕获请求URI并移交给HandlerMapping。HandlerMapping使用控制器的方法查找映射bean，其中控制器返回逻辑名称(视图)。然后，此逻辑名称由HandlerMapping发送到DispatcherServlet。然后DispatcherServlet告诉ViewResolver通过附加前缀和后缀来提供视图的完整位置，然后DispatcherServlet将视图提供给客户端。|308513|entityMap^0|8|H|0|0|0|0|H|M|6|10|H|0|0|6|E|Q|1C|6|0|0|0|0|A|H|12|E|1H|E|31|E|3I|H|42|H|4L|C|5J|H|0^^$0|@$1|2|3|4|5|6|7|Z|8|@$9|10|A|11|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|12|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|13|8|@]|D|@]|E|$]]|$1|I|3|J|5|K|7|14|8|@$9|15|A|16|B|C]|$9|17|A|18|B|C]|$9|19|A|1A|B|C]]|D|@]|E|$]]|$1|L|3|M|5|K|7|1B|8|@$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]]|D|@]|E|$]]|$1|N|3|-4|5|6|7|1I|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|1J|8|@]|D|@]|E|$]]|$1|Q|3|R|5|S|7|1K|8|@]|D|@]|E|$T|U]]|$1|V|3|W|5|6|7|1L|8|@$9|1M|A|1N|B|C]|$9|1O|A|1P|B|C]|$9|1Q|A|1R|B|C]|$9|1S|A|1T|B|C]|$9|1U|A|1V|B|C]|$9|1W|A|1X|B|C]|$9|1Y|A|1Z|B|C]|$9|20|A|21|B|C]]|D|@]|E|$]]|$1|X|3|-4|5|6|7|22|8|@]|D|@]|E|$]]]|Y|$]]

We can say like <code>DispatcherServlet</code> taking care of everything in Spring MVC.

At web container start up:

<ol>
<li><code>DispatcherServlet</code> will be loaded and initialized by calling
<code>init()</code> method</li>
<li><code>init()</code> of <code>DispatcherServlet</code> will try to identify the Spring
 Configuration Document with naming conventions like
 <code>"servlet_name-servlet.xml"</code> then all beans can be identified.</li>
</ol>

Example:

<pre><code>public class DispatcherServlet extends HttpServlet {

 ApplicationContext ctx = null;

 public void init(ServletConfig cfg){
 // 1. try to get the spring configuration document with default naming conventions
 String xml = "servlet_name" + "-servlet.xml";

 //if it was found then creates the ApplicationContext object
 ctx = new XmlWebApplicationContext(xml);
 }
 ...
}
</code></pre>

So, in generally <code>DispatcherServlet</code> capture request URI and hand over to <code>HandlerMapping</code>. <code>HandlerMapping</code> search mapping bean with method of controller, where controller returning logical name(view). Then this logical name is send to <code>DispatcherServlet</code> by <code>HandlerMapping</code>. Then <code>DispatcherServlet</code> tell <code>ViewResolver</code> to give full location of view by appending prefix and suffix, then <code>DispatcherServlet</code> give view to the client.

