Improve environment querying

Author: zhangrongfan

mybatis-boost-spring-boot-autoconfigure/src/main/java/cn/mybatisboost/spring/boot/autoconfigure/EnvironmentHolder.java

@@ -10,7 +10,7 @@ public class EnvironmentHolder implements EnvironmentPostProcessor {
 
     public static ConfigurableEnvironment getEnvironment() {
         if (environment == null) {
-            throw new Error("Environment haven't been set yet");
+            throw new EnvironmentNotSetError("Environment haven't been set yet");
         }
         return environment;
     }
@@ -19,4 +19,11 @@ public static ConfigurableEnvironment getEnvironment() {
     public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {
         EnvironmentHolder.environment = environment;
     }
+
+    public static class EnvironmentNotSetError extends Error {
+
+        EnvironmentNotSetError(String message) {
+            super(message);
+        }
+    }
 }

mybatis-boost-spring-boot-autoconfigure/src/main/java/cn/mybatisboost/spring/boot/autoconfigure/NosqlConfiguration.java

@@ -13,10 +13,16 @@
 public class NosqlConfiguration implements ImportBeanDefinitionRegistrar {
 
     private static Logger logger = LoggerFactory.getLogger(NosqlConfiguration.class);
-    private static boolean mapUnderscoreToCamelCase = EnvironmentHolder.getEnvironment()
-            .getProperty("mybatis.configuration.map-underscore-to-camel-case", boolean.class, false);
+    private static boolean mapUnderscoreToCamelCase;
 
     static {
+        try {
+            mapUnderscoreToCamelCase = EnvironmentHolder.getEnvironment()
+                    .getProperty("mybatis.configuration.map-underscore-to-camel-case",
+                            boolean.class, false);
+        } catch (EnvironmentHolder.EnvironmentNotSetError e) {
+            logger.info("Use default mapUnderscoreToCamelCase value", e);
+        }
         try {
             CtClass ctClass = ClassPool.getDefault().get("org.mybatis.spring.mapper.ClassPathMapperScanner");
             ctClass.getDeclaredMethod("checkCandidate").insertAfter("if ($_) " +