Product <-_has_many_-> CategorieIf you want to serialize the a product object with their categories. Just add the flexjson.jar to your webapp add this lines :
@GET
@Path("{id}")
@ProduceMime("application/json")
public String getJSONProduct(@PathParam("id") Integer id){
return new JSONSerializer().exclude("*.class") // Exclude the property class from the json
.include("categories")
.serialize(product);
}
See the output :
curl -v -H "Accept: application/json" http://localhost:8080/rest-json/resource/product/1
> Host: localhost:8080
> Accept: application/json
>
< HTTP/1.1 200 OK
< Server: Apache-Coyote/1.1
< Content-Type: application/json
< Transfer-Encoding: chunked
< Date: Mon, 21 Jul 2008 13:25:11 GMT
<
* Connection #0 to host localhost left intact
* Closing connection #0
{"categories":[{"id":1,"name":"mobile"}],
"description":"A great mobile device !",
"id":1,"name":"iphone"}
@GET
@Path("{id}")
@ProduceMime("application/xml")
public Product getProduct(@PathParam("id") Integer id) {
//...
return product;
}
Jersey uses JAXB to marshall the product object to XML. You can also customize the XML output with jaxb annotations.
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Product implements Serializable {
@XmlAttribute
private Integer Id;
//...
}
This customization will produce an XML output that contains a Product element with an id attribute. Ok now, let's try the service :
curl -v -H "Accept: application/xml" http://localhost:8080/rest-json/resources/product/1 > GET /rest-json/resources/product HTTP/1.1 > User-Agent: curl/7.16.3 (powerpc-apple-darwin8.0) libcurl/7.16.3 OpenSSL/0.9.7l zlib/1.2.3 > Host: localhost:8080 > Accept: application/xml > < HTTP/1.1 200 OK < Server: Apache-Coyote/1.1 < Content-Type: application/xml < Content-Length: 200 < Date: Wed, 09 Jul 2008 20:32:10 GMT < * Connection #0 to host localhost left intact * Closing connection #0 <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <product id="1"> <name>myphone</name> <description>A great mobile device !</description> <category> <id>1</id> <name>mobile</name> </category> </product>To produce a JSON output just add the jettison-1.0-RC1.jar file from the jersey distribution to your webapp and change the mime type parameter of the @ProduceMime annotation like this :
@GET
@Path("{id}")
@ProduceMime({"application/json","application/xml"})
public Product getProduct(@PathParam("id") Integer id) {
//...
return product;
}
You have now a REST resource which returns XML or JSON, the response format depends of the Accept header of the HTTP request :
curl -v -H "Accept: application/json" http://localhost:8080/rest-json/resources/product/1
> GET /rest-json/resources/product/1 HTTP/1.1
> User-Agent: curl/7.16.3 (powerpc-apple-darwin8.0) libcurl/7.16.3 OpenSSL/0.9.7l zlib/1.2.3
> Host: localhost:8080
> Accept: application/json
>
< HTTP/1.1 200 OK
< Server: Apache-Coyote/1.1
< Content-Type: application/json
< Transfer-Encoding: chunked
< Date: Wed, 09 Jul 2008 20:47:26 GMT
<
* Connection #0 to host localhost left intact
* Closing connection #0
{"product":{"@id":"1","name":"myphone",
"description":"A great mobile device !",
"category":{"id":"1","name":"mobile"}}}
It's very easy and powerful ! But if you look in details the JSON output you'll notice that the Product's property id is ""@id":"1"" and not ""id":1" ?!
In this case the Product object is marshalling by JAXB and converted to JSON by JETTISON. The returned JSON is mapped on the XML object representation.
If you want to produce a more simpler JSON like that :
{"product":{"id":1,"name":"myphone"}
You have to remove all JAXB annotations from the Product classe. You'll lose the XML customization and in some cases the XML output could be too verbose or not readable (for human ).If you use Tomcat as web-server (Tomcat 6 + NIO have good performances), you can use a Servlet filter to set a far future Expires header for static components like images.
Here an example of my servlet filter to set the Expires header :
public class HeaderFilter implements Filter {
private static final Log log = LogFactory.getLog(HeaderFilter.class);
private FilterConfig filterConfig;
private Map<String, String> headersMap;
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
String headerParam = filterConfig.getInitParameter("header");
if (headerParam == null) {
log.warn("No headers were found in the web.xml (init-param) for the HeaderFilter !");
return;
}
// Init the header list :
headersMap = new LinkedHashMap();
if (headerParam.contains("|")) {
String[] headers = headerParam.split("|");
for (String header : headers) {
parseHeader(header);
}
} else {
parseHeader(headerParam);
}
// Log configured headers .
if (log.isInfoEnabled()) {
log.info("The following headers were registered in the HeaderFilter :");
Set<Entry<String, String>> headers = headersMap.entrySet();
for (Entry<String, String> item : headers) {
log.info(item.getKey() + ':' + item.getValue());
}
}
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
if (headersMap != null) {
// Add the header to the response
Set<Entry<String, String>> headers = headersMap.entrySet();
for (Entry<String, String> header : headers) {
((HttpServletResponse) response).setHeader(header.getKey(), header.getValue());
}
}
// Continue
chain.doFilter(request, response);
}
public void destroy() {
this.filterConfig = null;
this.headersMap = null;
}
private void parseHeader(String header) {
String headerName = header.substring(0, header.indexOf(":"));
if (!headersMap.containsKey(headerName)) {
headersMap.put(headerName, header.substring(header.indexOf(":") + 1));
}
}
}
To use this filter in your webapp, just edit your web.xml to add this lines :
Set HTTP headers for a mapping.
HeaderFilter
juliusdev.filter.HeaderFilter
Add an Expires Header
header
Expires: Thu, 15 Apr 2010 20:00:00 GMT
HeaderFilter
*.jpg
REQUEST
This filter add the following Expires header to all jpg files, telling the browser that this response won't be stale until April 15, 2010. :
I encourage you to read all the bests practices !.
To fix this issue you have to download the no-dependencies version of cglib here and replace the cglib-2.1.3.jar file by the cglib-nodep-2.1_3.jar. After, you can remove the asm-attrs.jar, asm.jar jars and add the jersey.jar, jsr311-api.jar, asm-3.1.jar in your lib directory.
@GET
@ProduceMime("application/xml")
public Product getProduct(@PathParam("id")
Integer id) {
// Get the product ...
return product;
}
In this case the method must be invoke by a GET HTTP request, the response will have the content type 'application/xml' and returns some xml content.
To invoke this web method you have to call the following URL :
Play with jersey, you'll love it :-)ServletAdaptor com.sun.ws.rest.impl.container.servlet.ServletAdaptor 1 ServletAdaptor /resource/*
Hey, can you replace this select box by checks boxes in this web form ?
Hum .... I have already mapped this combo box to an enum in my hibernate entity mapping. I must change that property to a set of enums (ManyToOne relation) :
@Enumerated(EnumType.STRING) @Column(name="color") private ColorEnum color = ColorEnum.RED;to
@CollectionOfElements
@JoinTable( name="item_colors",joinColumns={@JoinColumn(name="item_id")} )
@Cascade(value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
@Enumerated(value=EnumType.STRING)
@Column( name="color", length=25 )
private Set<ColorEnum> colors = new LinkedHashSet<ColorEnum>();
In the previous mapping the color property was mapped on a simple VARCHAR(25) of the item table. And in the second case i created a new table (MySQL) like this :
CREATE TABLE `item_colors` ( `item_id` INT NOT NULL, `color` VARCHAR(25) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL, PRIMARY KEY (`item_id`, `color`) ) CHARACTER SET utf8;
