Go语言中处理Base64编码HTTP请求体的二进制转换

package main

import (
    "encoding/base64"
    "io"
    "log"
    "net/http"
    "bytes" // 用于演示将解码数据存入内存
    // "os" // 用于演示将解码数据存入文件
)

func handleBase64Upload(w http.ResponseWriter, r *http.Request) {
    // 确保请求方法是POST或其他预期的方法
    if r.Method != http.MethodPost {
        http.Error(w, "Only POST method is allowed", http.StatusMethodNotAllowed)
        return
    }

    // 创建Base64解码器
    // dec 是一个 io.Reader，它会从 r.Body 读取 Base64 编码数据并进行解码
    dec := base64.NewDecoder(base64.StdEncoding, r.Body)

    // ... 接下来处理解码后的数据
}

func handleBase64Upload(w http.ResponseWriter, r *http.Request) {
    if r.Method != http.MethodPost {
        http.Error(w, "Only POST method is allowed", http.StatusMethodNotAllowed)
        return
    }
    defer r.Body.Close() // 确保关闭请求体

    dec := base64.NewDecoder(base64.StdEncoding, r.Body)

    // 创建一个 bytes.Buffer 来存储解码后的二进制数据
    buf := &bytes.Buffer{}

    // 使用 io.Copy 将解码器中的数据复制到缓冲区
    // io.Copy 会持续从 dec 读取，直到 dec 返回 io.EOF 或遇到错误
    n, err := io.Copy(buf, dec)
    if err != nil {
        log.Printf("Error copying decoded data: %v", err)
        http.Error(w, "Failed to decode base64 data", http.StatusInternalServerError)
        return
    }

    log.Printf("Successfully decoded %d bytes into buffer.", n)

    // 现在，buf.Bytes() 包含了原始的二进制数据
    // 例如，如果这是一个图片，您可以将其保存为文件或进一步处理
    // fmt.Printf("Decoded data (first 50 bytes): %x\n", buf.Bytes()[:min(50, len(buf.Bytes()))])

    w.WriteHeader(http.StatusOK)
    w.Write([]byte("Base64 data decoded and processed successfully!"))
}

// 辅助函数，用于防止切片越界
func min(a, b int) int {
    if a < b {
        return a
    }
    return b
}

// ... (之前的导入和 handleBase64Upload 函数定义)

import (
    // ... 其他导入
    "os"
)

func handleBase64UploadToFile(w http.ResponseWriter, r *http.Request) {
    if r.Method != http.MethodPost {
        http.Error(w, "Only POST method is allowed", http.StatusMethodNotAllowed)
        return
    }
    defer r.Body.Close()

    dec := base64.NewDecoder(base64.StdEncoding, r.Body)

    // 创建一个文件用于写入解码后的数据
    outputFile, err := os.Create("decoded_output.bin")
    if err != nil {
        log.Printf("Error creating output file: %v", err)
        http.Error(w, "Failed to create output file", http.StatusInternalServerError)
        return
    }
    defer outputFile.Close() // 确保关闭文件

    // 使用 io.Copy 将解码器中的数据直接写入文件
    n, err := io.Copy(outputFile, dec)
    if err != nil {
        log.Printf("Error copying decoded data to file: %v", err)
        http.Error(w, "Failed to write decoded data to file", http.StatusInternalServerError)
        return
    }

    log.Printf("Successfully decoded %d bytes and saved to decoded_output.bin", n)

    w.WriteHeader(http.StatusOK)
    w.Write([]byte("Base64 data decoded and saved to file successfully!"))
}