SpringBoot的@Value注解如何设置默认值

@RestController
public class ConfigController {
    // ①未指定默认值
    @Value("${user.username}")
    private String username;
    
    // ②指定默认值为“unknown”
    @Value("${projectName:unknown}")
    private String projectName;
}

package com.oashiro.example.test;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class User{
    public String address;

    @Value("${address-config:浙江省杭州市西湖区}")
    public void steAddress(String address){
        this.address=address;
    }

    public String getAddress(){
        return this.address;
    }

    @Override
    public String toString() {
        return "User{" +
                "address='" + address + '\'' +
                '}';
    }
}

package com.oashiro.example.test;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import static org.junit.jupiter.api.Assertions.*;

@SpringBootTest
class UserTest {

    @Autowired
    private User user;

    @BeforeEach
    public void setup(){
        System.out.println("开始测试1");
    }
    
	@AfterEach
    public void teardown(){
        System.out.println("测试结束1");
    }

    @Test
    public void printUser(){
        System.out.println(user);
        //预期结果（浙江省）与实际获取的默认结果（浙江省杭州市西湖区）作对比
        assertEquals("浙江省",user.getAddress());
    }
}