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How to understand DubboDefaultProperties EnvironmentPostProcessor, I believe that many inexperienced people are at a loss about it. Therefore, this paper summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

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This paper mainly studies DubboDefaultPropertiesEnvironmentPostProcessor.

DubboDefaultPropertiesEnvironmentPostProcessor

Dubbo-spring-boot-project-2.7.3/dubbo-spring-boot-compatible/autoconfigure/src/main/java/org/apache/dubbo/spring/boot/env/DubboDefaultPropertiesEnvironmentPostProcessor.java

Public class DubboDefaultPropertiesEnvironmentPostProcessor implements EnvironmentPostProcessor, Ordered {/ * * The name of default {@ link PropertySource} defined in SpringApplication#configurePropertySources method. * / public static final String PROPERTY_SOURCE_NAME = "defaultProperties"; / * The property name of "spring.main.allow-bean-definition-overriding". * Please refer to: https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.1-Release-Notes#bean-overriding * / public static final String ALLOW_BEAN_DEFINITION_OVERRIDING_PROPERTY = "spring.main.allow-bean-definition-overriding"; @ Override public void postProcessEnvironment (ConfigurableEnvironment environment, SpringApplication application) {MutablePropertySources propertySources = environment.getPropertySources (); Map defaultProperties = createDefaultProperties (environment) If (! CollectionUtils.isEmpty (defaultProperties)) {addOrReplace (propertySources, defaultProperties);}} @ Override public int getOrder () {return LOWEST_PRECEDENCE;} private Map createDefaultProperties (ConfigurableEnvironment environment) {Map defaultProperties = new HashMap (); setDubboApplicationNameProperty (environment, defaultProperties); setDubboConfigMultipleProperty (defaultProperties); setDubboApplicationQosEnableProperty (defaultProperties); setAllowBeanDefinitionOverriding (defaultProperties); return defaultProperties } private void setDubboApplicationNameProperty (Environment environment, Map defaultProperties) {String springApplicationName = environment.getProperty (SPRING_APPLICATION_NAME_PROPERTY); if (StringUtils.hasLength (springApplicationName) & &! environment.containsProperty (DUBBO_APPLICATION_NAME_PROPERTY)) {defaultProperties.put (DUBBO_APPLICATION_NAME_PROPERTY, springApplicationName) }} private void setDubboConfigMultipleProperty (Map defaultProperties) {defaultProperties.put (DUBBO_CONFIG_MULTIPLE_PROPERTY, Boolean.TRUE.toString ());} private void setDubboApplicationQosEnableProperty (Map defaultProperties) {defaultProperties.put (DUBBO_APPLICATION_QOS_ENABLE_PROPERTY, Boolean.FALSE.toString ()) } / * * Set {@ link # ALLOW_BEAN_DEFINITION_OVERRIDING_PROPERTY "spring.main.allow-bean-definition-overriding"} to be * true as default. * * @ param defaultProperties the default {@ link Properties properties} * @ see # ALLOW_BEAN_DEFINITION_OVERRIDING_PROPERTY * @ since 2.7.1 * / private void setAllowBeanDefinitionOverriding (Map defaultProperties) {defaultProperties.put (ALLOW_BEAN_DEFINITION_OVERRIDING_PROPERTY, Boolean.TRUE.toString ()) } / * Copy from BusEnvironmentPostProcessor#addOrReplace (MutablePropertySources, Map) * * @ param propertySources {@ link MutablePropertySources} * @ param map Default Dubbo Properties * / private void addOrReplace (MutablePropertySources propertySources, Map map) {MapPropertySource target = null If (propertySources.contains (PROPERTY_SOURCE_NAME)) {PropertySource source = propertySources.get (PROPERTY_SOURCE_NAME); if (source instanceof MapPropertySource) {target = (MapPropertySource) source For (String key: map.keySet ()) {if (! target.containsProperty (key)) {target.getSource () .put (key, map.get (key)) } if (target = = null) {target = new MapPropertySource (PROPERTY_SOURCE_NAME, map);} if (! propertySources.contains (PROPERTY_SOURCE_NAME)) {propertySources.addLast (target);}

DubboDefaultPropertiesEnvironmentPostProcessor implements EnvironmentPostProcessor and Ordered interface; the postProcessEnvironment method first gets the MutablePropertySources from environment, then creates the default configuration defaultProperties through createDefaultProperties (DUBBO_APPLICATION_NAME_PROPERTY is set to springApplicationName by default, DUBBO_CONFIG_MULTIPLE_PROPERTY is set to true, and DUBBO_APPLICATION_QOS_ENABLE_PROPERTY is false). Finally, defaultProperties is overwritten to propertySources;getOrder by addOrReplace method, and LOWEST_PRECEDENCE is returned by the propertySources;getOrder method.

