Java SecurityManager checkPackageDefinition（）方法与示例

SecurityManager类的checkPackageDefinition()方法 (SecurityManager Class checkPackageDefinition() method)

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

  checkPackageDefinition()方法在java.lang包中可用。

• We call getProperty("package.definition") to get a list of restricted packages and it checks when our pkg_name starts with or similar to any of the list of restricted packages and when it matches then it calls checkPermission with the RuntimePermission("defineClassInPackage."+pkg_name).

  我们调用getProperty(“ package.definition”)来获取受限程序包列表，它会检查何时pkg_name以任何受限程序包列表开头或相似，并且何时匹配，然后使用RuntimePermission(“ defineClassInPackage)调用checkPermission。 “ + pkg_name)。

• checkPackageDefinition() 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.

  checkPackageDefinition()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。

• checkPackageDefinition() method may throw an exception at the time of defining the class in the given package.

  在给定包中定义类时， checkPackageDefinition()方法可能会引发异常。

  SecurityException – This exception may throw when the calling thread does not have the right to define classes in the given package.

  SecurityException-当调用线程无权在给定包中定义类时，可能引发此异常。

Syntax:

句法：

    public void checkPackageDefinition(String pkg_def);

Parameter(s):

参数：

• String pkg_def – represents the name of the package.

  字符串pkg_def –表示软件包的名称。

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 checkPackageDefinition(String pkg_def)
// method of SecurityManager 

public class checkPackageDefinition extends SecurityManager {
     
    // override checkPackageDefinition() method of SecurityManager
    public void checkPackageDefinition(String pkg_def) {
     
        throw new SecurityException("Restricted...");
    }

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

        // Instantiating a checkPackageDefinition object
        checkPackageDefinition cpd = new checkPackageDefinition();

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

        // By using checkPackageDefinition(pkg_def) method is to check 
        // that package is defined or not
        cpd.checkPackageDefinition("java.lang");

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

Output

输出量

Exception in thread "main" java.lang.SecurityException: Restricted...
	at checkPackageDefinition.checkPackageDefinition(checkPackageDefinition.java:8)
	at checkPackageDefinition.main(checkPackageDefinition.java:25)

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