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Go Web 编程快速入门 07.2 - 模板（2）：解析与执行（含Demo）

news 2025/10/25 7:24:31

在上一章中，我们学习了Go模板的基础语法和最佳实践。本章将深入探讨模板的解析机制和执行流程，通过详细的代码演示和实际项目，帮助你理解模板引擎的内部工作原理，掌握高级模板技术。

1. 模板解析机制深入

1.1 模板解析流程

package mainimport ("fmt""html/template""text/template""strings""os""time""sync"
)// TemplateParser 模板解析器
type TemplateParser struct {textTemplates map[string]*text.template.Template    // 文本模板缓存htmlTemplates map[string]*html.template.Template    // HTML模板缓存funcMap       template.FuncMap                       // 自定义函数映射mutex         sync.RWMutex                          // 读写锁保护并发访问parseStats    map[string]*ParseStats                // 解析统计信息
}// ParseStats 解析统计信息
type ParseStats struct {ParseTime     time.Duration `json:"parse_time"`     // 解析耗时ParseCount    int           `json:"parse_count"`    // 解析次数LastParsed    time.Time     `json:"last_parsed"`    // 最后解析时间TemplateSize  int           `json:"template_size"`  // 模板大小ErrorCount    int           `json:"error_count"`    // 错误次数LastError     string        `json:"last_error"`     // 最后错误信息
}// NewTemplateParser 创建模板解析器
func NewTemplateParser() *TemplateParser {return &TemplateParser{textTemplates: make(map[string]*text.template.Template),htmlTemplates: make(map[string]*html.template.Template),parseStats:    make(map[string]*ParseStats),funcMap: template.FuncMap{// 时间处理函数"now": func() string {return time.Now().Format("2006-01-02 15:04:05")},"formatTime": func(layout, timeStr string) string {t, err := time.Parse("2006-01-02T15:04:05Z", timeStr)if err != nil {return timeStr}return t.Format(layout)},// 字符串处理函数"upper":    strings.ToUpper,"lower":    strings.ToLower,"title":    strings.Title,"trim":     strings.TrimSpace,"contains": strings.Contains,"replace":  strings.ReplaceAll,"split":    strings.Split,"join":     strings.Join,// 数学函数"add": func(a, b int) int { return a + b },"sub": func(a, b int) int { return a - b },"mul": func(a, b int) int { return a * b },"div": func(a, b int) int { if b != 0 { return a / b }return 0},// 条件函数"default": func(defaultVal, val interface{}) interface{} {if val == nil || val == "" {return defaultVal}return val},},}
}// ParseTextTemplate 解析文本模板
func (tp *TemplateParser) ParseTextTemplate(name, content string) error {tp.mutex.Lock()defer tp.mutex.Unlock()startTime := time.Now()// 初始化统计信息if tp.parseStats[name] == nil {tp.parseStats[name] = &ParseStats{}}stats := tp.parseStats[name]stats.ParseCount++stats.TemplateSize = len(content)stats.LastParsed = startTime// 创建新模板并添加自定义函数tmpl := text.template.New(name).Funcs(tp.funcMap)// 解析模板内容parsedTemplate, err := tmpl.Parse(content)if err != nil {stats.ErrorCount++stats.LastError = err.Error()return fmt.Errorf("解析文本模板 %s 失败: %w", name, err)}// 记录解析耗时stats.ParseTime = time.Since(startTime)// 存储解析后的模板tp.textTemplates[name] = parsedTemplatefmt.Printf("✅ 文本模板 '%s' 解析成功 (耗时: %v, 大小: %d 字节)\n", name, stats.ParseTime, stats.TemplateSize)return nil
}// ParseHTMLTemplate 解析HTML模板
func (tp *TemplateParser) ParseHTMLTemplate(name, content string) error {tp.mutex.Lock()defer tp.mutex.Unlock()startTime := time.Now()// 初始化统计信息if tp.parseStats[name] == nil {tp.parseStats[name] = &ParseStats{}}stats := tp.parseStats[name]stats.ParseCount++stats.TemplateSize = len(content)stats.LastParsed = startTime// 创建新HTML模板并添加自定义函数tmpl := html.template.New(name).Funcs(html.template.FuncMap(tp.funcMap))// 解析模板内容parsedTemplate, err := tmpl.Parse(content)if err != nil {stats.ErrorCount++stats.LastError = err.Error()return fmt.Errorf("解析HTML模板 %s 失败: %w", name, err)}// 记录解析耗时stats.ParseTime = time.Since(startTime)// 存储解析后的模板tp.htmlTemplates[name] = parsedTemplatefmt.Printf("✅ HTML模板 '%s' 解析成功 (耗时: %v, 大小: %d 字节)\n", name, stats.ParseTime, stats.TemplateSize)return nil
}// GetParseStats 获取解析统计信息
func (tp *TemplateParser) GetParseStats() map[string]*ParseStats {tp.mutex.RLock()defer tp.mutex.RUnlock()// 创建副本避免并发问题statsCopy := make(map[string]*ParseStats)for name, stats := range tp.parseStats {statsCopy[name] = &ParseStats{ParseTime:    stats.ParseTime,ParseCount:   stats.ParseCount,LastParsed:   stats.LastParsed,TemplateSize: stats.TemplateSize,ErrorCount:   stats.ErrorCount,LastError:    stats.LastError,}}return statsCopy
}// ExecuteTextTemplate 执行文本模板
func (tp *TemplateParser) ExecuteTextTemplate(name string, data interface{}) (string, error) {tp.mutex.RLock()tmpl, exists := tp.textTemplates[name]tp.mutex.RUnlock()if !exists {return "", fmt.Errorf("文本模板 %s 不存在", name)}var buf strings.Builderif err := tmpl.Execute(&buf, data); err != nil {return "", fmt.Errorf("执行文本模板 %s 失败: %w", name, err)}return buf.String(), nil
}// ExecuteHTMLTemplate 执行HTML模板
func (tp *TemplateParser) ExecuteHTMLTemplate(name string, data interface{}) (string, error) {tp.mutex.RLock()tmpl, exists := tp.htmlTemplates[name]tp.mutex.RUnlock()if !exists {return "", fmt.Errorf("HTML模板 %s 不存在", name)}var buf strings.Builderif err := tmpl.Execute(&buf, data); err != nil {return "", fmt.Errorf("执行HTML模板 %s 失败: %w", name, err)}return buf.String(), nil
}// PrintStats 打印统计信息
func (tp *TemplateParser) PrintStats() {stats := tp.GetParseStats()fmt.Println("\n=== 模板解析统计信息 ===")for name, stat := range stats {fmt.Printf("\n📄 模板: %s\n", name)fmt.Printf("   解析次数: %d\n", stat.ParseCount)fmt.Printf("   解析耗时: %v\n", stat.ParseTime)fmt.Printf("   模板大小: %d 字节\n", stat.TemplateSize)fmt.Printf("   最后解析: %s\n", stat.LastParsed.Format("2006-01-02 15:04:05"))fmt.Printf("   错误次数: %d\n", stat.ErrorCount)if stat.LastError != "" {fmt.Printf("   最后错误: %s\n", stat.LastError)}}
}