blocks|key|3046091|text|在Spring+MVC中，所有传入的请求都通过单个servlet。这个servlet+--+DispatcherServlet+--是前端控制器。前端控制器是web应用开发中一种典型的设计模式。在这种情况下，单个servlet接收所有请求并将它们传输到应用程序的所有其他组件。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3046092|DispatcherServlet的任务是向特定的Spring+MVC控制器发送请求。|3046093|通常我们有很多控制器，DispatcherServlet引用以下映射器之一来确定目标控制器：|3046094|3046095|BeanNameUrlHandlerMapping;|unordered-list-item|3046096|ControllerBeanNameHandlerMapping;|3046097|ControllerClassNameHandlerMapping;|3046098|DefaultAnnotationHandlerMapping;|3046099|SimpleUrlHandlerMapping.|3046100|3046101|如果未执行任何配置，则DispatcherServlet默认使用BeanNameUrlHandlerMapping和DefaultAnnotationHandlerMapping。|3046102|识别出目标控制器后，DispatcherServlet会向其发送请求。控制器根据请求执行一些工作(或将其委托给其他对象)，并将模型和视图的名称返回给DispatcherServlet。|3046103|视图的名称只是一个逻辑名称。然后使用此逻辑名称搜索实际的视图(以避免与控制器和特定视图耦合)。然后，DispatcherServlet引用ViewResolver并将视图的逻辑名称映射到视图的特定实现。|3046104|ViewResolver的一些可能实现包括：|3046105|3046106|BeanNameViewResolver;|3046107|ContentNegotiatingViewResolver;|3046108|FreeMarkerViewResolver;|3046109|InternalResourceViewResolver;|3046110|JasperReportsViewResolver;|3046111|ResourceBundleViewResolver;|3046112|TilesViewResolver;|3046113|UrlBasedViewResolver;|3046114|VelocityLayoutViewResolver;|3046115|VelocityViewResolver;|3046116|XmlViewResolver;|3046117|XsltViewResolver.|3046118|3046119|当DispatcherServlet确定将显示结果的视图时，它将被呈现为响应。|3046120|最后，DispatcherServlet将Response对象返回给客户端。|3046121|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/handler/BeanNameUrlHandlerMapping.html|1|http://docs.spring.io/spring-framework/docs/2.5.6/api/org/springframework/web/servlet/mvc/support/ControllerBeanNameHandlerMapping.html|2|http://docs.spring.io/spring-framework/docs/2.5.x/api/org/springframework/web/servlet/mvc/support/ControllerClassNameHandlerMapping.html|3|http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/mvc/annotation/DefaultAnnotationHandlerMapping.html|4|http://docs.spring.io/spring-framework/docs/2.5.x/api/org/springframework/web/servlet/handler/SimpleUrlHandlerMapping.html|5|https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/ViewResolver.html|6|http://docs.spring.io/spring-framework/docs/2.0.8/api/org/springframework/web/servlet/view/BeanNameViewResolver.html|7|http://docs.spring.io/autorepo/docs/spring/3.2.5.RELEASE/javadoc-api/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.html|8|https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/freemarker/FreeMarkerViewResolver.html|9|http://docs.spring.io/spring-framework/docs/2.5.6/api/org/springframework/web/servlet/view/InternalResourceViewResolver.html|10|https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/jasperreports/JasperReportsViewResolver.html|11|http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/ResourceBundleViewResolver.html|12|https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/tiles2/TilesViewResolver.html|13|http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/UrlBasedViewResolver.html|14|http://docs.spring.io/spring-framework/docs/2.0.x/api/org/springframework/web/servlet/view/velocity/VelocityLayoutViewResolver.html|15|https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/velocity/VelocityViewResolver.html|16|https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/XmlViewResolver.html|17|https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/xslt/XsltViewResolver.html^0|1A|H|0|0|H|0|B|H|0|0|0|P|0|P|0|0|0|W|0|W|1|0|0|X|0|X|2|0|0|V|0|V|3|0|0|N|0|N|4|0|0|B|H|W|P|1M|V|0|A|H|22|H|0|1E|H|1X|C|1X|C|5|0|0|C|0|0|0|K|0|K|6|0|0|U|0|U|7|0|0|M|0|M|8|0|0|S|0|S|9|0|0|P|0|P|A|0|0|Q|0|Q|B|0|0|H|0|H|C|0|0|K|0|K|D|0|0|Q|0|Q|E|0|0|K|0|K|F|0|0|F|0|F|G|0|0|G|0|G|H|0|0|1|H|0|3|H|L|8|0^^$0|@$1|2|3|4|5|6|7|34|8|@$9|35|A|36|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|37|8|@$9|38|A|39|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|3A|8|@$9|3B|A|3C|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|3D|8|@]|D|@]|E|$]]|$1|K|3|L|5|M|7|3E|8|@$9|3F|A|3G|B|C]]|D|@$9|3H|A|3I|1|3J]]|E|$]]|$1|N|3|O|5|M|7|3K|8|@$9|3L|A|3M|B|C]]|D|@$9|3N|A|3O|1|3P]]|E|$]]|$1|P|3|Q|5|M|7|3Q|8|@$9|3R|A|3S|B|C]]|D|@$9|3T|A|3U|1|3V]]|E|$]]|$1|R|3|S|5|M|7|3W|8|@$9|3X|A|3Y|B|C]]|D|@$9|3Z|A|40|1|41]]|E|$]]|$1|T|3|U|5|M|7|42|8|@$9|43|A|44|B|C]]|D|@$9|45|A|46|1|47]]|E|$]]|$1|V|3|-4|5|6|7|48|8|@]|D|@]|E|$]]|$1|W|3|X|5|6|7|49|8|@$9|4A|A|4B|B|C]|$9|4C|A|4D|B|C]|$9|4E|A|4F|B|C]]|D|@]|E|$]]|$1|Y|3|Z|5|6|7|4G|8|@$9|4H|A|4I|B|C]|$9|4J|A|4K|B|C]]|D|@]|E|$]]|$1|10|3|11|5|6|7|4L|8|@$9|4M|A|4N|B|C]|$9|4O|A|4P|B|C]]|D|@$9|4Q|A|4R|1|4S]]|E|$]]|$1|12|3|13|5|6|7|4T|8|@$9|4U|A|4V|B|C]]|D|@]|E|$]]|$1|14|3|-4|5|6|7|4W|8|@]|D|@]|E|$]]|$1|15|3|16|5|M|7|4X|8|@$9|4Y|A|4Z|B|C]]|D|@$9|50|A|51|1|52]]|E|$]]|$1|17|3|18|5|M|7|53|8|@$9|54|A|55|B|C]]|D|@$9|56|A|57|1|58]]|E|$]]|$1|19|3|1A|5|M|7|59|8|@$9|5A|A|5B|B|C]]|D|@$9|5C|A|5D|1|5E]]|E|$]]|$1|1B|3|1C|5|M|7|5F|8|@$9|5G|A|5H|B|C]]|D|@$9|5I|A|5J|1|5K]]|E|$]]|$1|1D|3|1E|5|M|7|5L|8|@$9|5M|A|5N|B|C]]|D|@$9|5O|A|5P|1|5Q]]|E|$]]|$1|1F|3|1G|5|M|7|5R|8|@$9|5S|A|5T|B|C]]|D|@$9|5U|A|5V|1|5W]]|E|$]]|$1|1H|3|1I|5|M|7|5X|8|@$9|5Y|A|5Z|B|C]]|D|@$9|60|A|61|1|62]]|E|$]]|$1|1J|3|1K|5|M|7|63|8|@$9|64|A|65|B|C]]|D|@$9|66|A|67|1|68]]|E|$]]|$1|1L|3|1M|5|M|7|69|8|@$9|6A|A|6B|B|C]]|D|@$9|6C|A|6D|1|6E]]|E|$]]|$1|1N|3|1O|5|M|7|6F|8|@$9|6G|A|6H|B|C]]|D|@$9|6I|A|6J|1|6K]]|E|$]]|$1|1P|3|1Q|5|M|7|6L|8|@$9|6M|A|6N|B|C]]|D|@$9|6O|A|6P|1|6Q]]|E|$]]|$1|1R|3|1S|5|M|7|6R|8|@$9|6S|A|6T|B|C]]|D|@$9|6U|A|6V|1|6W]]|E|$]]|$1|1T|3|-4|5|6|7|6X|8|@]|D|@]|E|$]]|$1|1U|3|1V|5|6|7|6Y|8|@$9|6Z|A|70|B|C]]|D|@]|E|$]]|$1|1W|3|1X|5|6|7|71|8|@$9|72|A|73|B|C]|$9|74|A|75|B|C]]|D|@]|E|$]]|$1|1Y|3|-4|5|6|7|76|8|@]|D|@]|E|$]]]|1Z|$20|$5|21|22|23|E|$24|25]]|26|$5|21|22|23|E|$24|27]]|28|$5|21|22|23|E|$24|29]]|2A|$5|21|22|23|E|$24|2B]]|2C|$5|21|22|23|E|$24|2D]]|2E|$5|21|22|23|E|$24|2F]]|2G|$5|21|22|23|E|$24|2H]]|2I|$5|21|22|23|E|$24|2J]]|2K|$5|21|22|23|E|$24|2L]]|2M|$5|21|22|23|E|$24|2N]]|2O|$5|21|22|23|E|$24|2P]]|2Q|$5|21|22|23|E|$24|2R]]|2S|$5|21|22|23|E|$24|2T]]|2U|$5|21|22|23|E|$24|2V]]|2W|$5|21|22|23|E|$24|2X]]|2Y|$5|21|22|23|E|$24|2Z]]|30|$5|21|22|23|E|$24|31]]|32|$5|21|22|23|E|$24|33]]]]

