反射——获取成员变量-蒲公英云

反射——获取成员变量

1、Class对象获取成员变量：

Class类的常用方法（获取Field对象）：

创建Person类：

package pers.reflect.person;
public class Person {
private String name;
private int age;
public String hobby;
public String height;
protected String sex;
String address;
public Person(){
}
public Person(String name,int age){
    this.name=name;
    this.age=age;
}
@Override
public String toString() {
    return "Person [name=" + name + ", age=" + age + ", hobby=" + hobby
            + ", height=" + height + ", sex=" + sex + ", address=" + address
            + "]";
}
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;
}
}
import java.lang.reflect.Field;
import pers.reflect.person.Person;
public class ReflectDemo {
    public static void main(String[] args) throws SecurityException,
            NoSuchFieldException, IllegalArgumentException,
            IllegalAccessException {
        Class c = Person.class;
        System.out.println("getFields()，获取公共的成员变量：");
        Field[] fields = c.getFields();
        for (Field field : fields) {
            System.out.println(field);
        }
        System.out.println("getField(),获取指定的公共的成员变量：");
        Field hobbyField = c.getField("hobby");
        System.out.println(hobbyField);
        System.out.println("getDeclaredFields()，获取所有的成员变量，与修饰符无关。");
        Field[] fields1 = c.getDeclaredFields();
        for (Field field : fields1) {
            System.out.println(field);
        }
        System.out.println("获取私有的指定的成员变量");
        Field nameField = c.getDeclaredField("age");
        System.out.println(nameField);
    }
}

2、Field类的常用方法：

（1）返回变量的类型：

（2）返回属性的名字：

import java.lang.reflect.Field;
import pers.reflect.person.Person;
public class ReflectDemo1 {
public static void main(String[] args) {
    Class c = Person.class;
    System.out.println("getDeclaredFields()，获取所有的成员变量，与修饰符无关。");
    System.out.println(); Field[] fields1 = c.getDeclaredFields(); for (Field field : fields1) { System.out.println("成员变量："+field); System.out.println("属性的类型："+field.getType()); System.out.println("属性的名字："+field.getName()); System.out.println(); } } }

import java.lang.reflect.Field;
import pers.reflect.person.Person;
public class ReflectDemo2 {
public static void main(String[] args) throws SecurityException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
    Class c = Person.class;
    System.out.println("getField(),获取指定的公共的成员变量：");
    Field hobbyField = c.getField("hobby"); System.out.println(hobbyField); Person p=new Person(); Object value=hobbyField.get(p); System.out.println(value); hobbyField.set(p, "张可可"); System.out.println(p); System.out.println(); } }

访问不是被public修饰的成员变量（要用暴力反射，否者无法访问）：

import java.lang.reflect.Field;
import pers.reflect.person.Person;
public class ReflectDemo3 {
    public static void main(String[] args) throws SecurityException,
            NoSuchFieldException, IllegalArgumentException,
            IllegalAccessException {
        Class c = Person.class;
        Field nameField = c.getDeclaredField("name");
        nameField.setAccessible(true);//暴力反射
        System.out.println(nameField); Person p = new Person(); Object value = nameField.get(p); System.out.println(value); nameField.set(p, "赵晓霞"); System.out.println(p); } }
setAccessible(true)；忽略权限修饰符的安全检查。