本文内容：

react-native-fs的简单使用

• 下载文件(图片、文件、视频、音频)
• 将文本写入本地 txt
• 读取txt文件内容
• 在已有的txt上添加新的文本
• 删除文件
• 上传文件 only iOS

github链接: https://github.com/itinance/react-native-fs

另外还有一个下载的库 ：https://github.com/wkh237/react-native-fetch-blob

安装步骤

第一步：

npm install react-native-fs --save

第二步：

react-native link react-native-fs

OK 即可开始使用(不放心的可以按照github上的对比一下)

简单使用

import RNFS from 'react-native-fs';

下载文件

/*下载文件*/
    downloadFile() {
        // On Android, use "RNFS.DocumentDirectoryPath" (MainBundlePath is not defined)

        // 图片
        // const downloadDest = `${RNFS.MainBundlePath}/${((Math.random() * 1000) | 0)}.jpg`;
        // const formUrl = 'http://img.kaiyanapp.com/c7b46c492261a7c19fa880802afe93b3.png?imageMogr2/quality/60/format/jpg';

        // 文件
        // const downloadDest = `${RNFS.MainBundlePath}/${((Math.random() * 1000) | 0)}.zip`;
        // const formUrl = 'http://files.cnblogs.com/zhuqil/UIWebViewDemo.zip';

        // 视频
        // const downloadDest = `${RNFS.MainBundlePath}/${((Math.random() * 1000) | 0)}.mp4`;
        // http://gslb.miaopai.com/stream/SnY~bbkqbi2uLEBMXHxGqnNKqyiG9ub8.mp4?vend=miaopai&
        // https://gslb.miaopai.com/stream/BNaEYOL-tEwSrAiYBnPDR03dDlFavoWD.mp4?vend=miaopai&
        // const formUrl = 'https://gslb.miaopai.com/stream/9Q5ADAp2v5NHtQIeQT7t461VkNPxvC2T.mp4?vend=miaopai&';

        // 音频
        const downloadDest = `${RNFS.MainBundlePath}/${((Math.random() * 1000) | 0)}.mp3`;
        // http://wvoice.spriteapp.cn/voice/2015/0902/55e6fc6e4f7b9.mp3
        const formUrl = 'http://wvoice.spriteapp.cn/voice/2015/0818/55d2248309b09.mp3';

        const options = {
            fromUrl: formUrl,
            toFile: downloadDest,
            background: true,
            begin: (res) => {
                console.log('begin', res);
                console.log('contentLength:', res.contentLength / 1024 / 1024, 'M');
            },
            progress: (res) => {

                let pro = res.bytesWritten / res.contentLength;

                this.setState({
                    progressNum: pro,
                });
            }
        };
        try {
            const ret = RNFS.downloadFile(options);
            ret.promise.then(res => {
                console.log('success', res);

                console.log('file://' + downloadDest)

            }).catch(err => {
                console.log('err', err);
            });
        }
        catch (e) {
            console.log(error);
        }

    }

将文本写入本地 txt

 /*将文本写入本地 txt*/
    writeFile() {
        // create a path you want to write to
        const path = RNFS.MainBundlePath + '/test.txt';

        // write the file
        RNFS.writeFile(path, '这是一段文本，YES', 'utf8')
            .then((success) => {
                console.log('path', path);
            })
            .catch((err) => {
                console.log(err.message);
            });
    }

读取txt文件内容

/*读取txt文件内容*/
    readFile() {
        // create a path you want to delete
        const path = RNFS.MainBundlePath + '/test.txt';

        return RNFS.readFile(path)
            .then((result) => {
                console.log(result);

                this.setState({
                    readTxtResult: result,
                })
            })
            .catch((err) => {
                console.log(err.message);

            });
    }

在已有的txt上添加新的文本

/*在已有的txt上添加新的文本*/
    appendFile() {
        const path = RNFS.MainBundlePath + '/test.txt';

        return RNFS.appendFile(path, '新添加的文本', 'utf8')
            .then((success) => {
                console.log('success');
            })
            .catch((err) => {
                console.log(err.message);

            });
    }

删除文件

    /*删除文件*/
    deleteFile() {
        // create a path you want to delete
        const path = RNFS.MainBundlePath + '/test.txt';

        return RNFS.unlink(path)
            .then(() => {
                console.log('FILE DELETED');
            })
            // `unlink` will throw an error, if the item to unlink does not exist
            .catch((err) => {
                console.log(err.message);
            });
    }

上传文件 only iOS

 /*上传文件 only iOS*/
    uploadFile() {
        const uploadSrc = `${RNFS.MainBundlePath}/test.txt`;

        const uploadUrl = 'http://buz.co/rnfs/upload-tester.php';

        const options = {
            toUrl: uploadUrl,
            files: [{name: 'myfile', filename: 'test.txt', filepath: uploadSrc, filetype: 'text/plain'}],
            background: true,
            method: 'POST', // PUT
            begin: (res) => {
                console.log('begin', res);
            },
            progress: (res) => {
                console.log('progress', res);
            }
        };

        const ret = RNFS.uploadFiles(options);

        return ret.promise.then(res => {
            const response = JSON.parse(res.body);
            console.log(response);

        })
            .catch(err => {
                console.log('err', err);
            });
    }

demo:https://github.com/chjwrr/RN-react-native-fs