1.2 模板语法树分析

// TemplateAnalyzer 模板分析器
type TemplateAnalyzer struct {parser *TemplateParser
}// TemplateInfo 模板信息
type TemplateInfo struct {Name         string            `json:"name"`          // 模板名称Type         string            `json:"type"`          // 模板类型 (text/html)Variables    []string          `json:"variables"`     // 使用的变量Functions    []string          `json:"functions"`     // 使用的函数Actions      []string          `json:"actions"`       // 使用的动作Complexity   int               `json:"complexity"`    // 复杂度评分Dependencies []string          `json:"dependencies"`  // 依赖的其他模板Metadata     map[string]string `json:"metadata"`      // 元数据
}// NewTemplateAnalyzer 创建模板分析器
func NewTemplateAnalyzer(parser *TemplateParser) *TemplateAnalyzer {return &TemplateAnalyzer{parser: parser,}
}// AnalyzeTemplate 分析模板
func (ta *TemplateAnalyzer) AnalyzeTemplate(name, content string) *TemplateInfo {info := &TemplateInfo{Name:         name,Variables:    []string{},Functions:    []string{},Actions:      []string{},Dependencies: []string{},Metadata:     make(map[string]string),}// 确定模板类型if strings.Contains(content, "<html>") || strings.Contains(content, "<!DOCTYPE") {info.Type = "html"} else {info.Type = "text"}// 分析变量使用info.Variables = ta.extractVariables(content)// 分析函数使用info.Functions = ta.extractFunctions(content)// 分析动作使用info.Actions = ta.extractActions(content)// 计算复杂度info.Complexity = ta.calculateComplexity(content)// 提取元数据info.Metadata["size"] = fmt.Sprintf("%d", len(content))info.Metadata["lines"] = fmt.Sprintf("%d", strings.Count(content, "\n")+1)return info
}// extractVariables 提取变量
func (ta *TemplateAnalyzer) extractVariables(content string) []string {var variables []stringvariableMap := make(map[string]bool)// 简化的变量提取逻辑lines := strings.Split(content, "\n")for _, line := range lines {if strings.Contains(line, "{{") && strings.Contains(line, "}}") {// 提取 {{.Variable}} 格式的变量start := strings.Index(line, "{{")end := strings.Index(line, "}}")if start != -1 && end != -1 && end > start {variable := strings.TrimSpace(line[start+2 : end])if strings.HasPrefix(variable, ".") && !strings.Contains(variable, " ") {varName := strings.TrimPrefix(variable, ".")if !variableMap[varName] {variables = append(variables, varName)variableMap[varName] = true}}}}}return variables
}// extractFunctions 提取函数
func (ta *TemplateAnalyzer) extractFunctions(content string) []string {var functions []stringfunctionMap := make(map[string]bool)// 常见的模板函数commonFunctions := []string{"add", "sub", "mul", "div", "mod","eq", "ne", "lt", "le", "gt", "ge","and", "or", "not","len", "index", "printf", "print", "println","html", "js", "urlquery","upper", "lower", "title", "trim","now", "formatTime", "default",}for _, fn := range commonFunctions {if strings.Contains(content, fn+" ") || strings.Contains(content, fn+"(") {if !functionMap[fn] {functions = append(functions, fn)functionMap[fn] = true}}}return functions
}// extractActions 提取动作
func (ta *TemplateAnalyzer) extractActions(content string) []string {var actions []stringactionMap := make(map[string]bool)// 常见的模板动作commonActions := []string{"if", "else", "end", "range", "with", "define", "template", "block"}for _, action := range commonActions {if strings.Contains(content, "{{"+action) || strings.Contains(content, "{{ "+action) {if !actionMap[action] {actions = append(actions, action)actionMap[action] = true}}}return actions
}// calculateComplexity 计算复杂度
func (ta *TemplateAnalyzer) calculateComplexity(content string) int {complexity := 0// 基础复杂度：模板大小complexity += len(content) / 100// 控制结构复杂度complexity += strings.Count(content, "{{if") * 2complexity += strings.Count(content, "{{range") * 3complexity += strings.Count(content, "{{with") * 2// 函数调用复杂度complexity += strings.Count(content, "{{") - strings.Count(content, "{{.")return complexity
}// PrintAnalysis 打印分析结果
func (ta *TemplateAnalyzer) PrintAnalysis(info *TemplateInfo) {fmt.Printf("\n=== 模板分析报告: %s ===\n", info.Name)fmt.Printf("类型: %s\n", info.Type)fmt.Printf("复杂度: %d\n", info.Complexity)if len(info.Variables) > 0 {fmt.Printf("变量 (%d个): %s\n", len(info.Variables), strings.Join(info.Variables, ", "))}if len(info.Functions) > 0 {fmt.Printf("函数 (%d个): %s\n", len(info.Functions), strings.Join(info.Functions, ", "))}if len(info.Actions) > 0 {fmt.Printf("动作 (%d个): %s\n", len(info.Actions), strings.Join(info.Actions, ", "))}fmt.Printf("元数据:\n")for key, value := range info.Metadata {fmt.Printf("  %s: %s\n", key, value)}
}

