Javassist动态构造一个Class类代码示例

╰+哭是因爲堅強的太久メ 2023-10-07 08:45 10阅读 0赞

package com.zhangxueliang.demo;
    
    import java.io.IOException;
    import java.lang.reflect.Field;
    import java.lang.reflect.Method;
    import java.util.Arrays;
    import javassist.CannotCompileException;
    import javassist.ClassPool;
    import javassist.CtClass;
    import javassist.CtField;
    import javassist.CtMethod;
    import javassist.CtNewMethod;
    import javassist.NotFoundException;
    
    /**
     * 动态构造一个Class
     * @author 张学亮
     *
     */
    public class JavassistDemo {
    
        public static void main(String[] args) throws CannotCompileException, IOException, NotFoundException {
    
            ClassPool pool = ClassPool.getDefault();
    
            //定义类
            CtClass stuClass = pool.makeClass("com.zhangxueliang.Student");
    
            //加载类
    //      CtClass cc =  pool.get(classname);
    
            //id属性
            CtField idField = new CtField(CtClass.longType, "id", stuClass);
            stuClass.addField(idField);
    
            //name属性
            CtField nameField = new CtField(pool.get("java.lang.String"), "name", stuClass);
            stuClass.addField(nameField);
    
            //age属性
            CtField ageField = new CtField(CtClass.intType, "age", stuClass);
            stuClass.addField(ageField);
    
            CtMethod getMethod = CtNewMethod.make("public int getAge() { return this.age;}", stuClass);
            CtMethod setMethod = CtNewMethod.make("public void setAge(int age) { this.age = age;}", stuClass);
    
            stuClass.addMethod(getMethod);
            stuClass.addMethod(setMethod);
    
            stuClass.writeFile("e:\\Practice_Demo");
    
            Class<?> clazz = stuClass.toClass();
            System.out.println("class:"+clazz.getName());
    
            System.out.println("------------属性列表------------");
            Field[] fields = clazz.getDeclaredFields();
            for (Field field : fields) {
                System.out.println(field.getType()+"\t"+field.getName());
            }
    
            System.out.println("------------方法列表------------");
            //方法
            Method[] methods = clazz.getDeclaredMethods();
            for (Method method: methods){
                System.out.println(method.getReturnType()+"\t"+method.getName()+"\t"+Arrays.toString(method.getParameterTypes()));
            }
    
        }
    
    }