Spring Boot 环境变量读取 和 属性对象的绑定

网上看到的一些方法，结合我看到的 和我们现在使用的。整理成此文；

第一种方法

参见catoop的博客之 Spring Boot 环境变量读取 和 属性对象的绑定（尊重原创）

第二种方法

• class不用继承任何东西，只需在类中添加属性

@Injectprivate Environment env;

• 调用

OTHER_DIR = env.getProperty("converter.sourcedir");

converter.sourcedir是yml中的配置，如下

converter:    sourcedir: /a/b/c/d

---

继续深究，Environment的源码：

/* * Copyright 2002-2013 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package org.springframework.core.env;/** * Interface representing the environment in which the current application is running. * Models two key aspects of the application environment: <em>profiles</em> and * <em>properties</em>. Methods related to property access are exposed via the * {@link PropertyResolver} superinterface. * * <p>A <em>profile</em> is a named, logical group of bean definitions to be registered * with the container only if the given profile is <em>active</em>. Beans may be assigned * to a profile whether defined in XML or via annotations; see the spring-beans 3.1 schema * or the {@link org.springframework.context.annotation.Profile @Profile} annotation for * syntax details. The role of the {@code Environment} object with relation to profiles is * in determining which profiles (if any) are currently {@linkplain #getActiveProfiles * active}, and which profiles (if any) should be {@linkplain #getDefaultProfiles active * by default}. * * <p><em>Properties</em> play an important role in almost all applications, and may * originate from a variety of sources: properties files, JVM system properties, system * environment variables, JNDI, servlet context parameters, ad-hoc Properties objects, * Maps, and so on. The role of the environment object with relation to properties is to * provide the user with a convenient service interface for configuring property sources * and resolving properties from them. * * <p>Beans managed within an {@code ApplicationContext} may register to be {@link * org.springframework.context.EnvironmentAware EnvironmentAware} or {@code @Inject} the * {@code Environment} in order to query profile state or resolve properties directly. * * <p>In most cases, however, application-level beans should not need to interact with the * {@code Environment} directly but instead may have to have {@code ${...}} property * values replaced by a property placeholder configurer such as * {@link org.springframework.context.support.PropertySourcesPlaceholderConfigurer * PropertySourcesPlaceholderConfigurer}, which itself is {@code EnvironmentAware} and * as of Spring 3.1 is registered by default when using * {@code <context:property-placeholder/>}. * * <p>Configuration of the environment object must be done through the * {@code ConfigurableEnvironment} interface, returned from all * {@code AbstractApplicationContext} subclass {@code getEnvironment()} methods. See * {@link ConfigurableEnvironment} Javadoc for usage examples demonstrating manipulation * of property sources prior to application context {@code refresh()}. * * @author Chris Beams * @since 3.1 * @see PropertyResolver * @see EnvironmentCapable * @see ConfigurableEnvironment * @see AbstractEnvironment * @see StandardEnvironment * @see org.springframework.context.EnvironmentAware * @see org.springframework.context.ConfigurableApplicationContext#getEnvironment * @see org.springframework.context.ConfigurableApplicationContext#setEnvironment * @see org.springframework.context.support.AbstractApplicationContext#createEnvironment */public interface Environment extends PropertyResolver {    /**     * Return the set of profiles explicitly made active for this environment. Profiles     * are used for creating logical groupings of bean definitions to be registered     * conditionally, for example based on deployment environment.  Profiles can be     * activated by setting {@linkplain AbstractEnvironment#ACTIVE_PROFILES_PROPERTY_NAME     * "spring.profiles.active"} as a system property or by calling     * {@link ConfigurableEnvironment#setActiveProfiles(String...)}.     * <p>If no profiles have explicitly been specified as active, then any {@linkplain     * #getDefaultProfiles() default profiles} will automatically be activated.     * @see #getDefaultProfiles     * @see ConfigurableEnvironment#setActiveProfiles     * @see AbstractEnvironment#ACTIVE_PROFILES_PROPERTY_NAME     */    String[] getActiveProfiles();    /**     * Return the set of profiles to be active by default when no active profiles have     * been set explicitly.     * @see #getActiveProfiles     * @see ConfigurableEnvironment#setDefaultProfiles     * @see AbstractEnvironment#DEFAULT_PROFILES_PROPERTY_NAME     */    String[] getDefaultProfiles();    /**     * Return whether one or more of the given profiles is active or, in the case of no     * explicit active profiles, whether one or more of the given profiles is included in     * the set of default profiles. If a profile begins with '!' the logic is inverted,     * i.e. the method will return true if the given profile is <em>not</em> active.     * For example, <pre class="code">env.acceptsProfiles("p1", "!p2")</pre> will     * return {@code true} if profile 'p1' is active or 'p2' is not active.     * @throws IllegalArgumentException if called with zero arguments     * or if any profile is {@code null}, empty or whitespace-only     * @see #getActiveProfiles     * @see #getDefaultProfiles     */    boolean acceptsProfiles(String... profiles);}