2. 模板执行流程详解

2.1 执行上下文管理

// ExecutionContext 执行上下文
type ExecutionContext struct {Data         interface{}            `json:"data"`          // 模板数据Variables    map[string]interface{} `json:"variables"`     // 临时变量StartTime    time.Time              `json:"start_time"`    // 开始时间EndTime      time.Time              `json:"end_time"`      // 结束时间Duration     time.Duration          `json:"duration"`      // 执行耗时OutputSize   int                    `json:"output_size"`   // 输出大小ErrorMessage string                 `json:"error_message"` // 错误信息MemoryUsage  int64                  `json:"memory_usage"`  // 内存使用
}// TemplateExecutor 模板执行器
type TemplateExecutor struct {parser    *TemplateParseranalyzer  *TemplateAnalyzercontexts  map[string]*ExecutionContext // 执行上下文历史mutex     sync.RWMutex                 // 读写锁
}// NewTemplateExecutor 创建模板执行器
func NewTemplateExecutor(parser *TemplateParser) *TemplateExecutor {return &TemplateExecutor{parser:   parser,analyzer: NewTemplateAnalyzer(parser),contexts: make(map[string]*ExecutionContext),}
}// ExecuteWithContext 带上下文执行模板
func (te *TemplateExecutor) ExecuteWithContext(templateName string, data interface{}, isHTML bool) (string, *ExecutionContext, error) {// 创建执行上下文ctx := &ExecutionContext{Data:      data,Variables: make(map[string]interface{}),StartTime: time.Now(),}// 记录内存使用（简化实现）ctx.MemoryUsage = int64(te.estimateMemoryUsage(data))var result stringvar err error// 执行模板if isHTML {result, err = te.parser.ExecuteHTMLTemplate(templateName, data)} else {result, err = te.parser.ExecuteTextTemplate(templateName, data)}// 记录执行结果ctx.EndTime = time.Now()ctx.Duration = ctx.EndTime.Sub(ctx.StartTime)ctx.OutputSize = len(result)if err != nil {ctx.ErrorMessage = err.Error()}// 保存执行上下文te.mutex.Lock()contextKey := fmt.Sprintf("%s_%d", templateName, ctx.StartTime.Unix())te.contexts[contextKey] = ctxte.mutex.Unlock()return result, ctx, err
}// estimateMemoryUsage 估算内存使用
func (te *TemplateExecutor) estimateMemoryUsage(data interface{}) int {// 简化的内存估算逻辑switch v := data.(type) {case string:return len(v)case []byte:return len(v)case map[string]interface{}:size := 0for key, value := range v {size += len(key) + te.estimateMemoryUsage(value)}return sizecase []interface{}:size := 0for _, item := range v {size += te.estimateMemoryUsage(item)}return sizedefault:return 64 // 默认估算值}
}// GetExecutionHistory 获取执行历史
func (te *TemplateExecutor) GetExecutionHistory() map[string]*ExecutionContext {te.mutex.RLock()defer te.mutex.RUnlock()// 创建副本history := make(map[string]*ExecutionContext)for key, ctx := range te.contexts {history[key] = &ExecutionContext{Data:         ctx.Data,Variables:    ctx.Variables,StartTime:    ctx.StartTime,EndTime:      ctx.EndTime,Duration:     ctx.Duration,OutputSize:   ctx.OutputSize,ErrorMessage: ctx.ErrorMessage,MemoryUsage:  ctx.MemoryUsage,}}return history
}// PrintExecutionStats 打印执行统计
func (te *TemplateExecutor) PrintExecutionStats() {history := te.GetExecutionHistory()fmt.Println("\n=== 模板执行统计 ===")totalExecutions := len(history)var totalDuration time.Durationvar totalOutputSize interrorCount := 0for key, ctx := range history {fmt.Printf("\n🚀 执行: %s\n", key)fmt.Printf("   开始时间: %s\n", ctx.StartTime.Format("2006-01-02 15:04:05"))fmt.Printf("   执行耗时: %v\n", ctx.Duration)fmt.Printf("   输出大小: %d 字节\n", ctx.OutputSize)fmt.Printf("   内存使用: %d 字节\n", ctx.MemoryUsage)if ctx.ErrorMessage != "" {fmt.Printf("   ❌ 错误: %s\n", ctx.ErrorMessage)errorCount++} else {fmt.Printf("   ✅ 成功执行\n")}totalDuration += ctx.DurationtotalOutputSize += ctx.OutputSize}fmt.Printf("\n📊 总体统计:\n")fmt.Printf("   总执行次数: %d\n", totalExecutions)fmt.Printf("   成功次数: %d\n", totalExecutions-errorCount)fmt.Printf("   失败次数: %d\n", errorCount)fmt.Printf("   总耗时: %v\n", totalDuration)fmt.Printf("   平均耗时: %v\n", totalDuration/time.Duration(max(totalExecutions, 1)))fmt.Printf("   总输出大小: %d 字节\n", totalOutputSize)if totalExecutions > 0 {fmt.Printf("   平均输出大小: %d 字节\n", totalOutputSize/totalExecutions)fmt.Printf("   成功率: %.2f%%\n", float64(totalExecutions-errorCount)/float64(totalExecutions)*100)}
}// max 辅助函数
func max(a, b int) int {if a > b {return a}return b
}

