TEXTBOOKS RESTful Web Services - First Application

User.java

package.com . _ tutorialspoint ;  

import java . io . Serializable ; import javax . xml . bind . annotation . XMLElement ; import javax . xml . bind . annotation . XmlRootElement ; @XmlRootElement ( name = "user" )  
 
 
  

public class User implements Serializable { private static final long serialVersionUID = 1L ; private int id ; private Stringname ; _ private String profession ; public User (){}       
        
     
     
      
     
    
   public User ( int id , String name , String profession ){ this . id = id ; this . name = name ; this . profession = profession ; } public int getId () { return id ; } @XmlElement public void setId ( int id ) { this . id     
       
       
       
     
      
       
     
    
      
      = id ; } public String getName () { return name ; } @XmlElement public void setName ( String name ) { this . name = name ; } public String getProfession () { return profession ; } @XmlElement public void setProfession ( String profession ) { this . 
    
      
       
    
   
      
       
    
      
       
    
    
      
      profession = profession ; } } 
      
 

UserDao.java

package.com . _ tutorialspoint ;  

import java . io . file ; import java . io . FileInputStream ; import java . io . FileNotFoundException ; import java . io . FileOutputStream ; import java . io . IOException ; import java . io . ObjectInputStream ; import java . io . ObjectOutputStream ; 
 
  
 
 
 
 
import java . util . ArrayList ; import java . util . List ; 
  

public class UserDao { public List < User > getAllUsers (){    
     
      
      List < User > userList = null ; try { File file = new File ( "Users.dat" ); if (! file . exists ()) { User user = new User ( 1 , "Mahesh" , "Teacher" );  
            userList = new ArrayList < User >();  
            userList . add ( user );  
        
            
            
                   
            saveUserList ( userList ); } else { FileInputStream fis = new FileInputStream ( file ); ObjectInputStream ois = new ObjectInputStream ( fis );  
            userList = ( List < User >) ois . readObject ();  
            ois . close (); } } catch ( IOException e ) { 
          
          
               
                
          
          
         e . printStackTrace (); } catch ( ClassNotFoundException e ) {  
         e . printStackTrace (); } return userList ; } private void saveUserList ( List < User > userList ) { try { File file = new File ( "Users.dat" ); FileOutputStream fos ;   
         fos = new 
          
         
       
    
     
        
            
           FileOutputStream ( file ); ObjectOutputStream oos = new ObjectOutputStream ( fos );  
         oos . writeObject ( userList );  
         oos . close (); } catch ( FileNotFoundException e ) {  
         e . printStackTrace (); } catch ( IOException e ) {  
         e . printStackTrace (); } } 
            
          
          
       
       
}

UserService.java

package.com . _ tutorialspoint ;  

import java . util . List ; import javax . ws . rs . GET ; import javax . ws . rs . path ; import javax . ws . rs . Produces ; import javax . ws . rs . core . mediatype ; @Path ( "/UserService" ) 
 
 
 
  
 

public class UserService { UserDao userDao = new UserDao (); @GET @Path ( "/users" ) @Produces ( MediaType . APPLICATION_XML ) public List < User > getUsers (){ return userDao . getAllUsers (); } }     
       
    
    
    
     
       
     

There are two important points to note about the main program:

UserService.java

• The first step is to specify the path for the web service using the @Path annotation on the UserService.

• The second step is to specify the path for the specific web service method using the @Path annotation on the UserService method.

The first step is to specify the path for the web service using the @Path annotation on the UserService.

The second step is to specify the path for the specific web service method using the @Path annotation on the UserService method.

Creating a Web.xml Configuration File

You need to create a Web xml configuration file, which is an XML file and is used to specify the Jersey platform servlet for our application.

web.xml

<? xml version = "1.0" encoding = "UTF-8" ?> xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" xmlns = "http://java.sun .com/xml/ns/javaee" xsi:schemaLocation = "http://java.sun.com/xml/ns/javaee     
     
       
   
   http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id = "WebApp_ID" version = "3.0" >  User Management   < servlet-name> Jersey RESTful Application   org.glassfish.jersey.servlet.ServletContainer    jersey.config.server.provider .packages   com.tutorialspoint      Jersey RESTful Application  
         
    
    
       
       
       
          
          
       
    
    
        /rest/*    
       
      

Program Deployment

When you've finished creating the source and web configuration files, you'll be ready for this step, which compiles and runs your program. To do this, using Eclipse, export your application as a war file and deploy it to tomcat.

To create a WAR file using Eclipse, choose File → Export → Web → War File and finally select the project's UserManagement and destination folder. To deploy the war file to Tomcat, place the UserManagement.war file in the Tomcat installation directory → webapps directory and start Tomcat.

Program launch

We use Postman , a Chrome extension, to test our web services.

Make a request to UserManagement to get a list of all users. Put http://localhost:8080/UserManagement/rest/UserService/users in a POSTMAN with a GET request and see the following result.

Congratulations, you have successfully created your first RESTful application.