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Créer Java RESTful Client avec Jersey Client

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1- The objective of the document

Dans ce document, je vais vous donner des instructions de créer Java RESTful Client en utilisant Jersey Client API pour appeler RESTful web service.
Les exemples présents dans ce document se refèrent RESTful Web service dans la leçon précédente, vous pouvez voir ici:

2- Create Maven Project

Assurez- vous que votre projet utilise Java >=6, parce que dans ce projet, il utilisera des bibliothèques JAXB, qui étaient construit dans Jdk6 ou plus récent.
Project Properties:
La déclaration de la bibliothèque Jersey Client:
pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
    http://maven.apache.org/xsd/maven-4.0.0.xsd">
    
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.o7planning</groupId>
    <artifactId>JerseyRESTClient</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>JerseyRESTClient</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
    
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>


        <!-- https://mvnrepository.com/artifact/com.sun.jersey/jersey-client -->
        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-client</artifactId>
            <version>1.19.2</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.sun.jersey/jersey-json -->
        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-json</artifactId>
            <version>1.19.2</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.sun.jersey/jersey-bundle -->
        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-bundle</artifactId>
            <version>1.19.2</version>
        </dependency>

    </dependencies>
    
</project>

3- Model Classes

Par défaut, Jersey API est le défaut JAXB XML-Binding qui a utilisé à convertir un objet Java en XML et vice versa, vous devez attacher Annotation de JAXB sur des classes model afin d'annoter et d'expliquer la manière de convertissement pour JAXB.

Et MOXy est le défaut JSON-Binding pour que Jersey convertisse des objets JSON en Java et vice verssa, vous ne devez pas attacher Annotation quiconque sur des classes model.

Employee.java

package org.o7planning.jerseyrestclient.model;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "employee")
@XmlAccessorType(XmlAccessType.FIELD)
public class Employee {

  private String empNo;
  private String empName;
  private String position;

  // This default constructor is required if there are other constructors.
  public Employee() {

  }

  public Employee(String empNo, String empName, String position) {
      this.empNo = empNo;
      this.empName = empName;
      this.position = position;
  }

  public String getEmpNo() {
      return empNo;
  }

  public void setEmpNo(String empNo) {
      this.empNo = empNo;
  }

  public String getEmpName() {
      return empName;
  }

  public void setEmpName(String empName) {
      this.empName = empName;
  }

  public String getPosition() {
      return position;
  }

  public void setPosition(String position) {
      this.position = position;
  }


}

4- Get JSON to String

L'exemple suivant crée une classe, appel à RESTful Web Serivce pour récupérer les données en tant que JSON, le résultat renvoyé est une String.
GetJsonAsString.java

package org.o7planning.jerseyrestclient;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;

public class GetJsonAsString {

 public static void main(String[] args) {

     // Create Client
     Client client = Client.create();

     WebResource webResource = client.resource("http://localhost:8080/RESTfulCRUD/rest/employees/E01");

     ClientResponse response = webResource.accept("application/json").get(ClientResponse.class);

     // Status 200 is successful.
     if (response.getStatus() != 200) {
         System.out.println("Failed with HTTP Error code: " + response.getStatus());
         String error= response.getEntity(String.class);
         System.out.println("Error: "+error);
         return;
     }

     String output = response.getEntity(String.class);

     System.out.println("Output from Server .... \n");
     System.out.println(output);
 }

}

5- Get JSON to Object

L'exemple ci-dessous, Jersey Client convertit des données JSON en des objets Java.
GetJsonAsObject.java

package org.o7planning.jerseyrestclient;

import javax.ws.rs.core.MediaType;

import org.o7planning.jerseyrestclient.model.Employee;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.WebResource.Builder;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;
import com.sun.jersey.api.json.JSONConfiguration;

public class GetJsonAsObject {

  public static void main(String[] args) {

      ClientConfig clientConfig = new DefaultClientConfig();

      // Create Client based on Config
      Client client = Client.create(clientConfig);

      WebResource webResource = client.resource("http://localhost:8080/RESTfulCRUD/rest/employees/E01");

      Builder builder = webResource.accept(MediaType.APPLICATION_JSON) //
              .header("content-type", MediaType.APPLICATION_JSON);

      ClientResponse response = builder.get(ClientResponse.class);

      // Status 200 is successful.
      if (response.getStatus() != 200) {
          System.out.println("Failed with HTTP Error code: " + response.getStatus());
         String error= response.getEntity(String.class);
         System.out.println("Error: "+error);
          return;
      }

      System.out.println("Output from Server .... \n");

      Employee employee = (Employee) response.getEntity(Employee.class);

      System.out.println("Emp No .... " + employee.getEmpNo());
      System.out.println("Emp Name .... " + employee.getEmpName());
      System.out.println("Position .... " + employee.getPosition());

  }

}

6- Get JSON to List

Jersey peut convertir une JSON en une List.
L'exemple RESTful Web Service renvoie une List des objets.

