Springmvc 请求转发 No mapping found for HTTP request

快来打我* 2022-09-18 00:56 185阅读 0赞

If you are using tags like @RequestMapping, @Controller, etc, you have to use

<mvc:annotation-driven /> instead of <annotation-driven />.

MVC Simplifications in Spring 3.0

ENGINEERING

![null_s_20_d_mm][] KEITH DONALD

DECEMBER 21, 2009

As [Juergen][] and [Arjen][] have mentioned, Java developers everywhere have a smooth upgrade with Spring 3.0. Now that Spring 3 is out, I'd like to take you through some of the new *MVC*features you may not know about. I hope you find these features useful and can start putting them to work in your web applications immediately.

This is also the start of a series on "Spring 3 Simplifications", so expect more posts like these in the coming days and weeks.

## Configuration Simplification ##

Spring 3 introduces a [mvc][] namespace that greatly simplifies Spring MVC setup. Along with other enhancements, it has never been easier to get Spring web applications up and running. This can be illustrated by the [mvc-basic][] sample, which I will now walk you through.

[mvc-basic][] has been designed to illustrate a basic set of Spring MVC features. The project is available at our [spring-samples][] SVN repository, is buildable with Maven, and is importable into Eclipse. Start your review with [web.xml][] and notice the configuration there. Notably, a DispatcherServlet is configured with a single master Spring configuration file that initializes all other application components. The DispatcherServlet is configured as the default servlet for the application (mapped to "/"), allowing for clean, REST-ful URLs.

Inside the master [servlet-context.xml][], you'll find a typical setup. On the first line, component scanning has been turned on to discover application components from the classpath. On the next line, you'll find the first new Spring MVC 3 feature in action:

<mvc:annotation-driven />

This tag registers the HandlerMapping and HandlerAdapter required to dispatch requests to your @Controllers. In addition, it applies sensible defaults based on what is present in your classpath. Such defaults include:

*  Using the Spring 3 Type [ConversionService][] as a simpler and more robust alternative to JavaBeans PropertyEditors
 *  Support for formatting Number fields with [@NumberFormat][NumberFormat]
 *  Support for formatting Date, Calendar, and Joda Time fields with [@DateTimeFormat][DateTimeFormat], if Joda Time is on the classpath
 *  Support for validating @Controller inputs with @Valid, if a JSR-303 Provider is on the classpath
 *  Support for reading and writing XML, if JAXB is on the classpath
 *  Support for reading and writing JSON, if [Jackson][] is on the classpath

Pretty cool, huh?

Moving on, the next line demonstrates another new feature:

<mvc:view-controller path="/" view-name="welcome" />

Behind the scenes, mvc:view-controller registers a ParameterizableViewController that selects a view for rendering. In this case, when "/" is requested, the welcome view is rendered. The actual view template is a .jsp resolved inside the /WEB-INF/views directory.

Moving on, the next line shows yet another new feature:

<mvc:interceptors>
        
        <bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor" />
    </mvc:interceptors>

The mvc:interceptors tag allows you to register HandlerInterceptors to apply to all controllers. Previously, to do this you had to explicitly register such interceptors *with each*HandlerMapping bean, which was repetitive. Also note this tag now lets you restrict which URL paths certain interceptors apply to.

Moving on, the next line hightlights a new feature added in version 3.0.4:

<mvc:resources mapping="/resources/**" location="/resources/" />

The mvc:resources tag lets you configure a handler for static resources, such as css and javascript files. In this case, requests for /resources/\*\* are mapped to files inside the /resources directory.

Putting things in motion, if you deploy the sample you should see the welcome view render:

[![mvc-basic][mvc-basic 1]][mvc-basic 1]

Feel free to activate the different language links to have the LocaleChangeInterceptor switch the user locale.

## Data Binding Simplification ##

The next set of new features I'll illustrate pertain to @Controller binding and validation. As I[blogged about][] a few weeks ago, there is a lot new in this area.

