Java SecurityManager checkMemberAccess（）方法与示例

SecurityManager类的checkMemberAccess()方法 (SecurityManager Class checkMemberAccess() method)

checkMemberAccess() method is available in java.lang package.
checkMemberAccess()方法在java.lang包中可用。
In checkMemberAccess() method we access public members and classes that have similar class loaders like caller by default and in other cases, it calls checkPermission("accessDeclaredMembers") permission.
在checkMemberAccess()方法中 ，默认情况下，我们访问具有类似类加载器的公共成员和类，例如调用者，在其他情况下，它调用checkPermission(“ accessDeclaredMembers”)权限。
checkMemberAccess() 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.
checkMemberAccess()方法是一个非静态方法，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。
checkMemberAccess() method may throw an exception at the time of accessing members.
checkMemberAccess()方法在访问成员时可能会引发异常。
- SecurityException – This exception may throw when the calling thread does not have the right to access members.
- NullPointerException – This exception may throw when the given first parameter is null.

Syntax:

句法：

    public void checkMemberAccess(Class cl, int type);

Parameter(s):

参数：

Class cl – represents the class that indication is to be operated on.
cl类 –表示要对其进行操作的类。
int type – represents the access type like PUBLIC OR DECLARED.
int type –表示访问类型，例如PUBLIC或DECLARED。

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 checkMemberAccess(Class cl, int type)
// method of SecurityManager 
import java.lang.reflect.*;
public class CheckMemberAccess extends SecurityManager {
public void checkMemberAccess(Class cl, int type) {
throw new SecurityException("Restricted..");
}
public static void main(String[] args) {
// By using setProperty() method is to set the policy property 
// with security manager
System.setProperty("java.security.policy", "file:/C:/java.policy");
// Instantiating a CheckMemberAccess object
CheckMemberAccess cma = new CheckMemberAccess();
// By using setSecurityManager() method is to set the
// security manager
System.setSecurityManager(cma);
// By using checkMemberAccess(Class,type) method is to check 
// accessibility of the member
cma.checkMemberAccess(CheckMemberAccess.class, Member.DECLARED);
// Display the message
System.out.println("Not Restricted..");
}
}

Output

输出量

Exception in thread "main" java.lang.SecurityException: Restricted..at CheckMemberAccess.checkMemberAccess(CheckMemberAccess.java:9)at CheckMemberAccess.main(CheckMemberAccess.java:27)