{"id":56504,"date":"2016-05-23T10:00:05","date_gmt":"2016-05-23T07:00:05","guid":{"rendered":"https:\/\/www.javacodegeeks.com\/?p=56504"},"modified":"2016-05-22T11:52:51","modified_gmt":"2016-05-22T08:52:51","slug":"content-negotiation-spring-framework","status":"publish","type":"post","link":"https:\/\/www.javacodegeeks.com\/2016\/05\/content-negotiation-spring-framework.html","title":{"rendered":"Content Negotiation in Spring Framework"},"content":{"rendered":"

1. Introduction<\/h2>\n

With what we had done with\u00a0BeanNameViewResolver<\/strong><\/a>, is that we just had created multiple bean views in Spring context to generate the expected output. Spring soon introduced the Content Negotiation strategy<\/strong>, where we can use the traditional RESTful\u00a0@ResponseBody<\/strong>\u00a0approach\u00a0and HTTP message converters, to return desired outputs in\u00a0JSON or XML, along with some flexibility and dynamicity it provides with\u00a0the configuration.<\/p>\n

Often we need to provide multiple representations (or views) of the same data returned by the controller. This is very elegantly achieved with Content negotiation in Spring.<\/p>\n

2. Implementation<\/h2>\n

To quickly start with the implementation, lets first create a new maven project. Click here to get help on creating your new maven project in Eclipse<\/a><\/p>\n

Let\u2019s now add the\u00a0needed dependencies to the pom.xml <\/strong>file.<\/p>\n

pom.xml<\/em><\/p>\n

<!-- Spring dependencies -->\r\n<dependency>\r\n\t<groupId>org.springframework<\/groupId>\r\n\t<artifactId>spring-core<\/artifactId>\r\n\t<version>4.2.1.RELEASE<\/version>\r\n<\/dependency>\r\n \r\n<dependency>\r\n\t<groupId>org.springframework<\/groupId>\r\n\t<artifactId>spring-web<\/artifactId>\r\n\t<version>4.2.1.RELEASE<\/version>\r\n<\/dependency>\r\n \r\n<dependency>\r\n\t<groupId>org.springframework<\/groupId>\r\n\t<artifactId>spring-webmvc<\/artifactId>\r\n\t<version>4.2.1.RELEASE<\/version>\r\n<\/dependency>\r\n \r\n<dependency>\r\n\t<groupId>javax.xml.bind<\/groupId>\r\n\t<artifactId>jaxb-api<\/artifactId>\r\n\t<version>2.2.6<\/version>\r\n<\/dependency>\r\n<dependency>\r\n\t<groupId>javax.xml<\/groupId>\r\n\t<artifactId>jaxb-impl<\/artifactId>\r\n\t<version>2.1<\/version>\r\n<\/dependency>\r\n \r\n<!-- Jackson JSON Processor -->\r\n<dependency>\r\n\t<groupId>com.fasterxml.jackson.core<\/groupId>\r\n\t<artifactId>jackson-databind<\/artifactId>\r\n\t<version>2.4.1<\/version>\r\n<\/dependency><\/pre>\n
Open web.xml<\/strong> and make sure you have the proper configuration done.<\/p>\n
web.xml<\/em><\/p>\n
<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?>\r\n<web-app xmlns:xsi=\"http:\/\/www.w3.org\/2001\/XMLSchema-instance\"\r\n\txmlns=\"http:\/\/java.sun.com\/xml\/ns\/javaee\"\r\n\txsi:schemaLocation=\"http:\/\/java.sun.com\/xml\/ns\/javaee\r\n\thttp:\/\/java.sun.com\/xml\/ns\/javaee\/web-app_2_5.xsd\"\r\n\tid=\"WebApp_ID\" version=\"2.5\">\r\n \r\n\t<display-name>SpringMVCWithContentNegotiation<\/display-name>\r\n \r\n\t<servlet>\r\n\t\t<servlet-name>mvc-dispatcher<\/servlet-name>\r\n\t\t<servlet-class>org.springframework.web.servlet.DispatcherServlet<\/servlet-class>\r\n\t\t<load-on-startup>1<\/load-on-startup>\r\n\t<\/servlet>\r\n \r\n\t<servlet-mapping>\r\n\t\t<servlet-name>mvc-dispatcher<\/servlet-name>\r\n\t\t<url-pattern>\/*<\/url-pattern>\r\n\t<\/servlet-mapping>\r\n \r\n<\/web-app><\/pre>\n
Create a new context file as <servlet name>-servlet.xml<\/em>, which\u00a0has to be mvc-dispatcher-servlet.xml<\/strong>\u00a0with the following content.
 
