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NSURLProtocal子类的使用
//
// CustomURLProtocol.m
// NSURLProtocolExample
//
// Created by lujb on 15/6/15.
// Copyright (c) 2015年 lujb. All rights reserved.
//
#import "CustomURLProtocol.h"
static NSString * const URLProtocolHandledKey = @"URLProtocolHandledKey";
@interface CustomURLProtocol ()<NSURLConnectionDelegate>
@property (nonatomic, strong) NSURLConnection *connection;
@end
@implementation CustomURLProtocol
+ (BOOL)canInitWithRequest:(NSURLRequest *)request
{
//只处理http和https请求
NSString *scheme = [[request URL] scheme];
if ( ([scheme caseInsensitiveCompare:@"http"] == NSOrderedSame ||
[scheme caseInsensitiveCompare:@"https"] == NSOrderedSame))
{
//看看是否已经处理过了，防止无限循环
if ([NSURLProtocol propertyForKey:URLProtocolHandledKey inRequest:request]) {
return NO;
}
return YES;
}
return NO;
}
+ (NSURLRequest *) canonicalRequestForRequest:(NSURLRequest *)request {
NSMutableURLRequest *mutableReqeust = [request mutableCopy];
mutableReqeust = [self redirectHostInRequset:mutableReqeust];
return [NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.baidu.com"]];
}
+ (BOOL)requestIsCacheEquivalent:(NSURLRequest *)a toRequest:(NSURLRequest *)b
{
return [super requestIsCacheEquivalent:a toRequest:b];
}
- (void)startLoading
{
/* 如果想直接返回缓存的结果，构建一个NSURLResponse对象
if (cachedResponse) {
NSData *data = http://www.mamicode.com/cachedResponse.data; //缓存的数据
NSString *mimeType = cachedResponse.mimeType;
NSString *encoding = cachedResponse.encoding;
NSURLResponse *response = [[NSURLResponse alloc] initWithURL:self.request.URL
MIMEType:mimeType
expectedContentLength:data.length
textEncodingName:encoding];
[self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
[self.client URLProtocol:self didLoadData:data];
[self.client URLProtocolDidFinishLoading:self];
*/
NSMutableURLRequest *mutableReqeust = [[self request] mutableCopy];
//打标签，防止无限循环
[NSURLProtocol setProperty:@YES forKey:URLProtocolHandledKey inRequest:mutableReqeust];
self.connection = [NSURLConnection connectionWithRequest:mutableReqeust delegate:self];
}
- (void)stopLoading
{
[self.connection cancel];
}
#pragma mark - NSURLConnectionDelegate
- (void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
[self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
}
- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[self.client URLProtocol:self didLoadData:data];
}
- (void) connectionDidFinishLoading:(NSURLConnection *)connection {
[self.client URLProtocolDidFinishLoading:self];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
[self.client URLProtocol:self didFailWithError:error];
}
#pragma mark -- private
+(NSMutableURLRequest*)redirectHostInRequset:(NSMutableURLRequest*)request
{
if ([request.URL host].length == 0) {
return request;
}
NSString *originUrlString = [request.URL absoluteString];
NSString *originHostString = [request.URL host];
NSRange hostRange = [originUrlString rangeOfString:originHostString];
if (hostRange.location == NSNotFound) {
return request;
}
//定向到bing搜索主页
NSString *ip = @"cn.bing.com";
// 替换host
NSString *urlString = [originUrlString stringByReplacingCharactersInRange:hostRange withString:ip];
NSURL *url = [NSURL URLWithString:urlString];
request.URL = url;
return request;
}
@end
NSURLProtocal子类的使用