[add] 增加了备用数据库切换

src/main/java/com/waterquality/projectmanagement/config/database/MasterHealthChecker.java

@@ -0,0 +1,30 @@
+package com.waterquality.projectmanagement.config.database;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+
+import javax.sql.DataSource;
+import java.sql.Connection;
+import java.sql.Statement;
+
+@Component
+public class MasterHealthChecker {
+
+    @Autowired
+    @Qualifier("masterDataSource")
+    private DataSource masterDataSource;
+
+    // 每60秒检查一次主库
+    @Scheduled(fixedRate = 60000)
+    public void checkMasterHealth() {
+        try (Connection conn = masterDataSource.getConnection();
+             Statement stmt = conn.createStatement()) {
+            stmt.execute("SELECT 1"); // 执行简单查询检测主库
+            DynamicRoutingDataSource.setMasterAvailable(true);
+        } catch (Exception e) {
+            DynamicRoutingDataSource.setMasterAvailable(false); // 主库不可用
+        }
+    }
+}