JQuery, Spring MVC @RequestBody and JSON - making it work together

Question

I would like to have a bidirectional JSON to Java serialization

I'm using successfully the Java to JSON to JQuery path... (@ResponseBody) e.g.

@RequestMapping(value={"/fooBar/{id}"}, method=RequestMethod.GET)
     public @ResponseBody FooBar getFooBar(
            @PathVariable String id,
            HttpServletResponse response , ModelMap model) {
        response.setContentType("application/json");
...
}

and In JQuery I use

$.getJSON('fooBar/1', function(data) {
    //do something
});

this works well (e.g. annotations work already, thanks to all the answerers)

However, how do I do the reverse path: have JSON be serialized to a Java Object back using RequestBody?

no matter what I try, I can't get something like this to work:

@RequestMapping(value={"/fooBar/save"}, method=RequestMethod.POST)
public String saveFooBar(@RequestBody FooBar fooBar,
        HttpServletResponse response , ModelMap model) {

  //This method is never called. (it does when I remove the RequestBody...)
}

I have Jackson configured correctly (it serializes on the way out) and I have MVC set as annotations driven of course

How do I make it work? is it possible at all? or is Spring / JSON / JQuery is oneway (out)?

---

Update:

I changed this Jackson setting

<bean id="jsonHttpMessageConverter"
    class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter" />

<!-- Bind the return value of the Rest service to the ResponseBody. -->
<bean
    class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="messageConverters">
        <util:list id="beanList">
            <ref bean="jsonHttpMessageConverter" />
<!--            <ref bean="xmlMessageConverter" /> -->              
        </util:list>
    </property>
</bean>

To the (almost similiar one) suggested

<bean id="jacksonMessageConverter"
    class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"></bean>
    <bean
        class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
        <property name="messageConverters">
            <list>
                <ref bean="jacksonMessageConverter" />
            </list>
        </property>
    </bean> 

And it seems to work! I don't know what exactly did the trick, but it works...

Answer 1

I'm pretty sure you only have to register MappingJacksonHttpMessageConverter

(the easiest way to do that is through <mvc:annotation-driven /> in XML or @EnableWebMvc in Java)

See:

• this forum post and
• 7.6.5 Configuring Formatting in Spring MVC

---

Here's a working example:

Maven POM

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion><groupId>test</groupId><artifactId>json</artifactId><packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version><name>json test</name>
    <dependencies>
        <dependency><!-- spring mvc -->
            <groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>3.0.5.RELEASE</version>
        </dependency>
        <dependency><!-- jackson -->
            <groupId>org.codehaus.jackson</groupId><artifactId>jackson-mapper-asl</artifactId><version>1.4.2</version>
        </dependency>
    </dependencies>
    <build><plugins>
            <!-- javac --><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId>
            <version>2.3.2</version><configuration><source>1.6</source><target>1.6</target></configuration></plugin>
            <!-- jetty --><plugin><groupId>org.mortbay.jetty</groupId><artifactId>jetty-maven-plugin</artifactId>
            <version>7.4.0.v20110414</version></plugin>
    </plugins></build>
</project>

---

in folder src/main/webapp/WEB-INF

web.xml

<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    version="2.4">
    <servlet><servlet-name>json</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>json</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

json-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
                        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <import resource="classpath:mvc-context.xml" />

</beans>

---

in folder src/main/resources:

mvc-context.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <mvc:annotation-driven />
    <context:component-scan base-package="test.json" />
</beans>

---

In folder src/main/java/test/json

TestController.java

@Controller
@RequestMapping("/test")
public class TestController {

    @RequestMapping(method = RequestMethod.POST, value = "math")
    @ResponseBody
    public Result math(@RequestBody final Request request) {
        final Result result = new Result();
        result.setAddition(request.getLeft() + request.getRight());
        result.setSubtraction(request.getLeft() - request.getRight());
        result.setMultiplication(request.getLeft() * request.getRight());
        return result;
    }

}

Request.java

public class Request implements Serializable {
    private static final long serialVersionUID = 1513207428686438208L;
    private int left;
    private int right;
    public int getLeft() {return left;}
    public void setLeft(int left) {this.left = left;}
    public int getRight() {return right;}
    public void setRight(int right) {this.right = right;}
}

Result.java

public class Result implements Serializable {
    private static final long serialVersionUID = -5054749880960511861L;
    private int addition;
    private int subtraction;
    private int multiplication;

    public int getAddition() { return addition; }
    public void setAddition(int addition) { this.addition = addition; }
    public int getSubtraction() { return subtraction; }
    public void setSubtraction(int subtraction) { this.subtraction = subtraction; }
    public int getMultiplication() { return multiplication; }
    public void setMultiplication(int multiplication) { this.multiplication = multiplication; }
}

You can test this setup by executing mvn jetty:run on the command line, and then sending a POST request:

URL:        http://localhost:8080/test/math
mime type:  application/json
post body:  { "left": 13 , "right" : 7 }

I used the Poster Firefox plugin to do this.

Here's what the response looks like:

{"addition":20,"subtraction":6,"multiplication":91}