In Spring MVC, all incoming requests go through a single servlet. This servlet - <code>DispatcherServlet</code> - is the front controller. Front controller is a typical design pattern in the web applications development. In this case, a single servlet receives all requests and transfers them to all other components of the application.

The task of the <code>DispatcherServlet</code> is to send request to the specific Spring MVC controller.

Usually we have a lot of controllers and <code>DispatcherServlet</code> refers to one of the following mappers in order to determine the target controller:

<ul>
<li><a href="http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/handler/BeanNameUrlHandlerMapping.html" rel="noreferrer"><code>BeanNameUrlHandlerMapping</code></a>;</li>
<li><a href="http://docs.spring.io/spring-framework/docs/2.5.6/api/org/springframework/web/servlet/mvc/support/ControllerBeanNameHandlerMapping.html" rel="noreferrer"><code>ControllerBeanNameHandlerMapping</code></a>;</li>
<li><a href="http://docs.spring.io/spring-framework/docs/2.5.x/api/org/springframework/web/servlet/mvc/support/ControllerClassNameHandlerMapping.html" rel="noreferrer"><code>ControllerClassNameHandlerMapping</code></a>;</li>
<li><a href="http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/mvc/annotation/DefaultAnnotationHandlerMapping.html" rel="noreferrer"><code>DefaultAnnotationHandlerMapping</code></a>;</li>
<li><a href="http://docs.spring.io/spring-framework/docs/2.5.x/api/org/springframework/web/servlet/handler/SimpleUrlHandlerMapping.html" rel="noreferrer"><code>SimpleUrlHandlerMapping</code></a>.</li>
</ul>

If no configuration is performed, the <code>DispatcherServlet</code> uses <code>BeanNameUrlHandlerMapping</code> and <code>DefaultAnnotationHandlerMapping</code> by default.

When the target controller is identified, the <code>DispatcherServlet</code> sends request to it. The controller performs some work according to the request 
(or delegate it to the other objects), and returns back to the <code>DispatcherServlet</code> with the Model and the name of the View.

The name of the View is only a logical name. This logical name is then used to search for the actual View (to avoid coupling with the controller and specific View). Then <code>DispatcherServlet</code> refers to the <a href="https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/ViewResolver.html" rel="noreferrer"><code>ViewResolver</code></a> and maps the logical name of the View to the specific implementation of the View.

Some possible Implementations of the <code>ViewResolver</code> are:

<ul>
<li><a href="http://docs.spring.io/spring-framework/docs/2.0.8/api/org/springframework/web/servlet/view/BeanNameViewResolver.html" rel="noreferrer"><code>BeanNameViewResolver</code></a>;</li>
<li><a href="http://docs.spring.io/autorepo/docs/spring/3.2.5.RELEASE/javadoc-api/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.html" rel="noreferrer"><code>ContentNegotiatingViewResolver</code></a>;</li>
<li><a href="https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/freemarker/FreeMarkerViewResolver.html" rel="noreferrer"><code>FreeMarkerViewResolver</code></a>;</li>
<li><a href="http://docs.spring.io/spring-framework/docs/2.5.6/api/org/springframework/web/servlet/view/InternalResourceViewResolver.html" rel="noreferrer"><code>InternalResourceViewResolver</code></a>;</li>
<li><a href="https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/jasperreports/JasperReportsViewResolver.html" rel="noreferrer"><code>JasperReportsViewResolver</code></a>;</li>
<li><a href="http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/ResourceBundleViewResolver.html" rel="noreferrer"><code>ResourceBundleViewResolver</code></a>;</li>
<li><a href="https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/tiles2/TilesViewResolver.html" rel="noreferrer"><code>TilesViewResolver</code></a>;</li>
<li><a href="http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/UrlBasedViewResolver.html" rel="noreferrer"><code>UrlBasedViewResolver</code></a>;</li>
<li><a href="http://docs.spring.io/spring-framework/docs/2.0.x/api/org/springframework/web/servlet/view/velocity/VelocityLayoutViewResolver.html" rel="noreferrer"><code>VelocityLayoutViewResolver</code></a>;</li>
<li><a href="https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/velocity/VelocityViewResolver.html" rel="noreferrer"><code>VelocityViewResolver</code></a>;</li>
<li><a href="https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/XmlViewResolver.html" rel="noreferrer"><code>XmlViewResolver</code></a>;</li>
<li><a href="https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/view/xslt/XsltViewResolver.html" rel="noreferrer"><code>XsltViewResolver</code></a>.</li>
</ul>

When the <code>DispatcherServlet</code> determines the view that will display the results it will be rendered as the response.

