add backend

backend/src/main/java/com/yoyuzh/cqu/CquApiClient.java

@@ -0,0 +1,40 @@
+package com.yoyuzh.cqu;
+
+import com.yoyuzh.config.CquApiProperties;
+import lombok.RequiredArgsConstructor;
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.stereotype.Component;
+import org.springframework.web.client.RestClient;
+
+import java.util.List;
+import java.util.Map;
+
+@Component
+@RequiredArgsConstructor
+public class CquApiClient {
+
+    private final RestClient restClient;
+    private final CquApiProperties properties;
+
+    public List<Map<String, Object>> fetchSchedule(String semester, String studentId) {
+        if (properties.isMockEnabled()) {
+            return CquMockDataFactory.createSchedule(semester, studentId);
+        }
+        return restClient.get()
+                .uri(properties.getBaseUrl() + "/schedule?semester={semester}&studentId={studentId}", semester, studentId)
+                .retrieve()
+                .body(new ParameterizedTypeReference<>() {
+                });
+    }
+
+    public List<Map<String, Object>> fetchGrades(String semester, String studentId) {
+        if (properties.isMockEnabled()) {
+            return CquMockDataFactory.createGrades(semester, studentId);
+        }
+        return restClient.get()
+                .uri(properties.getBaseUrl() + "/grades?semester={semester}&studentId={studentId}", semester, studentId)
+                .retrieve()
+                .body(new ParameterizedTypeReference<>() {
+                });
+    }
+}