Java SecurityManager checkMulticast（）方法与示例

SecurityManager类的checkMulticast()方法 (SecurityManager Class checkMulticast() method)

• checkMulticast() method is available in java.lang package.

  checkMulticast()方法在java.lang包中可用。

• checkMulticast() method invokes SocketPermission(i_add.getHostAddress(),"accept,connect") permission to send, receive, join , leave IP multicast.

  checkMulticast()方法调用SocketPermission(i_add.getHostAddress()，“ accept，connect”)权限以发送，接收，加入和离开IP多播。

• checkMulticast() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  checkMulticast()方法是一种非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

• checkMulticast() method may throw an exception at the time of determining IP address.

  在确定IP地址时， checkMulticast()方法可能会引发异常。

  • SecurityException – This exception may throw when the calling thread is not allowed to use send, receive, join and leave IP multicast.
  • NullPointerException – This exception may throw when the given argument value is null.

Syntax:

句法：

    public void checkMulticast(InetAddress i_add);

Parameter(s):

参数：

• InetAddress i_add – represents the address of Internet Group Type.

  InetAddress i_add –表示Internet组类型的地址。

Return value:

返回值：

The return type of this method is void, it returns nothing.

此方法的返回类型为void ，不返回任何内容。

Example:

例：

// Java program to demonstrate the example 
// of void checkMulticast(InetAddress i_add)
// method of SecurityManager 

import java.net.*;

public class CheckMulticast extends SecurityManager {
     
    public static void main(String[] args) throws Exception {
     
        InetAddress i_add = InetAddress.getLocalHost();
        // By using setProperty() method is to set the policy property 
        // with security manager
        System.setProperty("java.security.policy", "file:/C:/java.policy");

        // Instantiating a CheckMulticast object
        CheckMulticast cm = new CheckMulticast();

        // By using setSecurityManager() method is to set the
        // security manager
        System.setSecurityManager(cm);

        // By using CheckMulticast(i_add) method is to check 
        // that ip address is accessible
        cm.checkMulticast(i_add);

        // Display the message
        System.out.println("Not Restricted..");
    }
}

Output

输出量

Exception in thread "main" java.security.AccessControlException: access denied ("java.net.SocketPermission" "127.0.0.1" "connect,accept,resolve")
	at java.base/java.security.AccessControlContext.checkPermission(AccessControlContext.java:472)
	at java.base/java.security.AccessController.checkPermission(AccessController.java:897)
	at java.base/java.lang.SecurityManager.checkPermission(SecurityManager.java:322)
	at java.base/java.lang.SecurityManager.checkMulticast(SecurityManager.java:971)
	at CheckMulticast.main(CheckMulticast.java:23)

翻译自: https://www.includehelp.com/java/securitymanager-checkmulticast-method-with-example.aspx