import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.env.MapPropertySource;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.util.StringUtils;
import javax.annotation.PostConstruct;
import java.io.*;
import java.nio.charset.StandardCharsets;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.HashMap;
import java.util.Map;
/**
 *
 * 自定義的配置數(shù)據(jù)源，繼承自Spring框架的 MapPropertySource 類，從一個(gè)名為 my.properties 的文件中讀取配置信息，并在每10秒鐘刷新一次。
 * @author Administrator
 */
@Slf4j
//@Component
public class FilePropertiesSource extends MapPropertySource {
    private static final Logger logger = LoggerFactory.getLogger(FilePropertiesSource.class);
    private static final String CONFIG_FILE_NAME = "my.properties";
    private static final DateTimeFormatter DATE_TIME_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    public FilePropertiesSource() {
        super("filePropertiesSource", new HashMap<>());
    }
    /**
     * 從配置文件中讀取配置，10s 更新一次
     */
    @PostConstruct
    @Scheduled(fixedRate = 10_000)
    public void refreshSource() throws IOException {
        logger.info("開始讀取配置文件 {}", CONFIG_FILE_NAME);
        InputStream inputStream = getClass().getClassLoader().getResourceAsStream(CONFIG_FILE_NAME);
        if (inputStream == null) {
            throw new FileNotFoundException("配置文件 " + CONFIG_FILE_NAME + " 不存在");
        }
        Map<String, String> newProperties = new HashMap<>();
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8))) {
            String line;
            while ((line = reader.readLine()) != null) {
                line = line.trim();
                if (StringUtils.isEmpty(line) || line.startsWith("#")) {
                    continue;
                }
                String[] pair = StringUtils.split(line, "=");
                if (pair == null || pair.length != 2) {
                    logger.warn("忽略配置項(xiàng) {}", line);
                    continue;
                }
                String key = pair[0].trim();
                String value = pair[1].trim();
                logger.debug("讀取配置項(xiàng) {} = {}", key, value);
                newProperties.put(key, value);
            }
        } catch (IOException e) {
            logger.error("讀取配置文件 {} 出現(xiàn)異常：{}", CONFIG_FILE_NAME, e.getMessage(), e);
            throw e;
        }
        synchronized (this) {
            source.clear();
            source.putAll(newProperties);
        }
        logger.info("讀取配置文件完成，共讀取 {} 個(gè)配置項(xiàng)，時(shí)間 {}", newProperties.size(), LocalDateTime.now().format(DATE_TIME_FORMATTER));
    }
    /**
     * 覆蓋 getProperty 方法，實(shí)現(xiàn)實(shí)時(shí)獲取配置
     *
     * @param key 配置項(xiàng)的 key
     * @return 配置項(xiàng)的值
     */
    @Override
    public Object getProperty(String key) {
        return source.get(key);
    }
}

import com.lfsun.bootdynamicenv.config.FilePropertiesSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.ConfigurableEnvironment;
/**
 * 一個(gè)Spring配置類，定義了一個(gè)名為 filePropertiesSource 的Bean，并將其加入到環(huán)境變量中。
 */
@Configuration
public class AutoConfig {
    @Bean
    public FilePropertiesSource filePropertiesSource(ConfigurableEnvironment environment) {
        FilePropertiesSource filePropertiesSource = new FilePropertiesSource();
        // 屬性源是按照添加的順序進(jìn)行合并的，后添加的屬性源中的屬性會(huì)覆蓋前面添加的屬性源中的同名屬性。
        // 因此，為了確保我們自定義的屬性源中的屬性優(yōu)先級(jí)最高，我們需要將它添加到屬性源列表的最后。這樣就能保證后添加的屬性源中的屬性值會(huì)覆蓋之前的同名屬性。
        environment.getPropertySources().addLast(filePropertiesSource);
        return filePropertiesSource;
    }
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.DependsOn;
import org.springframework.core.env.Environment;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@DependsOn("filePropertiesSource")
@EnableScheduling
@RestController
@SpringBootApplication
public class Application {
    @Autowired
    private Environment environment;
    @Value("${user-name}")
    private String userName;
    @GetMapping(path = "get")
    public String getProperty(String key) {
        return userName + "  |  " + environment.getProperty(key);
    }
    public static void main(String[] args) {
        SpringApplication.run(Application.class);
    }
}