Jackson FasterXML : How does Spring know how to json object? - json

Question

I am currently following this tutorial about Spring MVC and REST service. It is a simple hello world project.
There is something I don't understand. In the pom.xml we set jackson dependency but it is never configurated. How does Spring know how to json object ?
Here is samples of code :
pom xml (dependencies) :
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${springframework.version}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>${jackson.library}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-xml</artifactId>
<version>${jackson.library}</version>
</dependency>
</dependencies>
AppConfiguration :
#Configuration
#EnableWebMvc
#ComponentScan(basePackages = "package.to.scan")
public class AppConfiguration {
}
AppInitializer :
public class AppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
#Override
protected Class<?>[] getRootConfigClasses() {
return new Class[] { AppConfiguration.class };
}
#Override
protected Class<?>[] getServletConfigClasses() {
return null;
}
#Override
protected String[] getServletMappings() {
return new String[] { "/" };
}
}
AppController :
#RestController
public class AppController {
#RequestMapping("/")
public String welcome() {
return "Welcome to RestTemplate Example.";
}
#RequestMapping("/hello/{player}")
public Message message(#PathVariable String player) {
Message msg = new Message(player, "Hello " + player);
return msg;
}
}
Model :
public class Message {
String name;
String text;
public Message(){
}
public Message(String name, String text) {
this.name = name;
this.text = text;
}
public String getName() {
return name;
}
public String getText() {
return text;
}
}

Answer 1

Spring has a default set of HttpMessageConverters, one of them being MappingJackson2HttpMessageConverter, which is used if the content type is json and if Jackson is available in the classpath.