从CORS策略阻止从源“ http：// localhost：4200”访问“ http：// localhost：8080 / BeginSignup”处的访问

如何解决从CORS策略阻止从源“ http：// localhost：4200”访问“ http：// localhost：8080 / BeginSignup”处的访问

我正在尝试将提取POST请求发送到我的Golang AppEngine API。但是，我收到了CORS政策错误，也不知道为什么。这是我的代码：

这是从Angular调用API的代码

private async sendHTTPPut(data: UserInfo,func: string) {
    let requestHeaders = { 'Content-Type': 'application/json','Access-Control-Allow-Origin': '*' } as HeadersInit;

    console.log(requestHeaders)

    return await fetch(
        this.endpoint + func,{
          method: 'POST',headers: requestHeaders,body: JSON.stringify(data),mode: "cors"
        }
    )
  }

这是处理CORS的服务器代码：

func StartApp() {
    router = mux.NewRouter()

    router.HandleFunc("/",hello)
    router.HandleFunc("/hello",hello)
    router.HandleFunc("/AcceptMember",AcceptMember)
    router.HandleFunc("/CreateTeam",CreateTeam)
    router.HandleFunc("/Leave",Leave)
    router.HandleFunc("/InviteMember",InviteMember)
    router.HandleFunc("/BeginSignup",BeginSignup)
    router.HandleFunc("/ProcessSignup",ProcessSignup)
    router.HandleFunc("/CompleteSignup",CompleteSignup)
    // Scoring
    router.HandleFunc("/GetLocalscore",GetLocalscore)

    allowedOrigins := handlers.AllowedOrigins([]string { "* always" })
    allowedHeaders := handlers.AllowedHeaders([]string { "Content-Type" })

    if err := http.ListenAndServe(":8080",handlers.CORS(allowedOrigins,allowedHeaders)(router)); err != nil {
        log.Fatal(err)
    }
}

这是发送到服务器的请求：

Request URL: http://localhost:8080/BeginSignup
Referrer Policy: no-referrer-when-downgrade

Provisional headers are shown
Access-Control-Allow-Origin: *
Content-Type: application/json
Referer: http://localhost:4200/
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML,like Gecko) Chrome/85.0.4183.121 Safari/537.36 Edg/85.0.564.68

PAYLOAD
{member: {phoneNum: "0648503047"},…}
member: {phoneNum: "0648503047"}
score: null
team: {teamName: ".None",teamMembers: ["0648503047"],teamleader: "0648503047"}

这是从服务器发送回的响应：

Request URL: http://localhost:8080/BeginSignup
Request Method: OPTIONS
Status Code: 200 OK
Remote Address: [::1]:8080
Referrer Policy: no-referrer-when-downgrade
Content-Length: 0
Date: Mon,05 Oct 2020 20:34:51 GMT
Accept: */*
Accept-Encoding: gzip,deflate,br
Accept-Language: en-US,en;q=0.9
Access-Control-Request-Headers: access-control-allow-origin,content-type
Access-Control-Request-Method: POST
Connection: keep-alive
Host: localhost:8080
Origin: http://localhost:4200
Referer: http://localhost:4200/
Sec-Fetch-Dest: empty
sec-fetch-mode: cors
sec-fetch-site: same-site
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML,like Gecko) Chrome/85.0.4183.121 Safari/537.36 Edg/85.0.564.68

解决方法

我假设您正在开发模式（ng serve）中运行角度。在这种情况下，CORS错误来自角度。

您必须添加一个proxy.conf.json，其中包含src中不同端点的条目：

{
    "/api/*": {
        "target": "http://localhost:<your-port>","secure": false,"logLevel": "debug"
    }
}

并在您的angular.json中引用此文件：

"serve": {
          "builder": "@angular-devkit/build-angular:dev-server","options": {
            "browserTarget": "<your-app>:build","proxyConfig": "src/proxy.conf.json"
          },...
        },