DubboDefaultPropertiesEnvironmentPostProcessorTest

Dubbo-spring-boot-project-2.7.3/dubbo-spring-boot-autoconfigure/src/test/java/org/apache/dubbo/spring/boot/env/DubboDefaultPropertiesEnvironmentPostProcessorTest.java

Public class DubboDefaultPropertiesEnvironmentPostProcessorTest {private DubboDefaultPropertiesEnvironmentPostProcessor instance = new DubboDefaultPropertiesEnvironmentPostProcessor (); private SpringApplication springApplication = new SpringApplication (); @ Test public void testOrder () {Assert.assertEquals (Ordered.LOWEST_PRECEDENCE, instance.getOrder ());} @ Test public void testPostProcessEnvironment () {MockEnvironment environment = new MockEnvironment (); / / Case 1: Not Any property instance.postProcessEnvironment (environment, springApplication) / / Get PropertySources MutablePropertySources propertySources = environment.getPropertySources (); / / Nothing to change PropertySource defaultPropertySource = propertySources.get ("defaultProperties"); Assert.assertNotNull (defaultPropertySource); Assert.assertEquals ("true", defaultPropertySource.getProperty ("dubbo.config.multiple"); Assert.assertEquals ("false", defaultPropertySource.getProperty ("dubbo.application.qos-enable")) / / Case 2: Only set property "spring.application.name" environment.setProperty ("spring.application.name", "demo-dubbo-application"); instance.postProcessEnvironment (environment, springApplication); defaultPropertySource = propertySources.get ("defaultProperties"); Object dubboApplicationName = defaultPropertySource.getProperty ("dubbo.application.name"); Assert.assertEquals ("demo-dubbo-application", dubboApplicationName) / / Case 3: Only set property "dubbo.application.name" / / Rest environment environment = new MockEnvironment (); propertySources = environment.getPropertySources (); environment.setProperty ("dubbo.application.name", "demo-dubbo-application"); instance.postProcessEnvironment (environment, springApplication); defaultPropertySource = propertySources.get ("defaultProperties"); Assert.assertNotNull (defaultPropertySource) DubboApplicationName = environment.getProperty ("dubbo.application.name"); Assert.assertEquals ("demo-dubbo-application", dubboApplicationName); / / Case 4: If "defaultProperties" PropertySource is present in PropertySources / / Rest environment environment = new MockEnvironment (); propertySources = environment.getPropertySources (); propertySources.addLast (new MapPropertySource ("defaultProperties", new HashMap () Environment.setProperty ("spring.application.name", "demo-dubbo-application"); instance.postProcessEnvironment (environment, springApplication); defaultPropertySource = propertySources.get ("defaultProperties"); dubboApplicationName = defaultPropertySource.getProperty ("dubbo.application.name"); Assert.assertEquals ("demo-dubbo-application", dubboApplicationName); / / Case 5: Rest dubbo.config.multiple and dubbo.application.qos-enable environment = new MockEnvironment () PropertySources = environment.getPropertySources (); propertySources.addLast (new MapPropertySource ("defaultProperties", new HashMap ()); environment.setProperty ("dubbo.config.multiple", "false"); environment.setProperty ("dubbo.application.qos-enable", "true"); instance.postProcessEnvironment (environment, springApplication); Assert.assertEquals ("false", environment.getProperty ("dubbo.config.multiple")) Assert.assertEquals ("true", environment.getProperty ("dubbo.application.qos-enable"))

The testPostProcessEnvironment method verifies the addOrReplace method of DubboDefaultPropertiesEnvironmentPostProcessor through MockEnvironment.

Summary

DubboDefaultPropertiesEnvironmentPostProcessor implements EnvironmentPostProcessor and Ordered interface; the postProcessEnvironment method first gets the MutablePropertySources from environment, then creates the default configuration defaultProperties through createDefaultProperties (DUBBO_APPLICATION_NAME_PROPERTY is set to springApplicationName by default, DUBBO_CONFIG_MULTIPLE_PROPERTY is set to true, and DUBBO_APPLICATION_QOS_ENABLE_PROPERTY is false). Finally, defaultProperties is overwritten to propertySources;getOrder by addOrReplace method, and LOWEST_PRECEDENCE is returned by the propertySources;getOrder method.

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DubboDefaultPropertiesEnvironmentPostProcessor

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