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Spring MVC 3.1 Update

Rossen Stoyanchev

SpringSource, VMware

Java Config
New @MVC Infrastructure
Consumes/Produces
URI Variables
Redirect & Flash Attributes
UriComponentsBuilder
Multipart Request Support
HDIV Integration

Java Config

MVC Namespace

Targets the 80%
A simple starting point
Minimizes boilerplate
Transparency .. ?
Flexibility .. ?

MVC Java Config

(Spring 3.1)

Designed with this experience in mind
Transparency is key in MVC config
So is flexibility

Simple Starting Point


    // Equivalent to <mvc:annotation:driven/>

    @EnableWebMvc
    @Configuration
    public class WebConfig {

    }

Built-in Customizations


@EnableWebMvc
@Configuration
public class WebConfig {
















}

Built-in Customizations


@EnableWebMvc
@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
















}

Built-in Customizations


@EnableWebMvc
@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {

  @Override
  protected void addFormatters(FormatterRegistry registry) {
    // ...
  }











}

Built-in Customizations


@EnableWebMvc
@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {

  @Override
  protected void addFormatters(FormatterRegistry registry) {
    // ...
  }

  @Override
  public void addInterceptors(InterceptorRegistry reg){
    // Equivalent to <mvc:interceptors>
  }






}

Built-in Customizations


@EnableWebMvc
@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {

  @Override
  protected void addFormatters(FormatterRegistry registry) {
    // ...
  }

  @Override
  public void addInterceptors(InterceptorRegistry reg){
    // Equivalent to <mvc:interceptors>
  }


  // ... more available



}

Advanced Customizations

Remove @EnableWebMvc
Extend WebMvcConfigurationSupport

Advanced Customizations


@EnableWebMvc
@Configuration
public class WebConfig extends WebMvcConfigurerAdapter{

  @Override
  public void addInterceptors(InterceptorRegistry reg){
    // Equivalent to <mvc:interceptors>
  }








  }

}

Advanced Customizations



@Configuration
public class WebConfig extends WebMvcConfigurerAdapter{

  @Override
  public void addInterceptors(InterceptorRegistry reg){
    // Equivalent to <mvc:interceptors>
  }








  }

}

Advanced Customizations



@Configuration
public class WebConfig extends WebMvcConfigurationSupport{

  @Override
  public void addInterceptors(InterceptorRegistry reg){
    // Equivalent to <mvc:interceptors>
  }








  }

}

Advanced Customizations



@Configuration
public class WebConfig extends WebMvcConfigurationSupport{

  @Override
  public void addInterceptors(InterceptorRegistry reg){
    // Equivalent to <mvc:interceptors>
  }

  @Override
  @Bean
  public RequestMappingHandlerAdapter 
                requestMappingHandlerAdapter() {



  }

}

Advanced Customizations



@Configuration
public class WebConfig extends WebMvcConfigurationSupport{

  @Override
  public void addInterceptors(InterceptorRegistry reg){
    // Equivalent to <mvc:interceptors>
  }

  @Override
  @Bean
  public RequestMappingHandlerAdapter 
                requestMappingHandlerAdapter() {

      // Create or let "super" create and customize 
      // RequestMappingHandlerAdapter ...
  }

}

This topic covered in more detail:

Later Today @ 12:45

"Configuration Enhancements in Spring 3.1"

@MVC Infrastructure

@MVC

Introduced in Spring 2.5
Expanded for REST in Spring 3.0
Overall very successful
Does more
More flexible

What Is The

@MVC Infrastructure?

DefaultAnnotationHandlerMapping
AnnotationMethodHandlerAdapter
AnnotationMethodHandlerExceptionResolver

About The @MVC Infrastructure

Replaced controller class hierarchy
Not very customizable
Some legacy quirks

No concept of selecting a method (rather than a controller) resulting in duplicated handler method selection, inability to split HTTP methods across controllers, etc.

The New

@MVC Infrastructure

RequestMappingHandlerMapping
RequestMappingHandlerAdapter
ExceptionHandlerExceptionResolver

Named after..

