feat(gateway): 实现API网关响应模板和请求映射增强功能

- 添加getLastHttpStepId方法获取最后HTTP步骤ID用于响应体设置判断
- 实现响应模板功能支持自定义JSON响应格式通过responseTemplate配置
- 增强请求映射逻辑支持查询参数、请求头和请求体的灵活映射与合并
- 优化HTTP步骤处理器中的请求载荷转换和响应映射逻辑
- 在START节点中支持公共参数自动继承到后续HTTP步骤
- 添加查询参数环境变量绑定便于JSONata表达式访问
- 实现向后兼容的默认响应格式保持现有功能不变

zt-module-databus/zt-module-databus-server/src/main/java/com/zt/plat/module/databus/framework/integration/gateway/domain/ApiDefinitionAggregate.java

@@ -40,4 +40,23 @@ public class ApiDefinitionAggregate {
         return credentialBindings == null ? Collections.emptyList() : credentialBindings;
     }
 
+    /**
+     * 获取最后一个 HTTP 步骤的 ID（order 最大的 HTTP 步骤）
+     * 用于判断是否需要设置 responseBody
+     */
+    public Long getLastHttpStepId() {
+        return getSteps().stream()
+                .filter(stepDef -> "HTTP".equalsIgnoreCase(stepDef.getStep().getType()))
+                .max((s1, s2) -> {
+                    Integer order1 = s1.getStep().getStepOrder();
+                    Integer order2 = s2.getStep().getStepOrder();
+                    if (order1 == null && order2 == null) return 0;
+                    if (order1 == null) return -1;
+                    if (order2 == null) return 1;
+                    return order1.compareTo(order2);
+                })
+                .map(stepDef -> stepDef.getStep().getId())
+                .orElse(null);
+    }
+
 }

zt-module-databus/zt-module-databus-server/src/main/java/com/zt/plat/module/databus/framework/integration/gateway/expression/JsonataExpressionEvaluator.java

@@ -43,6 +43,13 @@ public class JsonataExpressionEvaluator implements ExpressionEvaluator {
             environment.setVariable("vars", objectMapper.valueToTree(context.getVariables() == null ? java.util.Collections.emptyMap() : context.getVariables()));
             environment.setVariable("headers", objectMapper.valueToTree(context.getHeaders() == null ? java.util.Collections.emptyMap() : context.getHeaders()));
             environment.setVariable("ctx", objectMapper.valueToTree(context.getInvocation()));
+
+            // 直接绑定查询参数，方便访问
+            if (context.getInvocation() != null && context.getInvocation().getRequestQueryParams() != null) {
+                environment.setVariable("query", objectMapper.valueToTree(context.getInvocation().getRequestQueryParams()));
+            } else {
+                environment.setVariable("query", objectMapper.valueToTree(java.util.Collections.emptyMap()));
+            }
         } catch (EvaluateRuntimeException e) {
             throw ServiceExceptionUtil.exception(API_JSONATA_BIND_FAILED);
         }

zt-module-databus/zt-module-databus-server/src/main/java/com/zt/plat/module/databus/framework/integration/gateway/step/impl/StartStepHandler.java

@@ -18,10 +18,19 @@ import org.springframework.stereotype.Component;
 
 import java.time.Duration;
 import java.time.Instant;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
 import static com.zt.plat.module.databus.service.gateway.impl.GatewayServiceErrorCodeConstants.API_STEP_START_EXECUTION_FAILED;
 
 /**
  * Handler for START orchestration nodes.
+ *
+ * <p>增强功能：START 节点的映射结果会存入 context.requestBody，
+ * 使得后续 HTTP 步骤可以自动继承这些公共参数，避免重复配置。
+ *
+ * <p>注意：不将参数存入 context.variables，避免与后续步骤的响应结果冲突。
+ * variables 应该保留给步骤执行结果使用。
  */
 @Component
 @RequiredArgsConstructor
@@ -40,11 +49,22 @@ public class StartStepHandler implements ApiStepHandler {
             Instant start = Instant.now();
             Object snapshotBefore = GatewayExpressionHelper.snapshotRequest(payload);
             try {
-                ExpressionSpec spec = ExpressionSpecParser.parse(stepDefinition.getStep().getRequestMappingExpr(), ExpressionTypeEnum.JSON);
+                ExpressionSpec spec = ExpressionSpecParser.parse(
+                    stepDefinition.getStep().getRequestMappingExpr(),
+                    ExpressionTypeEnum.JSON
+                );
                 if (spec != null) {
-                    Object evaluated = expressionExecutor.evaluate(spec, payload, payload.getRequestBody(), headers);
+                    // 将查询参数合并到 payload 中，使表达式可以通过 $.query.k 访问
+                    // 这样和 HTTP 步骤的映射逻辑保持一致
+                    Object enrichedPayload = enrichPayloadWithQuery(payload.getRequestBody(), payload.getRequestQueryParams());
+
+                    Object evaluated = expressionExecutor.evaluate(spec, payload, enrichedPayload, headers);
+
+                    // 应用上下文变更（包括 requestBody、requestQuery 等）
+                    // 支持字段级映射，将外部字段名转换为内部字段名
                     GatewayExpressionHelper.applyContextMutations(payload, evaluated, true, false);
                 }
+
                 payload.addStepResult(ApiStepResult.builder()
                         .stepId(stepDefinition.getStep().getId())
                         .stepType(stepDefinition.getStep().getType())
@@ -70,4 +90,26 @@ public class StartStepHandler implements ApiStepHandler {
             return payload;
         };
     }
+
+    /**
+     * 将查询参数合并到 payload 中，使表达式可以通过 $.query.k 访问
+     * 这样可以避免 JSONata 环境变量访问的限制
+     */
+    private Object enrichPayloadWithQuery(Object originalPayload, Map<String, Object> queryParams) {
+        if (queryParams == null || queryParams.isEmpty()) {
+            return originalPayload;
+        }
+
+        Map<String, Object> enriched = new LinkedHashMap<>();
+
+        // 如果原始 payload 是 Map，复制所有字段
+        if (originalPayload instanceof Map) {
+            enriched.putAll((Map<String, Object>) originalPayload);
+        }
+
+        // 添加查询参数到 query 字段
+        enriched.put("query", new LinkedHashMap<>(queryParams));
+
+        return enriched;
+    }
 }