SpringBoot2.X 項目使用外置絕對路徑的配置文件

spring-boot-absolute-config

前言

　　該工程是為解決應用部署應用時指定配置文件存放位置的問題.

　　SpringBoot項目默認加載以下位置的配置文件:

classpath:
file:./
classpath:config/
file:./config/:

　　想要指定外部的配置文件, 一種方法就是通過啟動腳本來控制:

在啟動腳本中添加:
-Dspring.config.location=文件絕對路徑

但有時候有些項目需要兼容之前的老項目,就會遇到使用外部絕對路徑的來指定配置文件了,每次都在啟動腳本中添加,顯然不是很合適.因此誕生了該工程.

實現方式

通過實現 EnvironmentPostProcessor 接口, 自定義實現方法:

public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application)

來實現加載自定義配置文件.

package com.github.springboot.absolute.config;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.context.config.ConfigFileApplicationListener;
import org.springframework.boot.env.EnvironmentPostProcessor;
import org.springframework.boot.env.PropertiesPropertySourceLoader;
import org.springframework.boot.env.PropertySourceLoader;
import org.springframework.boot.env.YamlPropertySourceLoader;
import org.springframework.core.Ordered;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.PropertySource;
import org.springframework.core.io.PathResource;
import org.springframework.core.io.Resource;
import org.springframework.util.StringUtils;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.List;

/**
 * <p> 自定義環境加載策略
 * <p>需要在classpath下application.yml或application.properties中指定文件位置</p>
 * <p>key=config.file.absolute.path</p>
 *
 * @author lijinghao
 * @version : MyEnvironmentPostProcessor.java, v 0.1 2018年09月13日 下午4:55:55 lijinghao Exp $
 */
public class MyEnvironmentPostProcessor implements EnvironmentPostProcessor, Ordered {

    /**,
     * 指定加載外部文件類型: [.properties], [.yml], [.yaml]
     */
    private static final String SUFFIX_TYPE_YML                             = ".yml";
    private static final String SUFFIX_TYPE_YAML                            = ".yaml";
    private static final String SUFFIX_TYPE_PROPERTIES                      = ".properties";

    /**
     * 指定外部配置文件路徑的KEY
     */
    private static final String CONFIG_FILE_ABSOLUTE_PATH                   = "config.file.absolute.path";

    private static final int DEFAULT_ORDER                                  = ConfigFileApplicationListener.DEFAULT_ORDER + 1;

    /**
     * Post-process the given {@code env}.
     *
     * @param environment the env to post-process
     * @param application the application to which the env belongs
     */
    @Override
    public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {

        try {

            // Get file absolute path
            String path = environment.getProperty(CONFIG_FILE_ABSOLUTE_PATH);
            if (StringUtils.isEmpty(path)) {
                System.out.println("WARNING: External file path to be loaded is not configured.[config.file.absolute.path]");
                return;
            }

            System.out.println("INFO: Loading external file: \"" + path + "\"");

            // Loading external file
            Resource resource = new PathResource(path);

            PropertySourceLoader loader;

            if (resource.exists() && resource.isFile()) {
                String filename = resource.getFilename();
                String fileSuffix = filename.substring(filename.indexOf("."));

                if (SUFFIX_TYPE_PROPERTIES.equalsIgnoreCase(fileSuffix)) {
                    loader = new PropertiesPropertySourceLoader();

                } else if (SUFFIX_TYPE_YML.equalsIgnoreCase(fileSuffix)
                        || SUFFIX_TYPE_YAML.equalsIgnoreCase(fileSuffix)) {
                    loader = new YamlPropertySourceLoader();

                } else {
                    throw new RuntimeException("Unsupported file types: " + fileSuffix);
                }
            }else {
                throw new FileNotFoundException("Cannot find the file : \"" + path +"\"");
            }

            List<PropertySource<?>> sources = loader.load("externalFiles", resource);
            for (PropertySource<?> source : sources) {
                environment.getPropertySources().addLast(source);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }


    /**
     * Get the order value of this object.
     * <p>Higher values are interpreted as lower priority. As a consequence,
     * the object with the lowest value has the highest priority (somewhat
     * analogous to Servlet {@code load-on-startup} values).
     * <p>Same order values will result in arbitrary sort positions for the
     * affected objects.
     *
     * @return the order value
     * @see #HIGHEST_PRECEDENCE
     * @see #LOWEST_PRECEDENCE
     */
    @Override
    public int getOrder() {
        return DEFAULT_ORDER;
    }

}

　　在classpath:META-INF 下創建：spring.factories

　　添加如下內容：

org.springframework.boot.env.EnvironmentPostProcessor=com.github.springboot.absolute.config.MyEnvironmentPostProcessor

 

使用說明

1. 引入pom文件

   <dependency>
        <groupId>com.github.springboot</groupId>
      	<artifactId>absolute-config</artifactId>
      	<version>1.0.0-RELEASE</version>
    </dependency>

2. 在classpath下的配置文件中增加參數

    如,在application.yml中添加
    config.file.absolute.path: /opt/app/config/**/**/application.yml 

3. 重啟項目

   重啟項目時,會自動加載指定位置的配置文件;

注意事項

1. 支持配置文件的格式

   1) classpath下SpringBoot默認加載application.properties、application.yml或application.yaml;
   2) 外置配置文件可以是以.properties、.yml或.yaml結尾（注意配置內容的格式）；

2. 外部加載的配置文件,不能使用原始配置文件的key

   如: server.port: 8090
    此參數只在classpath下的配置文件中生效,在外部加載的配置文件中不生效.

   此類key主要是在 ConfigFileApplicationListener 中進行加載.

3. 引入了配置文件,但沒配置config.file.absolute.path

   此時不會報錯,只會在啟動時打印提醒的語句.

4. 配置了錯誤的config.file.absolute.path

   此時在項目啟動時會打印出錯誤的異常棧,但不影響程序的正常啟動.

   但是,如果你的項目中依賴了外置配置文件中的內容,可能會報錯.

　　具體源代碼詳見：https://github.com/lthaoshao/spring-boot-absolute-config