@RequestMapping HandlerMapping
@RequestMapping HandlerAdapter
@ExceptionHandler ExceptionResolver

New Abstractions

HandlerMethod
HandlerMethodArgumentResolver
HandlerMethodReturnValueHandler

What Is Possible Now

Custom request conditions
Build request mappings from any source
Inspect controller method in interceptors
Customize any argument or return value
Design own method signature

Demo

https://github.com/rstoyanchev/spring-mvc-31-demo

Configuration

New infrastructure classes are "on" if using MVC namespace or Java config
Old infrastructure classes still available but no new features
Remaining slides assume new infrastructure classes

Consumes/Produces

Input Media Type


@ResponseBody
@RequestMapping(
        method=RequestMethod.POST,
        header="Content-Type=application/json")

public String save(@RequestBody JavaBean javaBean) {

}

Input Media Type


@ResponseBody
@RequestMapping(
        method=RequestMethod.POST, 
        consumes="application/json")

public String save(@RequestBody JavaBean javaBean) {

}

The Moving Parts

headers="Content-Type=text/plain"
is converted to consumes="text/plain"
Same semantics

Output Media Type


    @ResponseBody
    @RequestMapping(
        method=RequestMethod.GET
        header="Accept=application/json")

    public JavaBean get() {

    }

Output Media Type


    @ResponseBody
    @RequestMapping(
        method=RequestMethod.GET, 
        produces="application/json") 

    public JavaBean get() {

    }

The Moving Parts

headers="Accept=text/plain"
is converted to produces="text/plain"
Refined semantics
Aligned with JAX-RS

Semantics

"Produces" used not only for mapping
Affects the actual content type written
Accepts more general media type

For Example

Request for "text/*"
Matches to method produces = "text/plain"
So does a request for "*/*"
And so does a request without Accept header

Another Example

produces = "application/json"
Request for "*/*"
Content type written is "application/json"
Not any configured message converter

Yet Another Example

produces = "text/plain;charset=UTF-8"
Request for "text/plain"
Content type written is "text/plain;charset=UTF-8"
Matches producible type

What About?

Request for `"/"` (or without Accept) header


    @RequestMapping 
    public String get(Model model) {


    }

    @ResponseBody
    @RequestMapping(produces="application/json") 
    public JavaBean get() {

    }

What About?

Request for `"/"` (or without Accept) header


    @RequestMapping 
    public String get(Model model) {
        // This method is chosen

    }

    @ResponseBody
    @RequestMapping(produces="application/json") 
    public JavaBean get() {

    }

What About?

Request for `"/"` (or without Accept) header


    @RequestMapping 
    public String get(Model model) {
        // This method is chosen
        // As a match to '*/*'
    }

    @ResponseBody
    @RequestMapping(produces="application/json") 
    public JavaBean get() {

    }

Code Samples

https://github.com/SpringSource/spring-mvc-showcase

MappingController.java

ResponseController.java

URI Variables

Data Binding & URI Variables



@RequestMapping(
    value="/people/{firstName}/{lastName}/SSN")

public void search(Person person) {

    // person.getFirstName() is populated
    // person.getLastName()  is populated

}

Rendering & Path Variables

@PathVariable values
merged into the model before rendering
Individal View types "opt out"
E.g. MappingJacksonJsonView, MarshallingView

Example



@RequestMapping("/apps/edit/{slug}")
public String editForm(@PathVariable String slug){



}

Example



@RequestMapping("/apps/edit/{slug}")
public String editForm(@PathVariable String slug){

    // No need to add "slug" to the model

}

`"redirect:"` & URI Vars

URI template redirect string
Expanded from model values & current request URI vars
Variables are encoded

Example


@RequestMapping(
    value="/{year}/{month}/{slug}/rooms",
    method=RequestMethod.POST)

public String createRoom() {




    return "redirect:/{year}/{month}/{slug}";
}

Example


@RequestMapping(
    value="/{year}/{month}/{slug}/rooms",
    method=RequestMethod.POST)

public String createRoom() {

    // No need to add "year", "month", & "slug"


    return "redirect:/{year}/{month}/{slug}";
}

Example


@RequestMapping(
    value="/{year}/{month}/{slug}/rooms",
    method=RequestMethod.POST)

public String createRoom() {

    // No need to add "year", "month", & "slug"
    // They will be used in RedirectView

    return "redirect:/{year}/{month}/{slug}";
}

Model Attributes & URI Vars

A URI variable (or request param) can be used to instantiate a @ModelAttribute argument
If the model attribute name matches the URI variable (or request param) name
And there is a registered Converter<String, Account>

