Java REST API Frameworks

Java has been a popular programming language for developing robust and scalable applications for many years. With the rise of REST APIs, Java has again proven its worth by providing numerous frameworks for building RESTful APIs. A REST API is an interface that enables communication between applications and allows them to exchange data.

In this article, we'll be discussing the top four Java REST API frameworks, their pros and cons, and a CRUD example to help you choose the right one for your next project.

1. Spring Boot

Spring Boot is one of the most popular Java frameworks for building REST APIs. It offers a range of features and tools to help you quickly develop RESTful services. With its built-in support for various data sources, it makes it easy to create CRUD operations for your database.

Pros:

• Easy to use and set up.
• Built-in support for multiple data sources.
• Supports a variety of web applications, including RESTful, WebSockets, and more.
• Offers a large library of plugins and modules to add additional functionality.

Cons:

• Steep learning curve for beginners.
• Can be too heavy for smaller projects.
• Requires a good understanding of Java and the Spring framework.

Example CRUD Operations in Spring Boot:

lessCopy code// Creating a resource
@PostMapping("/users")
public User createUser(@RequestBody User user) {
    return userRepository.save(user);
}

// Reading a resource
@GetMapping("/users/{id}")
public User getUserById(@PathVariable Long id) {
    return userRepository.findById(id).orElse(null);
}

// Updating a resource
@PutMapping("/users/{id}")
public User updateUser(@PathVariable Long id, @RequestBody User user) {
    User existingUser = userRepository.findById(id).orElse(null);
    if (existingUser != null) {
        existingUser.setUsername(user.getUsername());
        existingUser.setPassword(user.getPassword());
        return userRepository.save(existingUser);
    }
    return null;
}

// Deleting a resource
@DeleteMapping("/users/{id}")
public void deleteUser(@PathVariable Long id) {
    userRepository.deleteById(id);
}

2. Jersey

Jersey is another Java framework for building REST APIs. It provides a simple and easy-to-use API for creating RESTful services and is widely used for building microservices. Jersey is also fully compatible with JAX-RS, making it an ideal choice for developing RESTful applications.

Pros:

• Simple and easy to use.
• Compatible with JAX-RS.
• Ideal for building microservices.
• Offers a large library of plugins and modules to add additional functionality.

Cons:

• Can be slow compared to other frameworks.
• Can be difficult to debug.
• Requires a good understanding of Java and REST APIs.

Example CRUD Operations in Jersey:

lessCopy code// Creating a resource
@POST
@Consumes(MediaType.APPLICATION_JSON)
public Response createUser(User user) {
    userRepository.save(user);
    return Response.status(Response.Status.CREATED).build();
}

// Reading a resource
@GET
@Path("/{id}")
@Produces(MediaType.APPLICATION_JSON)
public Response getUserById(@PathParam("id") Long id) {
  User user = userRepository.findById(id).orElse(null); 
  if (user != null) { 
    return Response.ok(user).build(); 
  } 
  return Response.status(Response.Status.NOT_FOUND).build(); 
}

// Updating a resource
@PUT
@Path("/{id}")
@Consumes(MediaType.APPLICATION_JSON)
public Response updateUser(@PathParam("id") Long id, User user) { 
  User existingUser = userRepository.findById(id).orElse(null); 
  if (existingUser != null) { 
     existingUser.setUsername(user.getUsername()); 
     existingUser.setPassword(user.getPassword()); 
     userRepository.save(existingUser); 
     return Response.ok().build(); 
  } 
  return Response.status(Response.Status.NOT_FOUND).build(); 
}

//Deleting a resource 
@DELETE @Path("/{id}") 
public Response deleteUser(@PathParam("id") Long id) { 
  User user = userRepository.findById(id).orElse(null); 
  if (user != null) { 
     userRepository.delete(user); 
     return Response.ok().build(); 
  } 
  return Response.status(Response.Status.NOT_FOUND).build(); 
}

3. Play Framework 

Play Framework is a high-performance framework for building REST APIs in Java. It offers a lightweight and flexible architecture, making it easy to develop and deploy applications quickly. Play is designed to work with Java 8 and Scala, making it a great choice for modern applications.

