golang实例代理

package main

import (
    "bytes"
    "encoding/json"
    "io/ioutil"
    "log"
    "net/http"
    "net/http/httputil"
    "net/url"
)

const PORT = "1330"
const A_CONDITION_URL = "http://localhost:1331"
const B_CONDITION_URL = "http://localhost:1332"
const DEFAULT_CONDITION_URL = "http://localhost:1333"

type requestPayloadStruct struct {
    ProxyCondition string `json:"proxy_condition"`
}

func getListenAddress() string {
    return ":" + PORT
}

func logSetup() {
    log.Printf("Server will run on: %s\n", getListenAddress())
    log.Printf("Redirecting to A url: %s\n", A_CONDITION_URL)
    log.Printf("Redirecting to B url: %s\n", B_CONDITION_URL)
    log.Printf("Redirecting to Default url: %s\n", DEFAULT_CONDITION_URL)
}

func requestBodyDecoder(request *http.Request) *json.Decoder {
    body, err := ioutil.ReadAll(request.Body)
    if err != nil {
        log.Printf("Error reading body: %v", err)
        panic(err)
    }
    request.Body = ioutil.NopCloser(bytes.NewBuffer(body))
    return json.NewDecoder(ioutil.NopCloser(bytes.NewBuffer(body)))
}

func parseRequestBody(request *http.Request) requestPayloadStruct {
    decoder := requestBodyDecoder(request)
    var requestPayload requestPayloadStruct
    err := decoder.Decode(&requestPayload)
    if err != nil {
        panic(err)
    }
    return requestPayload
}

func getProxyUrl(proxyConditionRaw string) string {
    proxyCondition := strings.ToUpper(proxyConditionRaw)
    if proxyCondition == "A" {
        return A_CONDITION_URL
    }
    if proxyCondition == "B" {
        return B_CONDITION_URL
    }
    return DEFAULT_CONDITION_URL
}

func serveReverseProxy(target *url.URL, response http.ResponseWriter, request *http.Request) {
    proxy := httputil.NewSingleHostReverseProxy(target)
    proxy.ServeHTTP(response, request)
}

func handleRequestAndRedirect(response http.ResponseWriter, request *http.Request) {
    requestPayload := parseRequestBody(request)
    url := getProxyUrl(requestPayload.ProxyCondition)
    target, _ := url.Parse(url)
    serveReverseProxy(target, response, request)
}

func main() {
    logSetup()
    http.HandleFunc("/", handleRequestAndRedirect)
    if err := http.ListenAndServe(getListenAddress(), nil); err != nil {
        panic(err)
    }
}

在这个例子中，我们首先定义了一些常量和请求体的结构。logSetup函数用于打印日志信息。requestBodyDecoder和parseRequestBody函数用于解析请求体中的JSON数据。getProxyUrl函数根据请求体中的条件返回相应的代理URL。serveReverseProxy函数创建一个反向代理并处理HTTP请求。

要运行这个代理服务器，你可以将代码保存到main.go文件中，然后使用go run main.go命令启动服务器。服务器将监听指定的端口，并根据请求体中的内容将请求转发到不同的后端服务。