如何在React Native(Expo)中创建文本文件?

时间:2019-02-08 05:01:00

标签: reactjs react-native expo

这是我正在尝试的功能。

saveFile = () => {
    let filename = Expo.FileSystem.documentDirectory + "text.txt";
    Expo.FileSystem.writeAsStringAsync(filename, "Hello World");
}

loadFile = () => {
    let filename = Expo.FileSystem.documentDirectory + "text.txt";
    let str = Expo.FileSystem.readAsStringAsync(filename, "Hello World");
    //alert(str);
}

警告:

[Unhandled promise rejection: Error: Argument of an incompatible class: class java.lang.String cannot be passed as an argument to parameter expecting interface java.util.Map.]

但是有一个警告,有人知道怎么做吗?

-------------更新:console.log输出--------------

[15:27:36] Promise {
[15:27:36]   "_40": 0,
[15:27:36]   "_55": null,
[15:27:36]   "_65": 0,
[15:27:36]   "_72": null,
[15:27:36] }

------------------更新:代码更新---------------

saveFile = async () => {
    let filename = Expo.FileSystem.documentDirectory + "text.txt";
    await FileSystem.writeAsStringAsync(filename, "Hello World", { encoding: FileSystem.EncodingTypes.UTF8 });
}

loadFile = async () => {
    let filename = Expo.FileSystem.documentDirectory + "text.txt";
    file = await FileSystem.readAsStringAsync(filename, { encoding: FileSystem.EncodingTypes.UTF8 });
    return file;
}

getTextFromFile = () => {
    value = this.loadFile();
    alert(value);
    console.log(value);
}

您好世界似乎没有写入文件
------------更新-------------
我添加了一行,text.txt文件出现在我的Android仿真器的Document / DCIM / text.txt中,但是必须使用“ MediaLibrary.createAssetAsync”,如果是的话,如何控制文件夹名称? / p>

await MediaLibrary.createAssetAsync(`${FileSystem.documentDirectory}text.txt`);

1 个答案:

答案 0 :(得分:0)

我已经修改了问题中的代码,最后设法完成了这项工作。此功能在Downloads文件夹中创建.txt文件:

import * as MediaLibrary from 'expo-media-library';
import * as FileSystem from 'expo-file-system';
import * as Permissions from 'expo-permissions';

saveFile = async () => {
    const { status } = await Permissions.askAsync(Permissions.CAMERA_ROLL);
    if (status === "granted") {
        let fileUri = FileSystem.documentDirectory + "text.txt";
        await FileSystem.writeAsStringAsync(fileUri, "Hello World", { encoding: FileSystem.EncodingType.UTF8 });
        const asset = await MediaLibrary.createAssetAsync(fileUri)
        await MediaLibrary.createAlbumAsync("Download", asset, false)
    }
}