异步发送表单数据到JavaBean，并响应JSON文本返回

1）  提交表单后，将JavaBean信息以JSON文本形式返回到浏览器

<form>
        编号：<input type="text" name="id" value="1"/><br/>
        姓名：<input type="text" name="name" value="哈哈"/><br/>
        薪水：<input type="text" name="sal" value="5000"/><br/>
        <input type="button" value="异步提交注册"/>
    </form>
    
    <script type="text/javascript">
        $(":button").click(function(){
            var url = "${pageContext.request.contextPath}/user/add.action";
            var sendData = {
                "id":1,
                "name":"哈哈",
                "sal":5000
            };
            $.post(url,sendData,function(backData,textStatus,ajax){
                alert(ajax.responseText);
            });
        });
    </script>

public class User {
    private Integer id;
    private String name;
    private Double sal;
    public User(){}
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Double getSal() {
        return sal;
    }
    public void setSal(Double sal) {
        this.sal = sal;
    }
}

@Controller
@RequestMapping(value="/user")
public class UserAction {

    @RequestMapping(value="/add")
    public @ResponseBody User add(User user) throws Exception{
        System.out.println(user.getId()+":"+user.getName()+":"+user.getSal());
        return user;
    }
    
}

spring.xml

 <!-- Action控制器 -->
      <context:component-scan base-package="loaderman.javaee.springmvc.app25"/>      


        <!-- 配适器 -->
      <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
              <property name="messageConverters">
                     <list>
                      <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"/>
                     </list>
              </property>
      </bean>