Java Java.io.FilePermission用法及代码示例

java.io.FilePermission 类用于表示对文件或目录的访问。这些访问采用路径名和与路径名关联的一组操作的形式(指定要打开的文件以及扩展名和路径)。例如，在 FilePermission(“GEEKS.txt”, “read”) 中，“GEEKS.txt” 是路径，“read” 是正在执行的操作。这些行动如下：

read : 文件的读取权限
write : 对文件的写权限
delete : 通过调用File.delete删除文件的权限
readlink : 读取链接权限
execute : 执行了权限

宣言：

public final class FilePermission
   extends Permission
      implements Serializable

构造函数：

FilePermission(String p, String a) : Creates a new file permission object with "a" action.

FilePermission类的方法：

等于(对象FP_obj)：java.io.FilePermission.equals(对象FP_obj)告诉两个(即使用该对象检查 FP_obj 路径名和文件名)FilePermission 对象是否相等。
Syntax :

public boolean equals(Object FP_obj)
Parameters : 
FP_obj : the FilePermission object to be verified with this object
返回：
true : if both the objects are equal else, false.
Exception : 
----------

执行：

Java


// Java Program illustrating equals() method
import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        boolean bool = false;
        // Creating new FilePermissions("Path", "action")
        FilePermission FP_obj1 = new FilePermission("GEEKS", "read");
        FilePermission FP_obj2 = new FilePermission("ABC", "write");
        FilePermission FP_obj3 = new FilePermission("GEEKS", "read");
        // Use of equals method 
        bool = FP_obj2.equals(FP_obj1);
        System.out.println("Whether FP_obj1 equals FP_obj2 : " + bool);
        bool = FP_obj2.equals(FP_obj3);
        System.out.println("Whether FP_obj2 equals FP_obj2 : " + bool);
        bool = FP_obj1.equals(FP_obj3);
        System.out.println("Whether FP_obj3 equals FP_obj1 : " + bool);
    }
}

输出：

Whether FP_obj1 equals FP_obj2 : false
Whether FP_obj2 equals FP_obj2 : false
Whether FP_obj3 equals FP_obj1 : true

getActions(): java.io.FilePermission.getActions()告诉这个FilePermission对象的动作。如果对象有两个操作：删除和读取，则该方法将返回“读取，删除”。在这种情况下，此方法返回“canonical string”：读、写、执行、删除、readlink
Syntax :

public String getActions()
Parameters : 
----------
返回：
canonical string : representing the actions associated with the object.
Exception : 
----------

Implementation :

Java


// Java Program illustrating getActions() method
import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Creating new FilePermissions
        FilePermission FP_obj1 = new FilePermission("GEEKS", "read, delete, write");
        FilePermission FP_obj2 = new FilePermission("ABC", "write, read, execute");
        FilePermission FP_obj3 = new FilePermission("GEEKS", "delete, readlink, read");
        // Use of getActions() method 
        String str = FP_obj1.getActions();
        System.out.println("Actions with FP_obj1 : " + str);
        str = FP_obj2.getActions();
        System.out.println("Actions with FP_obj2 : " + str);
        str = FP_obj3.getActions();
        System.out.println("Actions with FP_obj3 : " + str);
    }
}

输出：

Actions with FP_obj1 : read,write,delete
Actions with FP_obj2 : read,write,execute
Actions with FP_obj3 : read,delete,readlink

hashCode(): java.io.FilePermission.hashCode()返回带参数的 FilePermission 对象的哈希码
Syntax :

public int hashCode()
Parameters : 
--------
返回：
hash code value for the argumented object
Exception : 
----------

执行：

Java


// Java Program illustrating hashCode() method
import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Creating new FilePermissions
        FilePermission FP_obj1=new FilePermission("GEEKS", "read, delete, write");
        // Use of hashCode() method
        int i = FP_obj1.hashCode();
        System.out.println("hashCode value for FP_obj1 : " + i);
    }
}

输出：

hashCode value for FP_obj1 : 0

暗示(权限参数)：java.io.FilePermission.implies(权限参数)告诉 FilePermision 是否具有争论的权限。Syntax :

public boolean implies(Permission arg)
Parameters : 
arg : Permission to be checked 
返回：
true if the FilePermission object has the argumented Permission else, false
Exception : 
----------

Implementation :

Java


// Java Program illustrating implies() method
import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Creating new FilePermissions
        FilePermission FP_obj1 = new FilePermission("GEEKS", "read");
        FilePermission FP_obj2 = new FilePermission("ABC", "write");
        FilePermission FP_obj3 = new FilePermission("GEEKS", "delete");
        // Use of implies() method
        boolean check = FP_obj1.implies(FP_obj2);
        System.out.println("Using implies() for FP_obj1 : " + check);
                 
        // Checked here with the same FilePermission object
        check = FP_obj2.implies(FP_obj2);
        System.out.println("Using implies() for FP_obj2 : " + check);
         
    }
}

输出：

Using implies() for FP_obj1 : false
Using implies() for FP_obj2 : true

newPermissionCollection():java.io.FilePermission.newPermissionCollection()创建具有FilePermission 对象的PermissionCollection 对象。Syntax :

public PermissionCollection newPermissionCollection()
Parameters : 
arg : Permission to be checked 
返回：
new PermissionCollection object having the FilePermission objects.
Exception : 
----------

Implementation :

Java


// Java Program illustrating newPermissionCollection() method
import java.io.*;
import java.security.PermissionCollection;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Creating new FilePermissions
        FilePermission FP_obj1 = new FilePermission("GEEKS.txt", "read");
         
        // Creating new PermissionCollection
        // Use of newPermissionCollection() 
        PermissionCollection FP = FP_obj1.newPermissionCollection();
         
        // Collecting the Permissions of FP_obj1 for FP
        FP.add(FP_obj1);
         
        boolean check = FP.implies(new FilePermission("GEEKS.txt", "read"));
        System.out.println("Is newPermissionCollection() working : " + check);
    }
}

输出：

Is newPermissionCollection() working : true

相关用法

注：本文由纯净天空筛选整理自佚名大神的英文原创作品 Java.io.FilePermission Class in Java。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。