java 通过反射获取类属性结构，类方法，类父类及其泛型，类，接口和包

Posted 2020-11-22 zsbenn

首先自定义三个类

package reflection1;

public interface MtInterface {
    void info();
}

package reflection1;

import java.io.Serializable;

public class Creature<T> implements Serializable {
    private char gender;
    public double weight;
    
    private void breath() {
        System.out.println("呼吸");
    }
    public void eat() {
        System.out.println("吃饭");
    }
}

package reflection1;


public class Person extends Creature<String> implements Comparable<String>,MtInterface {
    
    private String name;
    int age;
    public int id;
    
    public Person() {
        super();
    }
    private Person(String name) {
        super();
        this.name = name;
    }
    Person(String name, int age) {
        super();
        this.name = name;
        this.age = age;
    }
    public Person(String name, int age, int id) {
        super();
        this.name = name;
        this.age = age;
        this.id = id;
    }
    
    private String show(String nation) {
        System.out.println("nation="+nation);
        return nation;
    }
    public String display(String interests) {
        return interests;
    }
    
    @Override
    public void info() {
        System.out.println("我是人");
    }

    @Override
    public int compareTo(String o) {
        return 0;
    }
    
    private static void showDesc() {
        System.out.println("i am zsben");
    }
    @Override
    public String toString() {
        return "Person [name=" + name + ", age=" + age + ", id=" + id + "]";
    }
    
}

然后通过反射获取类属性结构

package reflection2;

import java.lang.module.ModuleDescriptor.Exports.Modifier;
import java.lang.reflect.Field;

import org.junit.jupiter.api.Test;

import reflection1.*;

/*
 * 获取当前运行时类的属性结构
 * */

public class FieldTest {
    @Test
    public void test1() {
        Class clazz = Person.class;
        
        //获取属性结构
        //getFields():获取当前运行时类及其父类中所有public的属性
        Field [] fields = clazz.getFields();
        for(Field f:fields)
            System.out.println(f);
        
        System.out.println("");
        
        //getDeclaredFields():获得当前运行时类的所有属性，不包含父类的属性，不考虑权限
        fields = clazz.getDeclaredFields();
        for(Field f:fields)
            System.out.println(f);
        
        System.out.println("");
    }
    
    //权限修饰符：数据类型 变量名
    @Test
    public void test2() {
        Class clazz = Person.class;
        Field [] fields = clazz.getDeclaredFields();
        for(Field f:fields) {
            System.out.println(f);
            //1.权限修饰符
            int modifiers = f.getModifiers();
            System.out.println(modifiers);
            
            //2.数据类型
            Class type = f.getType();
            System.out.println(type);
            
            //3.变量名
            String name = f.getName();
            System.out.println(name);
            
            System.out.println("");
        }
    }
}

View Code

获取类方法

package reflection2;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;

import org.junit.jupiter.api.Test;

import reflection.Person;

/*
 * 获取运行时类的方法结构
 * 
 * */

public class MethodTest {
    @Test
    public void test1() {
        Class clazz = Person.class;
        //getMethods():获取当前类及其父类所有public方法
        Method[] methods = clazz.getMethods();
        for(Method m:methods) {
            System.out.println(m);
        }
        System.out.print(‘
‘);
        
        //获取当前运行时类中的所有方法
        methods = clazz.getDeclaredMethods();
        for(Method m:methods) {
            System.out.println(m);
        }
    }
    /*
     * 权限修饰符，返回值类型，方法名(参数类型1   参数1，参数类型2  参数2，参数类型3  参数3...)
     * */
    @Test
    public void test2() {
        //1.获取方法声明的注解
        Class clazz = Person.class;
        Method[]methods = clazz.getDeclaredMethods();
        for(Method m:methods) {
            System.out.println(m);
            //1.获得方法声明的注解
            Annotation[] annos = m.getAnnotations();
            for(Annotation a:annos) {
                System.out.println(a);
            }
            
            //2.获取权限修饰符
            int modifier = m.getModifiers();
            System.out.println(modifier);
            
            //3.返回值类型
            System.out.println(m.getReturnType().getName());
            
            //4.方法名
            System.out.println(m.getName());
            
            //5.形参列表
            Class [] parameterTypes = m.getParameterTypes();
            if(!(parameterTypes == null && parameterTypes.length==0)) {
                for(int i=0;i<parameterTypes.length;i++) {
                    Class p = parameterTypes[i];
                    System.out.println(p.getName()+" args_"+i);
                }
            }
            
            //6.抛出的异常
            Class [] exceptionTypes = m.getExceptionTypes();
            for(Class e:exceptionTypes)
                System.out.println(e.getName());
        }
    }
    
}

View Code

父类及其泛型，所在包，接口

package reflection2;

import java.lang.reflect.Constructor;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;

import reflection1.Person;

public class OtherTest {
    /*
     * 获取构造器结构
     * */
    @Test
    public void test1() {
        Class clazz = Person.class;
        Constructor[] constructors = clazz.getConstructors();
        for(Constructor c:constructors)
            System.out.println(c);
        
        System.out.println();
        
        constructors = clazz.getDeclaredConstructors();
        for(Constructor c:constructors)
            System.out.println(c);
    }
    /*
     * 获取运行时类的父类
     * */
    @Test
    public void test2() {
         Class clazz = Person.class;
         Class superClass = clazz.getSuperclass();
         System.out.println(superClass);
         
    }
    
    /*
     * 获取运行时带泛型的父类
     * */
    @Test
    public void test3() {
         Class clazz = Person.class;
         Type superClass = clazz.getGenericSuperclass();
         System.out.println(superClass);
         
    }
    /*
     * 获取运行时带泛型的父类的泛型
     * */
    @Test
    public void test4() {
         Class clazz = Person.class;
         Type superClass = clazz.getGenericSuperclass();
         ParameterizedType paramType = (ParameterizedType)superClass;
         //获取泛型类型
         Type[] types = paramType.getActualTypeArguments();
         System.out.println(types[0].getTypeName());
    }
    
    /*
     * 获取运行时类的接口
     * */
    @Test
    public void test5() {
        Class clazz = Person.class;
        Class[] interfaces = clazz.getInterfaces();
        for(Class c:interfaces)
            System.out.println(c);
        
        System.out.println();
        Class[]interfaces1 = clazz.getSuperclass().getInterfaces();
        for(Class c:interfaces1)
            System.out.println(c);
    }
    
    /*
     * 获取类运行时所在包
     * */
    @Test
    public void test6() {
        Class clazz = Person.class;
        Package package1 = clazz.getPackage();
        System.out.println(package1);
    }
}

View Code