Java中的 SecureRandom getInstance() 方法及示例
getInstance(字符串算法)
Java.security.SecureRandom类的getInstance()方法用于返回实现指定随机数生成器 (RNG) 算法的 SecureRandom 对象。
此方法遍历已注册的安全提供者列表，从最喜欢的提供者开始。返回一个新的 SecureRandom 对象，该对象封装来自支持指定算法的第一个 Provider 的 SecureRandomSpi 实现。
句法：
public static SecureRandom
getInstance( String algorithm )
throws NoSuchAlgorithmException参数：该方法以标准的RNG算法为参数。
返回值：此方法返回新的SecureRandom对象。
异常：此方法抛出NoSuchAlgorithmException - 如果没有提供程序支持指定算法的 SecureRandomSpi 实现。
笔记：
- 这些程序不会在在线 IDE 上运行。
- 每次 Secure Random 类都会产生随机输出。
下面是说明getInstance()方法的示例：
示例 1：
// Java program to demonstrate
// nextBytes() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
{
try {
// creating the object of SecureRandom and getting instance
// By using getInstance() method
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
// Declaring the string variable
String str = "Tajmahal";
// Declaring the byte Array
// converting string into byte
byte[] b = str.getBytes();
// printing the byte array
System.out.println("Byte array before operation : "
+ Arrays.toString(b));
// generating user-specified number of random bytes
// using nextBytes() method
sr.nextBytes(b);
// printing the new byte array
System.out.println("Byte array after operation : "
+ Arrays.toString(b));
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (ProviderException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出：
Byte array before operation : [84, 97, 106, 109, 97, 104, 97, 108]
Byte array after operation : [124, -66, -62, -5, -71, -4, 30, 16]示例 2：
// 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 SecureRandom and getting instance
// By using getInstance() method
System.out.println("Trying to get the instance of TAJMAHAL");
SecureRandom sr = SecureRandom.getInstance("TAJMAHAL");
// Declaring the string variable
String str = "Tajmahal";
// Declaring the byte Array
// converting string into byte
byte[] b = str.getBytes();
// printing the byte array
System.out.println("Byte array before operation : "
+ Arrays.toString(b));
// generating user-specified number of random bytes
// using nextBytes() method
sr.nextBytes(b);
// printing the new byte array
System.out.println("Byte array after operation : "
+ Arrays.toString(b));
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (ProviderException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出：
Trying to get the instance of TAJMAHAL
Exception thrown : java.security.NoSuchAlgorithmException: TAJMAHAL SecureRandom not availablegetInstance(字符串算法，Provider提供者)
Java.security.SecureRandom类的getInstance()方法用于返回实现指定随机数生成器 (RNG) 算法的 SecureRandom 对象。
返回一个封装来自指定 Provider 对象的 SecureRandomSpi 实现的新 SecureRandom 对象。请注意，指定的提供者对象不必在提供者列表中注册。
返回的 SecureRandom 对象尚未播种。要播种返回的对象，请调用 setSeed 方法。如果未调用 setSeed，则第一次调用 nextBytes 将强制 SecureRandom 对象自行播种。如果之前调用了 setSeed，则不会发生这种自播。
句法：
public static SecureRandom
getInstance( String algorithm, Provider provider )
throws NoSuchAlgorithmException参数：此方法将以下参数作为参数
- algorithm – RNG 算法的名称。
- 提供者——提供者。
返回值：此方法返回新的 SecureRandom 对象。
异常：此方法抛出以下异常
- NoSuchAlgorithmException –如果指定算法的 SecureRandomSpi 实现不能从指定的 Provider 对象获得。
- IllegalArgumentException –如果指定的提供者为空。
笔记：
- 这些程序不会在在线 IDE 上运行。
- 每次 Secure Random 类都会产生随机输出。
下面是说明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 SecureRandom object SecureRandom sr1 = new SecureRandom(new byte[] { 1, 2, 3, 4 }); // creating Provider object Provider pd = sr1.getProvider(); // creating the object of SecureRandom and getting instance // By using getInstance() method SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", pd); // Declaring the string variable String str = "Tajmahal"; // Declaring the byte Array // converting string into byte byte[] b = str.getBytes(); // printing the byte array System.out.println("Byte array before operation : " + Arrays.toString(b)); // generating user-specified number of random bytes // using nextBytes() method sr.nextBytes(b); // printing the new byte array System.out.println("Byte array after operation : " + Arrays.toString(b)); } catch (NoSuchAlgorithmException e) { System.out.println("Exception thrown : " + e); } catch (ProviderException e) { System.out.println("Exception thrown : " + e); } } }输出：
Byte array before operation : [84, 97, 106, 109, 97, 104, 97, 108] Byte array after operation : [109, 55, 116, -15, -83, 126, -128, 88]注意：以下程序在在线IDE中产生以下异常
抛出异常： Java.security.ProviderException：初始化失败示例 2：
// Java program to demonstrate // getInstance() method import java.security.*; import java.util.*; public class GFG1 { public static void main(String[] argv) { try { // creating SecureRandom object SecureRandom sr1 = new SecureRandom(new byte[] { 1, 2, 3, 4 }); // creating Provider object Provider pd = sr1.getProvider(); // creating the object of SecureRandom and getting instance // By using getInstance() method System.out.println("Trying to getting the instance of TAJMAHAL "); SecureRandom sr = SecureRandom.getInstance("TAJMAHAL", pd); // Declaring the string variable String str = "Tajmahal"; // Declaring the byte Array // converting string into byte byte[] b = str.getBytes(); // printing the byte array System.out.println("Byte array before operation : " + Arrays.toString(b)); // generating user-specified number of random bytes // using nextBytes() method sr.nextBytes(b); // printing the new byte array System.out.println("Byte array after operation : " + Arrays.toString(b)); } catch (NoSuchAlgorithmException e) { System.out.println("Exception thrown : " + e); } catch (ProviderException e) { System.out.println("Exception thrown : " + e); } } }输出：
