Java中的 SecureRandom generateSeed() 方法及示例

Java.security.SecureRandom类的generateSeed()方法用于返回给定数量的种子字节，使用此类用于为自身播种的种子生成算法计算得出。此调用可用于播种其他随机数生成器。

句法：

public byte[] generateSeed(int numBytes)

参数：此方法将要生成的种子字节数作为参数。

返回值：此方法返回生成的种子字节。

下面是说明generateSeed()方法的示例：

笔记：

1. 该程序不会在在线 IDE 上运行。
2. 每次 Secure Random 类都会产生随机输出。

示例 1：

Java

// Java program to demonstrate
// generateSeed() method
 
import java.security.*;
import java.util.*;
 
public class GFG1 {
    public static void main(String[] argv)
    {
        try {
 
            // creating the object of SecureRandom
            SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
 
            // getting the generated seed by into byte array
            // by using method generateSeed()
            byte[] arr = sr.generateSeed(8);
 
            // printing the byte array
            System.out.println(Arrays.toString(arr));
        }
 
        catch (NoSuchAlgorithmException e) {
 
            System.out.println("Exception thrown : " + e);
        }
    }
}

输出：

[24, -16, -12, 25, -3, 66, -90, 103]

示例 2：

Java

// Java program to demonstrate
// generateSeed() method
 
import java.security.*;
import java.util.*;
 
public class GFG1 {
    public static void main(String[] argv)
    {
        try {
 
            // creating the object of SecureRandom getting the instance of TAJMAHAL
            System.out.println("Trying to get the instance from an unknown source");
            SecureRandom sr = SecureRandom.getInstance("TAJMAHAL");
 
            // getting the generated seed by into byte array
            // by using method generateSeed()
            byte[] arr = sr.generateSeed(5);
 
            // printing the byte array
            System.out.println("Seed Bytes: " + Arrays.toString(arr));
        }
 
        catch (NoSuchAlgorithmException e) {
 
            System.out.println("Exception thrown : " + e);
        }
    }
}

输出：

Trying to get the instance from an unknown source
Exception thrown : java.security.NoSuchAlgorithmException: TAJMAHAL SecureRandom not available