Java 中的 MessageDigest reset()方法，示例
原文:https://www . geesforgeks . org/messagedigest-reset-method-in-Java-with-examples/
Java . security . MessageDigest类的 reset() 方法用于将当前消息摘要值重置为此 messagedigest 对象的默认消息摘要值。 语法:
public void reset()
返回值:这个方法没有什么可返回的。 以下举例说明复位()方法: 例 1:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// toString() method
import java.security.*;
import java.nio.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
{
try {
byte[] barr = { 10, 20, 30, 40 };
// creating object of MessageDigest
MessageDigest msd1
= MessageDigest.getInstance("MD5");
// display the digest value before Updation
System.out.println("MessageDigest before update : "
+ (ByteBuffer.wrap(
msd1.digest()))
.getShort());
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.wrap(barr);
// update MessageDigest value
// using update() method
msd1.update(bb);
// display the digest value before Updation
System.out.println("\nMessageDigest after update : "
+ (ByteBuffer.wrap(
msd1.digest()))
.getShort());
// reset MessageDigest value
// using reset() method
msd1.reset();
// display the digest value after reset
System.out.println("\nMessageDigest after reset : "
+ (ByteBuffer.wrap(
msd1.digest()))
.getShort());
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (ProviderException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Output:
MessageDigest before update : -11235
MessageDigest after update : 30835
MessageDigest after reset : -11235
例 2:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// toString() method
import java.security.*;
import java.nio.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
{
try {
byte[] barr = { 10, 20, 30, 40 };
// creating object of MessageDigest
MessageDigest msd1
= MessageDigest.getInstance("SHA-256");
// display the digest value before Updation
System.out.println("MessageDigest before update : "
+ (ByteBuffer.wrap(
msd1.digest()))
.getShort());
// creating object of ByteBuffer
// and allocating size capacity
ByteBuffer bb = ByteBuffer.wrap(barr);
// update MessageDigest value
// using update() method
msd1.update(bb);
// display the digest value before Updation
System.out.println("\nMessageDigest after update : "
+ (ByteBuffer.wrap(
msd1.digest()))
.getShort());
// reset MessageDigest value
// using reset() method
msd1.reset();
// display the digest value after reset
System.out.println("\nMessageDigest after reset : "
+ (ByteBuffer.wrap(
msd1.digest()))
.getShort());
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (ProviderException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Output:
MessageDigest before update : -7248
MessageDigest after update : 24403
MessageDigest after reset : -7248
参考: https://docs . Oracle . com/javase/9/docs/API/Java/security/messagedigest . html # reset–
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