添加 优雅的使用枚举参数

enum-spring-boot-starter/README.md

@@ -0,0 +1,91 @@
+# 优雅的使用枚举参数
+
+## 接受格式为 json (Content-Type: application/json)
+
+推荐使用 jackson 注解，最终将显示 value 字段，前端传值也是 传 int型的 value 字段
+
+```
+@Getter
+@AllArgsConstructor
+public enum UserStatus {
+
+    NORMAL(1, "正常"),
+    FREEZE(2, "冻结");
+
+    @JsonValue
+    private final int value;
+    private final String text;
+
+    @JsonCreator
+    public static UserStatus valueOf(int value) {
+        for (UserStatus status : UserStatus.values()) {
+            if (status.value == value) {
+                return status;
+            }
+        }
+        return null;
+    }
+}
+```
+
+## 接受格式为 form (GET 或者 POST FORM)
+
+列如
+
+```
+@RestController
+@RequestMapping
+public class EnumConverterController {
+    @RequestMapping("UserStatus")
+    public (@UserStatus userStatusRequestParam UserStatus userStatus) {
+
+        return userStatus;
+    }
+}
+```
+
+此时使用不到jackson注解`@JsonValue`,因为他使用了 Spring 的 Converter，所以我们需要自定义Converter
+参考 `EnumConverterFactory`
+
+```
+@RequiredArgsConstructor
+public class EnumConverterFactory implements ConverterFactory<String, Enum> {
+
+    @SuppressWarnings("rawtypes")
+    private static final Map<Class, Converter> CONVERTERS = new ConcurrentHashMap<>(64);
+    private final List<EnumConverter> enumConverters;
+
+
+    @Override
+    public <T extends Enum> Converter<String, T> getConverter(Class<T> targetType) {
+        return CONVERTERS.computeIfAbsent(targetType, (key) -> new StringToEnum<T>(targetType, enumConverters));
+    }
+
+    private static class StringToEnum<T extends Enum> implements Converter<String, T> {
+
+        private final Class<T> enumType;
+        private final List<EnumConverter> enumConverters;
+
+        StringToEnum(Class<T> enumType, List<EnumConverter> enumConverters) {
+            this.enumType = enumType;
+            this.enumConverters = enumConverters;
+        }
+
+
+        @Override
+        public T convert(String source) {
+            if (source.isEmpty()) {
+                // It's an empty enum identifier: reset the enum value to null.
+                return null;
+            }
+            for (EnumConverter enumConverter : enumConverters) {
+                T convert = enumConverter.convert(source, enumType);
+                if (convert != null) {
+                    return convert;
+                }
+            }
+            return null;
+        }
+    }
+}
+```

enum-spring-boot-starter/src/test/java/com/admin4j/framework/controller/EnumConverterController.java

@@ -17,5 +17,4 @@ public UserStatus userStatus(@RequestParam UserStatus userStatus) {
 
         return userStatus;
     }
-
 }