VS Code扩展中监听Git分支切换事件的实现指南

npm install chokidar

import * as vscode from 'vscode';
import * as path from 'path';

function getGitHeadPath(): string | undefined {
    if (!vscode.workspace.workspaceFolders || vscode.workspace.workspaceFolders.length === 0) {
        return undefined;
    }
    // 假设我们只关心第一个工作区根目录
    const workspaceRoot = vscode.workspace.workspaceFolders[0].uri.fsPath;
    return path.join(workspaceRoot, '.git', 'HEAD');
}

import * as vscode from 'vscode';
import * as path from 'path';
import * as chokidar from 'chokidar';
import * as fs from 'fs'; // 用于读取文件内容

let gitHeadWatcher: chokidar.FSWatcher | undefined;

function getGitHeadPath(): string | undefined {
    if (!vscode.workspace.workspaceFolders || vscode.workspace.workspaceFolders.length === 0) {
        return undefined;
    }
    const workspaceRoot = vscode.workspace.workspaceFolders[0].uri.fsPath;
    return path.join(workspaceRoot, '.git', 'HEAD');
}

export function activate(context: vscode.ExtensionContext) {
    console.log('VS Code Git Branch Listener Extension activated.');

    const gitHeadFilePath = getGitHeadPath();

    if (gitHeadFilePath) {
        // 初始化chokidar观察者
        gitHeadWatcher = chokidar.watch(gitHeadFilePath, {
            persistent: true, // 保持观察者活动状态
            ignoreInitial: false, // 首次运行时不触发'add'或'change'事件
            awaitWriteFinish: { // 等待文件写入完成后再触发事件，避免读取不完整文件
                stabilityThreshold: 50,
                pollInterval: 10
            }
        });

        // 监听'change'事件，表示文件内容已更新
        gitHeadWatcher.on('change', async (filePath) => {
            console.log(`Git HEAD file changed: ${filePath}`);
            try {
                const headContent = await fs.promises.readFile(filePath, 'utf8');
                const currentBranch = parseGitHeadContent(headContent);
                if (currentBranch) {
                    vscode.window.showInformationMessage(`Git分支已切换到: ${currentBranch}`);
                    // 在这里触发你的扩展功能
                    // 例如：updateStatusBarItem(currentBranch);
                    // 例如：refreshGitRelatedViews();
                } else {
                    vscode.window.showInformationMessage(`Git HEAD处于分离状态或无法解析`);
                }
            } catch (error) {
                console.error(`Error reading Git HEAD file: ${error}`);
            }
        });

        // 监听'error'事件，处理观察者本身的错误
        gitHeadWatcher.on('error', (error) => {
            console.error(`Watcher error: ${error}`);
            vscode.window.showErrorMessage(`Git HEAD文件监控出现错误: ${error.message}`);
        });

        // 将watcher添加到订阅列表，以便在扩展停用时自动清理
        context.subscriptions.push(new vscode.Disposable(() => {
            if (gitHeadWatcher) {
                gitHeadWatcher.close();
                console.log('Git HEAD watcher closed.');
            }
        }));
    } else {
        vscode.window.showWarningMessage('未找到Git仓库根目录，无法监控Git HEAD文件。');
    }
}

// 解析.git/HEAD文件内容，提取当前分支名
function parseGitHeadContent(content: string): string | undefined {
    const branchRefMatch = content.match(/^ref: refs\/heads\/(.*)$/m);
    if (branchRefMatch && branchRefMatch[1]) {
        return branchRefMatch[1].trim();
    }
    // 如果是分离头指针，内容会是提交哈希，这里简单返回 undefined
    return undefined;
}

export function deactivate() {
    console.log('VS Code Git Branch Listener Extension deactivated.');
    // activate中已通过context.subscriptions处理，此处可省略或用于其他清理
}