Java Console readPassword()用法及代码示例

Java中的Console类的readPassword()方法有两种类型：

1. Java中Console类的readPassword()方法用于在禁用了回显的情况下从控制台读取密码或密码。

用法:

public char[] readPassword()

参数：此方法不接受任何参数。

返回值：此方法返回一个字符数组，其中包含从控制台读取的密码或口令。如果流结束，则返回null。

异常：如果发生I /O错误，则此方法将引发IOError。

注意：System.console()在在线IDE中返回null。

以下示例程序旨在说明IO包中Console类中的readPassword()方法：

程序1:

// Java program to illustrate 
// Console readPassword() method 
  
import java.io.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
        // Create the console object 
        Console cnsl 
            = System.console(); 
  
        if (cnsl == null) { 
            System.out.println( 
                "No console available"); 
            return; 
        } 
  
        // Read line 
        String str = cnsl.readLine( 
            "Enter username:"); 
  
        // Print username 
        System.out.println( 
            "Username:" + str); 
  
        // Read password 
        // into character array 
        char[] ch = cnsl.readPassword( 
            "Enter password:"); 
  
        // Print password 
        System.out.println( 
            "Password:" + ch); 
    } 
}

输出：

程序2:

// Java program to illustrate 
// Console readPassword() method 
  
import java.io.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
        // Create the console object 
        Console cnsl 
            = System.console(); 
  
        if (cnsl == null) { 
            System.out.println( 
                "No console available"); 
            return; 
        } 
  
        // Read line 
        String str = cnsl.readLine( 
            "Enter username:"); 
  
        // Print username 
        System.out.println( 
            "Username:" + str); 
  
        // Read password 
        // into character array 
        char[] ch = cnsl.readPassword( 
            "Enter password:"); 
  
        // Print password 
        System.out.println( 
            "Password:" + ch); 
    } 
}

输出：

2. Java中Console类的readPassword(String，Object)方法用于通过提供格式化的提示从控制台读取密码或密码。它返回字符数组中的密码。

用法:

public char[] readPassword(String fmt,
                      Object... args)

参数：此方法接受两个参数：

fmt-它表示字符串的格式。
args-它表示由字符串格式的格式说明符引用的参数。

返回值：此方法返回包含从控制台读取的密码或密码短语的字符数组。如果流结束，则返回null。

异常：

IllegalFormatException-如果字符串格式包含非法语法，或者格式说明符与给定参数不兼容，或者给定格式字符串或其他非法条件，则此方法将引发IllegalFormatException。
IOError-如果发生I /O错误，则此方法将引发IOError。

以下示例程序旨在说明IO包中Console类中的readPassword(String，Object)方法：

程序1:

// Java program to illustrate 
// Console readPassword(String, Object) method 
  
import java.io.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
        // Create the console object 
        Console cnsl 
            = System.console(); 
  
        if (cnsl == null) { 
            System.out.println( 
                "No console available"); 
            return; 
        } 
  
        String fmt = "%2$5s %3$10s%n"; 
  
        // Read line 
        String un = cnsl.readLine( 
            fmt, "Enter", "Username:"); 
  
        // Print username 
        System.out.println( 
            "Username:" + un); 
  
        // Read password 
        // into character array 
        char[] pwd = cnsl.readPassword( 
            fmt, "Enter", "Password:"); 
  
        // Print password 
        System.out.println( 
            "Password:" + pwd); 
    } 
}

输出：

程序2:

// Java program to illustrate 
// Console readPassword(String, Object) method 
  
import java.io.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
        // Create the console object 
        Console cnsl 
            = System.console(); 
  
        if (cnsl == null) { 
            System.out.println( 
                "No console available"); 
            return; 
        } 
  
        String fmt = "%2$5s %3$10s%n"; 
  
        // Read line 
        String un = cnsl.readLine( 
            fmt, "Enter", "Username:"); 
  
        // Print username 
        System.out.println( 
            "Username:" + un); 
  
        // Read password 
        // into character array 
        char[] pwd = cnsl.readPassword( 
            fmt, "Enter", "Password:"); 
  
        // Print password 
        System.out.println( 
            "Password:" + pwd); 
    } 
}

输出：

参考文献：
1. https://docs.oracle.com/javase/10/docs/api/java/io/Console.html#readPassword()
2. https://docs.oracle.com/javase/10/docs/api/java/io/Console.html#readPassword(java.lang.String, java.lang.Object…)

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注：本文由纯净天空筛选整理自pp_pankaj大神的英文原创作品 Console readPassword() method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。