📜  Java中的提供者 keySet() 方法及示例

📅  最后修改于: 2022-05-13 01:54:28.842000             🧑  作者: Mango

Java中的提供者 keySet() 方法及示例

Java.security.Provider类的keySet()方法用于返回此提供程序中包含的属性键的不可修改的 Set 视图。

句法:

public Set keySet()

返回值:此方法返回此映射中包含的键的集合视图

以下是说明keySet()方法的示例:

方案一:

// Java program to demonstrate
// keySet() method
  
import java.security.*;
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
    {
        // Declaring int value i
        int i = 10;
  
        try {
            // creating the object of SecureRandom
            SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
  
            // getting the Provider of the SecureRandom sr
            // by using method getProvider()
            Provider provider = sr.getProvider();
  
            // Declaring the variable of set type
            Set keyset;
  
            // getting unmodifiable Set view of the keyset
            keyset = provider.keySet();
  
            // Creating the object of iterator to iterate set
            Iterator iter = keyset.iterator();
  
            // printing the set elements
            System.out.println("unmodifiable Set view : \n ");
            while (i > 0) {
                System.out.println("Value is : " + iter.next());
                i--;
            }
        }
  
        catch (NoSuchAlgorithmException e) {
  
            System.out.println("Exception thrown : " + e);
        }
    }
}
输出:
unmodifiable Set view : 
 
Value is : Alg.Alias.Signature.SHA1/DSA
Value is : Alg.Alias.Signature.1.2.840.10040.4.3
Value is : Alg.Alias.Signature.DSS
Value is : SecureRandom.SHA1PRNG ImplementedIn
Value is : KeyStore.JKS
Value is : Alg.Alias.MessageDigest.SHA-1
Value is : MessageDigest.SHA
Value is : KeyStore.CaseExactJKS
Value is : CertStore.com.sun.security.IndexedCollection ImplementedIn
Value is : Signature.SHA256withDSA

方案二:

// Java program to demonstrate
// keySet() method
  
import java.security.*;
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
    {
        // Declaring int value i
        int i = 10;
  
        try {
            // creating the object of Signature
            Signature sr = Signature.getInstance("SHA1withDSA");
  
            // getting the Provider of the  Signature sr
            // by using method getProvider()
            Provider provider = sr.getProvider();
  
            // Declaring the variable of set type
            Set keyset;
  
            // getting unmodifiable Set view of the keyset
            keyset = provider.keySet();
  
            // Creating the object of iterator to iterate set
            Iterator iter = keyset.iterator();
  
            // printing the set elements
            System.out.println("unmodifiable Set view : \n ");
            while (i > 0) {
                System.out.println("Value is : " + iter.next());
                i--;
            }
        }
  
        catch (NoSuchAlgorithmException e) {
  
            System.out.println("Exception thrown : " + e);
        }
    }
}
输出:
unmodifiable Set view : 
 
Value is : Alg.Alias.Signature.SHA1/DSA
Value is : Alg.Alias.Signature.1.2.840.10040.4.3
Value is : Alg.Alias.Signature.DSS
Value is : SecureRandom.SHA1PRNG ImplementedIn
Value is : KeyStore.JKS
Value is : Alg.Alias.MessageDigest.SHA-1
Value is : MessageDigest.SHA
Value is : KeyStore.CaseExactJKS
Value is : CertStore.com.sun.security.IndexedCollection ImplementedIn
Value is : Signature.SHA256withDSA