URL Suffixes Strategy

URL Parameter Strategy

It is one of the Strategy in Spring MVC for developing the Content Negotiation Mechanism. In this URL Suffixes we take url suffix value to validate the format of the data through HTTP Request. Actually, we can do this in two different data formats namely JSON and XML. In this Article we will learn JSON data format in all strategies. Now we will give the controller code for this URL Suffixes Strategy.

API Syntax:

http://localhost:8080/user/id.json

UserController.java:

Java

package com.gfg.articles; 
  
import java.util.HashMap; 
import java.util.Map; 
import org.springframework.http.HttpStatus; 
import org.springframework.http.MediaType; 
import org.springframework.http.ResponseEntity; 
import org.springframework.web.bind.annotation.GetMapping; 
import org.springframework.web.bind.annotation.PathVariable; 
import org.springframework.web.bind.annotation.RestController; 
  
@RestController
public class UserController{ 
  
    private static final Map<Long, User> userMap = new HashMap<>(); 
  
    // Dummy data for demonstration 
    static { 
        userMap.put(1L, new User(1L, "John Doe", "john.doe@example.com")); 
        userMap.put(2L, new User(2L, "Jane Smith", "jane.smith@example.com")); 
        userMap.put(3L, new User(3L, "Alice Johnson", "alice.johnson@example.com")); 
        userMap.put(4L, new User(4L, "Bob Anderson", "bob.anderson@example.com")); 
        userMap.put(5L, new User(5L, "Eva Williams", "eva.williams@example.com")); 
    } 
  
    @GetMapping(value = "/user/{id}.{format}") 
    public ResponseEntity<User> getEmployeeById(@PathVariable long id, @PathVariable String format) { 
  
        User user = userMap.get(id); 
  
        if (user == null) { 
            return ResponseEntity.notFound().build(); 
        } 
  
        if ("json".equalsIgnoreCase(format)) { 
            return ResponseEntity.ok().contentType(MediaType.APPLICATION_JSON).body(user); 
        } else { 
            // Handle unsupported format 
            return ResponseEntity.status(HttpStatus.UNSUPPORTED_MEDIA_TYPE).build(); 
        } 
    } 
}

In the above code, we have taken 5 persons dummy data for testing the logic. After that we have created one HTTP GET mapping,this is the API endpoint in that GET mapping we have provided this value = “/user/{id}.{format}” it can check the suffix of the URL of HTTP in url section. If the given API url have json as suffix then The logic validate the data request format. Once it is valid then user data will displayed on the HTML page This entire process is done by findbyid in this logic.

Users Dummy Data:

static {
        userMap.put(1L, new User(1L, "John Doe", "john.doe@example.com"));
        userMap.put(2L, new User(2L, "Jane Smith", "jane.smith@example.com"));
        userMap.put(3L, new User(3L, "Alice Johnson", "alice.johnson@example.com"));
        userMap.put(4L, new User(4L, "Bob Anderson", "bob.anderson@example.com"));
        userMap.put(5L, new User(5L, "Eva Williams", "eva.williams@example.com"));
}

After this we develop logic of URL Suffixes Strategy within GET URL Mapping the UserController java class.

Java

@GetMapping(value = "/user/{id}.{format}") 
    public ResponseEntity<User> getEmployeeById(@PathVariable long id, @PathVariable String format) { 
  
        User user = userMap.get(id); 
  
        if (user == null) { 
            return ResponseEntity.notFound().build(); 
        } 
  
        if ("json".equalsIgnoreCase(format)) { 
            return ResponseEntity.ok().contentType(MediaType.APPLICATION_JSON).body(user); 
        } else { 
            // Handle unsupported format 
            return ResponseEntity.status(HttpStatus.UNSUPPORTED_MEDIA_TYPE).build(); 
        } 
    }

This GET mapping is used for getting data by using find by id with URL Suffix method. And we will show output also for better understanding the concept. After running the application then I got output like this,

API URL:

http://localhost:8080/user/2.json

You can observe in above API URL we 2.json means we requested the API in the form of JSON. if you remove that json suffix we got an error.

Output:

With suffix as json in API URL with id:

We have already data of id 2. You can observe in users dummy data section for conformation.

