JAX-RS之queryparam、PathParam、DefaultValue、FormParam、Context、RestController等

这几天做东西接触了JAX-RS的东西，没有系统的从开始就学，只是单纯去复制粘贴的用，主要用到了几个Annotations变量，具体如下：

queryparam、PathParam、FormParam、Context、RestController。下面就分别解释下他们的用法：

1.@queryparam

Path("/users")
public class UserService {

    @GET
    @Path("/query")
    public Response getUsers(
        @QueryParam("from") int from,
        @QueryParam("to") int to,
        @QueryParam("orderBy") List<String> orderBy) {

        return Response
           .status(200)
           .entity("getUsers is called, from : " + from + ", to : " + to
            + ", orderBy" + orderBy.toString()).build();

    }

}

这里，在url中输入"/users/query/from=1&to=100&orderBy=name&orderBy=age"，则输出一下结果：

getUsers is called, from : 1, to : 100, orderBy[name, age]

这里，也可以以动态方式获得，如下：

@Path("/users")
public class UserService {

    @GET
    @Path("/query")
    public Response getUsers(@Context UriInfo info) {

        String from = info.getQueryParameters().getFirst("from");
        String to = info.getQueryParameters().getFirst("to");
        List<String> orderBy = info.getQueryParameters().get("orderBy");

        return Response
           .status(200)
           .entity("getUsers is called, from : " + from + ", to : " + to
            + ", orderBy" + orderBy.toString()).build();

    }
 

URL：users/query?from=100&to=200&orderBy=age&orderBy=name 
输出为: 
getUsers is called, from : 100, to : 200, orderBy[age, name] 
注意这里把orderby后的两个参数读入为LIST处理了.

2.@pathParam

与@queryParam类似，但是，queryparam在url中是用键值对来传递，而在pathParam中是只出现值而不出现参数，

url如是："/users/2011/20/10"，例如：

@GET
    @Path("{year}/{month}/{day}")
    public Response getUserHistory(
            @PathParam("year") int year,
            @PathParam("month") int month,
            @PathParam("day") int day) {

       String date = year + "/" + month + "/" + day;

       return Response.status(200)
        .entity("getUserHistory is called, year/month/day : " + date)
        .build();

    }

这里通过上面的url将输出：

　　getUserHistory is called, year/month/day : 2011/20/10

可以用多个param，并且若path中有相同参数名，则采用最接近的参数名所对应的值，如

@Path("/customers/{id}")
public class CustomerResource {
    @Path("/address/{id}")
    @Produces("text/plain")
    @GET
    public String getAddress(@PathParam("id") String addressId) {...}
}

如：customers/123/address/456 , 则 addressId 的值为456.

3.@DefaultValue

@Path("/users")
public class UserService {

    @GET
    @Path("/query")
    public Response getUsers(
        @DefaultValue("1000") @QueryParam("from") int from,
        @DefaultValue("999")@QueryParam("to") int to,
        @DefaultValue("name") @QueryParam("orderBy") List<String> orderBy) {

        return Response
           .status(200)
           .entity("getUsers is called, from : " + from + ", to : " + to
            + ", orderBy" + orderBy.toString()).build();

    }

输入url为：/users/query

输出为：

getUsers is called, from : 1000, to : 999, orderBy[name]

4.@FormParam

FormParam用于提取post请求中的form数据，具体举例如下：

<FORM action="http://example.com/customers" method="post">
    <P>
        First name: <INPUT type="text" name="firstname"><BR>
        Last name: <INPUT type="text" name="lastname"><BR>
        <INPUT type="submit" value="Send">
    </P>
</FORM>

@Path("/customers")
public class CustomerResource {
    @POST
    public void createCustomer(@FormParam("firstname") String first,
        @FormParam("lastname") String last) {
            ...
    }
}

5.@context

当jax-rs服务基于servlet发布的时候 ，还可以通过@Context注入servlet中的ServletConfig , ServletContext ,HttpServletRequest , HttpServletResponse

然后REST就可以通过sessionid来保持住用户状态。举例如下：

@Path("UserContext")
public class UserContext {

    @Context UriInfo uriInfo;
    @Context HttpHeaders httpHeaders;
    @Context SecurityContext sc;
    @Context Request req;
    @Context Response resp;
    @Context HttpServletResponse response;
    @Context HttpServletRequest request;

    @GET
    public String hi(@QueryParam("name") String yourName ){
        if(yourName!=null)
            request.getSession().setAttribute("name", yourName);

        String username = (String) request.getSession().getAttribute("name");
        if(username!=null){
            System.out.println(request.getSession().getId() + ":" + username);
        }
        else{
            System.out.println(request.getSession().getId() + "没有用户");
        }
        return null;
    }
}

<!--在web.xml加入-->
  <servlet>
      <display-name>JAX-RS REST Servlet</display-name>
      <servlet-name>JAX-RS REST Servlet</servlet-name>
      <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
      <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
      <servlet-name>JAX-RS REST Servlet</servlet-name>
      <url-pattern>/services/*</url-pattern>
  </servlet-mapping>

在url中输入：”/rest/services/UserContext“则输出：

A46756539D2E39CC2CFFCB3FE1C99E70没有用户

若在url中输入：http://localhost:8080/rest/services/UserContext?name=hello

则输出：

A46756539D2E39CC2CFFCB3FE1C99E70:hello

6.@RestController

它继承自@Controller注解，我们可以开发REST服务的时候不需要使用@Controller而专门的@RestController

定义如下：

@Target(value=TYPE)
 @Retention(value=RUNTIME)
 @Documented
 @Controller
 @ResponseBody
public @interface RestController

7.还有cookieparam和headerparam等，此处没怎么接触，就先不学习了。