support char[] for generic invoke #2003 (#2137)

* support char[] for generic invoke, #2003

* add null or empty string testcase

Author: jerrick-zhu

dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/CompatibleTypeUtils.java

@@ -91,6 +91,19 @@ public static Object compatibleTypeConvert(Object value, Class<?> type) {
                 } catch (ClassNotFoundException e) {
                     throw new RuntimeException(e.getMessage(), e);
                 }
+            } else if (char[].class.equals(type)) {
+                // Process string to char array for generic invoke
+                // See
+                // - https://github.com/apache/incubator-dubbo/issues/2003
+                if (string == null) {
+                    return null;
+                }
+                else {
+                    int len = string.length();
+                    char[] chars = new char[len];
+                    string.getChars(0, len, chars, 0);
+                    return chars;
+                }
             }
         } else if (value instanceof Number) {
             Number number = (Number) value;

dubbo-common/src/test/java/com/alibaba/dubbo/common/utils/CompatibleTypeUtilsTest.java

@@ -67,6 +67,17 @@ public void testCompatibleTypeConvert() throws Exception {
 
             result = CompatibleTypeUtils.compatibleTypeConvert("2011-12-11 12:24:12", Date.class);
             assertEquals(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("2011-12-11 12:24:12"), (Date) result);
+
+            result = CompatibleTypeUtils.compatibleTypeConvert("ab", char[].class);
+            assertEquals(2, ((char[]) result).length);
+            assertEquals('a', ((char[]) result)[0]);
+            assertEquals('b', ((char[]) result)[1]);
+
+            result = CompatibleTypeUtils.compatibleTypeConvert("", char[].class);
+            assertEquals(0, ((char[]) result).length);
+
+            result = CompatibleTypeUtils.compatibleTypeConvert(null, char[].class);
+            assertEquals(null, result);
         }
 
         {