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Provider getService() and getServices() method in Java

  • Last Updated : 12 Jun, 2019

getService( String type, String algorithm)

The getService() method of java.security.Provider class is used to get the service describing this Provider’s implementation of the specified type of this algorithm or alias.

If no such implementation exists, this method returns null. If there are two matching services, one added to this provider using putService() and one added via put(), the service added via putService() is returned.

Syntax:

public Provider.Service getService(String type, String algorithm)

Parameters: This method takes the following argument as a parameter.

  • type– the type of service requested.
  • algorithm– the case insensitive algorithm name (or alternate alias) of the service requested.

Return Value: This method returns the service describing this Provider’s matching service or null if no such service exists.



Exception: This method throws NullPointerException if type or algorithm is null.

Below are the examples to illustrate the getService() method:

Example 1:




// Java program to demonstrate
// getService() method
  
import java.security.*;
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
  
        try {
            // creating the object of  SecureRandom
            Signature sr = Signature.getInstance("SHA1withDSA", "SUN");
  
            // getting the Provider of the SecureRandom sr
            // by using method getProvider()
            Provider provider = sr.getProvider();
  
            // getting the service of the provider using getServices() method
            Provider.Service service1 = provider
                                            .getService("Signature", sr.getAlgorithm());
  
            // printing the service
            System.out.println("Provider service : " + service1);
        }
  
        catch (NoSuchAlgorithmException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}
Output:
Provider service : SUN: Signature.SHA1withDSA -> sun.security.provider.DSA$SHA1withDSA
  aliases: [DSA, DSS, SHA/DSA, SHA-1/DSA, SHA1/DSA, SHAwithDSA, DSAWithSHA1, OID.1.2.840.10040.4.3, 1.2.840.10040.4.3, 1.3.14.3.2.13, 1.3.14.3.2.27]
  attributes: {ImplementedIn=Software, KeySize=1024, SupportedKeyClasses=java.security.interfaces.DSAPublicKey|java.security.interfaces.DSAPrivateKey}

Example 2: To show NullPointerException thrown by getService() method.




// Java program to demonstrate
// getService() method
  
import java.security.*;
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
  
        try {
            // creating the object of  SecureRandom
            Signature sr = Signature.getInstance("SHA1withDSA", "SUN");
  
            // getting the Provider of the SecureRandom sr
            // by using method getProvider()
            Provider provider = sr.getProvider();
  
            // getting the service of the provider using getServices() method
            Provider.Service service1 = provider
                                            .getService(null, sr.getAlgorithm());
  
            // printing the service
            System.out.println("Provider service : " + service1);
        }
  
        catch (NoSuchAlgorithmException e) {
            System.out.println("Exception thrown : " + e);
        }
  
        catch (NullPointerException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}
Output:
Exception thrown : java.lang.NullPointerException

getServices()

The getServices() method of java.security.Provider class is used to get an unmodifiable Set of all services supported by this Provider.

Syntax:

public Set<Provider.Service> getServices()

Return Value: This method returns an unmodifiable Set of all services supported by this Provider.

Below are the examples to illustrate the getServices() method:

Program 1:




// Java program to demonstrate
// getService() method
  
import java.security.*;
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
        // Declaring int variable
        int i = 5;
  
        try {
            // creating the object of  SecureRandom
            Signature sr = Signature.getInstance("SHA1withDSA", "SUN");
  
            // getting the Provider of the SecureRandom sr
            // by using method getProvider()
            Provider provider = sr.getProvider();
  
            // Declaring the variable of set<Map> type
            Set<Provider.Service> servicelist;
  
            // getting the service of the provider using getServices() method
            servicelist = provider.getServices();
  
            // Creating the object of iterator to iterate set
            Iterator<Provider.Service> iter = servicelist.iterator();
  
            // printing the set elements
            System.out.println("Provider servicelist : \n ");
            while (i > 0) {
                System.out.println("Value is : " + iter.next());
                i--;
            }
        }
  
        catch (NoSuchAlgorithmException e) {
            System.out.println("Exception thrown : " + e);
        }
  
        catch (NullPointerException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}
Output:
Provider servicelist : 
 
Value is : SUN: SecureRandom.NativePRNG -> sun.security.provider.NativePRNG

Value is : SUN: SecureRandom.SHA1PRNG -> sun.security.provider.SecureRandom
  attributes: {ImplementedIn=Software}

Value is : SUN: SecureRandom.NativePRNGBlocking -> sun.security.provider.NativePRNG$Blocking

Value is : SUN: SecureRandom.NativePRNGNonBlocking -> sun.security.provider.NativePRNG$NonBlocking

Value is : SUN: Signature.SHA1withDSA -> sun.security.provider.DSA$SHA1withDSA
  aliases: [DSA, DSS, SHA/DSA, SHA-1/DSA, SHA1/DSA, SHAwithDSA, DSAWithSHA1, OID.1.2.840.10040.4.3, 1.2.840.10040.4.3, 1.3.14.3.2.13, 1.3.14.3.2.27]
  attributes: {ImplementedIn=Software, KeySize=1024, SupportedKeyClasses=java.security.interfaces.DSAPublicKey|java.security.interfaces.DSAPrivateKey}

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