2.2 性能监控与优化

// PerformanceMonitor 性能监控器
type PerformanceMonitor struct {executor    *TemplateExecutormetrics     map[string]*PerformanceMetricsmutex       sync.RWMutexalertThreshold time.Duration // 告警阈值
}// PerformanceMetrics 性能指标
type PerformanceMetrics struct {TemplateName    string        `json:"template_name"`    // 模板名称ExecutionCount  int           `json:"execution_count"`  // 执行次数TotalDuration   time.Duration `json:"total_duration"`   // 总耗时AverageDuration time.Duration `json:"average_duration"` // 平均耗时MinDuration     time.Duration `json:"min_duration"`     // 最小耗时MaxDuration     time.Duration `json:"max_duration"`     // 最大耗时ErrorRate       float64       `json:"error_rate"`       // 错误率ThroughputPerSec float64      `json:"throughput_per_sec"` // 每秒吞吐量LastExecuted    time.Time     `json:"last_executed"`    // 最后执行时间
}// NewPerformanceMonitor 创建性能监控器
func NewPerformanceMonitor(executor *TemplateExecutor) *PerformanceMonitor {return &PerformanceMonitor{executor:       executor,metrics:        make(map[string]*PerformanceMetrics),alertThreshold: 100 * time.Millisecond, // 默认100ms告警阈值}
}// RecordExecution 记录执行
func (pm *PerformanceMonitor) RecordExecution(templateName string, duration time.Duration, hasError bool) {pm.mutex.Lock()defer pm.mutex.Unlock()if pm.metrics[templateName] == nil {pm.metrics[templateName] = &PerformanceMetrics{TemplateName: templateName,MinDuration:  duration,MaxDuration:  duration,}}metrics := pm.metrics[templateName]metrics.ExecutionCount++metrics.TotalDuration += durationmetrics.AverageDuration = metrics.TotalDuration / time.Duration(metrics.ExecutionCount)metrics.LastExecuted = time.Now()// 更新最小/最大耗时if duration < metrics.MinDuration {metrics.MinDuration = duration}if duration > metrics.MaxDuration {metrics.MaxDuration = duration}// 计算错误率if hasError {// 简化实现：假设错误计数存储在其他地方// 这里只是演示概念}// 计算吞吐量（简化实现）if metrics.AverageDuration > 0 {metrics.ThroughputPerSec = float64(time.Second) / float64(metrics.AverageDuration)}// 检查是否需要告警if duration > pm.alertThreshold {fmt.Printf("⚠️  性能告警: 模板 %s 执行耗时 %v 超过阈值 %v\n", templateName, duration, pm.alertThreshold)}
}// GetMetrics 获取性能指标
func (pm *PerformanceMonitor) GetMetrics() map[string]*PerformanceMetrics {pm.mutex.RLock()defer pm.mutex.RUnlock()// 创建副本metricsCopy := make(map[string]*PerformanceMetrics)for name, metrics := range pm.metrics {metricsCopy[name] = &PerformanceMetrics{TemplateName:     metrics.TemplateName,ExecutionCount:   metrics.ExecutionCount,TotalDuration:    metrics.TotalDuration,AverageDuration:  metrics.AverageDuration,MinDuration:      metrics.MinDuration,MaxDuration:      metrics.MaxDuration,ErrorRate:        metrics.ErrorRate,ThroughputPerSec: metrics.ThroughputPerSec,LastExecuted:     metrics.LastExecuted,}}return metricsCopy
}// PrintPerformanceReport 打印性能报告
func (pm *PerformanceMonitor) PrintPerformanceReport() {metrics := pm.GetMetrics()fmt.Println("\n=== 模板性能报告 ===")for _, metric := range metrics {fmt.Printf("\n📈 模板: %s\n", metric.TemplateName)fmt.Printf("   执行次数: %d\n", metric.ExecutionCount)fmt.Printf("   总耗时: %v\n", metric.TotalDuration)fmt.Printf("   平均耗时: %v\n", metric.AverageDuration)fmt.Printf("   最小耗时: %v\n", metric.MinDuration)fmt.Printf("   最大耗时: %v\n", metric.MaxDuration)fmt.Printf("   吞吐量: %.2f 次/秒\n", metric.ThroughputPerSec)fmt.Printf("   最后执行: %s\n", metric.LastExecuted.Format("2006-01-02 15:04:05"))// 性能评级if metric.AverageDuration < 10*time.Millisecond {fmt.Printf("   性能评级: 🟢 优秀\n")} else if metric.AverageDuration < 50*time.Millisecond {fmt.Printf("   性能评级: 🟡 良好\n")} else if metric.AverageDuration < 100*time.Millisecond {fmt.Printf("   性能评级: 🟠 一般\n")} else {fmt.Printf("   性能评级: 🔴 需要优化\n")}}
}// SetAlertThreshold 设置告警阈值
func (pm *PerformanceMonitor) SetAlertThreshold(threshold time.Duration) {pm.alertThreshold = thresholdfmt.Printf("📊 性能告警阈值已设置为: %v\n", threshold)
}

