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