In the sample, if you activate the @Controller Example link the following form should render:

[![mvc-basic-form][]][mvc-basic-form]

From there, if you change the locale you should see internationalized field formatting kick in. For example, switching from **en** to **de** would cause the Renewal Date 12/21/10 to be formatted 21.12.10. This behavior and the form's validation rules are driven by model annotations:

public class Account {
        
    
        @NotNull
        @Size(min=1, max=25)
        private String name;
    
        @NotNull
        @NumberFormat(style=Style.CURRENCY)
        private BigDecimal balance = new BigDecimal("1000");
    
        @NotNull
        @NumberFormat(style=Style.PERCENT)
        private BigDecimal equityAllocation = new BigDecimal(".60");
    
        @DateTimeFormat(style="S-")
        @Future
        private Date renewalDate = new Date(new Date().getTime() + 31536000000L);
    
    }

Form submit is handled by the following [AccountController][] method:

@RequestMapping(method=RequestMethod.POST)
    public String create(@Valid Account account, BindingResult result) {
        
        if (result.hasErrors()) {
        
            return "account/createForm";
        }
        this.accounts.put(account.assignId(), account);
        return "redirect:/account/" + account.getId();
    }

This method is called *after binding and validation*, where validation of the Account input is triggered by the @Valid annotation. If there are any validation errors, the createForm will be re-rendered, else the Account will be saved and the user will be redirected; e.g. to http://localhost:8080/mvc-basic/account/1.

For an illustration of another cool new feature, try requesting an account that does not exist; e.g. /account/99.

## Summary ##

Spring 3 is a great release containing numerous new features and simplifications across many exciting areas. I hope you found this post on some of the new Spring MVC enhancements useful. As I mentioned at the top, expect more to come in the "Spring 3 Simplifications" series, where we will continue to show new and interesting things you can do with the latest version of the framework.

Happy Holidays!

[null_s_20_d_mm]: /images/20220828/c34798c74c9c47bc8c9489561746160f.png
[Juergen]: http://blog.springsource.com/2009/12/16/spring-framework-3-0-goes-ga/
[Arjen]: http://www.infoq.com/presentations/Whats-New-in-Spring-3.0
[mvc]: http://static.springsource.org/schema/mvc/spring-mvc.xsd
[mvc-basic]: https://src.springframework.org/svn/spring-samples/mvc-basic/trunk/
[spring-samples]: https://src.springframework.org/svn/spring-samples
[web.xml]: https://src.springframework.org/svn/spring-samples/mvc-basic/trunk/src/main/webapp/WEB-INF/web.xml
[servlet-context.xml]: https://src.springframework.org/svn/spring-samples/mvc-basic/trunk/src/main/webapp/WEB-INF/spring/appServlet/servlet-context.xml
[ConversionService]: http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/validation.html#core-convert
[NumberFormat]: http://static.springsource.org/spring/docs/3.0.x/javadoc-api/org/springframework/format/annotation/NumberFormat.html
[DateTimeFormat]: http://static.springsource.org/spring/docs/3.0.x/javadoc-api/org/springframework/format/annotation/DateTimeFormat.html
[Jackson]: http://jackson.codehaus.org/
[mvc-basic 1]: https://github-camo.global.ssl.fastly.net/49c48d00c10f775d2da4a565cb400c466e341311/687474703a2f2f626c6f672e737072696e67736f757263652e636f6d2f77702d636f6e74656e742f75706c6f6164732f323030392f31322f6d76632d62617369632e706e67
[blogged about]: http://blog.springsource.com/2009/11/17/spring-3-type-conversion-and-validation/
[mvc-basic-form]: https://github-camo.global.ssl.fastly.net/a6af4352473fa7b790c0be44383af3898915a5a1/687474703a2f2f626c6f672e737072696e67736f757263652e636f6d2f77702d636f6e74656e742f75706c6f6164732f323030392f31322f6d76632d62617369632d666f726d2e706e67
[AccountController]: https://src.springframework.org/svn/spring-samples/mvc-basic/trunk/src/main/java/org/springframework/samples/mvc/basic/account/AccountController.java