JAVA学习--反射属性操作

    //获取对应的运行时类的属性
    @Test
    public void test1(){
        Class clazz = Person.class;
        //1.getFields():只能获取到运行时类中及其父类中声明为public的属性
        Field[] fields = clazz.getFields();
        
        for(int i = 0;i < fields.length;i++){
            System.out.println(fields[i]);
        }
        System.out.println();
        //2.getDeclaredFields():获取运行时类本身声明的所有的属性
        Field[] fields1 = clazz.getDeclaredFields();
        for(Field f : fields1){
            System.out.println(f.getName());
        }
    }

//权限修饰符  变量类型 变量名
    //获取属性的各个部分的内容
    @Test
    public void test2(){
        Class clazz = Person.class;
        Field[] fields1 = clazz.getDeclaredFields();
        for(Field f : fields1){
            //1.获取每个属性的权限修饰符
            int i = f.getModifiers();
            String str1 = Modifier.toString(i);
            System.out.print(str1 + " ");
            //2.获取属性的类型
            Class type = f.getType();
            System.out.print(type.getName() + " ");
            //3.获取属性名
            System.out.print(f.getName());
            
            System.out.println();
        }
    }

//调用运行时类中指定的属性
    @Test
    public void test3() throws Exception{
        Class clazz = Person.class;
        //1.获取指定的属性
        //getField(String fieldName):获取运行时类中声明为public的指定属性名为fieldName的属性
        Field name = clazz.getField("name");
        //2.创建运行时类的对象 
        Person p = (Person)clazz.newInstance();
        System.out.println(p);
        //3.将运行时类的指定的属性赋值
        name.set(p,"Jerry");
        System.out.println(p);
        System.out.println("%"+name.get(p));
        
        System.out.println();
        //getDeclaredField(String fieldName):获取运行时类中指定的名为fieldName的属性
        Field age = clazz.getDeclaredField("age");
        //由于属性权限修饰符的限制，为了保证可以给属性赋值，需要在操作前使得此属性可被操作。
        age.setAccessible(true);
        age.set(p,10);
        System.out.println(p);
        
//        Field id = clazz.getField("id");
        
    }

 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;

public interface MyInterface extends Serializable{

}