3. 实际演示项目：新闻发布系统

3.1 新闻数据模型

// NewsArticle 新闻文章
type NewsArticle struct {ID          int       `json:"id"`Title       string    `json:"title"`Content     string    `json:"content"`Summary     string    `json:"summary"`Author      Author    `json:"author"`Category    Category  `json:"category"`Tags        []Tag     `json:"tags"`PublishedAt time.Time `json:"published_at"`UpdatedAt   time.Time `json:"updated_at"`ViewCount   int       `json:"view_count"`LikeCount   int       `json:"like_count"`Status      string    `json:"status"` // published, draft, archivedFeatured    bool      `json:"featured"`ImageURL    string    `json:"image_url"`
}// NewsCategory 新闻分类
type NewsCategory struct {ID          int    `json:"id"`Name        string `json:"name"`Description string `json:"description"`Color       string `json:"color"`Icon        string `json:"icon"`
}// NewsTag 新闻标签
type NewsTag struct {ID    int    `json:"id"`Name  string `json:"name"`Color string `json:"color"`
}// NewsAuthor 新闻作者
type NewsAuthor struct {ID       int    `json:"id"`Name     string `json:"name"`Email    string `json:"email"`Avatar   string `json:"avatar"`Bio      string `json:"bio"`Position string `json:"position"`
}// NewsSite 新闻站点
type NewsSite struct {Title       string                 `json:"title"`Description string                 `json:"description"`Logo        string                 `json:"logo"`Articles    []NewsArticle          `json:"articles"`Categories  []NewsCategory         `json:"categories"`Tags        []NewsTag              `json:"tags"`Authors     []NewsAuthor           `json:"authors"`Stats       map[string]int         `json:"stats"`Config      map[string]interface{} `json:"config"`
}// NewsTemplateSystem 新闻模板系统
type NewsTemplateSystem struct {parser   *TemplateParserexecutor *TemplateExecutormonitor  *PerformanceMonitorsite     *NewsSite
}// NewNewsTemplateSystem 创建新闻模板系统
func NewNewsTemplateSystem() *NewsTemplateSystem {parser := NewTemplateParser()executor := NewTemplateExecutor(parser)monitor := NewPerformanceMonitor(executor)return &NewsTemplateSystem{parser:   parser,executor: executor,monitor:  monitor,site:     createSampleNewsSite(),}
}// createSampleNewsSite 创建示例新闻站点
func createSampleNewsSite() *NewsSite {// 创建作者authors := []NewsAuthor{{ID:       1,Name:     "张记者",Email:    "zhang@news.com",Avatar:   "/avatars/zhang.jpg",Bio:      "资深科技记者，专注Go语言和云原生技术报道",Position: "首席技术记者",},{ID:       2,Name:     "李编辑",Email:    "li@news.com",Avatar:   "/avatars/li.jpg",Bio:      "技术编辑，Web开发专家",Position: "技术编辑",},}// 创建分类categories := []NewsCategory{{ID: 1, Name: "技术新闻", Description: "最新技术动态和趋势", Color: "#007bff", Icon: "💻"},{ID: 2, Name: "开发工具", Description: "开发工具和框架介绍", Color: "#28a745", Icon: "🛠️"},{ID: 3, Name: "行业动态", Description: "IT行业最新动态", Color: "#ffc107", Icon: "📈"},}// 创建标签tags := []NewsTag{{ID: 1, Name: "Go语言", Color: "#00ADD8"},{ID: 2, Name: "Web开发", Color: "#FF6B6B"},{ID: 3, Name: "云原生", Color: "#4ECDC4"},{ID: 4, Name: "微服务", Color: "#45B7D1"},}// 创建文章articles := []NewsArticle{{ID:          1,Title:       "Go 1.22 正式发布：性能提升与新特性解析",Content:     "Go 1.22 版本带来了显著的性能提升和多项新特性，包括改进的垃圾回收器、更好的编译器优化以及标准库的增强...",Summary:     "Go 1.22 正式发布，带来性能提升和新特性，包括垃圾回收器改进和编译器优化。",Author:      authors[0],Category:    categories[0],Tags:        []NewsTag{tags[0]},PublishedAt: time.Now().Add(-2 * time.Hour),UpdatedAt:   time.Now().Add(-1 * time.Hour),ViewCount:   1250,LikeCount:   89,Status:      "published",Featured:    true,ImageURL:    "/images/go-1.22.jpg",},{ID:          2,Title:       "云原生应用开发最佳实践指南",Content:     "本文深入探讨云原生应用开发的最佳实践，包括容器化、微服务架构、DevOps流程等关键技术...",Summary:     "深入探讨云原生应用开发最佳实践，涵盖容器化、微服务和DevOps等关键技术。",Author:      authors[1],Category:    categories[0],Tags:        []NewsTag{tags[2], tags[3]},PublishedAt: time.Now().Add(-4 * time.Hour),UpdatedAt:   time.Now().Add(-3 * time.Hour),ViewCount:   890,LikeCount:   67,Status:      "published",Featured:    false,ImageURL:    "/images/cloud-native.jpg",},{ID:          3,Title:       "2024年Web开发趋势预测",Content:     "分析2024年Web开发的主要趋势，包括新兴框架、开发工具、性能优化技术等...",Summary:     "分析2024年Web开发主要趋势，包括新兴框架、开发工具和性能优化技术。",Author:      authors[0],Category:    categories[2],Tags:        []NewsTag{tags[1]},PublishedAt: time.Now().Add(-6 * time.Hour),UpdatedAt:   time.Now().Add(-5 * time.Hour),ViewCount:   2100,LikeCount:   156,Status:      "published",Featured:    true,ImageURL:    "/images/web-trends-2024.jpg",},}return &NewsSite{Title:       "技术新闻网",Description: "专业的技术新闻和开发资讯平台",Logo:        "/images/logo.png",Articles:    articles,Categories:  categories,Tags:        tags,Authors:     authors,Stats: map[string]int{"总文章数": len(articles),"总浏览量": 4240,"总点赞数": 312,"注册用户": 1580,},Config: map[string]interface{}{"theme":           "light","language":        "zh-CN","timezone":        "Asia/Shanghai","articles_per_page": 10,"enable_comments":   true,},}
}

