攜程Apollo（阿波羅）配置中心在Spring Boot項目快速集成

前提：先搭建好本地的單機運行項目：http://www.cnblogs.com/EasonJim/p/7643630.html

說明：下面的示例是基於Spring Boot搭建的，對於Spring項目基本通用。遷移舊項目的配置下一篇說明，這里先就如何快速的集成Client和獲取配置的值進行實踐。

0、下面的示例都是基於官方提供的教程去實踐的，可以參考如下網址：

https://github.com/ctripcorp/apollo/wiki/Java%E5%AE%A2%E6%88%B7%E7%AB%AF%E4%BD%BF%E7%94%A8%E6%8C%87%E5%8D%97

https://github.com/ctripcorp/apollo/wiki/Apollo%E5%BC%80%E5%8F%91%E6%8C%87%E5%8D%97#23-java%E6%A0%B7%E4%BE%8B%E5%AE%A2%E6%88%B7%E7%AB%AF%E5%90%AF%E5%8A%A8

1、先新建好Spring Boot項目，這里使用了Web做測試，所以引用了Thymeleaf模板。

搭建參考：http://www.cnblogs.com/EasonJim/p/7519854.html

2、登錄Apollo上新建App和相關的配置項，可以參考如下配置：

3、在POM上引入Client的依賴，此時會有兩個包引入Client和Core。

        <dependency>
            <groupId>com.ctrip.framework.apollo</groupId>
            <artifactId>apollo-client</artifactId>
            <version>0.8.0</version>
        </dependency>

4、在項目上配置上面設置的app.id，注意此時是通過新建META-INF/app.properties文件實現的。

5、代碼實現

實現的功能是通過配置中心修改后，再次刷新頁面而不重啟應用的情況下能看到值的改變。

實現方式主要幾種在兩種，1為通過API的形式增加監聽回調函數來監聽值的改變后直接修改，2為通過注入Bean的方式使用Bean下的專用監聽注解實現回調監聽。

5.1、通過API的方式

代碼實現如下：

package com.jsoft.springboottest.springboottest1.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.ctrip.framework.apollo.Config;
import com.ctrip.framework.apollo.ConfigChangeListener;
import com.ctrip.framework.apollo.ConfigService;
import com.ctrip.framework.apollo.model.ConfigChange;
import com.ctrip.framework.apollo.model.ConfigChangeEvent;
import com.ctrip.framework.apollo.spring.annotation.EnableApolloConfig;

@Controller
public class IndexController {

    private static final Logger logger = LoggerFactory.getLogger(IndexController.class);

    private Config config; 　　 private int timeout; private int batch; private String url;

    @RequestMapping(value = "/index", method = RequestMethod.GET)
    public String index(Model model) {
        Entry entry = new Entry();
        entry.setText("Text");
        entry.setTitle("Title");
        model.addAttribute("entries", entry);
        model.addAttribute("entry", new Entry());
        
        model.addAttribute("url", url); model.addAttribute("timeout",timeout); model.addAttribute("batch",batch); logger.info("timeout:{}", timeout); logger.info("batch:{}", batch); logger.info("url:{}", url); return "index";
    }

    public IndexController() {
        config = ConfigService.getAppConfig(); config.addChangeListener(new ConfigChangeListener() { @Override public void onChange(ConfigChangeEvent changeEvent) { logger.info("Changes for namespace {}", changeEvent.getNamespace()); for (String key : changeEvent.changedKeys()) { ConfigChange change = changeEvent.getChange(key); logger.info("Change - key: {}, oldValue: {}, newValue: {}, changeType: {}", change.getPropertyName(), change.getOldValue(), change.getNewValue(), change.getChangeType()); if (key.equals("url")) { url = change.getNewValue(); } if(key.equals("batch")) { batch = Integer.valueOf(change.getNewValue()); } if (key.equals("timeout")) { timeout = Integer.valueOf(change.getNewValue()); } } } });
    }

}

說明：

通過新建Config對象，使用的是ConfigService.getAppConfig()獲取默認配置，也就是配置中心中的application.properties的，當然，getAppConfig可以指定不能的namespage。

