Java 中的 SecureRandom getInstance()方法，带示例
原文:https://www . geesforgeks . org/secureandom-getinstance-method-in-Java-with-examples/
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 secureandom 对象。
此方法遍历注册的安全提供程序列表，从最首选的提供程序开始。返回一个新的安全对象，该对象封装了来自第一个支持指定算法的提供程序的安全对象。
语法:
public static SecureRandom
getInstance( String algorithm )
throws NoSuchAlgorithmException
参数:该方法以标准 RNG 算法为参数。
返回值:这个方法返回新的 SecureRandom 对象。
异常:如果没有提供程序支持指定算法的 SecureRandomSpi 实现，此方法将引发nosuchalgorithm 异常。
注:
- 这些程序不会在联机集成开发环境中运行。
- 每次安全随机类都会产生随机输出。
以下是说明 getInstance() 方法的示例:
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]
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 available
getInstance(字符串算法，提供程序提供程序)
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 secureandom 对象。 返回一个新的安全对象，该对象封装了来自指定提供程序对象的安全对象接口实现。请注意，指定的提供程序对象不必在提供程序列表中注册。
返回的安全对象尚未植入。若要为返回的对象设定种子，请调用 setSeed 方法。如果不调用 setSeed，对 nextBytes 的第一次调用将强制 SecureRandom 对象对自身进行种子化。如果之前调用了 setSeed，则不会发生这种自播种。
语法:
public static SecureRandom
getInstance( String algorithm, Provider provider )
throws NoSuchAlgorithmException
参数:该方法将以下参数作为参数
- 算法–RNG 算法的名称。
- 提供商–提供商。
返回值:该方法返回新的 SecureRandom 对象。
异常:该方法抛出以下异常
- no suchalgorithm exception–如果指定的提供程序对象中没有指定算法的 SecureRandomSpi 实现，则为。
-
IllegalArgumentException – if the specified provider is null.
注:
- 这些程序不会在联机集成开发环境中运行。
- 每次安全随机类都会产生随机输出。
以下是说明 getInstance() 方法的示例:
例 1:
```java // 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:
java 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:以下程序在联机 IDE 中产生以下异常 抛出异常:Java . security . providerexception:init 失败
例 2:
```java // 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:
java Trying to getting the instance of TAJMAHAL Exception thrown : java.security.NoSuchAlgorithmException: no such algorithm: TAJMAHAL for provider SUNgetInstance(字符串算法，字符串提供程序)
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 secureandom 对象。
返回一个新的安全对象，该对象封装了来自指定提供程序的安全对象接口实现。指定的提供程序必须在安全提供程序列表中注册。
语法:
java public static SecureRandom getInstance( String algorithm, String provider ) throws NoSuchAlgorithmException, NoSuchProviderException参数:该方法将以下参数作为参数
- 算法–RNG 算法的名称。有关标准 RNG 算法名称的信息，请参见 Java 加密体系结构标准算法名称文档中的安全域部分。
- 提供者–提供者的名称。
返回值:该方法返回新的 SecureRandom 对象。
异常:该方法抛出以下异常
- no suchalgorithm exception–如果指定的提供程序无法提供指定算法的 SecureRandomSpi 实现。
- NoSuchProviderException–如果指定的提供商未在安全提供商列表中注册。
- IllegalArgumentException–如果提供程序名称为空。
注:
- 这些程序不会在联机集成开发环境中运行。
- 每次安全随机类都会产生随机输出。
以下是说明 getInstance() 方法的示例:
例 1:
```java // 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:
java Byte array before operation : [84, 97, 106, 109, 97, 104, 97, 108] Byte array after operation : [-11, 81, 39, 67, -95, -51, 115, -18]例 2:
```java // 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:
java Trying to take TAJMAHAL as a algorithm Exception thrown : java.security.NoSuchAlgorithmException: no such algorithm: TAJMAHAL for provider SUN例 3:
```java // 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:
java Trying to taking MOON as a provider Exception thrown : java.security.NoSuchProviderException: no such provider: MOON
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