携程Apollo（阿波罗）配置中心在Spring Boot项目快速集成

前提：先搭建好本地的单机运行项目：http://www.cnblogs.com/EasonJim/p/7643630.html

说明：下面的示例是基于Spring Boot搭建的，对于Spring项目基本通用。迁移旧项目的配置下一篇说明，这里先就如何快速的集成Client和获取配置的值进行实践。

0、下面的示例都是基于官方提供的教程去实践的，可以参考如下网址：

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项目，这里使用了Web做测试，所以引用了Thymeleaf模板。

搭建参考：http://www.cnblogs.com/EasonJim/p/7519854.html

2、登录Apollo上新建App和相关的配置项，可以参考如下配置：

3、在POM上引入Client的依赖，此时会有两个包引入Client和Core。

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

4、在项目上配置上面设置的app.id，注意此时是通过新建META-INF/app.properties文件实现的。

5、代码实现

实现的功能是通过配置中心修改后，再次刷新页面而不重启应用的情况下能看到值的改变。

实现方式主要几种在两种，1为通过API的形式增加监听回调函数来监听值的改变后直接修改，2为通过注入Bean的方式使用Bean下的专用监听注解实现回调监听。

5.1、通过API的方式

代码实现如下：

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());
                    }
                }                    
            }
        });
    }

}

说明：

通过新建Config对象，使用的是ConfigService.getAppConfig()获取默认配置，也就是配置中心中的application.properties的，当然，getAppConfig可以指定不能的namespage。

通过获取Config对象增加监听回调函数addChangeListener。监听指定的值变化后，重新赋值变量。

这种方式应该是最简单的，不用写特殊的注解去实现，但是可能在运行时也会发现，程序在一启动时不会去获取默认的配置值，比如timeout这些是空的，要解决这个问题时需要在Class上增加@EnableApolloConfig的注解，然后在属性上增加@Value的值即可，改动如下：

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());
                    }
                }                    
            }
        });
    }

}

说明：约定俗成，在@Value上获取值时记得增加默认值，以防止获取为空。

上面代码或许有些冗余，可以再提炼一下，因为config对象的值会实时更新，所以也不需要监听onChange事件，也不需要自己创建一个变量，最后代码实现如下：

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、通过注入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、通过@Configuration注入这个Bean，代码如下：

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，不然不会生效。并且留意到@Bean的注解，如果没有这个时，@ApolloConfigChangeListener不会生效。这个是关键所在，@ApolloConfigChangeListener只能用于Bean注入上，这个和API的方式有明显区别。

在代码上使用：

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();        
    }
}

说明：可以看出，只要@Autowired注入刚才的Bean就可以直接使用。

6、运行，一般只需要在/opt/settings/server.properties中配置了env=DEV就可以直接直接启动（因为Client在本地仓库的包上已经有了meta_server的信息），但是在IDE上也可以通过指定VM的参数，增加系统属性变量-D来实现调试，配置如下：

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

测试代码：https://github.com/easonjim/5_java_example/tree/master/apollotest/test1