refactor(apollo-common): 异常处理增加根本原因信息 (#5367)

* refactor(apollo-common): 异常处理增加根本原因信息

* refactor(apollo-common): 优化异常处理信息展示

* Update CHANGES.md

---------

Co-authored-by: Jason Song <[email protected]>

Author: youngzil

Diff for: CHANGES.md

@@ -9,6 +9,7 @@ Apollo 2.5.0
 * [Feature: Provide a new configfiles API to return the raw content of configuration files directly](https://github.com/apolloconfig/apollo/pull/5336)
 * [Feature: Enhanced instance configuration auditing and caching](https://github.com/apolloconfig/apollo/pull/5361)
 * [Feature: Provide a new open API to return the organization list](https://github.com/apolloconfig/apollo/pull/5365)
+* [Refactor: Exception handler adds root cause information](https://github.com/apolloconfig/apollo/pull/5367)
 
 ------------------
 All issues and pull requests are [here](https://github.com/apolloconfig/apollo/milestone/16?closed=1)

Diff for: apollo-common/src/main/java/com/ctrip/framework/apollo/common/controller/GlobalDefaultExceptionHandler.java

@@ -33,6 +33,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.slf4j.event.Level;
+import org.springframework.core.NestedExceptionUtils;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
@@ -53,6 +54,7 @@
 
 @ControllerAdvice
 public class GlobalDefaultExceptionHandler {
+
   private Gson gson = new Gson();
   private static Type mapType = new TypeToken<Map<String, Object>>() {
   }.getType();
@@ -115,7 +117,7 @@ private ResponseEntity<Map<String, Object>> handleError(HttpServletRequest reque
 
   private ResponseEntity<Map<String, Object>> handleError(HttpServletRequest request,
                                                           HttpStatus status, Throwable ex, Level logLevel) {
-    String message = ex.getMessage();
+    String message = getMessageWithRootCause(ex);
     printLog(message, ex, logLevel);
 
     Map<String, Object> errorAttributes = new HashMap<>();
@@ -169,4 +171,13 @@ private void printLog(String message, Throwable ex, Level logLevel) {
     Tracer.logError(ex);
   }
 
+  private String getMessageWithRootCause(Throwable ex) {
+    String message = ex.getMessage();
+    Throwable rootCause = NestedExceptionUtils.getMostSpecificCause(ex);
+    if (rootCause != ex) {
+      message += " [Cause: " + rootCause.getMessage() + "]";
+    }
+    return message;
+  }
+
 }