Java 中的 digestinputstream . setmessagedigest()方法，带示例
原文:https://www . geesforgeks . org/digest inputstream-setmessagedigest-Java 中的方法-示例/
Java . security . DigestInputStream类的 setMessageDigest() 方法，用于将指定的消息摘要分配给 DigestInputStream 对象。
语法:
public void setMessageDigest(MessageDigest digest)
返回值:这个方法没有什么可返回的。
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”。
以下是说明设置消息摘要()方法的示例:
例 1:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// setMessageDigest() 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 usng getInstance() method
MessageDigest sr
= MessageDigest.getInstance("MD5");
// creating and initializing
// object of InputStream
InputStream is
= new FileInputStream(
"f:/java/name.txt");
// creating and initializing
// object of DigestInputStream
DigestInputStream di
= new DigestInputStream(is, sr);
// display the result
System.out.println(
"MessageDigest before assigning : "
+ di.getMessageDigest());
// assigning the MessageDigest to this stream
// using setMessageDigest() method
di.setMessageDigest(
MessageDigest
.getInstance("SHA-1"));
// display the result
System.out.println(
"MessageDigest after assigning : "
+ di.getMessageDigest());
}
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);
}
}
}
Output:
MessageDigest before assigning : MD5 Message Digest from SUN,
MessageDigest after assigning : SHA-1 Message Digest from SUN,
例 2:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// setMessageDigest() 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 usng getInstance() method
MessageDigest sr
= MessageDigest.getInstance("SHA-1");
// creating and initializing
// object of InputStream
InputStream is
= new FileInputStream(
"f:/java/name.txt");
// creating and initializing
// object of DigestInputStream
DigestInputStream di
= new DigestInputStream(is, sr);
// display the result
System.out.println(
"MessageDigest before assigning : "
+ di.getMessageDigest());
// assigning the MessageDigest to this stream
// using setMessageDigest() method
di.setMessageDigest(
MessageDigest.getInstance("MD5"));
// display the result
System.out.println(
"MessageDigest after assigning : "
+ di.getMessageDigest());
}
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);
}
}
}
Output:
MessageDigest before assigning : SHA-1 Message Digest from SUN,
MessageDigest after assigning : MD5 Message Digest from SUN,
参考:T2【https://docs . Oracle . com/javase/9/docs/API/Java/security/digestinputstream . html # setMessageDigest-Java . security . messagedigest-T4】
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