问题描述
我有问题。我正在创建一个小文件上传器,用于上传照片。如果用户按下图标,就会出现一个文件上传器,然后他可以选择一张照片。选择照片后不显示。问题究竟出在哪里?
import React,{ useState } from 'react';
const Profilpic = () => {
const [preview,setPreview] = useState(null);
const fileSelectedHandler = (event) => {
console.log(event.target.files[0]);
if (event.target.files[0].size > 71680) {
alert('File is too big! Wie Samys Dick');
} else {
setPreview(event.target.files[0]);
}
};
return (
<div>
{preview ? (
<img src={preview} alt="Preview" width="150px" height="150px" />
) : (
<div>
<label htmlFor="myInput">
<i className="fas fa-user-circle"></i>
</label>
<input
id="myInput"
style={{ display: 'none' }}
type={'file'}
onChange={fileSelectedHandler}
/>
</div>
)}
</div>
);
};
export default Profilpic;
解决方法
首先从input标签中去掉style标签 然后用那个替换函数
const fileSelectedHandler = (event) => {
console.log(event.target.files[0]);
if (event.target.files[0].size > 71680) {
alert("File is too big! Wie Samys Dick");
} else {
const reader = new FileReader();
reader.readAsDataURL(event.target.files[0]);
reader.onloadend = () => {
setPreview(reader.result);
};
}
};
,
这对你有用。您只需为所选图片创建网址即可。
import { useState } from "react";
import "./styles.css";
export default function App() {
const [preview,setPreview] = useState(null);
const fileSelectedHandler = (event) => {
console.log(event.target.files[0]);
if (event.target.files[0].size > 71680) {
alert("File is too big! Wie Samys Dick");
} else {
let img = URL.createObjectURL(event.target.files[0]);
setPreview(img);
}
};
console.log(preview);
return (
<div>
{preview ? (
<img src={preview} alt="Preview" />
) : (
<input id="myInput" type="file" onChange={fileSelectedHandler} />
)}
</div>
);
}