Go语言文件内容高效合并与大容量输出陷阱解析

package main

import (
    "bytes"
    "fmt"
    "io/ioutil"
    "path"
    "regexp"
)

func main() {
    mainFilePath := "index.html" // 假设HTML文件在当前目录
    mainFileDir := path.Dir(mainFilePath) + "/"

    mainFileContent, err := ioutil.ReadFile(mainFilePath)
    if err != nil {
        fmt.Printf("Error reading main HTML file: %v\n", err)
        return
    }

    var finalFileContent bytes.Buffer

    // 正则表达式匹配 <script src="...">
    scriptReg, err := regexp.Compile(`<script src="(.*?)">`)
    if err != nil {
        fmt.Printf("Error compiling regex: %v\n", err)
        return
    }

    // 将HTML内容转换为字符串进行正则匹配
    scripts := scriptReg.FindAllStringSubmatch(string(mainFileContent), -1)

    for _, match := range scripts {
        if len(match) > 1 {
            jsFilePath := mainFileDir + match[1]
            subFileContent, err := ioutil.ReadFile(jsFilePath)
            if err != nil {
                fmt.Printf("Error reading JS file %s: %v\n", jsFilePath, err)
                continue // 继续处理下一个文件
            }

            // 将子文件内容写入缓冲区
            n, err := finalFileContent.Write(subFileContent)
            if err != nil {
                fmt.Printf("Error writing to buffer for %s: %v\n", jsFilePath, err)
                continue
            }
            fmt.Printf("Wrote %d bytes from %s to buffer.\n", n, jsFilePath)
        }
    }

    // 尝试打印最终合并的内容
    fmt.Println("Attempting to print final content string...")
    fmt.Println(finalFileContent.String())
    // fmt.Printf(">>> %#v\n", finalFileContent) // 另一种尝试打印的方式

    fmt.Println("Program finished.")
}

// 改进的错误检查示例
n, err := finalFileContent.Write(subFileContent)
if err != nil {
    fmt.Printf("Error writing %s to buffer: %v\n", jsFilePath, err)
    // 根据具体情况决定是继续还是终止
} else {
    fmt.Printf("Successfully wrote %d bytes from %s to buffer.\n", n, jsFilePath)
}

// 打印最终内容时也应检查错误
// 虽然 fmt.Println 不直接返回错误，但其底层可能失败
// 如果需要捕获输出错误，可以重定向标准输出或使用 io.Writer 接口

package main

import (
    "bytes"
    "fmt"
    "io/ioutil"
    "os"
    "path"
    "regexp"
)

func main() {
    mainFilePath := "index.html" // 示例：HTML文件路径
    mainFileDir := path.Dir(mainFilePath) + "/"

    // 创建一些示例文件用于测试
    // 实际应用中这些文件需要存在
    _ = ioutil.WriteFile("index.html", []byte(`<script src="a.js"></script><script src="b.js"></script><script src="c.js"></script>`), 0644)
    _ = ioutil.WriteFile("a.js", []byte("console.log('This is A');\n"), 0644)
    _ = ioutil.WriteFile("b.js", []byte("console.log('This is B');\n"), 0644)
    _ = ioutil.WriteFile("c.js", []byte("console.log('This is C');\n"), 0644)
    // 为了模拟大文件，可以重复写入
    largeContent := bytes.Repeat([]byte("console.log('Large Content');\n"), 3000) // 约60KB
    _ = ioutil.WriteFile("large.js", largeContent, 0644)
    _ = ioutil.WriteFile("index.html", []byte(`<script src="a.js"></script><script src="b.js"></script><script src="large.js"></script>`), 0644)


    mainFileContent, err := ioutil.ReadFile(mainFilePath)
    if err != nil {
        fmt.Printf("Error reading main HTML file: %v\n", err)
        return
    }

    var finalFileContent bytes.Buffer

    scriptReg, err := regexp.Compile(`<script src="(.*?)">`)
    if err != nil {
        fmt.Printf("Error compiling regex: %v\n", err)
        return
    }

    scripts := scriptReg.FindAllStringSubmatch(string(mainFileContent), -1)

    for _, match := range scripts {
        if len(match) > 1 {
            jsFilePath := mainFileDir + match[1]
            subFileContent, err := ioutil.ReadFile(jsFilePath)
            if err != nil {
                fmt.Printf("Error reading JS file %s: %v\n", jsFilePath, err)
                continue
            }

            n, err := finalFileContent.Write(subFileContent)
            if err != nil {
                fmt.Printf("Error writing to buffer for %s: %v\n", jsFilePath, err)
                continue
            }
            fmt.Printf("Wrote %d bytes from %s to buffer.\n", n, jsFilePath)
        }
    }

    // 将合并后的内容写入新文件
    outputFileName := "merged_scripts.js"
    err = ioutil.WriteFile(outputFileName, finalFileContent.Bytes(), 0644) // 0644是文件权限
    if err != nil {
        fmt.Printf("Error writing merged content to file %s: %v\n", outputFileName, err)
        return
    }

    fmt.Printf("Successfully merged all scripts into %s. Total size: %d bytes.\n", outputFileName, finalFileContent.Len())
    fmt.Println("Program finished.")

    // 清理示例文件
    os.Remove("index.html")
    os.Remove("a.js")
    os.Remove("b.js")
    os.Remove("c.js")
    os.Remove("large.js")
}

// 调试时打印前100个字节
if finalFileContent.Len() > 0 {
    fmt.Println("\n--- First 100 bytes of merged content ---")
    if finalFileContent.Len() > 100 {
        fmt.Println(string(finalFileContent.Bytes()[:100]))
    } else {
        fmt.Println(finalFileContent.String())
    }
    fmt.Println("------------------------------------------")
}