Provider中的条目具有不可修改的设置视图，可以使用entrySet()类java.security.Provider中的方法获得该视图。此方法不需要任何参数，并且会为Provider中的条目返回不可修改的集合视图。
演示此的程序如下所示-
import java.security.*;
import java.util.*;
public class Demo {
public static void main(String[] argv) {
try {
SecureRandom sRandom = SecureRandom.getInstance("SHA1PRNG");
Provider p = sRandom.getProvider();
Set<Map.Entry<Object, Object>> set = p.entrySet();
Iterator i = set.iterator();
System.out.println("The Unmodifiable Set View is as follows: \n ");
int x = 30;
while (x > 0) {
System.out.println(i.next());
x--;
}
} catch (NoSuchAlgorithmException e) {
System.out.println("Error!!! NoSuchAlgorithmException");
}
}
}输出结果
The Unmodifiable Set View is as follows: Alg.Alias.Signature.SHA1/DSA=SHA1withDSA Alg.Alias.Signature.1.2.840.10040.4.3=SHA1withDSA Alg.Alias.Signature.DSS=SHA1withDSA SecureRandom.SHA1PRNG ImplementedIn=Software KeyStore.JKS=sun.security.provider.JavaKeyStore$DualFormatJKS Alg.Alias.MessageDigest.SHA-1=SHA MessageDigest.SHA=sun.security.provider.SHA KeyStore.CaseExactJKS=sun.security.provider.JavaKeyStore$CaseExactJKS CertStore.com.sun.security.IndexedCollection ImplementedIn=Software Signature.SHA256withDSA=sun.security.provider.DSA$SHA256withDSA Alg.Alias.MessageDigest.OID.1.3.14.3.2.26=SHA Alg.Alias.Signature.DSA=SHA1withDSA KeyFactory.DSA ImplementedIn=Software KeyStore.JKS ImplementedIn=Software AlgorithmParameters.DSA ImplementedIn=Software Signature.NONEwithDSA=sun.security.provider.DSA$RawDSA Alg.Alias.CertificateFactory.X509=X.509 Signature.SHA256withDSA SupportedKeyClasses=java.security.interfaces.DSAPublicKey|java.security.interfaces.DSAPrivateKey CertStore.com.sun.security.IndexedCollection=sun.security.provider.certpath.IndexedCollectionCertStore Provider.id className=sun.security.provider.Sun Alg.Alias.MessageDigest.1.3.14.3.2.26=SHA Alg.Alias.Signature.SHA-1/DSA=SHA1withDSA KeyStore.DKS=sun.security.provider.DomainKeyStore$DKS CertificateFactory.X.509 ImplementedIn=Software Alg.Alias.Signature.OID.2.16.840.1.101.3.4.3.2=SHA256withDSA Alg.Alias.Signature.OID.2.16.840.1.101.3.4.3.1=SHA224withDSA Signature.SHA1withDSA KeySize=1024 Signature.NONEwithDSA KeySize=1024 CertPathValidator.PKIX ImplementedIn=Software KeyFactory.DSA=sun.security.provider.DSAKeyFactory