RESTEasy - A guide to implement CRUD Rest API

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RESTEasy is a JBoss project that provides various frameworks to help you build RESTful Web Services and RESTful Java applications. It is a fully certified and portable implementation of the JAX-RS 2.1 specification, a JCP specification that provides a Java API for RESTful Web Services over the HTTP protocol. It is licensed under the Apache 2.0.

In this article, we will look on developing CRUD services for product domain through RESTEasy 3 framework. All the examples can be deployed in Tomcat even though it is closely integrated with JBOSS WildFly as Resteasy framework is portable.

Start a simple web application maven project and add the following dependency. Resteasy-jaxrs is the RESTEasy framework jar, programmatic way of registering restlet is provided by resteasy-servlet-initializer and all marshalling/unmarshalling are done by jettison provider.

<properties>
  <resteasy-version> 3.7 <resteasy-version>
</properties>


<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-jaxrs</artifactId>
<version>${resteasy-version}</version>
</dependency>
<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-servlet-initializer</artifactId>
    <version>${resteasy-version}</version>
</dependency>
<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-jettison-provider</artifactId>
    <version>${resteasy-version}</version>
</dependency>

Application main class need to be created to initialize the path for rest services and enable auto scanning by returning null in getSingletons method.

 @ApplicationPath("/rest")
 public class ApplicationMain extends Application {

   @Override
   public Set<Object> getSingletons() {
       return null;
   }
 }

Instead you can have empty class with @ApplicationPath annotation.

 @ApplicationPath("/rest")
 public class ApplicationMain extends Application {

 }

Domain model of product defined as below. It has been JAXB annotated with XMLRootElement and date field is made transient so marshalling or unmarshalling is skipped.

 @XmlRootElement
 public class Product { 
    @XmlAttribute
    private Integer id;
    private String name;
    private Integer availableQty;
    private String brand;
   

    @XmlTransient
    private Date modifiedDate;

    public Product() {
       this.modifiedDate = new Date();
    }

    public Product(Integer id, String name, Integer availableQty, String brand) {
         this.id = id;
         this.name = name;
         this.availableQty = availableQty;
         this.brand = brand;
         this.modifiedDate = new Date();
    }

    public Product(Integer id, Product product) {
        this.id = id;
        this.name = product.getName();
        this.availableQty = product.getAvailableQty();
        this.brand = product.getBrand();
        this.modifiedDate = new Date();
   }

   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 int getAvailableQty() {
      return availableQty;
   }

   public void setAvailableQty(Integer availableQty) {
      this.availableQty = availableQty;
   }

   public String getBrand() {
      return brand;
   }

   public void setBrand(String brand) {
      this.brand = brand;
   }

   public Date getModifiedDate() {
      return modifiedDate;
   }

   public void setModifiedDate(Date modifiedDate) {
      this.modifiedDate = modifiedDate;
   }
 }

CRUD Services

All CRUD services are built from service class, each method doing one kind of operation. Request entity and Response entity are automatically marshalled by jettison provider. The methods below just returns the entity and RESTEasy framework builds the reponse with entity.

Post request to create Product

Create a JAX-RS service class and @POST annotation is used for creating new product. Id has been assigned based on product id availability and intialized with date. For simplicity, we will use Map to store the product informtion. 

@Path annotation defines the URL path for this API. 

@Path("products")
public class ProductService {

    Logger logger = Logger.getLogger(ProductService.class);

    private static Map<Integer, Product> inventory = new HashMap<>();
    static {
       inventory.put(1, new Product(1, "Inspiron Laptop", 5, "Dell"));
       inventory.put(2, new Product(2, "Power X", 3, "LG"));
       inventory.put(3, new Product(3, "Thumbdrive", 3, "Kingston"));
   }
   private static int maxProductId = 4;

   @POST
   @Path("/")
   @Consumes("application/json")
   @Produces("application/text")
   public String createProduct(Product productDetails) {
         Product newproduct = new Product(maxProductId++, productDetails);
         inventory.put(newproduct.getId(), newproduct);
         return "product created successfully";
   }

}

Build this project and create "resteasyexamples.war". Deploy the WAR file under Tomcat webapps folder. 

We will test the API using CURL command, post JSON product message body.

 curl -X POST -H 'Authorization: Basic YWRtaW46YWRtaW4=' -H 'Content-Type:application/json' -v http://localhost:8080/resteasyexamples/rest/products -d   '{"product": {"name":"headset","availableQty":7,"brand":"Sony"}}'

  < HTTP/1.1 200 
  < Content-Type: application/text
  < Content-Length: 28
  < Date: Sun, 26 May 2019 16:56:15 GMT
  < 
  * Connection #0 to host localhost left intact
   product created successfully

Retrieve all products

Get method with same slash can return all the products in the inventory. Below method is part of ProductService class.

