React无法使用Fetch API下载数据[重复]

Question

我正在尝试使用react应用程序从rest api下载数据。代码可以使用这个站点上的例子https://pusher.com/tutorials/consume-restful-api-react中的url，但当我将url更改为本地后端应用程序时，代码就不起作用了。

我的代码：

fetch("http://localhost:8080/AppRest/appController/getData?ID=1")
        .then(res => res.json())
        .then((data) => {
          alert(data)
          this.setState({ icos: data })
        })
        .catch(console.log)

[Error] Origin http://localhost:3000 is not allowed by Access-Control-Allow-Origin.
[Error] Fetch API cannot load http://localhost:8080/AppRest/appController/getData?ID=1 due to access control checks.
[Error] Failed to load resource: Origin http://localhost:3000 is not allowed by Access-Control-Allow-Origin. (getIcos, line 0)
[Log] TypeError: Origin http://localhost:3000 is not allowed by Access-Control-Allow-Origin.

HTTP/1.1 200 OK
Content-Length: 65
Content-Type: application/json
X-Frame-Options: SAMEORIGIN
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Server: Payara Server 5.2020.7 #badassfish

Answer 1

尝试指定请求选项

let url = "http://localhost:8080/AppRest/appController/getData?ID=1";
let reqOptions = {
    method: "GET"
}

fetch(url, reqOptions)
    .then(response => {
        if (!response.ok) {
            console.log(response.statusText);
        }
        return response.json();
    })
    .then(data => {
        return data;      
    }).catch(err => console.log(err));