如何在nativescript/angular android中导入/导出sqlite数据库? [英] How import/export sqlite database in nativescript/angular android?

问题描述

我正在尝试将整个sqlite database export放入具有button click的项目的SD卡memory中(备份功能).我用谷歌搜索，但似乎是负面的回应.我正在使用 https://github.com/NathanaelA/nativescript-sqlite plugin为了这.还需要使用文件选择器导入exported database.现在，我正在尝试使用带有nativescript的Java代码来达到它.任何nativescript方式的帮助将不胜感激.预先感谢.

I'm trying to export the whole sqlite database into sd card memory with a button click for a project (Backup feature). I googled for the same, but seems negative response. I'm using https://github.com/NathanaelA/nativescript-sqlite plugin for this. Also need to import the exported database with file picker. Right now, I'm trying to reach it using java code with nativescript. Any nativescript way help will be appreciated. Thanks in advance.

推荐答案

我为Android导出数据库的解决方案是创建一个开发人员页面并在其中添加一个按钮:

my solution to export database for android was to create a developer page and add a button in it :

已编辑

<Button class="btn  m-3" height="50" row="1" text="ExportDB" (tap)="exportDb()"></Button>

点击功能代码为:

public exportDb() {
    console.log('######################### exporting DB ##################');
    this.copyAndroidFileUsingStream('/data/data/{your package name }/databases/{database name}.db',
        fs.path.join(this.getDownloadFolderPath(), {output filename}.db));
}

public getDownloadFolderPath() {
    if (!!application.ios) {
        const fileManager = utilModule.ios.getter(NSFileManager, NSFileManager.defaultManager);
        const paths = fileManager.URLsForDirectoryInDomains(15, 1);
        const url = paths.objectAtIndex(0);
        return url.path;
    } else {
        return android.os.Environment.getExternalStoragePublicDirectory(
            android.os.Environment.DIRECTORY_DOWNLOADS).toString();
    }
}

// copy file only for android
    public copyAndroidFileUsingStream = (source, dest): void => {
        let is: java.io.InputStream = null;
        let os: java.io.OutputStream = null;
        try {
            is = new java.io.FileInputStream(source);
            os = new java.io.FileOutputStream(dest);
            //    let buffer = Array.create("byte", 1024);

            const buffer = Array.create('byte', 4096);
            let length: number;
            // tslint:disable-next-line:no-conditional-assignment
            while ((length = is.read(buffer)) > 0) {
                os.write(buffer, 0, length);
            }
        } catch (e) {
            this.errorService.handleError(e);
        } finally {
            console.log('copy done');
            is.close();
            os.close();
        }
    }

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