 @GET
 @Path("/")
 @Produces("application/json")
 public Collection<Product> getProducts() {
     return inventory.values();
 }

Below curl method returns product list.

 curl -H 'Authorization: Basic YWRtaW46YWRtaW4=' -i http://localhost:8080/resteasyexamples/rest/products   
 HTTP/1.1 200 
 Content-Type: application/json
 Transfer-Encoding: chunked
 Date: Sun, 26 May 2019 17:03:58 GMT

 [{"product":{"@id":1,"name":"Inspiron Laptop","availableQty":5,"brand":"Dell"}},{"product":{"@id":2,"name":"Power X","availableQty":3,"brand":"LG"}},{"product":{"@id":5,"name":"Keyboard","availableQty":4,"brand":"HP"}},{"product":{"@id":6,"name":"headset","availableQty":7,"brand":"Sony"}}]

Get Products By Id

Get method with id passed as path param is used to fetch the product for that id. Below method returns product object, Framework will take care of making it as HTTP response.

 @GET
 @Path("/{id}")
 @Produces("application/json")
 public Product getProduct(@PathParam("id") Integer id) {
    return inventory.get(id);
 }

 If you want more control on building your response and sending different HTTP status code then below function will help.

  @GET
  @Path("/{id}")
  @Produces("application/json")
  public Response getProduct(@PathParam("id") Integer id) {
     Product productEntity = inventory.get(id);
     return (productEntity != null) ?
               Response.status(200).entity(productEntity).build() :
               Response.status(404).entity("Product not found").build();
  }

 curl -H 'Authorization: Basic YWRtaW46YWRtaW4=' -i http://localhost:8080/resteasyexamples/rest/products/1 
 HTTP/1.1 200 
 Content-Type: application/json
 Transfer-Encoding: chunked 
 Date: Sun, 26 May 2019 17:17:46 GMT

 {"product":{"@id":1,"name":"Inspiron Laptop","availableQty":5,"brand":"Dell"}}

Update a Product for given ID

To modify a product, PUT method should be used. Send the modified product information as message body and its respective Id as path parameter. 

 @PUT
 @Path("/{id}")
 @Consumes("application/json")
 @Produces("application/text")
 public String updateProduct(@PathParam("id") Integer id, Product productDetails) {
     inventory.remove(id);
     Product updatedproduct = new Product(maxProductId++, productDetails);
     inventory.put(updatedproduct.getId(), updatedproduct);
     return "product updated successfully and new id - " + updatedproduct.getId();
 } 

curl command with PUT method, send modified product json details with its Id in the URL

curl -X PUT -H 'Authorization: Basic YWRtaW46YWRtaW4=' -H 'Content-Type:application/json' -v http://localhost:8080/resteasyexamples/rest/products/4 -d '{"product":{"name":"Keyboard","availableQty":4,"brand":"HP"}}'
* Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 8080 (#0)
> PUT /resteasyexamples/rest/products/4 HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.58.0
> Accept: */*
> Authorization: Basic YWRtaW46YWRtaW4=
> Content-Type:application/json
> Content-Length: 61
> 
* upload completely sent off: 61 out of 61 bytes
< HTTP/1.1 200 
< Content-Type: application/text
< Content-Length: 42
< Date: Sun, 26 May 2019 16:43:43 GMT
< 
* Connection #0 to host localhost left intact
product updated successfully and new id - 5

Delete product

 Delete JAX-RS method is annotated and the path parameter provided as product id will be used to remove the product.

  @DELETE
  @Path("/{id}")
  @Produces("application/text")
  public String deleteProduct(@PathParam("id") Integer id) {
     inventory.remove(id);
     return "product deleted successfully";
  }

curl command with delete method, product gets deleted which can be confirmed by invoking get all products.

curl -X DELETE -H 'Authorization: Basic YWRtaW46YWRtaW4=' -i http://localhost:8080/resteasyexamples/rest/products/6
HTTP/1.1 200 
Content-Type: application/text
Content-Length: 28
Date: Sun, 26 May 2019 17:23:15 GMT

product deleted successfully

Finally get call to verify the update and delete happened successfully.

curl -H 'Authorization: Basic YWRtaW46YWRtaW4=' -v http://localhost:8080/resteasyexamples/rest/products 
* Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET /resteasyexamples/rest/products HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.58.0
> Accept: */*
> Authorization: Basic YWRtaW46YWRtaW4=
> 
< HTTP/1.1 200 
< Content-Type: application/json
< Transfer-Encoding: chunked
< Date: Sun, 26 May 2019 17:23:22 GMT
< 
* Connection #0 to host localhost left intact
[{"product":{"@id":1,"name":"Inspiron Laptop","availableQty":5,"brand":"Dell"}},{"product":{"@id":2,"name":"Power X","availableQty":3,"brand":"LG"}},{"product":{"@id":5,"name":"Keyboard","availableQty":4,"brand":"HP"}}]

Reference:

RESTEasy Framework - https://resteasy.github.io/index.html

Code samples - https://github.com/nagappan080810/resteasy_workbook

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