通過獲取Config對象增加監聽回調函數addChangeListener。監聽指定的值變化后，重新賦值變量。

這種方式應該是最簡單的，不用寫特殊的注解去實現，但是可能在運行時也會發現，程序在一啟動時不會去獲取默認的配置值，比如timeout這些是空的，要解決這個問題時需要在Class上增加@EnableApolloConfig的注解，然后在屬性上增加@Value的值即可，改動如下：

package com.jsoft.springboottest.springboottest1.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.ctrip.framework.apollo.Config;
import com.ctrip.framework.apollo.ConfigChangeListener;
import com.ctrip.framework.apollo.ConfigService;
import com.ctrip.framework.apollo.model.ConfigChange;
import com.ctrip.framework.apollo.model.ConfigChangeEvent;
import com.ctrip.framework.apollo.spring.annotation.EnableApolloConfig;

@Controller
@EnableApolloConfig public class IndexController {

    private static final Logger logger = LoggerFactory.getLogger(IndexController.class);

    private Config config;

    @Value("${timeout:200}") private int timeout;
    @Value("${batch:200}") private int batch;
    @Value("${url:http://easonjim.com}") private String url;

    @RequestMapping(value = "/index", method = RequestMethod.GET)
    public String index(Model model) {
        Entry entry = new Entry();
        entry.setText("Text");
        entry.setTitle("Title");
        model.addAttribute("entries", entry);
        model.addAttribute("entry", new Entry());
        
        model.addAttribute("url", url);
        model.addAttribute("timeout",timeout);
        model.addAttribute("batch",batch);

        logger.info("timeout:{}", timeout);
        logger.info("batch:{}", batch);
        logger.info("url:{}", url);

        return "index";
    }

    public IndexController() {
        config = ConfigService.getAppConfig();
        config.addChangeListener(new ConfigChangeListener() {
            @Override
            public void onChange(ConfigChangeEvent changeEvent) {
                logger.info("Changes for namespace {}", changeEvent.getNamespace());
                for (String key : changeEvent.changedKeys()) {
                    ConfigChange change = changeEvent.getChange(key);
                    logger.info("Change - key: {}, oldValue: {}, newValue: {}, changeType: {}", change.getPropertyName(), change.getOldValue(), change.getNewValue(), change.getChangeType());

                    if (key.equals("url")) {
                        url = change.getNewValue();
                    }
                    if(key.equals("batch")) {
                        batch = Integer.valueOf(change.getNewValue());
                    }
                    if (key.equals("timeout")) {
                        timeout = Integer.valueOf(change.getNewValue());
                    }
                }                    
            }
        });
    }

}

說明：約定俗成，在@Value上獲取值時記得增加默認值，以防止獲取為空。

上面代碼或許有些冗余，可以再提煉一下，因為config對象的值會實時更新，所以也不需要監聽onChange事件，也不需要自己創建一個變量，最后代碼實現如下：

package com.jsoft.springboottest.springboottest1.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.ctrip.framework.apollo.Config;
import com.ctrip.framework.apollo.ConfigChangeListener;
import com.ctrip.framework.apollo.ConfigService;
import com.ctrip.framework.apollo.model.ConfigChange;
import com.ctrip.framework.apollo.model.ConfigChangeEvent;
import com.ctrip.framework.apollo.spring.annotation.EnableApolloConfig;

@Controller
public class IndexController2 {

    private static final Logger logger = LoggerFactory.getLogger(IndexController2.class);

    private Config config = ConfigService.getAppConfig();

    @RequestMapping(value = "/index2", method = RequestMethod.GET)
    public String index(Model model) {
        Entry entry = new Entry();
        entry.setText("Text");
        entry.setTitle("Title");
        model.addAttribute("entries", entry);
        model.addAttribute("entry", new Entry());
        
        model.addAttribute("url", config.getProperty("url", ""));
        model.addAttribute("timeout",config.getProperty("timeout", ""));
        model.addAttribute("batch",config.getProperty("batch", ""));

        logger.info("timeout:{}", config.getProperty("timeout", ""));
        logger.info("batch:{}", config.getProperty("batch", ""));
        logger.info("url:{}", config.getProperty("url", ""));

        return "index";
    }

}

5.2、通過注入Bean的方式

5.2.1、新建的Bean如下：

package com.jsoft.springboottest.springboottest1.controller;

import com.ctrip.framework.apollo.Config;
import com.ctrip.framework.apollo.model.ConfigChange;
import com.ctrip.framework.apollo.model.ConfigChangeEvent;
import com.ctrip.framework.apollo.spring.annotation.ApolloConfig;
import com.ctrip.framework.apollo.spring.annotation.ApolloConfigChangeListener;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;

import javax.annotation.PostConstruct;

public class AnnotatedBean {
    private static final Logger logger = LoggerFactory.getLogger(AnnotatedBean.class);

