Java中的 KeyStore isKeyEntry() 方法及示例

Java.security.KeyStore类的isKeyEntry()方法用于检查是否存在特定的指定密钥条目。它返回一个布尔值，说明相同。

句法：

public final boolean isKeyEntry(String alias) 
    throws KeyStoreException

参数：此方法接受别名的名称作为要检查其键条目的参数。

返回值：此方法返回一个布尔值，说明是否存在请求的键条目。

异常：如果您不初始化此密钥库，此方法将引发KeyStoreException 。

注意：本文中的所有程序都不会在在线 IDE 上运行，因为不存在“privatekey”密钥库。您可以在系统上的Java编译器上检查此代码。要检查此代码，请在您的系统上创建一个 Keystore 'privatekey' 并设置您自己的 Keystore 密码以访问该 Keystore。

下面是说明isCertificateEntry()方法的示例：

示例 1：

Java

// Java program to demonstrate isKeyEntry() method
 
import java.security.*;
import java.security.cert.*;
import java.util.*;
import java.io.*;
 
public class GFG {
    public static void main(String[] argv)
    {
        try {
 
            // creating the object of KeyStore
            // and getting instance
            // By using getInstance() method
            KeyStore sr = KeyStore.getInstance("JKS");
 
            // keystore password is required to access keystore
            char[] pass = ("123456").toCharArray();
 
            // creating and initializing object of InputStream
            InputStream is
                = new FileInputStream(
                    "f:/java/private key.store");
 
            // initializing keystore object
            sr.load(is, pass);
 
            // checking the presence of key entry
            // using isCertificateEntry() method
            Boolean status
                = sr.isKeyEntry("ftpkey");
 
            // display the result
            if (status)
                System.out.println("\nkey entry is present");
            else
                System.out.println("\nkey entry is not present");
        }
 
        catch (NoSuchAlgorithmException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (NullPointerException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (KeyStoreException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (FileNotFoundException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (IOException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (CertificateException e) {
 
            System.out.println("Exception thrown : " + e);
        }
    }
}

输出：

示例 2：对于KeyStoreException

Java

// Java program to demonstrate isKeyEntry() method
 
import java.security.*;
import java.security.cert.*;
import java.util.*;
import java.io.*;
 
public class GFG {
    public static void main(String[] argv)
    {
        try {
 
            // creating the object of KeyStore
            // and getting instance
            // By using getInstance() method
            KeyStore sr = KeyStore.getInstance("JKS");
 
            // keystore password is required to access keystore
            char[] pass = ("123456").toCharArray();
 
            // creating and initializing object of InputStream
            InputStream is
                = new FileInputStream(
                    "f:/java/private key.store");
 
            // initializing keystore object
            // sr.load(is, pass);
 
            // checking the presence of key entry
            // using isCertificateEntry() method
            Boolean status
                = sr.isKeyEntry("ftpkey");
 
            // display the result
            if (status)
                System.out.println("key entry is present");
            else
                System.out.println("key entry is not present");
        }
        catch (NullPointerException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (KeyStoreException e) {
 
            System.out.println("Exception thrown : " + e);
        }
        catch (FileNotFoundException e) {
 
            System.out.println("Exception thrown : " + e);
        }
    }
}

输出：

参考： https://docs.oracle.com/javase/9/docs/api/ Java/security/KeyStore.html#isKeyEntry-java.lang.String-