EnvironmentPostProcessor怎么做单元测试？阿里P7告诉你

港控/mmm° 2023-01-09 06:11 119阅读 0赞

### 简介 ###

从Spring Boot 1.3开始，我们可以在应用程序上下文刷新之前使用`EnvironmentPostProcessor`来自定义应用程序的`Environment`。`Environment`表示当前应用程序运行的环境，它可以统一访问各种属性源中的属性，如属性文件、JVM系统属性、系统环境变量和Servlet上下文参数。使用`EnvironmentPostProcessor`可以在bean初始化之前对`Environment`进行修改。

### 使用示例 ###

让我们设想一个需求，配置文件中的数据库密码是加密后的密文，如：

spring.datasource.password=js8sbAwkduzPTEWQrlDbTw==

在应用启动时，对密文进行解密后再进行数据库的连接。

针对这种需求，就可以通过`EnvironmentPostProcessor`对密文进行解密，重新放到`Environment`中。

#### 1.实现EnvironmentPostProcessor ####

package one.more;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.env.EnvironmentPostProcessor;
    import org.springframework.core.env.ConfigurableEnvironment;
    import org.springframework.core.env.PropertiesPropertySource;
    
    import java.util.Properties;
    
    public class DecodeEnvironmentPostProcessor implements EnvironmentPostProcessor { 
    
        public static final String SPRING_DATASOURCE_PASSWORD = "spring.datasource.password";
        public static final String AES_SECRET = "OneMore";
    
        @Override
        public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) { 
            String password = environment.getProperty(SPRING_DATASOURCE_PASSWORD);
            Properties properties = new Properties();
            properties.setProperty(SPRING_DATASOURCE_PASSWORD, AESUtil.decrypt(password, AES_SECRET));
            PropertiesPropertySource propertiesPropertySource = new PropertiesPropertySource(SPRING_DATASOURCE_PASSWORD,
                    properties);
            environment.getPropertySources().addFirst(propertiesPropertySource);
        }
    }

如果你希望`EnvironmentPostProcessor`按照特定的顺序被调用，可以实现`Ordered`接口，或者使用`@Order`注解。

#### 2.注册实现类 ####

想要在Spring Boot启动过程中调用这个实现类，我们还需要在`META-INF/ Spring .factories`中注册这个实现类：

org.springframework.boot.env.EnvironmentPostProcessor=
      one.more.DecodeEnvironmentPostProcessor

### 单元测试 ###

下面介绍本文的重点：怎么做`EnvironmentPostProcessor`实现类的单元测试，话不多说，直接上代码：

package one.more;
    
    import org.junit.Assert;
    import org.junit.Test;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.WebApplicationType;
    import org.springframework.boot.builder.SpringApplicationBuilder;
    import org.springframework.boot.env.EnvironmentPostProcessor;
    import org.springframework.context.ConfigurableApplicationContext;
    import org.springframework.core.env.ConfigurableEnvironment;
    import org.springframework.core.env.PropertiesPropertySource;
    
    import java.util.Properties;
    
    public class DecodeEnvironmentPostProcessorTest { 
    
        @Test
        public void testPostProcessEnvironment() { 
            DecodeEnvironmentPostProcessor processor = new DecodeEnvironmentPostProcessor();
            String password = "one-more";
            Properties properties = new Properties();
            properties.setProperty(DecodeEnvironmentPostProcessor.SPRING_DATASOURCE_PASSWORD,
                    AESUtil.encrypt(password, DecodeEnvironmentPostProcessor.AES_SECRET));
            ConfigurableEnvironment environment = getEnvironment(processor, properties);
    
            Assert.assertEquals(password,
                    environment.getProperty(DecodeEnvironmentPostProcessor.SPRING_DATASOURCE_PASSWORD));
    
        }
    
        /** * 获取一个经过EnvironmentPostProcessor处理过的Environment * * @param processor EnvironmentPostProcessor实现类的实例 * @param properties 预置准备做单元测试的属性 * @return 处理过的Environment */
        private ConfigurableEnvironment getEnvironment(EnvironmentPostProcessor processor, Properties properties) { 
            // 创建一个SpringApplication
            SpringApplication springApplication = new SpringApplicationBuilder()
                    .sources(DecodeEnvironmentPostProcessor.class)
                    .web(WebApplicationType.NONE).build();
            // 获取应用上下文
            ConfigurableApplicationContext context = springApplication.run();
            // 获取Environment
            ConfigurableEnvironment environment = context.getEnvironment();
            //添加准备做单元测试的属性
            environment.getPropertySources()
                    .addFirst(new PropertiesPropertySource("test", properties));
            processor.postProcessEnvironment(environment, springApplication);
            context.close();
            return environment;
        }
    }

### 附：加解密工具类代码 ###

package one.more;
    
    import org.apache.commons.codec.binary.Base64;
    
    import javax.crypto.Cipher;
    import javax.crypto.KeyGenerator;
    import javax.crypto.SecretKey;
    import javax.crypto.spec.SecretKeySpec;
    import java.security.NoSuchAlgorithmException;
    import java.security.SecureRandom;
    
    public class AESUtil { 
    
        private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";
        private static final String KEY_ALGORITHM = "AES";
    
        public static String encrypt(String content, String password) { 
            try { 
                Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
                byte[] byteContent = content.getBytes("utf-8");
                cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password));
                byte[] result = cipher.doFinal(byteContent);
                return Base64.encodeBase64String(result);
            } catch (Exception ex) { 
    
            }
            return null;
        }
    
        public static String decrypt(String content, String password) { 
            try { 
                Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
                cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password));
                byte[] result = cipher.doFinal(Base64.decodeBase64(content));
                return new String(result, "utf-8");
            } catch (Exception ex) { 
            }
            return null;
        }
    
        private static SecretKeySpec getSecretKey(final String password) { 
            KeyGenerator kg = null;
            try { 
                kg = KeyGenerator.getInstance(KEY_ALGORITHM);
                kg.init(128, new SecureRandom(password.getBytes()));
                SecretKey secretKey = kg.generateKey();
                return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);
            } catch (NoSuchAlgorithmException ex) { 
    
            }
            return null;
        }
    }

> 文章持续更新，微信搜索「**万猫学社**」第一时间阅读。  
> 关注后回复「**电子书**」，免费获取12本Java必读技术书籍。