how to generate http response using json in REST web service?

You will need to use JAXB Binding annotations to annotate your objects before Jersey serializes them to JSON. Below is an example class, note that you can reorder elements with the propOrder attribute of the @XmlType annotation. It is also possible to give XML elements names other than their method names.

@XmlRootElement
@XmlType(propOrder = { "name", "elements" })
public class ExampleObject implements Serializable {

    private static final long serialVersionUID = 1L;
    private Collection<String> elements = null;
    private String name = null;

    @XmlElementWrapper(name = "elements")
    @XmlElement(name = "element")
    public Collection<String> getElements() {
        return this.elements;
    }

    public String getName() {
        return this.name;
    }

    public void setElements(final Collection<String> elements) {
            this.elements = elements;
    }

    public void setName(final String name) {
            this.name = name;
    }

}