问题描述
我正在尝试编写一个在UIWebView中使用大量java脚本的应用程序。当需要时，一些java脚本会动态加载（使用jquery）。
I'm trying to write an application which uses a lot of java script inside a UIWebView. And some of this java script is loaded dynamically (with jquery) when it is needed.
index.html和jquery文件按预期加载，但不加载代码。 js文件。 code.js文件是这样的请求（从index.html剪断了java脚本代码）：
The index.html and the jquery files are loaded as expected but not the code.js file. The code.js file is request like this (snipped of the java script code from index.html):
function require(moduleName,filePath) {
var uri = filePath;
jQuery.ajax({
type: "GET",
url: uri,
async: false,
dataType: "script",
success: function(content) {
console.log("Receive content of "+moduleName);
},
error: function(XMLHttpRequest, textStatus, errorThrown) {
console.log("Error content of "+moduleName);
console.log("Status: " + textStatus);
console.log("Thrown error: " + errorThrown);
console.log("h" + XMLHttpRequest.getAllResponseHeaders());
console.log(XMLHttpRequest.responseText);
}
});
}
function start() {
require("test", "code.js");
}
在body标签的onload事件中调用start（）函数index.html。 code.js文件只包含以下三行代码：
The start() function is called in the onload event of the body tag of the index.html. The code.js file only contains the following three lines of code:
alert("Loaded file syncronosly");
// HEllo
alert("second");
我从这段代码得到的输出是这样的（我有一些额外的js代码转发控制台.log调用我省略的Xcode控制台）：
The output I get from this code looks like this (I have some additional js code which forwards the console.log calls to the Xcode console which I omitted):
UIWebView console: Error content of test
UIWebView console: Status: error
UIWebView console: Thrown error:
UIWebView console: h
UIWebView console: HTTP Error (0 error).
UIWebView console: alert("Loaded file syncronosly");
// HEllo
alert("second");
我尝试在重写的NSURLCache中返回code.js的内容时出现此行为类。最终的想法是拥有一个应用程序，其中一个部分在UIWebView中运行，而无需从外部Web服务器加载内容。
I get this behavior as soon as I try to return the content of code.js in the overridden NSURLCache class. The idea in the end is to have a application which of which a part runs in a UIWebView without the need to load the content from an external web server.
这是缓存类的缩写代码（LocalSubstitutionCache）：
This is the shortened code of the cache class (LocalSubstitutionCache):
NSString *pathString = [[request URL] absoluteString];
NSLog(@"request => %@", pathString);
NSString* fileToLoad = nil;
if ([pathString isEqualToString:@"http://example.com/index.html"]) {
fileToLoad = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"html"];
}
else if ([pathString hasPrefix:@"http://example.com/code.js"]) {
fileToLoad = [[NSBundle mainBundle] pathForResource:@"code" ofType:@"js"];
}
else if ([pathString isEqualToString:@"http://example.com/jquery-1.6.2.min.js"]) {
fileToLoad = [[NSBundle mainBundle] pathForResource:@"jquery-1.6.2.min" ofType:@"js"];
}
if (!fileToLoad) {
// No local data needed for this request let super handle it:
return [super cachedResponseForRequest:request];
}
NSData *data = [NSData dataWithContentsOfFile:fileToLoad];
NSURLResponse *response =
[[NSURLResponse alloc]
initWithURL:[request URL]
MIMEType:[self mimeTypeForPath:pathString]
expectedContentLength:[data length]
textEncodingName:nil];
cachedResponse =
[[NSCachedURLResponse alloc] initWithResponse:response data:data];
（缓存代码来自：）
现在在我的视图控制器（包含网页视图）中，我执行以下操作：
Now in my view controller (which contains a web view) I do the following:
- (void)viewDidLoad {
[super viewDidLoad];
// This line loads the content with the cache enabled (and does not work):
[_webview loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://example.com/index.html"]]];
}
现在有趣的是，当我用viewDidLoad方法替换代码时以下代码：
Now the interesting thing is that when I replace the code in the viewDidLoad method with the following code:
- (void) viewDidLoad {
[super viewDidLoad];
// This two line load the content without the cache:
NSString* fileToLoad = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"html"];
[_webview loadRequest:[NSURLRequest requestWithURL:[NSURL fileURLWithPath:fileToLoad]]];
}
现在一切正常，我显示了两个警报。所以我怀疑我在缓存中返回的内容与原始请求在被缓存捕获时返回的内容不同。
Now all is working fine and I get my two alert's displayed. So I suspect that what I'am returning in the cache is not the same as what the original request is returning when it is catches by the cache.