Pros: 

• Lightweight and flexible architecture. 
• High-performance 
• Supports Java 8 and Scala.
• Offers a large library of plugins and modules to add additional functionality. 

Cons: 

• Steep learning curve for beginners. 
• Can be difficult to debug. 
• Requires a good understanding of Java and REST APIs.

Example CRUD Operations in Play Framework:

lessCopy code// Creating a resource 
public Result createUser() { 
  JsonNode json = request().body().asJson(); 
  User user = Json.fromJson(json, User.class); 
  userRepository.save(user); 
  return ok(); 
}

// Reading a resource
public Result getUserById(Long id) { 
  User user = userRepository.findById(id).orElse(null); 
  if (user != null) { 
    return ok(Json.toJson(user)); 
  } 
  return notFound(); 
}

// Updating a resource 
public Result updateUser(Long id) { 
  User existingUser = userRepository.findById(id).orElse(null); 
  if (existingUser != null) { 
    JsonNode json = request().body().asJson(); 
    User user = Json.fromJson(json, User.class); 
    existingUser.setUsername(user.getUsername()); 
    existingUser.setPassword(user.getPassword()); 
    userRepository.save(existingUser); 
    return ok(); 
  } 
  return notFound(); 
}

// Deleting a resource 
public Result deleteUser(Long id) { 
  User user = userRepository.findById(id).orElse(null); 
  if (user != null) { 
     userRepository.delete(user); 
     return ok(); 
  } 
  return notFound(); 
}

4. Vert.x 

Vert.x is a modern, high-performance framework for building REST APIs in Java. It provides a lightweight and flexible architecture, making it easy to develop and deploy applications quickly. Vert.x supports both Java and JavaScript, making it a great choice for applications that require both.

Pros:

• Lightweight and flexible architecture. 
• High-performance 
• Supports both Java and JavaScript.
• Offers a large library of plugins and modules to add additional functionality.

Cons: 

• Steep learning curve for beginners. 
• Can be difficult to debug. 
• Requires a good understanding of Java and REST APIs.

Example CRUD Operations in Vert.x:

lessCopy code
// Creating a resource
router.post("/").handler(routingContext -> {
  JsonObject user = routingContext.getBodyAsJson();
  userRepository.save(user);
  routingContext.response().setStatusCode(201).end();
});

// Reading a resource
router.get("/:id").handler(routingContext -> {
  Long id = Long.valueOf(routingContext.request().getParam("id"));
  JsonObject user = userRepository.findById(id).orElse(null);
  if (user != null) {
    routingContext.response().end(user.encode());
  } else {
    routingContext.response().setStatusCode(404).end();
  }
});

// Updating a resource
router.put("/:id").handler(routingContext -> {
  Long id = Long.valueOf(routingContext.request().getParam("id"));
  JsonObject user = userRepository.findById(id).orElse(null);
  if (user != null) {
    JsonObject updatedUser = routingContext.getBodyAsJson();
    user.put("username", updatedUser.getString("username"));
    user.put("password", updatedUser.getString("password"));
    userRepository.save(user);
    routingContext.response().end();
  } else {
    routingContext.response().setStatusCode(404).end();
  }
});

// Deleting a resource
router.delete("/:id").handler(routingContext -> {
  Long id = Long.valueOf(routingContext.request().getParam("id"));
  userRepository.deleteById(id);
  routingContext.response().setStatusCode(204).end();
});

In conclusion, these are the top Java REST API frameworks that you can use to build robust and scalable REST APIs. Each framework has its own strengths and weaknesses, so it's important to choose the one that best fits your specific needs. Whether you're a beginner or an experienced Java developer, these frameworks offer all the tools and functionality you need to create high-performance REST APIs quickly and efficiently.