鉴于注释太多，抽出其中核心代码：

package org.springframework.core.env;public interface Environment extends PropertyResolver {    String[] getActiveProfiles();    String[] getDefaultProfiles();    boolean acceptsProfiles(String... profiles);}

可以看到Environment 又extends PropertyResolver

/* * Copyright 2002-2013 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package org.springframework.core.env;/** * Interface for resolving properties against any underlying source. * * @author Chris Beams * @since 3.1 * @see Environment * @see PropertySourcesPropertyResolver */public interface PropertyResolver {    /**     * Return whether the given property key is available for resolution, i.e.,     * the value for the given key is not {@code null}.     */    boolean containsProperty(String key);    /**     * Return the property value associated with the given key, or {@code null}     * if the key cannot be resolved.     * @param key the property name to resolve     * @see #getProperty(String, String)     * @see #getProperty(String, Class)     * @see #getRequiredProperty(String)     */    String getProperty(String key);    /**     * Return the property value associated with the given key, or     * {@code defaultValue} if the key cannot be resolved.     * @param key the property name to resolve     * @param defaultValue the default value to return if no value is found     * @see #getRequiredProperty(String)     * @see #getProperty(String, Class)     */    String getProperty(String key, String defaultValue);    /**     * Return the property value associated with the given key, or {@code null}     * if the key cannot be resolved.     * @param key the property name to resolve     * @param targetType the expected type of the property value     * @see #getRequiredProperty(String, Class)     */    <T> T getProperty(String key, Class<T> targetType);    /**     * Return the property value associated with the given key, or     * {@code defaultValue} if the key cannot be resolved.     * @param key the property name to resolve     * @param targetType the expected type of the property value     * @param defaultValue the default value to return if no value is found     * @see #getRequiredProperty(String, Class)     */    <T> T getProperty(String key, Class<T> targetType, T defaultValue);    /**     * Convert the property value associated with the given key to a {@code Class}     * of type {@code T} or {@code null} if the key cannot be resolved.     * @throws org.springframework.core.convert.ConversionException if class specified     * by property value cannot be found  or loaded or if targetType is not assignable     * from class specified by property value     * @see #getProperty(String, Class)     */    <T> Class<T> getPropertyAsClass(String key, Class<T> targetType);    /**     * Return the property value associated with the given key (never {@code null}).     * @throws IllegalStateException if the key cannot be resolved     * @see #getRequiredProperty(String, Class)     */    String getRequiredProperty(String key) throws IllegalStateException;    /**     * Return the property value associated with the given key, converted to the given     * targetType (never {@code null}).     * @throws IllegalStateException if the given key cannot be resolved     */    <T> T getRequiredProperty(String key, Class<T> targetType) throws IllegalStateException;    /**     * Resolve ${...} placeholders in the given text, replacing them with corresponding     * property values as resolved by {@link #getProperty}. Unresolvable placeholders with     * no default value are ignored and passed through unchanged.     * @param text the String to resolve     * @return the resolved String (never {@code null})     * @throws IllegalArgumentException if given text is {@code null}     * @see #resolveRequiredPlaceholders     * @see org.springframework.util.SystemPropertyUtils#resolvePlaceholders(String)     */    String resolvePlaceholders(String text);    /**     * Resolve ${...} placeholders in the given text, replacing them with corresponding     * property values as resolved by {@link #getProperty}. Unresolvable placeholders with     * no default value will cause an IllegalArgumentException to be thrown.     * @return the resolved String (never {@code null})     * @throws IllegalArgumentException if given text is {@code null}     * or if any placeholders are unresolvable     * @see org.springframework.util.SystemPropertyUtils#resolvePlaceholders(String, boolean)     */    String resolveRequiredPlaceholders(String text) throws IllegalArgumentException;}

第三种方法（最简单）

    @Value("${a.b.c.d}")    private String testValue;

a.b.c.d 是配置文件中的

就这样简单~~~