这是我的意思已经检查过：
Here is what I already checked for:
- 不使用工作案例的文件网址。我的原始代码从Web服务器获取未缓存的代码。但对于示例项目，我使用文件URL，因为这使项目更简单。
- 返回内容类型。在两种情况下都是text / javascript
- 特殊标头设置。我已经使用http代理检查了哪些标头在未缓存的请求上设置。没有设置特殊标头。
我最大的问题是jquery错误回调不会返回任何有用的错误信息。我只得到textStatus参数的错误输出。
My biggest issue is that the jquery error callback does not return any useful error information. I just get an output of error for the textStatus argument.
您可以从这里下载示例项目：
You can download the example project from here: http://dl.dropbox.com/u/5426092/LocalCacheJsInjectTest.zip
希望有人可以提供帮助我在这里
Hope somebody can help me here
推荐答案
经过更多的工作后，我找到了问题的解决方案。并在此回答我的发现。
After some more more work I found the solution to my problem. And answer here with what I found.
解决方案是创建一个自定义的NSURLProtocol实现，并在应用程序中将其注册为http协议的处理程序。代码看起来像这样（我在代码中省略了一些错误处理）：
The solution is to to create a custom NSURLProtocol implementation and register this in the application as handler for the http protocol. The code looks like this (I've omitted some error handling in the code):
#import "MyHttpURLProtocol.h"
@implementation MyHttpURLProtocol
+ (BOOL)canInitWithRequest:(NSURLRequest *)request {
return [[[request URL] scheme] isEqualToString:@"http"]; // we handle http requests
}
+ (NSURLRequest *)canonicalRequestForRequest:(NSURLRequest *)request {
return request;
}
- (void) startLoading {
id<NSURLProtocolClient> client = [self client];
NSURLRequest* request = [self request];
NSString *pathString = [[request URL] absoluteString];
NSString* fileToLoad = nil;
if ([pathString isEqualToString:@"http://example.com/index.html"]) {
fileToLoad = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"html"];
}
else if ([pathString hasPrefix:@"http://example.com/code.js"]) {
fileToLoad = [[NSBundle mainBundle] pathForResource:@"code" ofType:@"js"];
}
else if ([pathString isEqualToString:@"http://example.com/jquery-1.6.2.min.js"]) {
fileToLoad = [[NSBundle mainBundle] pathForResource:@"jquery-1.6.2.min" ofType:@"js"];
}
NSData* data = [NSData dataWithContentsOfFile:fileToLoad];
NSHTTPURLResponse* response = [[NSHTTPURLResponse alloc] initWithURL:[request URL] statusCode:200 HTTPVersion:@"HTTP/1.1" headerFields:[NSDictionary dictionary]];
[client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
[client URLProtocol:self didLoadData:data];
[client URLProtocolDidFinishLoading:self];
}
- (void) stopLoading {}
@end
此代码现在允许加载index.html文件，访问以下代码：
This code allows now to load the index.html file be accessing the following code:
[_webview loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://example.com/index.html"]]];
不要忘记在你的app delegate中注册自定义协议：
And don't forget to register the custom protocol in your app delegate:
[NSURLProtocol registerClass:[MyHttpURLProtocol class]];
在您找到解决方案后，解决方案的简单程度令人惊讶。以下是更新的示例项目的链接：
It's amazing how simple the solution can be after your found it. Here is the link to the updated example project: http://dl.dropbox.com/u/5426092/LocalCacheJsInjectTest-working.zip
为了完整起见，这里是博客文章的链接，它帮助我找到解决方案：
And for completeness sake here is the link to the blog post which helped me in finding the solution: http://www.infinite-loop.dk/blog/2011/09/using-nsurlprotocol-for-injecting-test-data/
这篇关于在UIWebView中动态加载javascript文件，本地缓存无法正常工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！