POST请求的forHTTPHeaderField

POST请求的forHTTPHeaderField

也许你的iOS项目中使用了AFNetworking2.0,或者是ASIHTTPRequest,对于http中POST请求的操作,你用了他们提供的现成的方法后,就再也无法理解这些请求是如何实现的了,这对于我们学习网络请求的原理是很不方便的说,因为不理解原理,那对于定制自己的网络类也就无从说起,无论AFNetworking2.0与ASIHTTPRequest多么好用,你用的再多也无法让你真正熟悉网络库从而写出适合自己的网络封装.

在开始这篇教程之前,先提供本人粗略封装的网络类供看官使用:

NETWorkRequest.h  +  NETWorkRequest.m

//
//  NETWorkRequest.h
//  NETWork
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import <Foundation/Foundation.h>

// block的相关定义
typedef void (^NETWorkRequestBlock)(NSMutableURLRequest *request);

@interface NETWorkRequest : NSObject

@property (nonatomic, strong, readonly) NSMutableURLRequest *request;

- (void)configRequest:(NETWorkRequestBlock)block;

@end

//
//  NETWorkRequest.m
//  NETWork
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import "NETWorkRequest.h"

@interface NETWorkRequest ()

@end

@implementation NETWorkRequest

- (instancetype)init
{
    self = [super init];
    if (self)
    {
        _request = [NSMutableURLRequest new];
    }
    return self;
}

- (void)configRequest:(NETWorkRequestBlock)block
{
    block(self.request);
}

@end

NETWorkConnection.h  +  NETWorkConnection.m

//
//  NETWorkConnection.h
//  NETWork
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import <Foundation/Foundation.h>
@class NETWorkRequest;

// block的相关定义
typedef void (^NETWorkConnectionBlock)(NSDictionary *info, NSData *data, NSError *error);

@interface NETWorkConnection : NSObject

@property (nonatomic, strong, readonly) NETWorkRequest  *request;

- (instancetype)initWithRequest:(NETWorkRequest *)request;
- (void)resultBlock:(NETWorkConnectionBlock)block;
- (void)start;

@end

//
//  NETWorkConnection.m
//  NETWork
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import "NETWorkConnection.h"
#import "NETWorkRequest.h"

@interface NETWorkConnection ()<NSURLConnectionDelegate, NSURLConnectionDataDelegate>

@property (nonatomic, copy)   NETWorkConnectionBlock  onncetionBlock;   // 网络连接用block
@property (nonatomic, assign) unsigned long long      expectedLength;   // 从服务器获取期望文件的大小

@property (nonatomic, strong) NSURLConnection        *conncetion;       // 网络连接
@property (nonatomic, strong) NSMutableData          *cacheData;        // 用于缓存的data数据
@property (nonatomic, strong) NSURLResponse          *response;         // 回复
@property (nonatomic, strong) NSMutableDictionary    *info;             // 一些链接的信息

@end

@implementation NETWorkConnection

- (instancetype)initWithRequest:(NETWorkRequest *)request
{
    self = [super init];
    if (self)
    {
        // 开始创建连接
        _conncetion = \
        [[NSURLConnection alloc] initWithRequest:request.request
                                        delegate:self
                                startImmediately:NO];

        // 创建数据容器
        _cacheData = [NSMutableData data];

        // 储存一些信息
        _info = [NSMutableDictionary new];
    }
    return self;
}

- (void)start
{
    [self.conncetion start];
}

#pragma mark - delegate
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    // 存储一些网络回复的信息
    [_info setObject:@(response.expectedContentLength) forKey:@"expectedContentLength"];
    if (response.suggestedFilename)
        [_info setObject:response.suggestedFilename forKey:@"suggestedFilename"];
    if (response.MIMEType)
        [_info setObject:response.MIMEType          forKey:@"MIMEType"];
    if (response.textEncodingName)
        [_info setObject:response.textEncodingName  forKey:@"textEncodingName"];
    if (response.URL.description)
        [_info setObject:response.URL.description   forKey:@"URL"];

    // 走HTTP协议的网络链接会执行括号类的方法
    if([response isKindOfClass:[NSHTTPURLResponse class]])
    {
        NSHTTPURLResponse *r = (NSHTTPURLResponse *)response;

        // 获取response
        _response = response;

        [_info setObject:r.allHeaderFields forKey:@"allHeaderFields"];
        [_info setObject:@(r.statusCode)   forKey:@"statusCode"];

        // 如果能获取到期望的数据长度就执行括号中的方法
        if ([r expectedContentLength] != NSURLResponseUnknownLength)
        {
            // 获取期望下载的数值
            _expectedLength  = [r expectedContentLength];
        }
    }
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)theData
{
    // 存储缓存数据
    [_cacheData appendData:theData];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    // 如果存在block则执行
    if (_onncetionBlock)
    {
        // 调用block
        _onncetionBlock(_info, _cacheData, nil);
    }
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    // 如果存在block则执行
    if (_onncetionBlock)
    {
        // 调用block
        _onncetionBlock(_info, nil, error);
    }
}

- (void)resultBlock:(NETWorkConnectionBlock)block
{
    // 防止循环引用
    __weak NSMutableDictionary *infoDic = _info;

    // 初始化block
    _onncetionBlock = ^(NSDictionary *info, NSData *data, NSError *error)
    {
        // 调用block
        block(infoDic, data, error);
    };
}

