feat(cache): 缓存常量与 key 构造器(前缀 + 环境隔离 + 锁 key 派生)

src/test/java/com/njcn/middle/cache/support/CacheKeyBuilderTest.java

@@ -0,0 +1,34 @@
+package com.njcn.middle.cache.support;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class CacheKeyBuilderTest {
+
+    @Test
+    void buildWithPrefixOnly() {
+        CacheKeyBuilder kb = new CacheKeyBuilder("cache:", false, "");
+        assertEquals("cache:user:1", kb.build("user:1"));
+    }
+
+    @Test
+    void buildWithEnvIsolation() {
+        CacheKeyBuilder kb = new CacheKeyBuilder("cache:", true, "prod");
+        assertEquals("cache:prod:user:1", kb.build("user:1"));
+    }
+
+    @Test
+    void envIsolationButBlankEnvFallsBack() {
+        CacheKeyBuilder kb = new CacheKeyBuilder("cache:", true, "");
+        assertEquals("cache:user:1", kb.build("user:1"));
+    }
+
+    @Test
+    void buildLockDerivesFromDataKey() {
+        assertEquals("cache:user:1:__lock__",
+                new CacheKeyBuilder("cache:", false, "").buildLock("user:1"));
+        assertEquals("cache:prod:user:1:__lock__",
+                new CacheKeyBuilder("cache:", true, "prod").buildLock("user:1"));
+    }
+}