Java SecureRandom generateSeed()方法及示例

java.security.SecureRandom 类的 generateSeed() 方法用于返回给定的种子字节数，该字节数是使用该类用来给自己播种的种子生成算法计算的。这个调用可以用来给其他随机数生成器添加种子。

语法

public byte[] generateSeed(int numBytes)

参数： 该方法以要生成的 种子字节数 为参数。

返回值： 该方法返回 生成的种子字节 。

下面是说明generateSeed()方法的例子。

注意

这个程序不会在在线IDE上运行。每次Secure Random类都会产生随机输出:

例子1 :

// 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]

例2 :

// 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 sourceException thrown : java.security.NoSuchAlgorithmException: TAJMAHAL SecureRandom not available