java 中的 Java . lang . instrument . Class definition 类

原文:https://www . geesforgeks . org/Java-lang-instrument-class definition-class-in-Java/

该类用于将提供的类和类文件字节绑定在一个类定义对象中。这些类提供了方法来提取关于类的类型和一个对象的类文件字节的信息。这个类是 java.lang.Object 类的子类。

类申报:

public final class ClassDefinition
extends Object

建造师:

| **Constructor** | **Description** | | --- | --- | | 类别定义(类别类,字节[]类文件) | This constructor creates a new instance of the class definition class by binding the provided class and class file bytes. |

方法:

| **方法** | **描述** | | --- | --- | | getDefinitionClass() | 此方法用于获取此类的类类型 | | getDefinitionClassFile() | 此方法用于获取包含新类文件的字节数组。 |

示例 1: 创建新 ClassDefinition 对象的 Java 程序

Java 语言(一种计算机语言，尤用于创建网站)

// Java program to create new ClassDefinition object
import java.lang.instrument.ClassDefinition;

// driver class
public class GFG {
    // demoClass
    static class demoClass {
        void msg() { System.out.println("GeeksForGeeks"); }
    }
    // main method
    public static void main(String[] args)
    {
        try {

            // creating demoClass object
            demoClass cls = new demoClass();

            // creating object of supplied class
            Class<?> theClass = cls.getClass();

            // creating array of class files
            byte[] classFiles = { 0 };

            // creating a new ClassDefinition object
            ClassDefinition classdefinition
                = new ClassDefinition(theClass, classFiles);
            System.out.println(
                "ClassDefinition object successfully created");
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Output

ClassDefinition object successfully created

示例 2: Java 程序说明 ClassDefinition 类方法

Java 语言(一种计算机语言，尤用于创建网站)

// Java program to illustrate ClassDefinition class methods
import java.lang.instrument.ClassDefinition;

// driver class
public class GFG {

    // demoClass
    static class demoClass {
        void msg() { System.out.println("GeeksForGeeks"); }
    }

    // main method
    public static void main(String[] args)
    {
        try {

            // creating demoClass object
            demoClass cls = new demoClass();

            // creating object of supplied class
            Class<?> theClass = cls.getClass();

            // creating array of class files
            byte[] classFiles = { 0 };

            // creating a new ClassDefinition object
            ClassDefinition classdefinition
                = new ClassDefinition(theClass, classFiles);

            // printing the class
            System.out.println(
                classdefinition.getDefinitionClass());

            // printing array of bytes that contain class
            // files
            System.out.println(
                classdefinition.getDefinitionClassFile());
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Output

class GFG$demoClass
[B@448139f0

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