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href="../security/shi-yong-rsa-ren-zheng.html">使用RSA认证</a> </li> </ul> <p class="caption"><span class="caption-text">服务打包和运行</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="../packaging/standalone.html">以standalone模式打包</a> </li> <li class="toctree-l1"><a class="reference internal" href="../packaging/web-container.html">以WEB容器模式打包</a> </li> </ul> <p class="caption"><span class="caption-text">专题文章</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="../using-java-chassis-in-spring-boot/using-java-chassis-in-spring-boot.html">在Spring Boot中使用java chassis</a> </li> <li class="toctree-l1"><a class="reference internal" href="../featured-topics/features.html">新功能介绍系列文章</a> </li> <li class="toctree-l1"><a class="reference internal" href="../featured-topics/compatibility.html">兼容问题和兼容性策略</a> </li> <li class="toctree-l1"><a class="reference internal" href="../featured-topics/upgrading.html">升级指导系列文章</a> </li> <li class="toctree-l1"><a class="reference internal" href="../featured-topics/performance.html">性能问题分析和调优</a> </li> </ul> <p class="caption"><span class="caption-text">常用配置项参考</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="../config-reference/rest-transport-client.html">REST Transport Client 配置项</a> </li> <li class="toctree-l1"><a class="reference internal" href="../config-reference/config-center-client.html">Config Center Client 配置项</a> </li> <li class="toctree-l1"><a class="reference internal" href="../config-reference/service-center-client.html">Service Center Client 配置项</a> </li> <li class="toctree-l1"><a class="reference internal" href="../config-reference/kie-client.html">ServiceComb Kie Client 配置项</a> </li> </ul> <p class="caption"><span class="caption-text">常见问题</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="../question-and-answer/faq.html">FAQ</a> </li> <li class="toctree-l1"><a class="reference internal" href="../question-and-answer/question_answer.html">Q & A</a> </li> <li class="toctree-l1"><a class="reference internal" href="../question-and-answer/interface-compatibility.html">微服务接口兼容常见问题</a> </li> </ul> </div> </div> </nav> <section data-toggle="wy-nav-shift" class="wy-nav-content-wrap"> <nav class="wy-nav-top" role="navigation" aria-label="Mobile navigation menu"> <i data-toggle="wy-nav-top" class="fa fa-bars"></i> <a href="../index.html">ServiceComb Java Chassis 开发指南</a> </nav> <div class="wy-nav-content"> <div class="rst-content"><div role="navigation" aria-label="breadcrumbs navigation"> <ul class="wy-breadcrumbs"> <li><a href="../index.html" class="icon icon-home" alt="Docs"></a> &raquo;</li> <li>管理服务配置 &raquo;</li> <li>在程序中读取配置信息</li> <li class="wy-breadcrumbs-aside"> </li> </ul> <hr/> </div> <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article"> <div class="section" itemprop="articleBody"> <h1 id="_1">在程序中读取配置信息</h1> <p>Java Chassis支持使用一致的API获取配置，开发者不需要关注从哪里读取配置项的 值，Java Chassis会自动从各处读取配置，并按照优先级进行合并以保证用户取到的是优先级最高的配置值。读取配置信息支持下面几种不同的方式。 </p> <h2 id="archaius-api">使用 archaius API</h2> <pre><code class="language-java">DynamicDoubleProperty myprop = DynamicPropertyFactory.getInstance() .getDoubleProperty(&quot;trace.handler.sampler.percent&quot;, 0.1); </code></pre> <p>以上例子表示声明了一个key为<code>trace.handler.sampler.percent</code>的动态配置对象，默认值为<code>0.1</code>。</p> <p>关于配置项API的具体方法可参考<a href="https://netflix.github.io/archaius/archaius-core-javadoc/com/netflix/config/DynamicPropertyFactory.html">archaius API</a>。</p> <p>archaius API 支持callback处理配置变更：</p> <pre><code class="language-java"> myprop.addCallback(new Runnable() { public void run() { // 当配置项的值变化时，该回调方法会被调用 System.out.println(&quot;trace.handler.sampler.percent is changed!&quot;); } }); </code></pre> <h2 id="java-chassis">使用Java Chassis配置注入机制</h2> <p>配置注入提供了一种简单的管理大量复杂配置的机制，开发者不需要使用 DynamicPropertyFactory 逐个读取配置项，增加配置监听， 而是定义一个简单的 JAVA Bean， 定义这个 Bean 的属性对应的配置项， 当配置信息变化的时候， Bean 的属性会自动刷新，极大 的简化了用户管理大量复杂配置的复杂度。 </p> <p>Bean 属性对应的配置项名称支持通配符， 一个属性可以关联若干配置项，可以声明这些配置项的优先级。 Java对象可以是一个 Java Bean，或是一个拥有public字段的类。</p> <ul> <li>配置注入对象</li> </ul> <p>我们首先设计两个Java类用于注入配置属性，分别用来演示不使用注解和使用注解的场景。使用注解:</p> <pre><code> ```Java @InjectProperties(prefix = "jaxrstest.jaxrsclient") public class Configuration { /* * 方法的 prefix 属性值 "override" 会覆盖标注在类定义的 @InjectProperties * 注解的 prefix 属性值。 * * keys属性可以为一个字符串数组，下标越小优先级越高。 * * 这里会按照如下顺序的属性名称查找配置属性，直到找到已被配置的配置属性，则停止查找： * 1) jaxrstest.jaxrsclient.override.high * 2) jaxrstest.jaxrsclient.override.low * * 测试用例： * jaxrstest.jaxrsclient.override.high: hello high * jaxrstest.jaxrsclient.override.low: hello low * 预期： * hello high */ @InjectProperty(prefix = "jaxrstest.jaxrsclient.override", keys = {"high", "low"}) public String strValue; /** * keys支持通配符，并在可以在将配置属性注入的时候指定通配符的代入对象。 * * 测试用例： * jaxrstest.jaxrsclient.k.value: 3 * 预期： * 3 */ @InjectProperty(keys = "${key}.value") public int intValue; /** * 通配符的代入对象可以是一个字符串List，优先级遵循数组元素下标越小优先级越高策略。 * * 测试用例： * jaxrstest.jaxrsclient.l1-1: 3.0 * jaxrstest.jaxrsclient.l1-2: 2.0 * * 预期： * 3.0 */ @InjectProperty(keys = "${full-list}") public float floatValue; /** * keys属性也支持多个通配符，优先级如下：首先通配符的优先级从左到右递减， * 然后如果通配符被代入List，遵循List中元素index越小优先级越高策略。 * * 测试用例： * jaxrstest.jaxrsclient.low-1.a.high-1.b: 1 * jaxrstest.jaxrsclient.low-1.a.high-2.b: 2 * jaxrstest.jaxrsclient.low-2.a.high-1.b: 3 * jaxrstest.jaxrsclient.low-2.a.high-2.b: 4 * 预期： * 1 */ @InjectProperty(keys = "${low-list}.a.${high-list}.b") public long longValue; /** * 可以通过注解的defaultValue属性指定默认值。如果字段未关联任何配置属性， * 定义的默认值会生效，否则默认值会被覆盖。 * * 测试用例： * 预期： * abc */ @InjectProperty(defaultValue = "abc") public String strDef; } ``` </code></pre> <p>不使用注解：</p> <pre><code> ```Java public class ConfigNoAnnotation { /* * 如果未提供@InjectProperties和@InjectProperty注解，会默认使用字段名作为配置属性名。 * 注意类名不作为前缀起作用。 * 此处将配置属性 strValue 绑定到该字段 */ public String strValue; } ``` </code></pre> <ul> <li>执行注入</li> </ul> <p>使用注解的场景：</p> <pre><code> ```Java ConfigWithAnnotation config = SCBEngine.getInstance().getPriorityPropertyManager() .createConfigObject(Configuration.class, "key", "k", "low-list", Arrays.asList("low-1", "low-2"), "high-list", Arrays.asList("high-1", "high-2"), "full-list", Arrays.asList("l1-1", "l1-2") ); ``` </code></pre> <p>Configuration对象的longValue字段按以下顺序查找已配置的属性:</p> <pre><code> 1. root.low-1.a.high-1.b 2. root.low-1.a.high-2.b 3. root.low-2.a.high-1.b 4. root.low-2.a.high-2.b </code></pre> <p>Configuration对象的floatValue字段按以下顺序查找已配置的属性:</p> <pre><code> 1. root.l1-1 2. root.l1-2 </code></pre> <p>不使用注解的场景：</p> <pre><code> ```Java ConfigNoAnnotation config = SCBEngine.getInstance() .getPriorityPropertyManager().createConfigObject(ConfigNoAnnotation.class); ``` </code></pre> <p>ConfigNoAnnotation 对象的 strValue 字段会查找已配置的属性 strValue，没有前缀和优先级。</p> <p><strong><em>注意事项:</em></strong> 2.1.0 之前的版本， 如果系统中存在大量调用createConfigObject的情况， 需要调用</p> <pre><code> ```Java priorityPropertyManager.unregisterConfigObject(config) ``` </code></pre> <p>进行显示回收。 2.1.0 及其之后的版本， 不需要调用这个接口，系统创建的对象是 WeakReference， 在未被 业务引用以后，会自动回收。 </p> <p>更多关于配置注入的用法，建议下载 java-chassis 的源码， 查看 TestConfigObjectFactory 类里面的示例。</p> <h2 id="spring-spring-boot">使用Spring 和 Spring Boot的配置机制读取配置</h2> <p>Java Chassis的配置信息，也可以通过Spring和Spring Boot的配置机制进行读取，比如@Value、@ConfigurationProperties等。 Java Chassis 将配置层次应用于Spring Environment中，Spring和Spring Boot读取配置的方式，也能够读取到<code>microservice.yaml</code>和动态配置的值。</p> </div> </div><footer> <div class="rst-footer-buttons" role="navigation" aria-label="Footer Navigation"> <a href="general-config.html" class="btn btn-neutral float-left" title="通用配置说明"><span class="icon icon-circle-arrow-left"></span> Previous</a> <a href="../references-handlers/intruduction.html" class="btn btn-neutral float-right" title="处理链介绍">Next <span class="icon icon-circle-arrow-right"></span></a> </div> <hr/> <div role="contentinfo"> <!-- Copyright etc --> </div> Built with <a 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