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Erstellen Sie einen Java RESTful Client mit Jersey Client

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1- Das Zweck des Dokument

In diesen Artikel werde ich Sie bei der Erstellung der Applikation Java RESTful Client anleiten, die Jersey Client API benutzt um auf RESTful web service aufzurufen.
Die Beispiele in diesem Dokument bezogen sich auf RESTful Web service in der letzten Unterricht. Sie können hier sehen:

2- Maven Project erstellen

Stellen Sie sicher, dass Ihr Projekt Java >=6 benutzt. Denn in diesem Projekt werden die Bibliotheke JAXB benutzt, die in jdk6 oder neuer eingebaut werden
Project Properties:
Die Deklaration der Bibliothek 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

Nach Default benutzt Jersey API JAXB als Default XML-Binding um die Objekt Java zu XML und umgekehrt umzuwandeln. Sie brauchen die Annotation von JAXB in die Klassen model heften um die Umwandlungen für JAXB zu annotieren.

Und MOXy ist Default JSON-Binding, damit Jersey die Objekte JSON zu Java und umgekehrt umwandelt. Sie brauchen die Annotation in die Klasse model nicht heften.

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 zu String

Das folgende Beispiel erstellt eine Klasse, die auf RESTful Web Serivce aufruft um die Daten in Format JSON zu holen. Das zurückgegebene Ergebnis ist ein 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 zu Object

Im folgenden Beispiel: Jersey Client wandelt die Daten JSON zur Objekte Java ​​​​​​​um.
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 als List

Jersey kann ein JSON zu einer List umwandeln.
Zum Beispiel RESTful Web Service gibt eine List von Objekte zurück.
@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;
   }

}
Die Applikation 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());
      }

  }

}
Das Beispiel laufen

7- Get XML als 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 als 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 als List

Das Beispiel RESTful Web Service gibt eine List der Objekte zurück.

@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

Die Verwendung von POST request zu Web serivce um eine Ressourcen zu erstellen. Das folgende Beispiel erstellt ein POST request mit der beigefügten Daten JSON um die Erstellung eines Employee anzufordern.
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);

    }

}
Das Beispiel laufen
Jersey Client kann ein Objekt Java zu JSON oder XML automatisch umwandeln um mit der Anforderung (request) zu schicken.
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 kann ein Objekt Java zu JSON oder XML automatisch umwandeln um mit der Anforderung (request) zu schicken.

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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