Java SecurityManager checkExec（）方法与示例

SecurityManager类的checkExec()方法 (SecurityManager Class checkExec() method)

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

  checkExec()方法在java.lang包中可用。

• checkExec() method calls checkPermission with FilePermission(commands,"execute") when the given argument holds an absolute path else it calls checkPermission with FilePermission("<>","execute").

  当给定参数拥有绝对路径时， checkExec()方法将使用FilePermission(commands，“ execute”)调用checkPermission，否则将使用FilePermission(“ << ALL FILES >>”，“ execute”)来调用checkPermission。

• checkExec() 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.

  checkExec()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。

• checkExec() method may throw an exception at the time of creating process.

  在创建过程时， checkExec()方法可能会引发异常。

  • SecurityException – This exception may throw when the calling thread is not allowed to create a subprocess and it is called for the current security manager by using exec() method of Runtime.
  • NullPointerException – This exception may throw when the given parameter is null.

Syntax:

句法：

    public void checkExec(String commands);

Parameter(s):

参数：

• String commands – represents the system-specific commands.

  字符串命令 –表示系统特定的命令。

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 checkExec(String commands)
// method of SecurityManager 

public class CheckExec {
     
    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 SecurityManager object
        SecurityManager smgr = new SecurityManager();

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

        // By using checkExec(String commands) method is to check 
        //that the given command is executable or not
        smgr.checkExec("TextPad.exe");

        // Display the message when command is executed
        System.out.println("Command Executed..");
    }
}

Output

输出量

Exception in thread "main" java.security.AccessControlException: access denied ("java.io.FilePermission" "<>" "execute")
	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.checkExec(SecurityManager.java:572)
	at CheckExec.main(CheckExec.java:20)

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