Java AlgorithmParameters getInstance()用法及代碼示例

getInstance(String algorithm)

java.security.AlgorithmParameters類的getInstance()方法返回應用分配的AlgorithmParameters算法的AlgorithmParameters類型的對象。

用法:

public static AlgorithmParameters
  getInstance(String algorithm)
  throws NoSuchAlgorithmException

參數：此方法將標準算法作為參數。

返回值：該方法提供了一個新的算法參數對象。

異常：此方法引發以下異常：

NoSuchAlgorithmException：–如果沒有提供者可支持特定算法的算法參數spi應用程序。
NullPointerException ：–如果算法為null。

下麵是說明getInstance()方法的示例：

示例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 AlgorithmParameters 
            // and getting instance 
            // By usng getInstance() method 
            AlgorithmParameters sr 
                = AlgorithmParameters 
                      .getInstance("DES"); 
  
            // getting the status 
            // of AlgorithmParameters object 
            String str = sr.toString(); 
  
            // printing the status 
            System.out.println("Status : " + str); 
        } 
  
        catch (NoSuchAlgorithmException e) { 
  
            System.out.println("Exception thrown : " + e); 
        } 
        catch (NullPointerException e) { 
  
            System.out.println("Exception thrown : " + e); 
        } 
    } 
}

輸出：

Status : null

示例2:顯示NoSuchAlgorithmException

// 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 AlgorithmParameters 
            // and getting instance 
            // By usng getInstance() method 
            AlgorithmParameters sr 
                = AlgorithmParameters.getInstance("GFG"); 
  
            // getting the status 
            // of AlgorithmParameters object 
            String str = sr.toString(); 
  
            // printing the status 
            System.out.println("Status : " + str); 
        } 
  
        catch (NoSuchAlgorithmException e) { 
  
            System.out.println("Exception thrown : " + e); 
        } 
        catch (NullPointerException e) { 
  
            System.out.println("Exception thrown : " + e); 
        } 
    } 
}

輸出：

Exception thrown :
 java.security.NoSuchAlgorithmException:
 GFG AlgorithmParameters not available

getInstance(String algorithm, Provider provider)

java.security.AlgorithmParameters類的getInstance()方法返回一個AlgorithmParameters類型的對象，該對象應用分配的algorithmParameters算法和分配的提供者對象。

用法:

public static AlgorithmParameters
  getInstance(String algorithm,  Provider provider)
  throws NoSuchAlgorithmException

參數：此方法尋求以下參數作為參數：

algorithm：是指定算法的名稱。
provider這是指定的提供者的名稱

返回值：該方法提供了一個新的算法參數對象。

異常：此方法引發以下異常：

NoSuchAlgorithmException：如果沒有提供者可支持特定算法的算法參數spi應用程序。
IllegalArgumentException：如果提供者為null。
NullPointerException ：如果算法為空

下麵是說明getInstance()方法的示例：

示例1:

// Java program to demonstrate 
// getInstance() method 
  
import java.security.*; 
import java.util.*; 
  
public class GFG1 { 
    public static void main(String[] argv) 
    { 
        try { 
            // creating AlgorithmParameterGenerator object 
            // and getting instance 
            // By usng getInstance() method 
            AlgorithmParameterGenerator sr 
                = AlgorithmParameterGenerator 
                      .getInstance("DiffieHellman"); 
  
            // creating Provider object 
            Provider pd = sr.getProvider(); 
  
            // getting algorithm name 
            // by using getAlgorithm() mathod 
            String algo = sr.getAlgorithm(); 
  
            // creating AlgorithmParameterGenerator object 
            // and getting instance 
            // By usng getInstance() method 
            AlgorithmParameterGenerator sr1 
                = AlgorithmParameterGenerator 
                      .getInstance(algo, pd); 
  
            // getting the status of 
            // AlgorithmParameterGenerator object 
            String str = sr1.toString(); 
  
            // printing the status 
            System.out.println("Status : " + str); 
        } 
  
        catch (NoSuchAlgorithmException e) { 
  
            System.out.println("Exception thrown : " + e); 
        } 
        catch (IllegalArgumentException e) { 
  
            System.out.println("Exception thrown : " + e); 
        } 
    } 
}

輸出：

Status : java.security.AlgorithmParameterGenerator@63947c6b

示例2:顯示NoSuchAlgorithmException

// Java program to demonstrate 
// getInstance() method 
  
import java.security.*; 
import java.util.*; 
  
public class GFG1 { 
    public static void main(String[] argv) 
    { 
        try { 
            // creating AlgorithmParameterGenerator object 
            // and getting instance 
            // By usng getInstance() method 
            AlgorithmParameterGenerator sr 
                = AlgorithmParameterGenerator 
                      .getInstance("DSA"); 
  
            // creating Provider object 
            Provider pd = sr.getProvider(); 
  
            // getting algorithm name 
            // by using getAlgorithm() mathod 
            String algo = sr.getAlgorithm(); 
  
            // creating AlgorithmParameterGenerator object 
            // and getting instance 
            // By usng getInstance() method 
            AlgorithmParameterGenerator sr1 
                = AlgorithmParameterGenerator 
                      .getInstance("GFG", pd); 
  
            // getting the status of 
            // AlgorithmParameterGenerator object 
            String str = sr1.toString(); 
  
            // printing the status 
            System.out.println("Status : " + str); 
        } 
  
        catch (NoSuchAlgorithmException e) { 
  
            System.out.println("Exception thrown : " + e); 
        } 
        catch (IllegalArgumentException e) { 
  
            System.out.println("Exception thrown : " + e); 
        } 
    } 
}

輸出：

Exception thrown :
 java.security.NoSuchAlgorithmException:
 no such algorithm: GFG for provider SUN

參考： https://docs.oracle.com/javase/9/docs/api/java/security/AlgorithmParameters.html

相關用法

注：本文由純淨天空篩選整理自RohitPrasad3大神的英文原創作品 AlgorithmParameters getInstance() method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。