@Path("/employees")
public class EmployeeService {

   // URI:
   // /contextPath/servletPath/employees
   @GET
   @Produces({ MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML })
   public List<Employee> getEmployees() {
       List<Employee> listOfCountries = EmployeeDAO.getAllEmployees();
       return listOfCountries;
   }

}
L'exemple Client:
GetJsonAsList.java

package org.o7planning.jerseyrestclient;

import java.util.List;

import javax.ws.rs.core.MediaType;

import org.o7planning.jerseyrestclient.model.Employee;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.GenericType;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.WebResource.Builder;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;

public class GetJsonAsList {

  public static void main(String[] args) {

      ClientConfig clientConfig = new DefaultClientConfig();

      // Create Client based on Config
      Client client = Client.create(clientConfig);

      WebResource webResource = client.resource("http://localhost:8080/RESTfulCRUD/rest/employees");

      Builder builder = webResource.accept(MediaType.APPLICATION_JSON) //
              .header("content-type", MediaType.APPLICATION_JSON);

      ClientResponse response = builder.get(ClientResponse.class);

      // Status 200 is successful.
      if (response.getStatus() != 200) {
          System.out.println("Failed with HTTP Error code: " + response.getStatus());
         String error= response.getEntity(String.class);
         System.out.println("Error: "+error);
          return;
      }

      GenericType<List<Employee>> generic = new GenericType<List<Employee>>() {
          // No thing
      };

      List<Employee> list = response.getEntity(generic);

      System.out.println("Output from Server .... \n");

      for (Employee emp : list) {
          System.out.println(" --- ");
          System.out.println("Emp No .... " + emp.getEmpNo());
          System.out.println("Emp Name .... " + emp.getEmpName());
          System.out.println("Position .... " + emp.getPosition());
      }

  }

}
Exécution de l'exemple:

7- Get XML to String

GetXmlAsString.java

package org.o7planning.jerseyrestclient;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;

public class GetXmlAsString {

  public static void main(String[] args) {

      // Create Client
      Client client = Client.create();

      WebResource webResource = client.resource("http://localhost:8080/RESTfulCRUD/rest/employees/E01");

      ClientResponse response = webResource.accept("application/xml").get(ClientResponse.class);

      // Status 200 is successful.
      if (response.getStatus() != 200) {
          System.out.println("Failed with HTTP Error code: " + response.getStatus());
         String error= response.getEntity(String.class);
         System.out.println("Error: "+error);
          return;
      }

      String output = response.getEntity(String.class);

      System.out.println("Output from Server .... \n");
      System.out.println(output);
  }

}

8- Get XML to Object

GetXmlAsObject.java

package org.o7planning.jerseyrestclient;

import javax.ws.rs.core.MediaType;

import org.o7planning.jerseyrestclient.model.Employee;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.WebResource.Builder;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;

public class GetXmlAsObject {

  public static void main(String[] args) {

      ClientConfig clientConfig = new DefaultClientConfig();

      // Create Client based on Config
      Client client = Client.create(clientConfig);

      WebResource webResource = client.resource("http://localhost:8080/RESTfulCRUD/rest/employees/E01");

      Builder builder = webResource.accept(MediaType.APPLICATION_XML) //
              .header("content-type", MediaType.APPLICATION_XML);

      ClientResponse response = builder.get(ClientResponse.class);

      // Status 200 is successful.
      if (response.getStatus() != 200) {
          System.out.println("Failed with HTTP Error code: " + response.getStatus());
         String error= response.getEntity(String.class);
         System.out.println("Error: "+error);
          return;
      }

      System.out.println("Output from Server .... \n");

      Employee employee = (Employee) response.getEntity(Employee.class);

      System.out.println("Emp No .... " + employee.getEmpNo());
      System.out.println("Emp Name .... " + employee.getEmpName());
      System.out.println("Position .... " + employee.getPosition());

  }

}

9- Get XML to List

L'exemple RESTful Web Service renvoie une List des objets.


@Path("/employees")
public class EmployeeService {

  // URI:
  // /contextPath/servletPath/employees
  @GET
  @Produces({ MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML })
  public List<Employee> getEmployees() {
      List<Employee> listOfCountries = EmployeeDAO.getAllEmployees();
      return listOfCountries;
  }

}
GetXmlAsList.java

package org.o7planning.jerseyrestclient;

import java.util.List;

import javax.ws.rs.core.MediaType;

import org.o7planning.jerseyrestclient.model.Employee;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.GenericType;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.WebResource.Builder;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;

public class GetXmlAsList {

   public static void main(String[] args) {

       ClientConfig clientConfig = new DefaultClientConfig();

       // Create Client based on Config
       Client client = Client.create(clientConfig);

       WebResource webResource = client.resource("http://localhost:8080/RESTfulCRUD/rest/employees");