<\/div> <\/div><\/p>\n
mvc-dispatcher-servlet.xml<\/em><\/p>\n
<beans xmlns=\"http:\/\/www.springframework.org\/schema\/beans\"\r\n\txmlns:context=\"http:\/\/www.springframework.org\/schema\/context\"\r\n\txmlns:mvc=\"http:\/\/www.springframework.org\/schema\/mvc\" xmlns:xsi=\"http:\/\/www.w3.org\/2001\/XMLSchema-instance\"\r\n\txsi:schemaLocation=\"http:\/\/www.springframework.org\/schema\/mvc http:\/\/www.springframework.org\/schema\/mvc\/spring-mvc.xsd\r\n\thttp:\/\/www.springframework.org\/schema\/beans http:\/\/www.springframework.org\/schema\/beans\/spring-beans-3.0.xsd http:\/\/www.springframework.org\/schema\/context \r\n        http:\/\/www.springframework.org\/schema\/context\/spring-context-3.0.xsd http:\/\/www.springframework.org\/schema\/mvc http:\/\/www.springframework.org\/schema\/mvc\/spring-mvc-3.0.xsd\">\r\n \r\n\t<mvc:annotation-driven\r\n\t\tcontent-negotiation-manager=\"contentNegotiationManager\">\r\n\t\t<mvc:path-matching registered-suffixes-only=\"true\" \/>\r\n\t<\/mvc:annotation-driven>\r\n \r\n\t<context:component-scan base-package=\"com.jcombat.controller\" \/>\r\n \r\n\t<!-- To disable path extension check in the path variable of URI -->\r\n\t<bean id=\"contentNegotiationManager\"\r\n\t\tclass=\"org.springframework.web.accept.ContentNegotiationManagerFactoryBean\">\r\n\t\t<property name=\"favorPathExtension\" value=\"true\" \/>\r\n\t\t<property name=\"ignoreAcceptHeader\" value=\"true\" \/>\r\n\t\t<property name=\"useJaf\" value=\"false\"\/>\r\n\t\t<property name=\"defaultContentType\" value=\"application\/json\" \/>\r\n\t\t<property name=\"mediaTypes\">\r\n\t\t\t<map>\r\n\t\t\t\t<entry key=\"json\" value=\"application\/json\" \/>\r\n\t\t\t\t<entry key=\"xml\" value=\"application\/xml\" \/>\r\n\t\t\t<\/map>\r\n\t\t<\/property>\r\n\t<\/bean>\r\n \r\n\t<!-- For Other media types -->\r\n\t<bean id=\"jspViewResolver\"\r\n\t\tclass=\"org.springframework.web.servlet.view.InternalResourceViewResolver\">\r\n\t\t<property name=\"prefix\" value=\"\/WEB-INF\/jsp\/\" \/>\r\n\t\t<property name=\"suffix\" value=\".jsp\" \/>\r\n\t<\/bean>\r\n \r\n<\/beans><\/pre>\n
\n
Note that the component-scanning is applied only to com.jcombat.controller package, so Spring can auto-detect the application controller.<\/p>\n<\/blockquote>\n
When making an HTTP request, we can specify\u00a0what type of response we\u00a0would like to have by setting the Accept\u00a0<\/strong>header property.\u00a0But due to improper working of the browsers with Accept headers, we mostly prefer ignoring the Accept headers in a Spring based web applications, which returns output in formats other than the HTML.<\/p>\n
With Java Activation Framework<\/strong> (JAF), we don\u2019t need to explicitly specify the media type mappings, instead it gets implicitly done by\u00a0JAF. To use JAF, we might need to add an extra dependency of activation.jar<\/strong>. Probably we just want to support two output formats i.e. JSON and XML, therefore we are opting\u00a0out of it and rather\u00a0specifying the\u00a0media type mappings explicitly.<\/p>\n
It\u2019s now time to write the controller, which should be like specified below.<\/p>\n
EmployeeController.java<\/em><\/p>\n
package com.jcombat.controller;\r\n \r\nimport org.springframework.stereotype.Controller;\r\nimport org.springframework.web.bind.annotation.RequestMapping;\r\nimport org.springframework.web.bind.annotation.RequestMethod;\r\nimport org.springframework.web.bind.annotation.ResponseBody;\r\n \r\nimport com.jcombat.bean.Employee;\r\n \r\n@Controller\r\npublic class EmployeeController {\r\n \r\n\t@RequestMapping(value = \"\/employeeData\", method = RequestMethod.GET, produces={\"application\/xml\", \"application\/json\"})\r\n\tpublic @ResponseBody Employee getEmployee() {\r\n\t\tEmployee employee = new Employee();\r\n\t\temployee.setEmailId(\"abc@gmail.com\");\r\n\t\temployee.setEmpId(\"123\");\r\n\t\temployee.setName(\"Ajit\");\r\n\t\treturn employee;\r\n\t}\r\n}<\/pre>\n
3. Useful Links<\/h2>\n