3.2 新闻模板定义

// SetupNewsTemplates 设置新闻模板
func (nts *NewsTemplateSystem) SetupNewsTemplates() {// 首页模板homePageTemplate := `
<!DOCTYPE html>
<html lang="zh-CN">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>{{.Title}} - 首页</title><style>body { font-family: Arial, sans-serif; margin: 0; padding: 0; background: #f5f5f5; }.header { background: #333; color: white; padding: 1rem; }.logo { font-size: 1.5em; font-weight: bold; }.nav { margin-top: 1rem; }.nav a { color: white; text-decoration: none; margin-right: 1rem; }.container { max-width: 1200px; margin: 0 auto; padding: 2rem; }.featured { background: white; border-radius: 8px; padding: 2rem; margin-bottom: 2rem; box-shadow: 0 2px 4px rgba(0,0,0,0.1); }.article-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 2rem; }.article-card { background: white; border-radius: 8px; padding: 1.5rem; box-shadow: 0 2px 4px rgba(0,0,0,0.1); }.article-title { font-size: 1.2em; font-weight: bold; margin-bottom: 0.5rem; color: #333; }.article-meta { color: #666; font-size: 0.9em; margin-bottom: 1rem; }.article-summary { line-height: 1.6; margin-bottom: 1rem; }.article-tags { margin-bottom: 1rem; }.tag { background: #e1f5fe; color: #0277bd; padding: 0.2rem 0.5rem; border-radius: 3px; font-size: 0.8em; margin-right: 0.5rem; }.stats { color: #888; font-size: 0.8em; }.sidebar { background: white; border-radius: 8px; padding: 1.5rem; }.stats-grid { display: grid; grid-template-columns: 1fr 300px; gap: 2rem; }</style>
</head>
<body><header class="header"><div class="container"><div class="logo">{{.Title}}</div><div class="nav"><a href="/">首页</a>{{range .Categories}}<a href="/category/{{.ID}}">{{.Icon}} {{.Name}}</a>{{end}}</div></div></header><div class="container"><div class="stats-grid"><main><!-- 特色文章 -->{{range .Articles}}{{if .Featured}}<div class="featured"><h1>🌟 特色文章</h1><div class="article-title">{{.Title}}</div><div class="article-meta">作者: {{.Author.Name}} | 分类: {{.Category.Icon}} {{.Category.Name}} | 发布: {{formatTime "2006-01-02 15:04" .PublishedAt.Format "2006-01-02T15:04:05Z"}}</div><div class="article-summary">{{.Summary}}</div><div class="article-tags">{{range .Tags}}<span class="tag">{{.Name}}</span>{{end}}</div><div class="stats">👁️ {{.ViewCount}} | 👍 {{.LikeCount}}</div></div>{{end}}{{end}}<!-- 文章列表 --><h2>📰 最新文章</h2><div class="article-grid">{{range .Articles}}<div class="article-card"><div class="article-title">{{.Title}}</div><div class="article-meta">{{.Author.Name}} | {{.Category.Icon}} {{.Category.Name}} | {{formatTime "01-02 15:04" .PublishedAt.Format "2006-01-02T15:04:05Z"}}</div><div class="article-summary">{{.Summary}}</div><div class="article-tags">{{range .Tags}}<span class="tag">{{.Name}}</span>{{end}}</div><div class="stats">👁️ {{.ViewCount}} | 👍 {{.LikeCount}}</div></div>{{end}}</div></main><aside class="sidebar"><h3>📊 网站统计</h3>{{range $key, $value := .Stats}}<div>{{$key}}: <strong>{{$value}}</strong></div>{{end}}<h3>📂 分类</h3>{{range .Categories}}<div style="margin-bottom: 0.5rem;"><span style="color: {{.Color}};">{{.Icon}}</span>{{.Name}}</div>{{end}}<h3>🏷️ 热门标签</h3>{{range .Tags}}<span class="tag" style="background-color: {{.Color}}20; color: {{.Color}};">{{.Name}}</span>{{end}}</aside></div></div>
</body>
</html>
`// 文章详情模板articleDetailTemplate := `
<!DOCTYPE html>
<html lang="zh-CN">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>{{.Title}} - {{$.Site.Title}}</title><style>body { font-family: Arial, sans-serif; margin: 0; padding: 0; background: #f5f5f5; line-height: 1.6; }.header { background: #333; color: white; padding: 1rem; }.container { max-width: 800px; margin: 0 auto; padding: 2rem; }.article { background: white; border-radius: 8px; padding: 2rem; box-shadow: 0 2px 4px rgba(0,0,0,0.1); }.article-title { font-size: 2em; font-weight: bold; margin-bottom: 1rem; color: #333; }.article-meta { color: #666; margin-bottom: 2rem; padding-bottom: 1rem; border-bottom: 