Finally, the <code>DispatcherServlet</code> returns the <code>Response</code> object back to the client.

blocks|key|306525|text|我知道这个问题已经被标记为已解决，但我想添加一个更新的图像来详细解释这个模式(来源:+spring+in+action+4)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|306526|​|306527|📷|atomic|offset|length|306528|306529|说明|style|BOLD|306530|当请求离开浏览器(1)时，它会携带有关用户请求内容的信息。至少，该请求将携带所请求的URL。但它也可以携带额外的数据，例如用户以表单形式提交的信息。|306531|请求之旅的第一站是Spring的DispatcherServlet。像大多数基于Java的web框架一样，Spring+MVC通过单个前端控制器servlet发送请求。前端控制器是一种常见的web应用程序模式，其中单个servlet将请求的责任委托给应用程序的其他组件，以执行实际处理。在Spring+MVC的情况下，DispatcherServlet是前端控制器。DispatcherServlet的任务是将请求发送到Spring+MVC控制器。控制器是处理请求的Spring组件。但是一个典型的应用程序可能有几个控制器，DispatcherServlet需要一些帮助来决定将请求发送到哪个控制器。因此，DispatcherServlet会查询一个或多个处理程序映射(2)，以确定请求的下一站在哪里。处理程序映射在做出决定时会特别注意请求所携带的URL。一旦选择了适当的控制器，DispatcherServlet就会轻松地将请求发送到所选的控制器(3)。在控制器处，请求丢弃其有效负载(用户提交的信息)，并耐心地等待控制器处理该信息。(实际上，一个设计良好的控制器本身很少或根本不执行处理，而是将业务逻辑的责任委托给一个或多个服务对象。)控制器执行的逻辑通常导致需要带回给用户并在浏览器中显示的一些信息。此信息称为模型。但是将原始信息发送回用户是不够的-它需要以用户友好的格式进行格式化，通常是HTML。为此，需要将信息提供给视图，通常是JavaServer页。控制器所做的最后一件事是打包模型数据，并标识应该呈现输出的视图的名称。然后，它将请求连同模型和视图名称一起发送回DispatcherServlet+(4)。因此，控制器不会耦合到特定的视图，传递回DispatcherServlet的视图名称不会直接标识特定的JSP。它甚至不一定表明视图是一个JSP。相反，它只带有一个逻辑名称，该名称将用于查找将产生结果的实际视图。DispatcherServlet咨询视图解析器(5)以将逻辑视图名称映射到特定视图实现，其可以是也可以不是JSP.既然DispatcherServlet知道哪个视图将呈现结果，那么请求的工作就快结束了。它的最后一站是视图实现(6)，通常是JSP，它在这里传递模型数据。请求的工作终于完成了。视图将使用模型数据来呈现输出，这些输出将由(不是很努力的)响应对象(7)传回客户机。|306532|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/d9fa7921357e6099fa5be152c4718533.png|imageAlt^0|0|0|0|1|0|0|0|0|2|0|8|3|0|9A|3|BS|3|JM|3|NB|3|PS|3|RM|3|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|12|8|@]|9|@$G|13|H|14|1|15]]|A|$]]|$1|I|3|C|5|6|7|16|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|17|8|@$G|18|H|19|L|M]]|9|@]|A|$]]|$1|N|3|O|5|6|7|1A|8|@$G|1B|H|1C|L|M]]|9|@]|A|$]]|$1|P|3|Q|5|6|7|1D|8|@$G|1E|H|1F|L|M]|$G|1G|H|1H|L|M]|$G|1I|H|1J|L|M]|$G|1K|H|1L|L|M]|$G|1M|H|1N|L|M]|$G|1O|H|1P|L|M]]|9|@]|A|$]]|$1|R|3|-4|5|6|7|1Q|8|@]|9|@]|A|$]]]|S|$T|$5|U|V|W|A|$X|Y|Z|-4]]]]

I know this question is marked as solved already but I want to add a newer image explaining this pattern in detail(source: spring in action 4):

<a href="https://i.stack.imgur.com/o2rzM.png" rel="noreferrer"><img src="https://i.stack.imgur.com/o2rzM.png" alt="enter image description here"></a>

Explanation

When the request leaves the browser (1), it carries information about what the user is asking for. At the least, the request will be carrying the requested URL. But it may also carry additional data, such as the information submitted in a form by the user.

