Javascript 尝试检查文件是否存在，如果不存在，请下载它_Javascript_Android_Html_Cordova

Javascript 尝试检查文件是否存在，如果不存在，请下载它

javascript android html cordova

Javascript 尝试检查文件是否存在，如果不存在，请下载它,javascript,android,html,cordova,Javascript,Android,Html,Cordova,嗨，伙计们，我正在尝试使用这个简单的代码来检查是否有一个文件，如果没有下载它。但它总是只显示我正在检查数据文件原因可能是什么我在这里找到了代码： index.html <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"&g

嗨，伙计们，我正在尝试使用这个简单的代码来检查是否有一个文件，如果没有下载它。但它总是只显示我正在检查数据文件

原因可能是什么

我在这里找到了代码：

index.html

 <!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
        <title></title>
        <meta name="description" content="">
        <meta name="viewport" content="width=device-width">
        <link rel="stylesheet" type="text/css" href="css/app.css" />
    </head>
    <body>

    <h2>My App</h2>
    <div id="status"></div>

    <script src="cordova.js"></script>  
    <script src="js/app.js"></script>
    </body>
</html>

这些只是android Studio中logcat的最后几行输出，因为在这里插入所有内容太多了：

10-22 16:46:40.927    2315-2315/? E/PGA﹕ PgaUtilsParamSize: unsuported param GL_CULL_FACE, assuming size 1
10-22 16:46:40.927    2315-2315/? E/PGA﹕ PgaUtilsParamSize: unsuported param GL_DITHER, assuming size 1

-22 16:47:48.367  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:48:43.477  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:48:48.827   30217-2359/? D/BstCommandProcessor-httpd﹕ command: ping
10-22 16:48:48.827   30217-2359/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:48:48.847   30217-2360/? D/BstCommandProcessor-httpd﹕ command: clipboard (with args)
10-22 16:48:48.847   30217-2360/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:49:38.587  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:50:33.697  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:50:42.037   30217-2361/? D/BstCommandProcessor-httpd﹕ command: ping
10-22 16:50:42.037   30217-2361/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:50:42.257   30217-2362/? W/BstCommandProcessor-httpd﹕ Reached maxLineLength limit while reading the content of a file
10-22 16:50:42.257   30217-2362/? D/BstCommandProcessor-httpd﹕ command: clipboard (with args)
10-22 16:50:42.267   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1969K, 24% free 6849K/8896K, paused 0ms, total 0ms
10-22 16:50:42.277   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1557K, 24% free 6850K/9004K, paused 10ms, total 10ms
10-22 16:50:42.287   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1318K, 24% free 6854K/9004K, paused 10ms, total 10ms
10-22 16:50:42.297   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1230K, 24% free 6851K/9012K, paused 10ms, total 10ms
10-22 16:50:42.307   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1215K, 24% free 6852K/9012K, paused 0ms, total 0ms
10-22 16:50:42.307   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1161K, 24% free 6858K/9012K, paused 0ms, total 0ms
10-22 16:50:42.317   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1101K, 24% free 6862K/9012K, paused 10ms, total 10ms
10-22 16:50:42.317   30217-2362/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:51:28.807  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:52:00.027  30100-30111/? D/dalvikvm﹕ GC_FOR_ALLOC freed 7538K, 38% free 12639K/20212K, paused 10ms, total 20ms
10-22 16:52:23.917  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:53:19.027  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:53:26.057   30217-2363/? D/BstCommandProcessor-httpd﹕ command: ping
10-22 16:53:26.057   30217-2363/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:53:26.077   30217-2364/? W/BstCommandProcessor-httpd﹕ Reached maxLineLength limit while reading the content of a file
10-22 16:53:26.077   30217-2364/? D/BstCommandProcessor-httpd﹕ command: clipboard (with args)
10-22 16:53:26.097   30217-2364/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1795K, 25% free 6825K/9020K, paused 10ms, total 10ms
10-22 16:53:26.097   30217-2364/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1489K, 25% free 6824K/9020K, paused 0ms, total 0ms
10-22 16:53:26.117   30217-2364/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1352K, 25% free 6825K/9020K, paused 10ms, total 10ms
10-22 16:53:26.117   30217-2364/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1251K, 25% free 6836K/9020K, paused 0ms, total 0ms
10-22 16:53:26.127   30217-2364/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:54:14.137  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:54:23.877   30217-2365/? D/BstCommandProcessor-httpd﹕ command: ping
10-22 16:54:23.877   30217-2365/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:54:23.887   30217-2366/? D/BstCommandProcessor-httpd﹕ command: clipboard (with args)
10-22 16:54:23.887   30217-2366/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:54:30.017  29999-30062/? D/ConnectivityService﹕ Sampling interval elapsed, updating statistics ..
10-22 16:54:30.017  29999-30062/? D/ConnectivityService﹕ Done.
10-22 16:54:30.017  29999-30062/? D/ConnectivityService﹕ Setting timer for 720seconds
10-22 16:54:30.197  29999-30062/? D/ConnectivityService﹕ handleInetConditionChange: net=1 != default=9 - ignore
10-22 16:55:09.247  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:55:41.237  29999-29999/? I/EntropyMixer﹕ Writing entropy...
10-22 16:56:04.357  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:56:59.467  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms

@金牛座22，您可能正在使用最新版本的编译器。对于刚接触Cordova/Phonegap的开发人员来说，这是一个常见的问题。你有一个白名单问题

许多常见白名单问题的修复另一种选择是这种快速修复方法——但要知道，这种快速修复方法消除了对白名单的所有需求。这会创建一个您可能不想绕过的对象

快速修复将此添加到config.xml中，仅用于PHONEGAP构建

答案是这样的：

从您点击的：

6未为编译器设置phonegap版本 7未为您的插件设置版本 10不在config.xml中添加新的白名单和白名单插件参数。 6号和7号

对于CLI版本，如果未为平台分配版本，或者未在config.xml中设置Phonegap版本，则将获得最新版本。如果你幸运的话，你的程序就像预期的那样工作。如果你运气不好，你会得到一组级联错误

幸运的是，霍莉·辛斯基（Holly Schinsky）写了一篇很好的博客文章来解释这一切：

Cordova/PhoneGap版本混淆

十年

这一相对较新的要求意味着——要访问任何网站或网络资源，必须使用白名单和白名单插件。如果您使用cordova，此要求将生效-android@4.0.0或者更好；包括cli-5.1.1和cli-5.2.0。但是，如果您的版本在4.0.0之前，比如说3.5.0或3.7.0，那么您将不必添加白名单要求

要明确的是，白名单已经存在了一段时间，但是插件和需求是非常新的。正如您所料，当白名单被添加时，事实上的开放存取功能被弃用了。或者换一种方式说，事实上的开放存取功能已经计划好并计划取消。此更改标志着删除开放存取功能的一个步骤

此外，内容安全策略CSP吸引了众多开发者，因为它的宣传太少了。根据您的使用情况和使用的Phonegap版本，CSP需要进入您使用的每个HTML页面，就像您必须等待“deviceready”一样。然而，在有些情况下根本不需要它。有些人对文档感到困惑，请仔细阅读。文档隐藏在许多最新文档页面的底部

最后，雷蒙德·卡姆登在他的博客中指出

相关链接

Phonegap构建论坛：现在需要白名单

有。。。在哪里？文件下载后最后一个函数不应该替换数据文件检查吗？控制台输出是什么样子的？你应该会得到一些日志语句。我插入了最后几行输出，我希望这会有所帮助。这正是我所需要的！谢谢，现在可以了：

10-22 16:46:40.927    2315-2315/? E/PGA﹕ PgaUtilsParamSize: unsuported param GL_CULL_FACE, assuming size 1
10-22 16:46:40.927    2315-2315/? E/PGA﹕ PgaUtilsParamSize: unsuported param GL_DITHER, assuming size 1