Example



@RequestMapping(
        value="/{account}", 
        method = RequestMethod.PUT)

public String update(Account account) {




}

Example



@RequestMapping(
        value="/{account}", 
        method = RequestMethod.PUT)

public String update(Account account) {

    // Account was retrieved from DB 
    // via Converter<String, Account>

}

Demo

https://github.com/rstoyanchev/spring-mvc-31-demo

CRUD Controller: org.springframework.samples.mvc31.crudcontroller

Redirect & Flash Attributes

Redirect URL

A redirect string can be URI template
Expanded from model attrs
Remaining attrs appended to query
But only if they're simple type
.. works but may lead to surprises

Example surprises ROO-2158, SPR-6796

What will the redirect URL be?



@Controller
public class SomeController {






    @RequestMapping(method=POST)
    public String save(Model model) {
        // ...
        return "redirect:/action";
    }
}

What will the redirect URL be?



@Controller
public class SomeController {

    @ModelAttribute
    public void populate(Model model) {

    }

    @RequestMapping(method=POST)
    public String save(Model model) {
        // ...
        return "redirect:/action";
    }
}

What will the redirect URL be?



@Controller
public class SomeController {

    @ModelAttribute
    public void populate(Model model) {
        model.addAttribute(..);
    }

    @RequestMapping(method=POST)
    public String save(Model model) {
        // ...
        return "redirect:/action";
    }
}

What will the redirect URL be?


@SessionAttributes(..)
@Controller
public class SomeController {

    @ModelAttribute
    public void populate(Model model) {
        model.addAttribute(..);
    }

    @RequestMapping(method=POST)
    public String save(Model model) {
        // ...
        return "redirect:/action";
    }
}

What Usually Makes Sense ...


@RequestMapping(method=POST)
public String save(Foo foo, Errors errors, 
                   Model model) {

    if (errors.hasErrors()) {
      return "edit";
    }








    return "redirect:/action";
}

What Usually Makes Sense ...


@RequestMapping(method=POST)
public String save(Foo foo, Errors errors, 
                   Model model) {

    if (errors.hasErrors()) {
      return "edit";
    }

    // Clear the model for redirect scenario
    model.asMap().clear()





    return "redirect:/action";
}

What Usually Makes Sense ...


@RequestMapping(method=POST)
public String save(Foo foo, Errors errors, 
                   Model model) {

    if (errors.hasErrors()) {
      return "edit";
    }

    // Clear the model for redirect scenario
    model.asMap().clear()

    // Add attributes for redirect
    model.addAttribute("foo", foo.getId());
    model.addAttribute("queryParam", "value");

    return "redirect:/action/{foo}";
}

`RedirectAttributes`

A new method argument type
Used to select attrs for redirect scenario
Initially empty
Used instead of model if controller redirects

Example


    @RequestMapping(method=POST)
    public String save(Foo foo, Errors errors, 
                       RedirectAttributes redirectAttrs){

      if (errors.hasErrors()) {
        return "edit"; 
      }

      redirectAttrs.addAttribute("id", foo.getId);
      redirectAttrs.addAttribute("queryParam", "value");

      return "redirect:/action/{id}";

    }

Attribute Formatting

RedirectAttributes formats added values with a DataBinder
Makes them eligible for use in the URL
Recall only simple type attributes appended to query

Example


    @RequestMapping(method=POST)
    public String save(Foo foo, Errors errors, 
                       RedirectAttributes redirectAttrs){




      redirectAttrs.addAttribute("date", new Date());

      return "redirect:/action";

    }

Example


    @RequestMapping(method=POST)
    public String save(Foo foo, Errors errors, 
                       RedirectAttributes redirectAttrs){

      // "date" is formatted
      // RedirectView will append it as query param

      redirectAttrs.addAttribute("date", new Date());

      return "redirect:/action";

    }

Using `Model` and `RedirectAttributes`

Both can be used.. in one method

Example


    @RequestMapping
    public String search(String text, 
                         Model model,
                         RedirectAttributes redirectAttrs){

        // Use Model if not redirecting
        // E.g. Ajax request

        // Use RedirectAttrs if redirecting

    }

What About This?


