JAVA学习--反射方法操作

    //1.获取运行时类的方法
    
    @Test
    public void test1(){
        Class clazz = Person.class;
        //1.getMethods():获取运行时类及其父类中所有的声明为public的方法
        Method[] m1 = clazz.getMethods();
        for(Method m : m1){
            System.out.println(m);
        }
        System.out.println();
        
        //2.getDeclaredMethods():获取运行时类本身声明的所有的方法
        Method[] m2 = clazz.getDeclaredMethods();
        for(Method m : m2){
            System.out.println(m);
        }
    }

//注解 权限修饰符 返回值类型 方法名 形参列表 异常
    @Test
    public void test2(){
        Class clazz = Person.class;
        
        Method[] m2 = clazz.getDeclaredMethods();
        for(Method m : m2){
            //1.注解
            Annotation[] ann = m.getAnnotations();
            for(Annotation a : ann){
                System.out.println(a);
            }
            
            //2.权限修饰符
            String str = Modifier.toString(m.getModifiers());
            System.out.print(str + " ");
            //3.返回值类型
            Class returnType = m.getReturnType();
            System.out.print(returnType.getName() + " ");
            //4.方法名
            System.out.print(m.getName() + " ");
            
            //5.形参列表
            System.out.print("(");
            Class[] params = m.getParameterTypes();
            for(int i = 0;i < params.length;i++){
                System.out.print(params[i].getName() + " args-" + i + " ");
            }
            System.out.print(")");
            
            //6.异常类型
            Class[] exps = m.getExceptionTypes();
            if(exps.length != 0){
                System.out.print("throws ");
            }
            for(int i = 0;i < exps.length;i++){
                System.out.print(exps[i].getName() + " ");
            }
            System.out.println();
        }
    }

//调用运行时类中指定的方法
    @Test
    public void test3() throws Exception{
        Class clazz = Person.class;
        //getMethod(String methodName,Class ... params):获取运行时类中声明为public的指定的方法
        Method m1 = clazz.getMethod("show");
        Person p = (Person)clazz.newInstance();
        //调用指定的方法：Object invoke(Object obj,Object ... obj)
        Object returnVal = m1.invoke(p);//我是一个人
        System.out.println(returnVal);//null
        
        Method m2 = clazz.getMethod("toString");
        Object returnVal1 = m2.invoke(p);
        System.out.println(returnVal1);//Person [name=null, age=0]
        //对于运行时类中静态方法的调用
        Method m3 = clazz.getMethod("info");
        m3.invoke(Person.class);
        
        //getDeclaredMethod(String methodName,Class ... params):获取运行时类中声明了的指定的方法
        Method m4 = clazz.getDeclaredMethod("display",String.class,Integer.class);
        m4.setAccessible(true);
        Object value = m4.invoke(p,"CHN",10);//我的国籍是：CHN
        System.out.println(value);//10
    }

 class Person extends Creature<String> implements Comparable,MyInterface{
    public String name;
    private int age;
    int id;
    //创建类时，尽量保留一个空参的构造器。
    public Person() {
        super();
//        System.out.println("今天天气很闷热");
    }
    public Person(String name) {
        super();
        this.name = name;
    }
    private Person(String name, int age) {
        super();
        this.name = name;
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    @MyAnnotation(value = "abc123")
    public void show(){
        System.out.println("我是一个人！");
    }
    
    private Integer display(String nation,Integer i) throws Exception{
        System.out.println("我的国籍是：" + nation);
        return i;
    }
    @Override
    public String toString() {
        return "Person [name=" + name + ", age=" + age + "]";
    }
    @Override
    public int compareTo(Object o) {
        // TODO Auto-generated method stub
        return 0;
    }
    
    public static void info(){
        System.out.println("中国人！");
    }
    
    class Bird{
        
    }
    
}

import static java.lang.annotation.ElementType.CONSTRUCTOR;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.LOCAL_VARIABLE;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.ElementType.TYPE;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({TYPE, FIELD, METHOD, PARAMETER, CONSTRUCTOR, LOCAL_VARIABLE})
@Retention(RetentionPolicy.RUNTIME)
public @interface MyAnnotation {
    String value();
}

public class Creature<T>{
    public double weight;
    
    public void breath(){
        System.out.println("呼吸！");
    }
}

 import java.io.Serializable; 2 3 public interface MyInterface extends Serializable{ 4 5 }