Java 中的提供者键()方法，示例

原文:https://www . geesforgeks . org/provider-key-method-in-Java-with-examples/

java.security.Provider 类的key()方法用于返回这个哈希表中的键的枚举。

语法:

public Enumeration keys()

返回值:这个方法返回这个哈希表中键的一个枚举。

以下是说明键()方法的示例:

程序 1:

Java 语言(一种计算机语言，尤用于创建网站)

// Java program to demonstrate
// keys() method

import java.security.*;
import java.util.*;

public class GFG1 {
    public static void main(String[] argv)
    {
        // Declaring int variable
        int i = 10;

        try {
            // creating the object of SecureRandom
            SecureRandom sr = SecureRandom.getInstance("NativePRNGBlocking");

            // getting the Provider of the SecureRandom sr
            // by using method getProvider()
            Provider provider = sr.getProvider();

            // Declaring the variable of Enumeration<Object> type
            Enumeration<Object> enume;

            // getting the enumeration of the keys
            enume = provider.keys();

            // printing the enumerated keys
            System.out.println("enumeration of the values: \n");
            while (i > 0) {
                System.out.println("Value is: " + enume.nextElement());
                i--;
            }
        }

        catch (NoSuchAlgorithmException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output: 

enumeration of the values: 

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

例 2:

Java 语言(一种计算机语言，尤用于创建网站)

// Java program to demonstrate
// keys() method

import java.security.*;
import java.util.*;

public class GFG1 {
    public static void main(String[] argv)
    {
        // Declaring int variable
        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 Enumeration<Object> type
            Enumeration<Object> enume;

            // getting the enumeration of the keys
            enume = provider.keys();

            // printing the enumerated keys
            System.out.println("enumeration of the values: \n");
            while (i > 0) {
                System.out.println("Value is: " + enume.nextElement());
                i--;
            }
        }

        catch (NoSuchAlgorithmException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output: 

enumeration of the values: 

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

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