gateway：增加 GlobalExceptionHandler 实现全局异常处理

yudao-gateway/src/main/java/cn/iocoder/yudao/gateway/util/WebFrameworkUtils.java

@@ -2,10 +2,18 @@ package cn.iocoder.yudao.gateway.util;
 
 import cn.hutool.core.map.MapUtil;
 import cn.hutool.core.util.StrUtil;
+import cn.hutool.extra.servlet.ServletUtil;
+import cn.iocoder.yudao.framework.common.util.json.JsonUtils;
 import cn.iocoder.yudao.module.system.api.oauth2.dto.OAuth2AccessTokenCheckRespDTO;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
 import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.web.server.ServerWebExchange;
+import reactor.core.publisher.Mono;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -17,6 +25,7 @@ import java.util.Map;
  *
  * @author 芋道源码
  */
+@Slf4j
 public class WebFrameworkUtils {
 
     @SuppressWarnings("UastIncorrectHttpHeaderInspection")
@@ -38,4 +47,28 @@ public class WebFrameworkUtils {
         httpHeaders.set(HEADER_TENANT_ID, tenantId);
     }
 
+    /**
+     * 返回 JSON 字符串
+     *
+     * @param exchange 响应
+     * @param object 对象，会序列化成 JSON 字符串
+     */
+    @SuppressWarnings("deprecation") // 必须使用 APPLICATION_JSON_UTF8_VALUE，否则会乱码
+    public static Mono<Void> writeJSON(ServerWebExchange exchange, Object object) {
+        // 设置 header
+        ServerHttpResponse response = exchange.getResponse();
+        response.getHeaders().setContentType(MediaType.APPLICATION_JSON_UTF8);
+        // 设置 body
+        return response.writeWith(Mono.fromSupplier(() -> {
+            DataBufferFactory bufferFactory = response.bufferFactory();
+            try {
+                return bufferFactory.wrap(JsonUtils.toJsonByte(object));
+            } catch (Exception ex) {
+                ServerHttpRequest request = exchange.getRequest();
+                log.error("[writeJSON][uri({}/{}) 发生异常]", request.getURI(), request.getMethod(), ex);
+                return bufferFactory.wrap(new byte[0]);
+            }
+        }));
+    }
+
 }