Java 中的 DigestOutputStream getMessageDigest()方法，带示例
原文:https://www . geesforgeks . org/digestoutputstream-getmessagedigest-method-in-Java-with-examples/
Java . security . DigestOutputStream类的 getMessageDigest() 方法提供了分配给这个 digestoutstream 对象的消息摘要。
语法:
public MessageDigest getMessageDigest()
返回值:该方法返回分配给它的消息摘要对象。
注意:本文中的所有程序都不会在联机 IDE 上运行，因为不存在“name”文件。您可以在系统的 Java 编译器上检查这些代码。要检查此代码，请在您的系统上创建一个文件“名称”。
以下是说明 getMessageDigest() 方法的示例:
例 1:
// Java program to demonstrate
// getInstance() method
import java.security.*;
import java.util.*;
import java.io.*;
public class GFG {
public static void main(String[] argv)
{
try {
// creating the object of MessageDigest
// and getting instance
// By using getInstance() method
MessageDigest sr
= MessageDigest.getInstance("MD5");
// creating and initializing
// object of OutputStream
OutputStream is
= new FileOutputStream("f:/java/name.txt");
// creating and initializing
// object of DigestOutputStream
DigestOutputStream di
= new DigestOutputStream(is, sr);
// getting the message digest
// using getMessageDigest() method
MessageDigest str
= di.getMessageDigest();
// display the result
System.out.println("Status : "
+ str.toString());
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (NullPointerException e) {
System.out.println("Exception thrown : " + e);
}
catch (FileNotFoundException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Status : MD5 Message Digest from SUN,
例 2:
// Java program to demonstrate
// getInstance() method
import java.security.*;
import java.util.*;
import java.io.*;
public class GFG {
public static void main(String[] argv)
{
try {
// creating the object of MessageDigest
// and getting instance
// By using getInstance() method
MessageDigest sr
= MessageDigest.getInstance("SHA-1");
// creating and initializing
// object of OutputStream
OutputStream is
= new FileOutputStream("f:/java/name.txt");
// creating and initializing
// object of DigestOutputStream
DigestOutputStream di
= new DigestOutputStream(is, sr);
// getting the message digest
// using getMessageDigest() method
MessageDigest str
= di.getMessageDigest();
// display the result
System.out.println("Status : "
+ str.toString());
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (NullPointerException e) {
System.out.println("Exception thrown : " + e);
}
catch (FileNotFoundException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Status : SHA-1 Message Digest from SUN,
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