Java DigestInputStream.toString()方法及实例

java.security.DigestInputStream 类的 toString() 方法以字符串格式提供DigestInputStream的对象。

语法：

public String toString()

返回值： 该方法返回字符串格式的DigestInputStream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’name’文件。你可以在你的系统上用Java编译器检查这段代码。要检查这段代码，请在你的系统上创建一个’name’文件。

以下是说明 toString() 方法的例子：

例子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 InputStream
            InputStream is
                = new FileInputStream("f:/java/name.txt");
 
            // creating and initializing
            // object of DigestInputStream
            DigestInputStream di
                = new DigestInputStream(is, sr);
 
            // getting the string representation
            // of DigestInputStream
            // 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 Input Stream] MD5 Message Digest from SUN, 

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 InputStream
            InputStream is
                = new FileInputStream("f:/java/name.txt");
 
            // creating and initializing
            // object of DigestInputStream
            DigestInputStream di
                = new DigestInputStream(is, sr);
 
            // getting the string
            // representation of DigestInputStream
            // 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 Input Stream] SHA-1 Message Digest from SUN, 

参考资料: https://docs.oracle.com/javase/9/docs/api/java/security/DigestInputStream.html#toString-