Trying to getting the instance of TAJMAHAL Exception thrown : java.security.NoSuchAlgorithmException: no such algorithm: TAJMAHAL for provider SUNgetInstance（字符串算法，字符串提供者）
Java.security.SecureRandom类的getInstance()方法用于返回实现指定随机数生成器 (RNG) 算法的 SecureRandom 对象。
返回一个封装来自指定提供者的 SecureRandomSpi 实现的新 SecureRandom 对象。指定的提供者必须在安全提供者列表中注册。
句法：
public static SecureRandom getInstance( String algorithm, String provider ) throws NoSuchAlgorithmException, NoSuchProviderException参数：此方法将以下参数作为参数
- algorithm – RNG 算法的名称。有关标准 RNG 算法名称的信息，请参阅Java Cryptography Architecture Standard Algorithm Name Documentation 中的 SecureRandom 部分。
- 提供者——提供者的名称。
返回值：此方法返回新的 SecureRandom 对象。
异常：此方法抛出以下异常
- NoSuchAlgorithmException – 如果指定算法的 SecureRandomSpi 实现不能从指定的提供者处获得。
- NoSuchProviderException – 如果指定的提供者未在安全提供者列表中注册。
- IllegalArgumentException – 如果提供者名称为 null 或为空。
笔记：
- 这些程序不会在在线 IDE 上运行。
- 每次 Secure Random 类都会产生随机输出。
下面是说明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) throws NoSuchAlgorithmException, NoSuchProviderException { try { // creating SecureRandom object SecureRandom sr1 = new SecureRandom(new byte[] { 1, 2, 3, 4 }); // creating Provider object Provider pd = sr1.getProvider(); // getting provider name // by using method getname() String provider = pd.getName(); // getting algorithm name // by using getAlgorithm() mathod String algo = sr1.getAlgorithm(); // creating the object of SecureRandom and getting instance // By using getInstance() method SecureRandom sr = SecureRandom.getInstance(algo, provider); // Declaring the string variable String str = "Tajmahal"; // Declaring the byte Array // converting string into byte byte[] b = str.getBytes(); // printing the byte array System.out.println("Byte array before operation : " + Arrays.toString(b)); // generating user-specified number of random bytes // using nextBytes() method sr.nextBytes(b); // printing the new byte array System.out.println("Byte array after operation : " + Arrays.toString(b)); } catch (NoSuchAlgorithmException e) { System.out.println("Exception thrown : " + e); } catch (ProviderException e) { System.out.println("Exception thrown : " + e); } } }输出：
Byte array before operation : [84, 97, 106, 109, 97, 104, 97, 108] Byte array after operation : [-11, 81, 39, 67, -95, -51, 115, -18]示例 2：
// Java program to demonstrate // getInstance() method import java.security.*; import java.util.*; public class GFG1 { public static void main(String[] argv) throws NoSuchAlgorithmException, NoSuchProviderException { try { // creating SecureRandom object SecureRandom sr1 = new SecureRandom(new byte[] { 1, 2, 3, 4 }); // creating Provider object Provider pd = sr1.getProvider(); // getting provider name // by using method getname() String provider = pd.getName(); // creating the object of SecureRandom and getting instance // By using getInstance() method System.out.println("Trying to take TAJMAHAL as a algorithm"); SecureRandom sr = SecureRandom.getInstance("TAJMAHAL", provider); // Declaring the string variable String str = "Tajmahal"; // Declaring the byte Array // converting string into byte byte[] b = str.getBytes(); // printing the byte array System.out.println("Byte array before operation : " + Arrays.toString(b)); // generating user-specified number of random bytes // using nextBytes() method sr.nextBytes(b); // printing the new byte array System.out.println("Byte array after operation : " + Arrays.toString(b)); } catch (NoSuchAlgorithmException e) { System.out.println("Exception thrown : " + e); } catch (ProviderException e) { System.out.println("Exception thrown : " + e); } } }输出：
Trying to take TAJMAHAL as a algorithm Exception thrown : java.security.NoSuchAlgorithmException: no such algorithm: TAJMAHAL for provider SUN示例 3：
// Java program to demonstrate // getInstance() method import java.security.*; import java.util.*; public class GFG1 { public static void main(String[] argv) throws NoSuchAlgorithmException, NoSuchProviderException { try { // creating SecureRandom object SecureRandom sr1 = new SecureRandom(new byte[] { 1, 2, 3, 4 }); // getting algorithm name // by using getAlgorithm() mathod String algo = sr1.getAlgorithm(); // creating the object of SecureRandom and getting instance // By using getInstance() method System.out.println("Trying to taking MOON as a provider"); SecureRandom sr = SecureRandom.getInstance(algo, "MOON"); // Declaring the string variable String str = "Tajmahal"; // Declaring the byte Array // converting string into byte byte[] b = str.getBytes(); // printing the byte array System.out.println("Byte array before operation : " + Arrays.toString(b)); // generating user-specified number of random bytes // using nextBytes() method sr.nextBytes(b); // printing the new byte array System.out.println("Byte array after operation : " + Arrays.toString(b)); } catch (NoSuchAlgorithmException e) { System.out.println("Exception thrown : " + e); } catch (NoSuchProviderException e) { System.out.println("Exception thrown : " + e); } } }输出：
Trying to taking MOON as a provider Exception thrown : java.security.NoSuchProviderException: no such provider: MOON