  @RequestMapping(method=POST)
  public String save(Foo foo, Errors errors){


      // Will the "default" model be used?
      // Or will it be ignored?

      return "redirect:/action";

  }

`"IgnoreDefaultModelOnRedirect"` Property

RequestMappingHandlerAdapter
Effectively disables use of "default" model on redirect
Default value is "false" by default
MVC namespace & Java config set it to "true"

Flash Attributes

Attrs temporily stored in the session
Before a redirect
Removed immediately after

Example


  @RequestMapping(method=POST)
  public String save(Entity entity, Errors errors, 
                     RedirectAttributes redirectAttrs){

    // ...






    return "redirect:/action";
  }

Example


  @RequestMapping(method=POST)
  public String save(Entity entity, Errors errors, 
                     RedirectAttributes redirectAttrs){

    // ...

    redirectAttrs.addFlashAttribute("message", "Success!");




    return "redirect:/action";
  }

Example


  @RequestMapping(method=POST)
  public String save(Entity entity, Errors errors, 
                     RedirectAttributes redirectAttrs){

    // ...

    redirectAttrs.addFlashAttribute("message", "Success!");

    // Attribute "message" will be available 
    // in model of controller following the redirect

    return "redirect:/action";
  }

Code Samples

https://github.com/SpringSource/spring-mvc-showcase

FormController.java

Working with Flash Attributes

Layered support
In @MVC use RedirectAttributes
Uses FlashMap underneath

Static Access to `FlashMap`

(Some Code Not In an @Controller)


// Before redirect

FlashMap flashMap = 
  RequestContextUtils.getOutputFlashMap(request);






// ..

Static Access to `FlashMap`

(Some Code Not In an @Controller)


// Before redirect

FlashMap flashMap = 
  RequestContextUtils.getOutputFlashMap(request);

// After redirect

Map<String, String> map = 
  RequestContextUtils.getInputFlashMap(request);

// ..

Pluggable Support

FlashMapManager
Discovered by DispatcherServlet
Matches requests to FlashMap instances
Stores instances in HTTP session

UriComponentsBuilder

How To Build a URI

UriTemplate
Encoding limitations
Flexible enough .. ?
Re-usable enough .. ?

SPR-8662, SPR-8403, path segments & query params cannot be encoded fully

`UriComponents`

Immutable container of URI's components
Provides access to components
Components may contain URI vars
Expand/encode operations

How To Create `UriComponents`

UriComponentsBuilder.fromPath(String)
UriComponentsBuilder.fromUriString(String)
Plus chained builder-style methods

Example




UriComponents uriComponents = 
  UriComponentsBuilder.fromPath("{path}")
    .queryParam("id", 123)
    .fragment("a")
    .build()
    .expand("/some path")
    .encode();

Example

// Full control over every step
// vs all in one shot

UriComponents uriComponents = 
  UriComponentsBuilder.fromPath("{path}")
    .queryParam("id", 123)
    .fragment("a")
    .build()
    .expand("/some path")
    .encode();

`UriTemplate & UriUtils` ?

Still available
Both use UriComponents internally

`UriComponents` For Redirect

An alternative to using "redirect:"
Max control over redirect URL
Useful in @ResponseBody methods too

Example


@RequestMapping
public String handle() {

    // ...

  UriComponents redirectUri = 
      UriComponentsBuilder.fromPath("/path/{id}")
        .query("q={q}")
        .build()
        .expand("123", "q1")
        .encode();

  return "redirect:" + redirectUri.toUriString();

}

Multipart Requests

Servlet 3.0 Support

StandardServletMultipartResolver
Use of resolver is optional
Required only with use of MultipartFile
Not for javax.servlet.http.Part args

`MultipartFile` Example


@RequestMapping(method = RequestMethod.POST)
public void create(
        @RequestParam("file") MultipartFile file){

    InputStream in = file.getInputStream();

    // ...

}

`javax.servlet.http.Part` Example


@RequestMapping(method = RequestMethod.POST)
public void create(
        @RequestParam("file") Part part){

    InputStream in = part.getInputStream();

    // ...

}

`@RequestPart`

Like @RequestBody but for the part of a "multipart/form-data" request
Request part content processed with HttpMessageConverter

Example



@RequestMapping(
    method = RequestMethod.POST, 
    consumes = { "multipart/form-data" })

public ResponseEntity<Object> void create(
    @RequestPart("json-data") @Valid JavaBean javaBean, 
    @RequestPart("file-data") MultipartFile file) {

   // ...

