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Getting Start Java EE Action-Based MVC
With Thymeleaf
Masatoshi Tada (Casareal ,Inc) JJUG CCC 2016 Spring
2016-5-21(Sat)
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About This Session
!Answer Your Question "Java EE is Useful Framework As Next Struts?"
!View is Thymeleaf !!Code on GitHub
! https://github.com/MasatoshiTada/jjug-action-based-mvc
! Sorry, comments are written in Japanese
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About Me
!Masatoshi Tada !Casareal, Inc!GlassFish User Group Japan !Trainer(Java EE/Spring/Swift) !Twitter:@suke_masa
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Agenda
① What’s "Action-Based MVC"? ② Getting Start MVC 1.0(EE 8) ③ Using Jersey MVC & RESTEasy HTML in
EE 7 ④ Other Java EE Technologies You Should
Know ⑤ Final Conclusions
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①What’s
"Action-Based MVC"?
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What’s Action-Based MVC?
!Web Framework which focuses HTTP request & response
!Most of framework are Action-Based ! Struts, Spring MVC, …
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What’s Action-Based MVC?
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View
View
Controller Model
request
response
Struts developer friendly
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What’s "Component-Based MVC"?
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View Backing Bean Model
GUI(VB, Android…) developer friendly -> Struts developer Un-Friendly
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Web Framework of Java EE
! JSF !Responses HTML !Component-Based
! JAX-RS !Responses JSON/XML !Action-Based
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There’s no Framework which is "Action-Based" and "Responses HTML"
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Java EE Standard Action-Based MVC!!
!Model-View-Controller API (MVC 1.0) ! Java EE 8 (2017 H1) !Based on JAX-RS
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②Getting Start
MVC 1.0
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MVC 1.0
!MVC 1.0 is Specification ! ≒Set of Interfaces, Annotations, and Exceptions
!Reference Implementation is Ozark ! Set of Implementation Classes of above
interfaces
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Main Functions of Struts
!Controller !Validation !Handling Exception !View Technology !Transaction Token
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in MVC 1.0?
!Controller → ⭕
!Validation → ⭕
!Handling Exception → ⭕
!View Technology → ❌
!Transaction Token → ❌
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Why No View Technologies in MVC?
!Non-Goal 1 of MVC specification"Define a new view (template) language and processor."
! Instead, MVC provides integration with many view technologies!
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View Technologies We Can Use in MVC 1.0
!MVC ! JSP, Facelets
!Ozark !Thymeleaf, Mustache, Freemarker,
Handlerbars, Velocity, AsciiDoc, …
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If you want to use other View, Implement ViewEngine interface
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Problems of JSP and Facelets
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! JSP !Mix of Logic and View ! Sometime Occurs XSS
!Facelets !Cannot Use All Features in MVC 1.0 !Bad Compatibility with JavaScript
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Let’s Use Thymeleaf!
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!Pure HTML! ! Isolate View and Logic absolutely! ! Good Compatibility with JavaScript!
! Link Expression is very useful! ! Internationalizing message!
! http://www.thymeleaf.org/doc/tutorials/2.1/usingthymeleaf.html#a-multi-language-welcome
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Using Thymeleaf in MVC 1.0
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<dependency> <groupId>org.glassfish.ozark.ext</groupId> <artifactId>ozark-thymeleaf</artifactId> <version>1.0.0-m02</version> <scope>compile</scope> </dependency>
! Just adding dependency like below
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Why No Transaction Token Feature?
! In Expert Group’s Mailing-List, "This is a client side concern" ! https://java.net/projects/mvc-spec/lists/
jsr371-experts/archive/2015-07/message/2 ! Spring MVC has no transaction token
feature, too.
