Java 中 KeyFactory getInstance()方法，带示例
原文:https://www . geesforgeks . org/key factory-getinstance-method-in-Java-with-examples/
字符串算法
java.security.KeyFactory 类的 getInstance() 方法返回一个 KeyFactory 类型的对象，该对象应用分配的 KeyFactory 算法。
语法:
public static KeyFactory
getInstance(String algorithm)
throws NoSuchAlgorithmException
参数:该方法寻求标准算法作为参数，其实例将被创建到该关键工厂实例。
返回值:这个方法返回一个新的密钥工厂对象。
异常:如果没有提供程序支持特定算法的密钥工厂 spi 应用程序，此方法将引发以下异常:
- no such algorithm 异常:.
- 空指针异常:如果算法为空。
以下是说明 getInstance() 方法的示例:
例 1:
// Java program to demonstrate
// getInstance() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
{
try {
// creating the object of KeyFactory
// and getting instance
// By using getInstance() method
KeyFactory sr
= KeyFactory.getInstance("DSA");
// getting the algorithm of KeyFactory object
String str = sr.getAlgorithm();
// printing the status
System.out.println("algorithm : " + str);
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (NullPointerException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
algorithm : DSA
示例 2: 显示 NoSuchAlgorithmException 异常
// Java program to demonstrate
// getInstance() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
{
try {
// creating the object of KeyFactory
// and getting instance
// By using getInstance() method
KeyFactory sr = KeyFactory.getInstance("GEEKS");
// getting the algorithm of KeyFactory object
String str = sr.getAlgorithm();
// printing the status
System.out.println("algorithm : " + str);
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (NullPointerException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Exception thrown :
java.security.NoSuchAlgorithmException:
GEEKS KeyFactory not available
getInstance(字符串算法，字符串提供程序)
java.security.KeyFactory 类的 getInstance() 方法返回一个 KeyFactory 类型的对象，该对象应用分配的 KeyFactory 算法和分配的提供程序对象。
语法:
public static KeyFactory
getInstance(String algorithm, String provider)
throws NoSuchAlgorithmException
参数:此方法寻求以下参数作为参数:
- Algorithm : This is the name of the algorithm used to obtain the instance.
- Provider : the name of the provider to be specified.
返回值:该方法返回一个新的密钥工厂对象。
异常:此方法引发以下异常:
- [Nosuchalogorithm exception: -If there is no provider available for the key factory spi application that supports a specific algorithm.
- 非法理由例外:【中文】和【中文】。
- null pointer exception: -If the algorithm is null
以下是说明 getInstance() 方法的示例:
例 1:
// Java program to demonstrate
// getInstance() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
{
try {
// creating the object of KeyFactory
// and getting instance
// By using getInstance() method
KeyFactory sr
= KeyFactory.getInstance(
"DSA", "SUN");
// getting the algorithm of KeyFactory object
String str = sr.getAlgorithm();
// printing the status
System.out.println("algorithm : " + str);
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (NullPointerException e) {
System.out.println("Exception thrown : " + e);
}
catch (NoSuchProviderException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
algorithm : DSA
示例 2: 显示 NoSuchAlgorithmException 异常
// Java program to demonstrate
// getInstance() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
{
try {
// creating the object of KeyFactory
// and getting instance
// By using getInstance() method
KeyFactory sr
= KeyFactory.getInstance(
"RSA", "SUN");
// getting the algorithm of KeyFactory object
String str = sr.getAlgorithm();
// printing the status
System.out.println("algorithm : " + str);
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (NullPointerException e) {
System.out.println("Exception thrown : " + e);
}
catch (NoSuchProviderException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Exception thrown :
java.security.NoSuchAlgorithmException:
no such algorithm: RSA for provider SUN
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