Java AlgorithmParameterGenerator getInstance()用法及代碼示例

getInstance(String algorithm)

java.security.AlgorithmParameterGenerator類的getInstance()方法用於返回實現指定算法的AlgorithmParameterGenerator類型的對象。

用法:

public static AlgorithmParameterGenerator 
  getInstance(String algorithm)
    throws NoSuchAlgorithmException

參數：此方法將“算法”的標準名稱作為參數。

返回值：此方法返回新的AlgorithmParameterGenerator對象。

異常：此方法引發以下異常：

NoSuchAlgorithmException：如果沒有提供者支持指定算法的AlgorithmParameterGeneratorSpi實現。
NullPointerException ：如果指定的算法為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 { 
            // Getting instance of 
            // AlgorithmParameterGenerator 
            // By usng getInstance() method 
            AlgorithmParameterGenerator sr 
                = AlgorithmParameterGenerator 
                      .getInstance("DSA"); 
  
            // getting the status of 
            // AlgorithmParameterGenerator 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: java.security.AlgorithmParameterGenerator@232204a1

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 { 
            // Getting instance of 
            // AlgorithmParameterGenerator 
            // By usng getInstance() method 
            AlgorithmParameterGenerator sr 
                = AlgorithmParameterGenerator 
                      .getInstance("GFG"); 
  
            // getting the status of 
            // AlgorithmParameterGenerator 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 AlgorithmParameterGenerator not available

Signature getInstance(String algorithm, Provider provider)

java.security.AlgorithmParameterGenerator類的getInstance()方法用於返回實現指定簽名算法和指定提供者對象的AlgorithmParameterGenerator對象。

用法:

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

參數：此方法將以下參數作為參數：

algorithm：這是所請求算法的名稱。
provider：指定的提供者

返回值：此方法返回新的AlgorithmParameterGenerator對象。

異常：此方法引發以下異常：

NoSuchAlgorithmException：如果指定的Provider對象不提供指定算法的AlgorithmParameterGeneratorSpi實現。
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 { 
            // Getting instance of 
            // AlgorithmParameterGenerator 
            // 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(); 
  
            // Getting instance of 
            // AlgorithmParameterGenerator 
            // 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@232204a1

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 { 
            // Getting instance of 
            // AlgorithmParameterGenerator 
            // By usng getInstance() method 
            AlgorithmParameterGenerator sr 
                = AlgorithmParameterGenerator 
                      .getInstance("GFG"); 
  
            // creating Provider object 
            Provider pd = sr.getProvider(); 
  
            // getting algorithm name 
            // by using getAlgorithm() mathod 
            String algo = sr.getAlgorithm(); 
  
            // Getting instance of 
            // AlgorithmParameterGenerator 
            // 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：

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

參考：

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 AlgorithmParameterGenerator 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。