Java 中 SecureRandom setSeed()方法，带示例
原文:https://www . geesforgeks . org/secureandom-setseed-method-in-Java-with-examples/
setSeed( byte[] seed )
Java . security . secureandom类的 setSeed() 方法用于重新播种这个随机对象。给定的种子补充而不是取代现有的种子。因此，重复调用保证永远不会降低随机性。
语法:
public void setSeed(byte[] seed)
参数:该方法以种子为参数。
注意:每次安全随机类都会产生随机输出
以下是说明设置种子()方法的示例:
例 1:
// Java program to demonstrate
// setSeed() 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");
// Declaring the string variable
String str = "Tajmahal";
// Declaring the byte Array b
byte[] b = str.getBytes();
// Reseeding the random object
sr.setSeed(b);
// getting the seeds
byte[] seeds = sr.getSeed(10);
// printing the seed serialwise
for (int i = 0; i < seeds.length; i++)
System.out.println("Seed[" + i + "] : " + seeds[i]);
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (ProviderException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Seed[0]:69
Seed[0] : 23
Seed[1] : -99
Seed[2] : -51
Seed[3] : 107
Seed[4] : 41
Seed[5] : -96
Seed[6] : -93
Seed[7] : -86
Seed[8] : 127
Seed[9] : 47
例 2:
// Java program to demonstrate
// setSeed() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
{
try {
// creating the object of SecureRandom
SecureRandom sr = new SecureRandom(new byte[] { 1, 2, 3, 4 });
// Declaring the string variable
String str = "Tajmahal";
// Declaring the byte Array b
byte[] b = str.getBytes();
// Reseeding the random object
sr.setSeed(b);
// getting the seeds
byte[] seeds = sr.getSeed(10);
// printing the seed serialwise
for (int i = 0; i < seeds.length; i++)
System.out.println("Seed[" + i + "]:" + seeds[i]);
}
catch (ProviderException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Seed[0]:92
Seed[1]:127
Seed[2]:28
Seed[3]:-127
Seed[4]:-100
Seed[5]:-110
Seed[6]:86
Seed[7]:-55
Seed[8]:48
Seed[9]:-78
setSeed(long seed)
Java . security . secureandom类的 setSeed(长种子)方法用于使用给定长种子中包含的八个字节重新播种这个随机对象。给定的种子补充而不是取代现有的种子。因此，重复调用保证永远不会降低随机性。
语法:
public void setSeed( long seed )
参数:该方法以种子为参数
注意:每次安全随机类都会产生随机输出
以下是说明设置种子()方法的示例:
例 1:
// Java program to demonstrate
// setSeed() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// creating the object of SecureRandom
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "SUN");
// Reseeding the random object
sr.setSeed(101L);
// getting the seeds
byte[] seeds = sr.getSeed(10);
// printing the seed serialwise
for (int i = 0; i < seeds.length; i++)
System.out.println("Seed[" + i + "] : " + seeds[i]);
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (ProviderException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Seed[0] : -36
Seed[1] : -65
Seed[2] : -94
Seed[3] : 16
Seed[4] : -104
例 2:
// Java program to demonstrate
// setSeed() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
{
try {
// creating the object of SecureRandom
SecureRandom sr = new SecureRandom(new byte[] { 1, 2, 3, 4 });
// Reseeding the random object
sr.setSeed(101L);
// getting the seeds
byte[] seeds = sr.getSeed(10);
// printing the seed serialwise
for (int i = 0; i < seeds.length; i++)
System.out.println("Seed[" + i + "]:" + seeds[i]);
}
catch (ProviderException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Seed[0]:-29
Seed[1]:-93
Seed[2]:6
Seed[3]:66
Seed[4]:126
Seed[5]:93
Seed[6]:-58
Seed[7]:-91
Seed[8]:-62
Seed[9]:-58
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