- (void)dealloc
{
    /* After this method is called, the connection’s delegate no longer
     receives any messages for the connection. If you want to reattempt
     the connection, you should create a new connection object. */
    [_conncetion cancel];
}

@end

Response Headers(从服务器得到的回复的头)

Common non-standard response headers(从服务器得到的非标准回复的头)

请写以下代码:

打印信息:

2014-06-12 17:15:33.731 NETWork[10975:60b] {
    MIMEType = "application/json";
    URL = "http://www.duitang.com/album/1733789/masn/p/0/1/";
    allHeaderFields =     {
        Connection = "keep-alive";
        "Content-Type" = "application/json;charset=UTF-8";
        Date = "Thu, 12 Jun 2014 09:15:33 GMT";
        Server = nginx;
        "Transfer-Encoding" = Identity;
        "X-Powered-By" = Japa;
    };
    expectedContentLength = "-1";
    statusCode = 200;
    suggestedFilename = 1;
    textEncodingName = "utf-8";
}

对照红色字体,仔细查一查上面的表,都出现了这些参数哦.

 上面的打印信息,是你对服务器请求之后,服务器Response给你的一个allHeaderFields信息,可以了解到服务器的一些状态值.

其实,我们给服务器发送POST请求的时候,有时候需要自己组织allHeaderFields信息,比如最常见的Content-Length.

request也有着一个Header Fields的列表:

Request Headers(标准请求头)

Common non-standard request headers(非标准请求头)

#define NUM_STRING(num)  [NSString stringWithFormat:@"%lu", (num)]

/**
 执行一个java脚本获取User-Agent字符串

 @return User-Agent字符串
 */
NS_INLINE NSString* UserAgent()
{
    UIWebView* webView = [[UIWebView alloc] initWithFrame:CGRectZero];
    NSString *userAgentString = [webView stringByEvaluatingJavaScriptFromString:
                                 @"navigator.userAgent"];

    return userAgentString;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    // 创建链接
    /* ============================================================================== */
    NETWorkRequest *request = [NETWorkRequest new];
    [request configRequest:^(NSMutableURLRequest *request)
     {
         // 配置网址链接
         request.URL = [NSURL URLWithString:@"http://webservice.webxml.com.cn/WebServices/MobileCodeWS.asmx/getMobileCodeInfo"];

         // 配置请求类型
         request.HTTPMethod = @"POST";

         // 配置请求报文
         NSString *dataString = @"mobileCode=15910514636&userID=";

         [request setValue:UserAgent()
        forHTTPHeaderField:@"User-Agent"];

         [request setValue:@"application/x-www-form-urlencoded"
        forHTTPHeaderField:@"Content-Type"];

         [request setValue:NUM_STRING([dataString toUTF8Data].length)
        forHTTPHeaderField:@"Content-Length"];

         // 配置包体
         request.HTTPBody = [dataString toUTF8Data];

         // 设置时间间隔
         request.timeoutInterval = 1.f;

         // 设置缓存策略
         request.cachePolicy = NSURLRequestUseProtocolCachePolicy;
     }];

    // 创建请求
    /* ============================================================================== */
    NETWorkConnection *connection = [[NETWorkConnection alloc] initWithRequest:request];
    [connection resultBlock:^(NSDictionary *info, NSData *data, NSError *error) {

        ONOXMLDocument *document = [ONOXMLDocument XMLDocumentWithData:data
                                                                 error:nil];
        NSLog(@"%@", document);

    }];

    // 开始请求
    /* ============================================================================== */
    [connection start];
}

一个POST请求由头和包体所组成,头就是上面列表中出现的那些参数,Body部分才是你需要传递的一些参数.

执行结果如下:

2014-06-12 17:29:52.137 NETWork[11061:60b] <string xmlns="http://WebXml.com.cn/">15910514636：北京 北京 北京移动全球通卡</string>

总结:

如果网络请求走HTTP协议的话,其实很容易.GET请求非常简单,不赘述,POST就是设置Headr Field以及Body的干活,也很简单,当你理解了这些后,封装一个自己的网络请求类真的超级简单哦.

附录:

正规携带参数的POST请求如下所示

// 配置
    NETWorkRequest *request = [[NETWorkRequest alloc] init];
    [request configRequest:^(NSMutableURLRequest *request) {

        // 网址
        NSString *urlString = @"http://trainddtestapi.tidoo.cn/acts/findLikeActAndCourseList.do";

        // 参数
        NSString *params    = @"appkey=peixunduoduo&citycode=100000&lat=39.909875&lng=116.502042&sign=f3f4491cc0ac8caccf0544df9e68baab×tamp=1404444014&userid=101";

        request.HTTPMethod  = @"POST";
        request.HTTPBody    = [params dataUsingEncoding:NSUTF8StringEncoding];
        request.URL         = [NSURL URLWithString:urlString];

    }];

    // 请求
    NETWorkConnection *connection = [[NETWorkConnection alloc] initWithRequest:request];
    [connection infoBlock:^(NSDictionary *info) {
        NSLog(@"%@", info);
    } progressBlock:^(long long currentBytes, long long totalBytes) {
    } resultBlock:^(NSDictionary *info, NSData *data, NSError *error) {
        NSString *result = [[NSString alloc] initWithData:data
                                                 encoding:NSUTF8StringEncoding];
        NSLog(@"%@", result);
    }];
    [connection start];