1px solid #eee; }.author-info { display: flex; align-items: center; margin-bottom: 1rem; }.author-avatar { width: 40px; height: 40px; border-radius: 50%; margin-right: 1rem; background: #ddd; }.article-content { font-size: 1.1em; line-height: 1.8; margin-bottom: 2rem; }.article-tags { margin: 2rem 0; }.tag { background: #e1f5fe; color: #0277bd; padding: 0.3rem 0.8rem; border-radius: 15px; margin-right: 0.5rem; }.article-stats { background: #f8f9fa; padding: 1rem; border-radius: 5px; margin-top: 2rem; }.back-link { display: inline-block; margin-bottom: 1rem; color: #007bff; text-decoration: none; }</style>
</head>
<body><header class="header"><div class="container"><a href="/" class="back-link">← 返回首页</a></div></header><div class="container"><article class="article"><h1 class="article-title">{{.Title}}</h1><div class="article-meta"><div class="author-info"><div class="author-avatar"></div><div><strong>{{.Author.Name}}</strong> - {{.Author.Position}}<br><small>{{.Author.Bio}}</small></div></div><div>📂 分类: {{.Category.Icon}} {{.Category.Name}} | 📅 发布: {{formatTime "2006年01月02日 15:04" .PublishedAt.Format "2006-01-02T15:04:05Z"}} | 🔄 更新: {{formatTime "2006年01月02日 15:04" .UpdatedAt.Format "2006-01-02T15:04:05Z"}}</div></div><div class="article-content">{{.Content}}</div><div class="article-tags">🏷️ 标签: {{range .Tags}}<span class="tag">{{.Name}}</span>{{end}}</div><div class="article-stats">📊 文章统计: 👁️ {{.ViewCount}} 次浏览 | 👍 {{.LikeCount}} 个赞 | 📝 状态: {{if eq .Status "published"}}✅ 已发布{{else if eq .Status "draft"}}📝 草稿{{else}}📦 已归档{{end}}</div></article></div>
</body>
</html>
`// 分类页面模板categoryPageTemplate := `
<!DOCTYPE html>
<html lang="zh-CN">
<head><meta charset="UTF-8"><title>{{.Category.Name}} - {{.Site.Title}}</title><style>body { font-family: Arial, sans-serif; margin: 0; padding: 0; background: #f5f5f5; }.header { background: #333; color: white; padding: 1rem; }.container { max-width: 1000px; margin: 0 auto; padding: 2rem; }.category-header { background: white; border-radius: 8px; padding: 2rem; margin-bottom: 2rem; text-align: center; }.category-icon { font-size: 3em; margin-bottom: 1rem; }.article-list { background: white; border-radius: 8px; padding: 2rem; }.article-item { border-bottom: 1px solid #eee; padding: 1.5rem 0; }.article-item:last-child { border-bottom: none; }</style>
</head>
<body><header class="header"><div class="container"><a href="/" style="color: white; text-decoration: none;">← 返回首页</a></div></header><div class="container"><div class="category-header"><div class="category-icon">{{.Category.Icon}}</div><h1>{{.Category.Name}}</h1><p>{{.Category.Description}}</p></div><div class="article-list"><h2>📰 {{.Category.Name}} 文章列表</h2>{{range .Articles}}<div class="article-item"><h3>{{.Title}}</h3><div style="color: #666; margin: 0.5rem 0;">{{.Author.Name}} | {{formatTime "2006-01-02 15:04" .PublishedAt.Format "2006-01-02T15:04:05Z"}}</div><p>{{.Summary}}</p><div style="color: #888; font-size: 0.9em;">👁️ {{.ViewCount}} | 👍 {{.LikeCount}}</div></div>{{end}}</div></div>
</body>
</html>
`// RSS订阅模板rssTemplate := `<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0"><channel><title>{{.Title}}</title><description>{{.Description}}</description><link>https://example.com</link><lastBuildDate>{{now}}</lastBuildDate>{{range .Articles}}<item><title>{{.Title}}</title><description>{{.Summary}}</description><author>{{.Author.Email}} ({{.Author.Name}})</author><category>{{.Category.Name}}</category><pubDate>{{formatTime "Mon, 02 Jan 2006 15:04:05 MST" .PublishedAt.Format "2006-01-02T15:04:05Z"}}</pubDate><guid>https://example.com/article/{{.ID}}</guid></item>{{end}}</channel>
</rss>
`// 添加模板到解析器nts.parser.ParseHTMLTemplate("home_page", homePageTemplate)nts.parser.ParseHTMLTemplate("article_detail", articleDetailTemplate)nts.parser.ParseHTMLTemplate("category_page", categoryPageTemplate)nts.parser.ParseTextTemplate("rss_feed", rssTemplate)
}

