dsh-lsp-java

dsh-lsp-java

Java language configuration pack for DeepSeek Harness (DSH). Eclipse JDT Language Server (jdtls) — the Eclipse Java language server. 中文：DSH 的 Java LSP「即插即用」语言包 —— 装上本包，.java 文件即可用 lsp 工具做代码导航。

This pack is one Cordis configuration plugin: it registers a configured @deepseek-ai/dsh-lsp-stdio instance on ctx.lsp with the server command, launch arguments, and extension mapping for Java. It implements no LSP protocol — the shared base does: @deepseek-ai/dsh-lsp (the seam) + @deepseek-ai/dsh-tool-lsp (the model-facing lsp tool with goToDefinition / findReferences / goToImplementation / hover). Twelve packs reuse one unchanged base.

Installing the language server

Download the Eclipse JDT Language Server (jdtls) bundle from the Eclipse Marketplace / project downloads, unzip it, and run its launcher. The bundle ships a bin/jdtls script (and a Windows batch) — put that directory on PATH. Requirements:

• JDK 17 or newer must be installed (java on PATH).

If only java -jar …/plugins/org.eclipse.equinox.launcher_*.jar is available, override the pack config:

- id: lsp-java
  name: '@dsh-lsp-packs/dsh-lsp-java'
  config:
    command: java
    args:
      - -jar
      - /absolute/path/to/org.eclipse.equinox.launcher_1.6.400.v20210924-0641.jar
      - -configuration
      - /absolute/path/to/config_linux
      - -data
      - /absolute/path/to/workspace

The launcher defaults to stdio mode. See the upstream anthropics/claude-plugins-official jdtls-lsp README for the same guidance.

⚠️ The plugin itself never downloads or installs the server binary — matching the upstream anthropics LSP plugins, the server is an external prerequisite. The plugin only resolves and launches it.

Supported extensions

| .java | java |

How the pack works

• Lazy start: the server process is not started at load. lsp-stdio launches it lazily on the first matching query and keeps one process per workspace.
• No-server fallback: if the executable cannot be resolved, the pack still loads; every lsp query for these extensions fails with a structured LSP_UNAVAILABLE error naming the command — the rest of the session is unaffected.
• Config overrides: every default below can be overridden from the composition row, e.g. a server installed at a non-standard path:

- id: lsp-java
  name: '@dsh-lsp-packs/dsh-lsp-java'
  config:
    command: /absolute/path/to/jdtls
    args:
      - --stdio
    extensionToLanguage:
      '.xyz': custom-language-id
    maxDocumentBytes: 8000000

All fields of the servers table documented in the @deepseek-ai/dsh-lsp-stdio README are accepted (command, args, env, extensionToLanguage, initializationOptions, configuration, byte/time bounds).

Mounting

1. Mount the shared base once (the lsp service, the lsp tool, and a filesystem/subprocess pair for the same execution world) — ready-made snippet in examples/base-composition.cordis.yml of the dsh-lsp-packs repo.
2. Install the pack (its cordis.yml is the dsh.bundle.patch, so the row inserts itself):

dsh plugin add @dsh-lsp-packs/dsh-lsp-java    # published name
dsh plugin add /path/to/dsh-lsp-packs/dsh-lsp-java  # or a local checkout

or compose the row directly (name resolved from the installed package):

- insert:
    - id: lsp-java
      name: '@dsh-lsp-packs/dsh-lsp-java'

Smoke test

pnpm vitest run --dir dsh-lsp-java   # or from the repo root: pnpm test

• Lane 1 (offline): asserts the defaults (command / args / extension table / provider id).
• Lane 2 (offline): asserts the missing-server fallback returns LSP_UNAVAILABLE.
• Lane 3 (needs the server): runs the four lsp operations against Sample.java; it auto-skips when jdtls is not on PATH.

jdtls initializes a full Eclipse workspace on first launch (visible startup latency) and prefers a project layout; the first query may take tens of seconds.

License

MIT — see LICENSE. The server binary is a third-party component with its own license.