Java中的 DigestOutputStream.toString() 方法及示例

Java.security.DigestOutputStream类的toString()方法用于提供字符串格式的 DigestOutputStream 对象。

句法：

public String toString()

返回值：该方法以字符串形式返回DigestOutputStream的对象。

注意：本文中的所有程序都不会在在线 IDE 上运行，因为不存在“名称”文件。您可以在系统上的Java编译器上检查此代码。要检查此代码，请在您的系统上创建一个文件“名称”。

下面是说明toString()方法的示例：

示例 1：

// Java program to demonstrate
// toString() 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 string
            // representation of DigestOutputStream
            // using toString() method
            String str = di.toString();
  
            // display the result
            System.out.println("Status : " + str);
        }
  
        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 : [Digest Output Stream] MD5 Message Digest from SUN, 

示例 2：

// Java program to demonstrate
// toString() 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 string representation
            // of DigestOutputStream
            // using toString() method
            String str = di.toString();
  
            // display the result
            System.out.println("Status : " + str);
        }
  
        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 : [Digest Output Stream] SHA-1 Message Digest from SUN, 

参考： https://docs.oracle.com/javase/9/docs/api/ Java/security/DigestOutputStream.html#setMessageDigest-java.security.MessageDigest-