The first stop in the request’s travels is at Spring’s DispatcherServlet. Like most Java- based web frameworks, Spring MVC funnels requests through a single front controller servlet. A front controller is a common web application pattern where a single servlet delegates responsibility for a request to other components of an application to per- form actual processing. In the case of Spring MVC, DispatcherServlet is the front controller.
The DispatcherServlet’s job is to send the request on to a Spring MVC controller. A controller is a Spring component that processes the request. But a typical application may have several controllers, and DispatcherServlet needs some help deciding which controller to send the request to. So the DispatcherServlet consults one or more handler mappings (2) to figure out where the request’s next stop will be. The handler mapping pays particular attention to the URL carried by the request when making its decision.
Once an appropriate controller has been chosen, DispatcherServlet sends the request on its merry way to the chosen controller (3). At the controller, the request drops off its payload (the information submitted by the user) and patiently waits while the controller processes that information. (Actually, a well-designed controller per- forms little or no processing itself and instead delegates responsibility for the business logic to one or more service objects.)
The logic performed by a controller often results in some information that needs to be carried back to the user and displayed in the browser. This information is referred to as the model. But sending raw information back to the user isn’t suffi- cient—it needs to be formatted in a user-friendly format, typically HTML. For that, the information needs to be given to a view, typically a JavaServer Page (JSP).
One of the last things a controller does is package up the model data and identify the name of a view that should render the output. It then sends the request, along with the model and view name, back to the DispatcherServlet (4).
So that the controller doesn’t get coupled to a particular view, the view name passed back to DispatcherServlet doesn’t directly identify a specific JSP. It doesn’t even necessarily suggest that the view is a JSP. Instead, it only carries a logical name that will be used to look up the actual view that will produce the result. The DispatcherServlet consults a view resolver (5) to map the logical view name to a spe- cific view implementation, which may or may not be a JSP.
Now that DispatcherServlet knows which view will render the result, the request’s job is almost over. Its final stop is at the view implementation (6), typically a JSP, where it delivers the model data. The request’s job is finally done. The view will use the model data to render output that will be carried back to the client by the (not- so-hardworking) response object (7).

blocks|key|3259989|text|Dispatcher+controller在图中显示，所有传入的请求都被用作前端控制器的dispatcher+servlet截获。dispatcher+servlet从XML文件中获取一个映射到处理程序的条目，并将请求转发给Controller。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3259990|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Dispatcher Controller are displayed in the figure all the incoming request is in intercepted by the dispatcher servlet that works as front controller.
The dispatcher servlet gets an entry to handler mapping from the XML file and forwords the request to the Controller.

blocks|key|3260015|text|<?xml+version='1.0'+encoding='UTF-8'+?>

<beans+xmlns="http://www.springframework.org/schema/beans"
+++++++xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+++++++xmlns:p="http://www.springframework.org/schema/p"
+++++++xmlns:aop="http://www.springframework.org/schema/aop"
+++++++xmlns:context="http://www.springframework.org/schema/context"
+++++++xmlns:mvc="http://www.springframework.org/schema/mvc"
+++++++xmlns:tx="http://www.springframework.org/schema/tx"
+++++++xsi:schemaLocation="http://www.springframework.org/schema/beans+http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
+++++++http://www.springframework.org/schema/aop+http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
+++++++http://www.springframework.org/schema/tx+http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
++++++++http://www.springframework.org/schema/mvc+http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
+++++++++++++++http://www.springframework.org/schema/context+http://www.springframework.org/schema/context/spring-context-4.0.xsd">

++++<bean+class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping"/>
++++<context:component-scan+base-package="com.demo"+/>
++++<context:annotation-config+/>

++++<mvc:annotation-driven+/>


++++<bean+id="viewResolver"
++++++++++class="org.springframework.web.servlet.view.InternalResourceViewResolver"
++++++++++p:prefix="/WEB-INF/jsp/"
++++++++++p:suffix=".jsp"+/>

++++<bean+id="jdbcTemplate"+class="org.springframework.jdbc.core.JdbcTemplate">
++++++++<property+name="dataSource"+ref="datasource"+/>
++++</bean>+

++++++++++<bean+id="datasource"+class="org.springframework.jdbc.datasource.DriverManagerDataSource">
++++++++<property+name="driverClassName"+value="com.mysql.jdbc.Driver"+/>++
++++++++<property+name="url"+value="jdbc:mysql://localhost:3306/employee"+/>
++++++++<property+name="username"+value="username"+/>
++++++++<property+name="password"+value="password"+/>
++++</bean>+