}

Multipart Request with JSON

POST /someUrl
Content-Type: multipart/mixed

--edt7Tfrdusa7r3lNQc79vXuhIIMlatb7PQg7Vp
Content-Disposition: json-data; name="meta-data"
Content-Type: application/json; charset=UTF-8
Content-Transfer-Encoding: 8bit

{
  "name": "value"
}
--edt7Tfrdusa7r3lNQc79vXuhIIMlatb7PQg7Vp
Content-Disposition: form-data; name="file"; filename="file.properties"
Content-Type: text/xml
Content-Transfer-Encoding: 8bit
... File Data ...

`@Valid`

Supported on @RequestBody & @RequestPart args
Produces MethodArgumentNotValidException
Handled in DefaultHandlerExceptionResolver.. SC_BAD_REQUEST (400) response code

HDIV Integration

HDIV

Java Web security framework
OWASP top ten vulnerabilities
Confidentiality of non-editable data
Editable data validation
CSRF token
...

HDIV Integrations

Spring MVC
Struts 1
Struts 2
JSF 1 & 2

Spring MVC Integration

(Spring 3.0)

Required form tag extension
Custom RedirectView

`RequestDataValueProcessor`

(Spring 3.1)

A contract for inspecting and potentially modifying request data values
Allows HDIV to plug in much more cleanly
Showcase application

Demo & References

http://github.com/hdiv/hdiv-spring-mvc-showcase

http://github.com/hdiv/hdiv

http://hdiv.org

Spring Config

Java config improvements
An up-to-date perspective and advice
"Configuration Enhancements in Spring 3.1"
Today 12:45

Spring MVC Test Support

@Controller and RestTemplate tests
Without ServletContainer
"Spring 3.1 and MVC Testing Support"
Friday 10:15

Questions?

Thank You!

Twitter: @rstoya05

Slides:
https://github.com/rstoyanchev/spring-mvc-31-update

Spring MVC 3.1 Update

Rossen Stoyanchev

SpringSource, VMware

Java Config

MVC Namespace

MVC Java Config

(Spring 3.1)

Simple Starting Point

Built-in Customizations

Built-in Customizations

Built-in Customizations

Built-in Customizations

Built-in Customizations

Advanced Customizations

Advanced Customizations

Advanced Customizations

Advanced Customizations

Advanced Customizations

Advanced Customizations

This topic covered in more detail:

"Configuration Enhancements in Spring 3.1"

@MVC Infrastructure

@MVC

What Is The

@MVC Infrastructure?

About The @MVC Infrastructure

The New

@MVC Infrastructure

Named after..

New Abstractions

What Is Possible Now

Demo

Configuration

Consumes/Produces

Input Media Type

Input Media Type

The Moving Parts

Output Media Type

Output Media Type

The Moving Parts

Semantics

For Example

Another Example

Yet Another Example

What About?

Request for "*/*" (or without Accept) header

What About?

Request for "*/*" (or without Accept) header

What About?

Request for "*/*" (or without Accept) header

Code Samples

URI Variables

Data Binding & URI Variables

Rendering & Path Variables

Example

Example

"redirect:" & URI Vars

Example

Example

Example

Model Attributes & URI Vars

Example

Example

Demo

Redirect & Flash Attributes

Redirect URL

What will the redirect URL be?

What will the redirect URL be?

What will the redirect URL be?

What will the redirect URL be?

What Usually Makes Sense ...

What Usually Makes Sense ...

What Usually Makes Sense ...

RedirectAttributes

Example

Attribute Formatting

Example

Example

Using Model and RedirectAttributes

Example

Request for `"/"` (or without Accept) header

Request for `"/"` (or without Accept) header

Request for `"/"` (or without Accept) header

`"redirect:"` & URI Vars

`RedirectAttributes`

Using `Model` and `RedirectAttributes`

`"IgnoreDefaultModelOnRedirect"` Property

Static Access to `FlashMap`

Static Access to `FlashMap`

`UriComponents`

How To Create `UriComponents`

`UriTemplate & UriUtils` ?

`UriComponents` For Redirect

`MultipartFile` Example

`javax.servlet.http.Part` Example

`@RequestPart`

`@Valid`

`RequestDataValueProcessor`