-22 16:47:48.367  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:48:43.477  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:48:48.827   30217-2359/? D/BstCommandProcessor-httpd﹕ command: ping
10-22 16:48:48.827   30217-2359/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:48:48.847   30217-2360/? D/BstCommandProcessor-httpd﹕ command: clipboard (with args)
10-22 16:48:48.847   30217-2360/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:49:38.587  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:50:33.697  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:50:42.037   30217-2361/? D/BstCommandProcessor-httpd﹕ command: ping
10-22 16:50:42.037   30217-2361/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:50:42.257   30217-2362/? W/BstCommandProcessor-httpd﹕ Reached maxLineLength limit while reading the content of a file
10-22 16:50:42.257   30217-2362/? D/BstCommandProcessor-httpd﹕ command: clipboard (with args)
10-22 16:50:42.267   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1969K, 24% free 6849K/8896K, paused 0ms, total 0ms
10-22 16:50:42.277   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1557K, 24% free 6850K/9004K, paused 10ms, total 10ms
10-22 16:50:42.287   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1318K, 24% free 6854K/9004K, paused 10ms, total 10ms
10-22 16:50:42.297   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1230K, 24% free 6851K/9012K, paused 10ms, total 10ms
10-22 16:50:42.307   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1215K, 24% free 6852K/9012K, paused 0ms, total 0ms
10-22 16:50:42.307   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1161K, 24% free 6858K/9012K, paused 0ms, total 0ms
10-22 16:50:42.317   30217-2362/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1101K, 24% free 6862K/9012K, paused 10ms, total 10ms
10-22 16:50:42.317   30217-2362/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:51:28.807  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:52:00.027  30100-30111/? D/dalvikvm﹕ GC_FOR_ALLOC freed 7538K, 38% free 12639K/20212K, paused 10ms, total 20ms
10-22 16:52:23.917  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:53:19.027  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:53:26.057   30217-2363/? D/BstCommandProcessor-httpd﹕ command: ping
10-22 16:53:26.057   30217-2363/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:53:26.077   30217-2364/? W/BstCommandProcessor-httpd﹕ Reached maxLineLength limit while reading the content of a file
10-22 16:53:26.077   30217-2364/? D/BstCommandProcessor-httpd﹕ command: clipboard (with args)
10-22 16:53:26.097   30217-2364/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1795K, 25% free 6825K/9020K, paused 10ms, total 10ms
10-22 16:53:26.097   30217-2364/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1489K, 25% free 6824K/9020K, paused 0ms, total 0ms
10-22 16:53:26.117   30217-2364/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1352K, 25% free 6825K/9020K, paused 10ms, total 10ms
10-22 16:53:26.117   30217-2364/? D/dalvikvm﹕ GC_FOR_ALLOC freed 1251K, 25% free 6836K/9020K, paused 0ms, total 0ms
10-22 16:53:26.127   30217-2364/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:54:14.137  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:54:23.877   30217-2365/? D/BstCommandProcessor-httpd﹕ command: ping
10-22 16:54:23.877   30217-2365/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:54:23.887   30217-2366/? D/BstCommandProcessor-httpd﹕ command: clipboard (with args)
10-22 16:54:23.887   30217-2366/? D/BstCommandProcessor-httpd﹕ response: {"result":"ok"}
10-22 16:54:30.017  29999-30062/? D/ConnectivityService﹕ Sampling interval elapsed, updating statistics ..
10-22 16:54:30.017  29999-30062/? D/ConnectivityService﹕ Done.
10-22 16:54:30.017  29999-30062/? D/ConnectivityService﹕ Setting timer for 720seconds
10-22 16:54:30.197  29999-30062/? D/ConnectivityService﹕ handleInetConditionChange: net=1 != default=9 - ignore
10-22 16:55:09.247  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:55:41.237  29999-29999/? I/EntropyMixer﹕ Writing entropy...
10-22 16:56:04.357  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms
10-22 16:56:59.467  30178-30897/? D/dalvikvm﹕ GC_FOR_ALLOC freed 736K, 29% free 2727K/3840K, paused 0ms, total 0ms