在Spring中使用ResponseBody注释返回Json无法正常工作

Question

I am working on a spring mvc web application, in which I am using Google Visualization API for generating some charts. I have a model class which contains 2 arraylists, which represent the data that I`m sending to the function that draws the chart (this is what i want to be converted to a JSON).

The model class:

@Component
public class JsonResponse {

private List<Integer> percentages = new ArrayList<Integer>();
private List<String> topics = new ArrayList<String>();

public JsonResponse(){
}

public List<Integer> getPercentages() {
    return percentages;
}

public void setPercentages(List<Integer> percentages) {
    this.percentages = percentages;
}

public List<String> getTopics() {
    return topics;
}

public void setTopics(List<String> topics) {
    this.topics = topics;
}
}

Then I ve got a @Component` annotated class which contains a method that returns a model object (of the class that I wrote above), with the 2 arraylists attributes populated.

@Component
public class ChartUtils {
    @Autowired
    public JsonResponse response;

    public JsonResponse listPieChartData( ModelAndView model ,int waveId ){

    //arraylists for chart generation
List<Integer> percentages = new ArrayList<Integer>();
List<String> topics = new ArrayList<String>();

    {... code for accessing the DB and processing some data and then populating the 2                  
     arraylists ... }

response.setTopics(topics);
response.setPercentages(percentages);

return response;}
}

So the Controller class, the one that has the mapping for the action that I am calling to gather data for the chart generation and in which I am calling listPieChartData method, from the class above, and in which I'm also using the @ResponseBody annotation is this:

@Controller
public class ChartController {

@Autowired
public ChartUtils utils;

@Autowired
public JsonResponse response;

@RequestMapping(value = "/drawPieChart", method = RequestMethod.GET )
@ResponseBody
public JsonResponse drawPieChart( ModelAndView model,
        @RequestParam(value = "id", defaultValue = "-1") int waveId ) {

    return utils.listPieChartData(model,waveId ); }

The JavaScript function that draws the chart :

function drawColumnChart(percentages, topics , div,width,height) {
    var data = new google.visualization.DataTable();

data.addColumn('string', 'Wave');
for (var i=0; i < topics.length; i++){
    data.addColumn( 'number', topics[i] ); 
}

    data.addRow( percentages );

    var wave=percentages[0];
    var options = {
        'title':'Generated Chart For '+wave,
        'backgroundColor': { fill: "none" },
        'is3D': true,
        'width':width,
        'height':height,
    };

var chart = new google.visualization.ColumnChart(document.getElementById(div));
chart.draw(data, options);

}

And the AJAX call to the controller's mapped method (for gathering data) that finally calls the above JS function to obtain the chart (I'm also sending the request param int id for the controller method , I didn't wrote that)

$("#button").live("click", function(){

var arrayP, arrayT;
$.ajax({
    url: "drawPieChart",      
contentType: "application/json",
data: params,
success: function(data) {
    $.each(data, function(messageIndex, message) {
    if (messageIndex === 0) {
            arrayP = message;
    } else {
    arrayT = message;
    }
        });
    drawPieChart(arrayP, arrayT,'chart_div',600,400);
    }
    });  
});

I know this is a lot of code :) but it's pretty simple code, to understand the flow better, here is how it`s working:

From a button input I'm calling, with AJAX, the mapped method to the drawPieChart action (which is in the ChartController class), this methods sends the response through invoking the listPieChart method (from the ChartUtils class), which returns a JsonResponse object, (which contains 2 arraylists). This JsonResponse should be converted to a JSON, because in the AJAX request, I'm telling that the request needs a JSON input (via contentType: "application/json"), and it should get it because I use @ResponseBody in the controller method mapped for this request.

I`m getting this response:

The resource identified by this request is only capable of generating responses with characteristics not acceptable according to the request "accept" headers ().
(HTTP Status 406)

Please correct me where I'm wrong, I just can't get this working and I can't figure out why...

And my servlet-context.xml :

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:beans="http://www.springframework.org/schema/beans"
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">

  <!-- DispatcherServlet Context: defines this servlet's request-processing      
infrastructure -->

  <!-- Enables the Spring MVC @Controller programming model -->
  <annotation-driven />

  <!-- Handles HTTP GET requests for /resources/** by efficiently serving up
      static resources in the ${webappRoot}/resources directory -->
  <resources mapping="/resources/**" location="/resources/" />

  <!-- Resolves views selected for rendering by @Controllers to .jsp resources
    in the /WEB-INF/views directory -->
  <beans:bean 
     class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <beans:property name="prefix" value="/WEB-INF/views/" />
    <beans:property name="suffix" value=".jsp" />
  </beans:bean>

  <context:component-scan base-package="com.bla.bla" />

  <beans:import resource="classpath:springJDBC.xml" />

</beans:beans>

Answer 1

So the problem was that i didn'd have all the Jackson dependencies declared in pom.xml. These are the dependencies for your maven project in case you want Spring 3 to automatically serialize an object for you , using the @ResponseBody annotation , as a response from a method. Noob stuff , but I didn't saw this mentioned in the examples that I found .

  <dependency>
        <groupId>org.codehaus.jackson</groupId>
        <artifactId>jackson-jaxrs</artifactId>
        <version>1.6.1</version>
    </dependency>

        <dependency>
    <groupId>org.codehaus.jackson</groupId>
    <artifactId>jackson-mapper-asl</artifactId>
    <version>1.9.9</version>
</dependency>

<dependency>
       <groupId>org.codehaus.jackson</groupId>
    <artifactId>jackson-core-asl</artifactId>
    <version>1.9.9</version>
</dependency>

Also , I had to change some stuff in the ajax call for invoking the method that is returning the json object with data for the chart generation :

$("#buttonPieGenerate").live("click", function(){

    $.ajax({
        url: "drawPieChart", //method from controller
        contentType: "application/json",
        data: params,
        success: function(data) {

        drawPieChart(data.percentages, data.topics,'chart_div',600,400);
        }
    });

});

I'm accessing the data in the Json object that I`m getting as a response from the call with data.percentages , data.topics .

Answer 2

A small update for the world of 2015:

<dependency>
    <!-- Just placing this on the classpath will enable JSON for @ResponseBody -->
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.5.3</version>
</dependency>