       Builder builder = webResource.accept(MediaType.APPLICATION_XML) //
               .header("content-type", MediaType.APPLICATION_XML);

       ClientResponse response = builder.get(ClientResponse.class);

       // Status 200 is successful.
       if (response.getStatus() != 200) {
           System.out.println("Failed with HTTP Error code: " + response.getStatus());
         String error= response.getEntity(String.class);
         System.out.println("Error: "+error);
           return;
       }

       GenericType<List<Employee>> generic = new GenericType<List<Employee>>() {
           // No thing
       };

       List<Employee> list = response.getEntity(generic);

       System.out.println("Output from Server .... \n");

       for (Employee emp : list) {
           System.out.println(" --- ");
           System.out.println("Emp No .... " + emp.getEmpNo());
           System.out.println("Emp Name .... " + emp.getEmpName());
           System.out.println("Position .... " + emp.getPosition());
       }

   }

}

10- Post JSON

Utiliser POST demande au Web serivce pour créer une nouvelle ressource. Par exemple, ci- dessous crée un POST demande de joindre des données JSON afin de créer un nouveau Employee.
PostJsonString.java

package org.o7planning.jerseyrestclient;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;

public class PostJsonString {

    public static void main(String[] args) {

        Client client = Client.create();

        WebResource webResource = client.resource("http://localhost:8080/RESTfulCRUD/rest/employees");

        // Data send to web service.
        String input = "{\"empNo\":\"E01\",\"empName\":\"New Emp1\",\"position\":\"Manager\"}";

       
        ClientResponse response = webResource.type("application/json").post(ClientResponse.class, input);

        if (response.getStatus() != 200) {
            System.out.println("Failed : HTTP error code : " + response.getStatus());
           
            String error= response.getEntity(String.class);
            System.out.println("Error: "+error);
            return;
        }

        System.out.println("Output from Server .... \n");
       
        String output = response.getEntity(String.class);
       
        System.out.println(output);

    }

}
Exécution de l'exemple:
Jersey Client peut automatiquement convertir un objet Java en JSON ou XML pour envoyer avec la demande.
PostJsonObject.java

package org.o7planning.jerseyrestclient;

import org.o7planning.jerseyrestclient.model.Employee;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;

public class PostJsonObject {

    public static void main(String[] args) {

        Client client = Client.create();

        WebResource webResource = client.resource("http://localhost:8080/RESTfulCRUD/rest/employees");

        // This object will be automatically converted into JSON
        Employee newEmp = new Employee("E05", "New Emp1", "Manager");

        ClientResponse response = webResource.type("application/json").post(ClientResponse.class, newEmp);

        if (response.getStatus() != 200) {
            System.out.println("Failed : HTTP error code : " + response.getStatus());

            String error = response.getEntity(String.class);
            System.out.println("Error: " + error);
            return;
        }

        System.out.println("Output from Server .... \n");

        String output = response.getEntity(String.class);

        System.out.println(output);

    }

}

11- Post XML

PostXmlString.java

package org.o7planning.jerseyrestclient;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;

public class PostXmlString {

  public static void main(String[] args) {

      Client client = Client.create();

      WebResource webResource = client.resource("http://localhost:8080/RESTfulCRUD/rest/employees");

      // Data send to web service.
      String input = "<employee>"//
                      + "<empNo>E05</empNo>"//
                      + "<empName>New Emp1</empName>"//
                      + "<position>Manager</position>"
                      + "</employee>";

       // Send XML and receive XML
       ClientResponse response = webResource.type("application/xml")//
               .accept("application/xml")//
               .post(ClientResponse.class, input);

      if (response.getStatus() != 200) {
          System.out.println("Failed : HTTP error code : " + response.getStatus());

          String error = response.getEntity(String.class);
          System.out.println("Error: " + error);
          return;
      }

      System.out.println("Output from Server .... \n");

      String output = response.getEntity(String.class);

      System.out.println(output);

  }

}
Jersey Client peut automatiquement convertir un objet Java en JSON ou XML pour envoyer avec la demande.
PostXmlObject.java

package org.o7planning.jerseyrestclient;

import org.o7planning.jerseyrestclient.model.Employee;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;

public class PostXmlObject {

    public static void main(String[] args) {

        Client client = Client.create();

        WebResource webResource = client.resource("http://localhost:8080/RESTfulCRUD/rest/employees");

        // This object will be automatically converted into XML
        Employee newEmp = new Employee("E05", "New Emp1", "Manager");

        // Send XML and receive XML
        ClientResponse response = webResource.type("application/xml")//
                .accept("application/xml") //
                .post(ClientResponse.class, newEmp);

        if (response.getStatus() != 200) {
            System.out.println("Failed : HTTP error code : " + response.getStatus());

            String error = response.getEntity(String.class);
            System.out.println("Error: " + error);
            return;
        }

        System.out.println("Output from Server .... \n");

        String output = response.getEntity(String.class);

        System.out.println(output);

    }

}

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