Without suffix as json in API URL with id:

After hitting the API URL without JSON as Suffix URL, we got error like this. Means when we hit this url the back-end logic checks the requested data format of API request. If Request format is valid then we got data otherwise we got error as output.

Spring MVC – Content Negotiation

Content Negotiation is a mechanism in the Spring MVC Pattern. The Spring MVC is a Java Framework that is used for developing web applications it is built on a Model-View-Controller pattern and it provides all the basic features of Spring Boot. Like Dependency Injection, Inversion of Control, and other features. Content Negotiation is one of the mechanisms which is available in Spring MVC.

It can allow the client or user to specify the desired response format, and this can be possible using HTTP Request and Spring MVC will return a response in specified format. The content Negotiation mechanism is flexible and user-friendly while receiving information through HTTP. Through this Content Negotiation mechanism, we can handle the data in the format of JSON and XML data format. Through the article, we will learn how Content Negotiation is working in Spring MVC with examples for better understanding.

Different ways to configure Content Negotiation in Spring MVC

There are three different ways to configure content negotiation in Spring MVC those are:

Using URL suffixes
Using a URL parameter
Using the Accept header

Prerequisites

Spring Tools Suite for development
Basic Knowledge of Spring MVC pattern functionality
Basic Knowledge of APIs
Knowledge in Spring Boot Application Development
Knowledge of HTTP Basics
Basic Knowledge of Request Mapping in Spring Boot

These things you should know to understand this Content Negotiation Mechanism functionality in Spring MVC. Otherwise, it will be a little bit difficult to understand.

Project Creation

Create a Spring Stater Project with required dependencies.
After that create one controller class in the main package of the project In that develop the required logic. No need to worry about this I will explain it below.
Now Created one POJO class in main package of the project for handling the user details with Setters and Getters methods.
Once complete the development of required logic. After that Run this project as Spring Boot App.

Project Dependencies:

dependencies {
    
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation group: 'com.fasterxml.jackson.core', name: 'jackson-core', version: '2.16.1'
    compileOnly 'org.projectlombok:lombok'
    developmentOnly 'org.springframework.boot:spring-boot-devtools'
    annotationProcessor 'org.projectlombok:lombok'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
}

Note: jackson-core is available in maven repository website not available in spring boot stater.

Project Folder Structure:

Now we will start development of types of strategies in Spring MVC for developing Content Negotiation Mechanism first we will start with URL suffixes after that URL parameter after that Accept header.

User POJO Class

The User POJO class is common for Content Negotiation Strategies This POJO class is used for Setting and Getting data by using Setters and Getters methods in POJO class. And It provides encapsulation to the data while data transformation.

Java

package com.gfg.articles; 
  
public class User { 
    private Long id; 
    private String name; 
    private String email; 
  
    public Long getId() { 
        return id; 
    } 
  
    public void setId(Long id) { 
        this.id = id; 
    } 
  
    public String getName() { 
        return name; 
    } 
  
    public void setName(String name) { 
        this.name = name; 
    } 
  
    public String getEmail() { 
        return email; 
    } 
  
    public void setEmail(String email) { 
        this.email = email; 
    } 
  
    public User(Long id, String name, String email) { 
        super(); 
        this.id = id; 
        this.name = name; 
        this.email = email; 
    } 
  
    public User() { 
        super(); 
    } 
  
} 

In other way also we can develop this pojo class by using lombok dependency in spring boot. We will provide that alternative way code in the below.

Java

package com.gfg.articles; 
  
import lombok.AllArgsConstructor; 
import lombok.Data; 
import lombok.NoArgsConstructor; 
  
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User { 
    private Long id; 
    private String name; 
    private String email; 
} 

@Data, @AllArgsConstructor, @NoArgsConstructor these annotations are used for managing the Setters and Getters methods as well as also manage default and parameterized constructors.

Tags:

#Geeks Premier League 2023 #Java-Spring-MVC #MVC #Advance Java #Geeks Premier League #Java #Java

URL Parameter Strategy

URL Suffixes Strategy

API Syntax:

Java

Users Dummy Data:

Java

Output:

With suffix as json in API URL with id:

Without suffix as json in API URL with id:

Spring MVC – Content Negotiation

Different ways to configure Content Negotiation in Spring MVC

Prerequisites

Project Creation

Project Dependencies:

Project Folder Structure:

User POJO Class

Java

Java

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