1、定义成员变量

package com.example.demo.controller;

import com.example.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.env.Environment;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import java.io.IOException;
import java.util.Map;

/**
 * @Description: TODO
 * @Author: Top
 * @Version: V1.0
 * @Date: 2020-01-15 15:03
 */
@RestController
@RequestMapping("/api/{edition}/page2")
public class MyPageHelperController2 {

    @Autowired
    private Environment env;

    @Autowired
    private UserService userServiceImpl;

    private String str1;

    private static String str2;

    @GetMapping("/myPage3")
    @ResponseBody
    public Map<Object, Object> expenseStatement(Object str) throws IOException {

        str1 = "zhangjiguo";
        System.out.println(str1);

        str2 = "guoguo";
        System.out.println(str2);
        return null;
    }

    @GetMapping("/myPage4")
    @ResponseBody
    public Map<Object, Object> expenseStatement2(Object str) throws IOException {

        System.out.println(str1);
        System.out.println(str2);

        return null;
    }

    @GetMapping("/myPage5")
    @ResponseBody
    public Map<Object, Object> expenseStatement3(Object str) throws IOException {

        str1 = "zhangsan";
        str2 = "jiji";
        System.out.println(str1);
        System.out.println(str2);

        return null;
    }
}

2、定义工具类，从容器中获取某个bean

package com.example.demo.common;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

@Component
public class SpringContextUtils implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    /**
     * 通过name获取 Bean.
     *
     * @param name
     * @return
     */
    public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    }

    /**
     * 通过class获取Bean.
     *
     * @param clazz
     * @param <T>
     * @return
     */
    public static <T> T getBean(Class<T> clazz) {
        return getApplicationContext().getBean(clazz);
    }

    /**
     * 通过name及Clazz返回指定的Bean
     *
     * @param name
     * @param clazz
     * @param <T>
     * @return
     */
    public static <T> T getBean(String name, Class<T> clazz) {
        return getApplicationContext().getBean(name, clazz);
    }

    @Autowired
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        SpringContextUtils.applicationContext = applicationContext;
    }

    /**
     * 获取applicationContext
     *
     * @return
     */
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }
}

3、修改成员变量

@RequestMapping("ok")
    public Object test2(){
        ApplicationContext applicationContext = SpringContextUtils.getApplicationContext();
        String[] beans = applicationContext.getBeanDefinitionNames();
        for (String beanName : beans) {
            // 拿到bean的Class对象
            Class<?> beanType = applicationContext.getType(beanName);
            if (beanType == null) {
                continue;
            }
            // 拿到当前bean类型的所有字段
            Field[] declaredFields = beanType.getDeclaredFields();
            if(!beanName.contains("myPageHelperController2") ){
                continue;
            }
            for (Field field : declaredFields) {
                // 从spring容器中拿到这个具体的bean对象
                Object bean = applicationContext.getBean(beanName);
                // 当前字段设置新的值
                try {
                    setFieldData(field, bean, "ffffff");
                    System.out.println("finished");
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
        return "ok";
    }

    private void setFieldData(Field field, Object bean, String data) throws Exception {
        // 注意这里要设置权限为true
        field.setAccessible(true);
        Class<?> type = field.getType();
        if (type.equals(String.class)) {
            field.set(bean, data);
        } else if (type.equals(Integer.class)) {
            field.set(bean, Integer.valueOf(data));
        } else if (type.equals(Long.class)) {
            field.set(bean, Long.valueOf(data));
        } else if (type.equals(Double.class)) {
            field.set(bean, Double.valueOf(data));
        } else if (type.equals(Short.class)) {
            field.set(bean, Short.valueOf(data));
        } else if (type.equals(Byte.class)) {
            field.set(bean, Byte.valueOf(data));
        } else if (type.equals(Boolean.class)) {
            field.set(bean, Boolean.valueOf(data));
        } else if (type.equals(Date.class)) {
            field.set(bean, new Date(Long.valueOf(data)));
        }
    }

示例二：

import java.lang.reflect.Field;
 
public class Main {
    public static void main(String[] args) throws Exception {
        // 创建一个Person类的实例
        Person person = new Person("John", 25);
        
        // 获取Person类的Class对象
        Class<?> clazz = person.getClass();
        
        // 获取name字段并设置新值
        Field nameField = clazz.getDeclaredField("name");
        nameField.setAccessible(true);
        nameField.set(person, "Tom");
        
        // 输出修改后的结果
        System.out.println(person.getName());   // 输出"Tom"
        
        // 获取age字段并设置新值
        Field ageField = clazz.getDeclaredField("age");
        ageField.setAccessible(true);
        ageField.setInt(person, 30);
        
        // 输出修改后的结果
        System.out.println(person.getAge());     // 输出30
    }
}
 
class Person {
    private String name;
    private int age;
    
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
    
    public String getName() {
        return name;
    }
    
    public int getAge() {
        return age;
    }
}