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How to Avoid Double-Submit-Problem
! See TERASOLUNA Guideline ! http://terasolunaorg.github.io/guideline/
5.1.0.RELEASE/en/ArchitectureInDetail/DoubleSubmitProtection.html
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Preparation : Enabling JAX-RS
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@ApplicationPath("/api") public class MyApplication extends Application { }
Inherit Application class
Add Annotation
jjug-mvc10/src/main/java/com/example/rest/MyApllication.java
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Basic Controller
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@Path("/employee") public class EmployeeController { @GET @Path("/index") @Controller public String index() { return "employee/index.html"; } } Path of View
(extention is REQUIRED)
Indicate as controller method
Mapping to URL & HTTP method
※Italic is feature of MVC
jjug-mvc10/src/main/java/com/example/rest/controller/EmployeeController.java
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Form Class
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public class EmployeeIdForm { @QueryParam("id") @NotBlank @Pattern(regexp = "[1-9][0-9]*") private String id; // setter/getter }
Mapping to "id" Query Parameter
Constraint of Bean Validation
jjug-mvc10/src/main/java/com/example/rest/form/EmployeeIdForm.java
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Send Object to View
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public class EmployeeController { @Inject private Models models;
@GET @Path("/result") @Controller @ValidateOnExecution(type=ExecutableType.NONE) public String result(…) { models.put("employee", employee); return "employee/result.html"; }
Box of Object (Map + Iterator)
Object referred by View
jjug-mvc10/src/main/java/com/example/rest/controller/EmployeeController.java
※Italic is feature of MVC
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Referring Object in View
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<table th:unless="${employee == null}"> <tr th:object="${employee}"> <td th:text="*{empId}">99999</td> <td th:text="*{name}">Taro Yamada</td> <td th:text="*{joinedDate}">2020-01-01</td> <td th:text="*{department.deptId}">99</td> <td th:text="*{department.name}">Admin</td> </tr> </table> WEB-INF/views is view folder
jjug-mvc10/src/main/webapp/WEB-INF/views/employee/result.html
Name put to Models
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Validation
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public class EmployeeController { @Inject private BindingResult br;
@GET @Path("/result") @Controller @ValidateOnExecution(type=ExecutableType.NONE) public String result( @Valid @BeanParam EmployeeIdForm form) { if (br.isFailed()) { models.put("bindingResult", br); return "employee/index.html"; // To input view
Box of Messages
Enable Validation
Error Processing
jjug-mvc10/src/main/java/com/example/rest/controller/EmployeeController.java
※Italic is feature of MVC
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Showing Error Messages
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<ul th:if="${bindingResult != null}"> <li th:each="message : ${bindingResult.allMessages}" th:text="${message}"> This is Dummy Message </li> </ul>
Get Messages From BindingResult
jjug-mvc10/src/main/webapp/WEB-INF/views/employee/index.html
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Writing Error Messages
!Write messages in src/main/resources/ValidationMessages.properties
! Specify Key of Message to "message" attribute in Annotation
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Specifying Error Message Key
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public class EmployeeIdForm { @QueryParam("id") @NotBlank(message = "{id.notblank}") @Pattern(regexp = "[1-9][0-9]*", message = "{id.pattern}") private String id; // setter/getter
Key of Message with "{}"
jjug-mvc10/src/main/java/com/example/rest/form/EmployeeIdForm.java
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Caution : MVC has No "Form-Binding" Feature
!@BeanParam is not "Form-Binding" !On error, If You want to leave values in
input-components on view, Write view as Next
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Implementing Form-Binding
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<form action="./result" method="get"> <input type="text" name="id" value="" th:value="${param.id == null} ? '' : ${param.id[0]}"/> <input type="submit" value="search"/> </form>
jjug-mvc10/src/main/webapp/WEB-INF/views/employee/index.html
Maybe Complex with selectbox …
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Handling Exception
! Implement ExceptionMapper interface !When error occurs, ExceptionMapper
catches Exception !You can implement multiple
ExceptionMappers
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ExceptionMapper class
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@Provider public class ExceptionMapper implements javax.ws.rs.ext.ExceptionMapper<Exception> { public Response toResponse( Exception exception) { // Forward to Error View… } }
Don’t Forget @Provider
Catches Exception as Method Argument
Implement ExceptionMapper
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Other Features of MVC
! Security (XSS, CSRF) !File Upload, Download !MvcContext (Easy Specifying URL) !Hybrid Class (HTML and REST)
!More Details, See GUGJ Slides below ! http://www.slideshare.net/masatoshitada7/java-ee-8mvc-10
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Conclusions of this chapter
!MVC 1.0 + Thymeleaf covers almost features of Struts!
!Need to implement Transaction Token and Form-Binding By Yourself
!Features of MVC are Simple, Reveraging existing Java EE Features.
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③Using Jersey MVC &
RESTEasy HTML in EE 7
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What framework should we use in Java EE 7?
!MVC 1.0 is Java EE 8 ! Java EE 8 will be released in 2017 H1
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Let’s use Jersey MVC or RESTEasy HTML in EE7!
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What’s Jersey MVC?
!Original Extension of Jersey(JAX-RS RI) ! Similar to MVC 1.0 !GlassFish/Payara inside !WebLogic not inside
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What’s RESTEasy HTML?