3.3 演示执行

// RunDemo 运行演示
func (nts *NewsTemplateSystem) RunDemo() {fmt.Println("=== 新闻发布系统模板演示 ===\n")// 设置模板nts.SetupNewsTemplates()// 演示首页渲染fmt.Println("1. 渲染首页...")homeResult, homeCtx, err := nts.executor.ExecuteWithContext("home_page", nts.site, true)if err != nil {fmt.Printf("❌ 首页渲染失败: %v\n", err)} else {fmt.Printf("✅ 首页渲染成功 (耗时: %v, 输出: %d 字节)\n", homeCtx.Duration, homeCtx.OutputSize)nts.monitor.RecordExecution("home_page", homeCtx.Duration, false)}// 演示文章详情渲染fmt.Println("\n2. 渲染文章详情...")articleData := map[string]interface{}{"Title":       nts.site.Articles[0].Title,"Content":     nts.site.Articles[0].Content,"Summary":     nts.site.Articles[0].Summary,"Author":      nts.site.Articles[0].Author,"Category":    nts.site.Articles[0].Category,"Tags":        nts.site.Articles[0].Tags,"PublishedAt": nts.site.Articles[0].PublishedAt,"UpdatedAt":   nts.site.Articles[0].UpdatedAt,"ViewCount":   nts.site.Articles[0].ViewCount,"LikeCount":   nts.site.Articles[0].LikeCount,"Status":      nts.site.Articles[0].Status,"Site":        nts.site,}detailResult, detailCtx, err := nts.executor.ExecuteWithContext("article_detail", articleData, true)if err != nil {fmt.Printf("❌ 文章详情渲染失败: %v\n", err)} else {fmt.Printf("✅ 文章详情渲染成功 (耗时: %v, 输出: %d 字节)\n", detailCtx.Duration, detailCtx.OutputSize)nts.monitor.RecordExecution("article_detail", detailCtx.Duration, false)}// 演示分类页面渲染fmt.Println("\n3. 渲染分类页面...")categoryData := map[string]interface{}{"Category": nts.site.Categories[0],"Articles": nts.site.Articles, // 简化：显示所有文章"Site":     nts.site,}categoryResult, categoryCtx, err := nts.executor.ExecuteWithContext("category_page", categoryData, true)if err != nil {fmt.Printf("❌ 分类页面渲染失败: %v\n", err)} else {fmt.Printf("✅ 分类页面渲染成功 (耗时: %v, 输出: %d 字节)\n", categoryCtx.Duration, categoryCtx.OutputSize)nts.monitor.RecordExecution("category_page", categoryCtx.Duration, false)}// 演示RSS订阅渲染fmt.Println("\n4. 渲染RSS订阅...")rssResult, rssCtx, err := nts.executor.ExecuteWithContext("rss_feed", nts.site, false)if err != nil {fmt.Printf("❌ RSS订阅渲染失败: %v\n", err)} else {fmt.Printf("✅ RSS订阅渲染成功 (耗时: %v, 输出: %d 字节)\n", rssCtx.Duration, rssCtx.OutputSize)nts.monitor.RecordExecution("rss_feed", rssCtx.Duration, false)}// 保存渲染结果到文件（可选）if len(homeResult) > 0 {if err := os.WriteFile("demo_home.html", []byte(homeResult), 0644); err == nil {fmt.Println("📄 首页HTML已保存到 demo_home.html")}}if len(detailResult) > 0 {if err := os.WriteFile("demo_article.html", []byte(detailResult), 0644); err == nil {fmt.Println("📄 文章详情HTML已保存到 demo_article.html")}}if len(rssResult) > 0 {if err := os.WriteFile("demo_rss.xml", []byte(rssResult), 0644); err == nil {fmt.Println("📄 RSS订阅XML已保存到 demo_rss.xml")}}// 打印统计信息nts.parser.PrintStats()nts.executor.PrintExecutionStats()nts.monitor.PrintPerformanceReport()
}// 主函数演示
func main() {fmt.Println("=== Go Web 编程快速入门 · 07.2 - 模板（2）：解析与执行（含Demo） ===\n")// 创建新闻模板系统newsSystem := NewNewsTemplateSystem()// 运行完整演示newsSystem.RunDemo()fmt.Println("\n=== 演示完成 ===")fmt.Println("本演示展示了：")fmt.Println("1. 模板解析机制和性能监控")fmt.Println("2. 执行上下文管理和统计分析")fmt.Println("3. 实际新闻发布系统的模板应用")fmt.Println("4. HTML和XML模板的综合使用")fmt.Println("5. 模板性能优化和错误处理")
}