fix: 修复若干问题，添加java lsp

backend/config.json

@@ -50,6 +50,12 @@
       "args": [
         "--stdio"
       ]
+    },
+    {
+      "language": "java",
+      "languageId": "java",
+      "command": "jdt-language-server-1.57.0-202602111032/jdtls.bat",
+      "args": []
     }
   ]
 }