!Original Extension of RESTEasy (other implementation of JAX-RS) !RESTEasy is inside WildFly/JBoss,
but RESTEasy HTML is not inside
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Basic Jersey MVC
!Register MvcFeature class to Your Application sub class (ResourceConfig is Convinient)
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@ApplicationPath("/api") public class MyApplication extends ResourceConfig { public MyApplication() { register(MvcFeature.class); property(MvcFeature.TEMPLATE_BASE_PATH, "/WEB-INF/views/"); packages(true, "com.example.rest"); } } jjug-jersey-mvc/src/main/java/com/example/rest/MyApplication.java
※Italic is Jersey MVC’s feature
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Basic Jersey MVC
!Return Viewable in controller methods
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@Path("/employee") public class EmployeeController { @GET @Path("/index") public ThymeleafViewable index(…) { return new ThymeleafViewable( "employee/index.html"); } }
My original class (Viewable’s subclass)
jjug-jersey-mvc/src/main/java/com/example/rest/controller/EmployeeControler.java
※Italic is Jersey MVC’s feature
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Basic Jersey MVC
!Add value to Viewable constructor’s 2nd parameter
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@Path("/employee") public class EmployeeController { @GET @Path("/result") public ThymeleafViewable result(…) { Map<String, Object> models = … return new ThymeleafViewable( "employee/result.html", models); }
Put objects to Map
jjug-jersey-mvc/src/main/java/com/example/rest/controller/EmployeeControler.java
※Italic is Jersey MVC’s feature
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How to Use Thymeleaf with Jersey MVC
! Implment TemplateProcessor interface (Provided by Jersey)
!AbstractTemplateProcessor class is useful ! implementation of TemplateProcessor
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ThymeleafTemplateProcessor
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@Provider public class ThymeleafTemplateProcessor extends AbstractTemplateProcessor<String> { private TemplateEngine templateEngine; @Inject public ThymeleafTemplateProcessor( Configuration config, ServletContext servletContext) { super(config, servletContext, "html", "html"); TemplateResolver templateResolver = new ServletContextTemplateResolver(); templateResolver.setPrefix((String) config.getProperty( MvcFeature.TEMPLATE_BASE_PATH)); templateEngine = new TemplateEngine(); templateEngine.setTemplateResolver(templateResolver); } // to next slide jjug-jersey-mvc/src/main/java/com/example/rest
/thymeleaf/ThymeleafTemplateProcessor.java
※Italic is Jersey MVC’s feature
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ThymeleafTemplateProcessor
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// 続き
@Override public void writeTo(...) { WebContext webContext = new WebContext( request, response, servletContext, request.getLocale()); Map<String, Object> map = (Map) viewable.getModel(); webContext.setVariables(map); templateEngine.process(viewable.getTemplateName(), webContext, response.getWriter()); } }
jjug-jersey-mvc/src/main/java/com/example/rest /thymeleaf/ThymeleafTemplateProcessor.java
Thymeleaf write the response
※Italic is Jersey MVC’s feature
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Validation in Jersey MVC
!Jersey provides @ErrorTemplate annotation to specify error view, but… !This annotation is feature for handling
exception (not for validation) !MVC 1.0 doesn’t have similar feature, so
migration will be difficult !Cannot use "Validation Group" and "Group
Sequence" (Features of Bean Validation)
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Validate in Controller Methods
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@Inject Validator validator; @GET @Path("/result") public ThymeleafViewable result( @BeanParam EmployeeIdForm form) { Set<ConstraintViolation<EmployeeIdForm>> violations = validator.validate(form); if (!violations.isEmpty()) { Map<String, Object> model = …; model.put("violations", violations); return new ThymeleafViewable( "employee/index.html", model); }
Execute Bean Validation
No @Valid to arguments
Validate
On error, return to input view
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Showing Error Message
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<ul th:if="${violations != null}"> <li th:each="violation : ${violations}" th:text="${violation.message}"> This is Dummy Message </li> </ul>
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About This Method
!Advantage !Pure JAX-RS code !Easy MVC 1.0 migration !Avoid excess framework customization
!Disadvantage ! It takes time and effort
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I Tried a variety of methods, this method is best
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Handling Exception
!ExceptionMapper ! Same to MVC 1.0 sample code
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Redirect
! JAX-RSのコードで書けばOK
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@GET @Path("/redirect") public Response redirect( @Context UriInfo uriInfo) throws Exception { URI location = uriInfo.getBaseUriBuilder() .path(HelloResource.class) .path("redirect2") .build(); return Response.status(Response.Status.FOUND) .location(location).build(); }
UriInfo has variety of method to build URI
Specify URI to Location header
Status code 3xx
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Basic RESTEasy HTML
!Create Application’s sub class !No need to register any specific class
! By JAX-RS "Providers"