    @Value("${timeout:200}")
    private int timeout;
    private int batch;

    @ApolloConfig
    private Config config;
    @ApolloConfig("FX.apollo")
    private Config anotherConfig;

    @PostConstruct
    void initialize() {
        logger.info("timeout is {}", timeout);
        logger.info("batch is {}", batch);

        logger.info("Keys for config: {}", config.getPropertyNames());
        logger.info("Keys for anotherConfig: {}", anotherConfig.getPropertyNames());
    }

    @Value("${batch:100}")
    public void setBatch(int batch) {
        this.batch = batch;
    }

    public int getBatch() {
        return batch;
    }

    public int getTimeout() {
        return timeout;
    }

    @ApolloConfigChangeListener("application") private void someChangeHandler(ConfigChangeEvent changeEvent) {
        logger.info("[someChangeHandler]Changes for namespace {}", changeEvent.getNamespace());
        if (changeEvent.isChanged("timeout")) {
            refreshTimeout();
        }
        if (changeEvent.isChanged("batch")) {
            setBatch(Integer.valueOf(changeEvent.getChange("batch").getNewValue()));
        }
    }

    @ApolloConfigChangeListener({ "application", "FX.apollo" })
    private void anotherChangeHandler(ConfigChangeEvent changeEvent) {
        logger.info("[anotherChangeHandler]Changes for namespace {}", changeEvent.getNamespace());
        for (String key : changeEvent.changedKeys()) {
            ConfigChange change = changeEvent.getChange(key);
            logger.info("[anotherChangeHandler]Change - key: {}, oldValue: {}, newValue: {}, changeType: {}", change.getPropertyName(), change.getOldValue(), change.getNewValue(), change.getChangeType());
        }
    }

    private void refreshTimeout() {
        // do some custom logic to update placeholder value
        timeout = config.getIntProperty("timeout", timeout);
        logger.info("Refreshing timeout to {}", timeout);
    }
}

5.2.2、通過@Configuration注入這個Bean，代碼如下：

package com.jsoft.springboottest.springboottest1.controller;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.ctrip.framework.apollo.spring.annotation.EnableApolloConfig;

@Configuration @EnableApolloConfig public class AnnotatedConfig {
    
    @Bean public AnnotatedBean annotatedBean() { return new AnnotatedBean(); }
}

注意：要增加@EnableApolloConfig和@Configuration，不然不會生效。並且留意到@Bean的注解，如果沒有這個時，@ApolloConfigChangeListener不會生效。這個是關鍵所在，@ApolloConfigChangeListener只能用於Bean注入上，這個和API的方式有明顯區別。

在代碼上使用：

package com.jsoft.springboottest.springboottest1.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {
    
    private static final Logger logger = LoggerFactory.getLogger(TestController.class);
    
    @Autowired private AnnotatedBean annotatedBean;
    
    @RequestMapping("/show")
    public String show(){
        
        logger.info("batch:{}",annotatedBean.getBatch()); logger.info("timeout:{}",annotatedBean.getTimeout()); return "Hello World"+" batch:"+annotatedBean.getBatch()+" timeout:"+annotatedBean.getTimeout();        
    }
}

說明：可以看出，只要@Autowired注入剛才的Bean就可以直接使用。

6、運行，一般只需要在/opt/settings/server.properties中配置了env=DEV就可以直接直接啟動（因為Client在本地倉庫的包上已經有了meta_server的信息），但是在IDE上也可以通過指定VM的參數，增加系統屬性變量-D來實現調試，配置如下：

如果到處JAR運行，直接java -jar Spring-Boot-Demo.jar即可，不需要增加什么參數（但前提是配置了/opt/settings/server.properties的env的值）。

 

測試代碼：https://github.com/easonjim/5_java_example/tree/master/apollotest/test1