</beans>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3260016|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>&lt;?xml version='1.0' encoding='UTF-8' ?&gt;
&lt;!-- was: &lt;?xml version="1.0" encoding="UTF-8"?&gt; --&gt;
&lt;beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns:p="http://www.springframework.org/schema/p"
 xmlns:aop="http://www.springframework.org/schema/aop"
 xmlns:context="http://www.springframework.org/schema/context"
 xmlns:mvc="http://www.springframework.org/schema/mvc"
 xmlns:tx="http://www.springframework.org/schema/tx"
 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
 http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
 http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
 http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd"&gt;

 &lt;bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping"/&gt;
 &lt;context:component-scan base-package="com.demo" /&gt;
 &lt;context:annotation-config /&gt;

 &lt;mvc:annotation-driven /&gt;


 &lt;bean id="viewResolver"
 class="org.springframework.web.servlet.view.InternalResourceViewResolver"
 p:prefix="/WEB-INF/jsp/"
 p:suffix=".jsp" /&gt;

 &lt;bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate"&gt;
 &lt;property name="dataSource" ref="datasource" /&gt;
 &lt;/bean&gt; 

 &lt;bean id="datasource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"&gt;
 &lt;property name="driverClassName" value="com.mysql.jdbc.Driver" /&gt; 
 &lt;property name="url" value="jdbc:mysql://localhost:3306/employee" /&gt;
 &lt;property name="username" value="username" /&gt;
 &lt;property name="password" value="password" /&gt;
 &lt;/bean&gt; 

&lt;/beans&gt;
</code></pre>

blocks|key|3260099|text|您可以说Dispatcher+Servlet充当任何请求的入口点和出口点。当请求到达时，它首先转到Dispatcher+Servlet(+DS+)，然后DS尝试标识其处理程序方法(您在控制器中定义的处理请求的方法)，一旦处理程序映射器(DS要求处理程序映射器)返回控制器，dispatcher+servlet就知道可以处理此请求的控制器，现在可以转到此控制器以进一步完成请求的处理。现在控制器可以响应一个适当的响应，然后DS转到视图解析器来识别视图所在的位置，一旦视图解析器告诉DS，它就会获取该视图，并将其作为最终响应返回给您。我添加了一张图片，这张图片是我从YouTube的Java+Guides频道获取的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3260100|​|3260101|📷|atomic|offset|length|3260102|3260103|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/ec8aa3ab78e1aff265556ad7a8e22963.png|imageAlt^0|0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@$G|V|H|W|1|X]]|A|$]]|$1|I|3|C|5|6|7|Y|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|Q|R|-4]]]]

You can say Dispatcher Servlet acts as an entry and exit point for any request. Whenever a request comes it first goes to the Dispatcher Servlet(DS) where the DS then tries to identify its handler method ( the methods you define in the controller to handle the requests ), once the handler mapper (The DS asks the handler mapper) returns the controller the dispatcher servlet knows the controller which can handle this request and can now go to this controller to further complete the processing of the request. Now the controller can respond with an appropriate response and then the DS goes to the view resolver to identify where the view is located and once the view resolver tells the DS it then grabs that view and returns it back to you as the final response. I am adding an image which I took from YouTube from the channel Java Guides.
<a href="https://i.stack.imgur.com/KA81b.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KA81b.png" alt="Dispatcher Servlet in Action" /></a>

In this image (which I got from <a href="http://maestric.com/wiki/lib/exe/fetch.php?w=&amp;h=&amp;cache=cache&amp;media=java:spring:spring_mvc.png" rel="noreferrer">here</a>), HTTP request sends something to Dispatcher Servlet. 

<img src="https://i.stack.imgur.com/nRDbB.png" alt="enter image description here">

My Question is what does Dispatcher Servlet do?

Is it something like getting the information thrown from the web page and throwing it to the controller?

What is Dispatcher Servlet in Spring?

容器

Java

在这个图像(我从获得)中，HTTP请求向Dispatcher Servlet发送了一些东西。​​我的问题是Dispatcher Servlet做了什么？这是不是有点像从网页上抛出的信息，然后把它扔给控制器呢？

问什么是Spring中的Dispatcher Servlet？
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问什么是Spring中的Dispatcher Servlet？EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问什么是Spring中的Dispatcher Servlet？
EN