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@ApplicationPath("/api") public class MyApplication extends Application { }
jjug-resteasy-html/src/main/java/com/example/rest/MyApplication.java
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Basic RESTEasy HTML
!Return Renderable in controller method
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<<interface>>
Renderable
View class (Forward)
Redirect class (Redirect)
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Using Thymeleaf in RESTEasy HTML
!Create Renderable implementation class
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<<interface>>
Renderable
View Redirect ThymeleafView
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ThymeleafView
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public class ThymeleafView implements Renderable { private String templateName; private Map<String, Object> models; private TemplateEngine templateEngine; public ThymeleafView(String templateName) { this(templateName, new HashMap<>()); } public ThymeleafView(String templateName, Map<String, Object> models) { this.templateName = templateName; this.models = models; } void setTemplateEngine(TemplateEngine templateEngine) { this.templateEngine = templateEngine; }
Implement Renderable
※Italic is RESTEasy HTML feature
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ThymeleafView
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// from previous slide @Override public void render(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException, WebApplicationException { response.setCharacterEncoding("UTF-8"); WebContext webContext = new WebContext( request, response, request.getServletContext(), request.getLocale()); webContext.setVariables(models); templateEngine.process(templateName, webContext, response.getWriter()); } }
Call TemplateEngine#process() in render()
※Italic is RESTEasy HTML feature
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Creating Interceptor Setting TemplateEngine to ThymeleafView
!Use JAX-RS WriterInterceptor !Create custom annotation with
NameBinding, to specify which controller apply interceptor
!There’re many ways(This is not only way)
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Creating annotation
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@NameBinding @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.METHOD, ElementType.TYPE}) @Documented public @interface ThymeleafController { }
Create annotation with @NameBinding
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Creating WriterInterceptor
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@Provider @ThymeleafController public class ThymeleafWriterInterceptor implements WriterInterceptor { private TemplateEngine templateEngine; @PostConstruct public void init() { TemplateResolver resolver = new ServletContextTemplateResolver(); resolver.setPrefix("/WEB-INF/views/"); templateEngine = new TemplateEngine(); templateEngine.setTemplateResolver(resolver); }
Specify annotation you created
Implement WriterInterceptor
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Creating WriterInterceptor
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@Override public void aroundWriteTo(WriterInterceptorContext context) throws IOException, WebApplicationException { Object entity = context.getEntity(); if (ThymeleafView.class.isAssignableFrom(entity.getClass())) { ThymeleafView thymeleafView = (ThymeleafView) context.getEntity(); thymeleafView.setTemplateEngine(templateEngine); } context.proceed(); } }
Set TemplateEngine before context.proceed()
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Controller
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@GET @Path("result") @ThymeleafController public ThymeleafView result(…) { Map<String, Object> models = …; models.put("employee", employee); return new ThymeleafView( "employee/result.html", models); }
Specify annotation →Applying interceptor
View path and values
※Italic is RESTEasy HTML feature
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Validation and Handling Exception
! Same as Jersey MVC sample code
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Conclusions of this chapter
! In Java EE 7, Use Jersey MVC or RESTEasy HTML!
!Controller methods, views and handling exceptions are same as MVC 1.0!
!They have no BindingResult, so validate in controller methods!
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④Other Java EE
Technologies You Should Know
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JAX-RS
! Specific features of MVC 1.0/Jersey MVC/RESTEasy HTML are not many
!To achieve what you want to do, and trouble-shooting, knowledge of JAX-RS is very important
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JAX-RS Reference
! JSR-339 JAX-RS 2.0 rev.A !You should learn Processing Pipeline
(Appendix C) !https://jcp.org/en/jsr/detail?id=339
! Jersey Document !RESTEasy Document
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Others
!Bean Validation !CDI ! JPA
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⑤Final Conclusions
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Final Conclusions
!MVC 1.0 + Thymeleaf covers almost features of Struts!
! In EE 7, Use Jersey MVC or RESTEasy HTML!
!Understanding JAX-RS is very important!
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Caution
! Jersey MVC and RESTEasy HTML are NOT "Java EE 7 standard" !They will be out of range
of server vendors’ support ! In "Java EE 7 standard",
JSF is the ONLY HTML Framework
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Enjoy Java EE!!
!Thank you!
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