Objective C 实现 http post multipart/form-data 类型的请求
下面介绍使用 Objective C 实现 http post 方法,发送 Content-Type 为 multipart/form-data 格式的数据,支持文件、图片的上传,模拟了 html 的表单数据提交。在 IOS 项目下获取文件的 mime type,需在 Xcode 的项目: Build Phases -> Link Binary With Libraries
,添加MobileCoreServices.framework
框架。可以参考 Objective C 根据文件的扩展名获取 MIME Type。添加文件 mime type,主要是为了告知后端服务器关于此文件的类型。
示例代码
文件 HttpPostMultipart.h
#import <Foundation/Foundation.h>
/// 实现Http Multipart 工具类
@interface HttpPostMultipart:NSObject
-(id)initWithUrl:(NSString *)urlString;
@property(nonatomic) NSMutableURLRequest *request;
@property(nonatomic) NSString *urlString;
@property(nonatomic) NSMutableDictionary *headers;
@property(nonatomic) NSMutableDictionary *fields;
@property(nonatomic) NSMutableDictionary *files;
/// 添加请求头
/// @param key 请求头key
/// @param value 请求头值
-(void)addHeader:(NSString *)key value:(NSString *)value;
/// 添加参数字段
/// @param key 请求字段 key
/// @param value 请求字段 value
-(void)addFormField:(NSString *)key value:(NSString *)value;
/// 添加文件
/// @param key 传输文件的key
/// @param path 文件路径
-(void)addFormFile:(NSString *)key path:(NSString *)path;
/// 执行请求
/// @param callback 回调块
- (void)finish:(void(^)(NSData *, NSURLResponse *, NSError *))callback;
@end
文件 HttpPostMultipart.m
#import "HttpPostMultipart.h"
#import <MobileCoreServices/MobileCoreServices.h>
@implementation HttpPostMultipart
-(id)initWithUrl:(NSString *)urlString{
self.request = [[NSMutableURLRequest alloc]init];
self.urlString = urlString;
self.headers = [[NSMutableDictionary alloc]init];
self.fields = [[NSMutableDictionary alloc]init];
self.files = [[NSMutableDictionary alloc]init];
return self;
}
-(void)addHeader:(NSString *)key value:(NSString *)value{
[self.headers setObject:value forKey:key];
}
-(void)addFormField:(NSString *)key value:(NSString *)value{
[self.fields setObject:value forKey:key];
}
-(void)addFormFile:(NSString *)key path:(NSString *)path{
[self.files setObject:path forKey:key];
}
- (void)finish:(void (^)(NSData *, NSURLResponse *, NSError *))callback{
NSURL *url = [[NSURL alloc]initWithString:self.urlString];
[self.request setURL:url];
[self.request setHTTPMethod:@"POST"];
// 增加请求头
for (NSString *key in self.headers){
NSString *value = self.headers[key];
[self.request setValue:value forHTTPHeaderField:key];
}
// 增加 Content-Type 头
NSString *boundary = @"unique-consistent-string";
NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];
[self.request setValue:contentType forHTTPHeaderField:@"Content-Type"];
// 增加 Post 参数字段
NSMutableData *body = [NSMutableData data];
for (NSString *key in self.fields){
NSString *value = self.fields[key];
// add params (all params are strings)
[body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=%@\r\n\r\n", key] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:@"%@\r\n", value] dataUsingEncoding:NSUTF8StringEncoding]];
}
// 添加文件
for (NSString *key in self.files){
NSString *path = self.files[key];
NSString *fileName = [path lastPathComponent];
NSString *fileExtension = [path pathExtension];
NSString *contentType = [self getMimeType:fileExtension];
[body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=%@; filename=%@\r\n", key, fileName] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:@"Content-Type: %@\r\n\r\n", contentType] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[NSData dataWithContentsOfFile:path]];
[body appendData:[[NSString stringWithFormat:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
}
if ([body length] > 0) {
[body appendData:[[NSString stringWithFormat:@"--%@--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
// setting the body of the post to the reqeust
[self.request setHTTPBody:body];
// set the content-length
NSString *postLength = [NSString stringWithFormat:@"%ld", [body length]];
[self.request setValue:postLength forHTTPHeaderField:@"Content-Length"];
}
void (^completionHandler)(NSData *, NSURLResponse *, NSError *) = ^(NSData *data, NSURLResponse *response, NSError *error) {
if (callback) {
callback(data, response, error);
}
};
[[[NSURLSession sharedSession] dataTaskWithRequest:self.request completionHandler:completionHandler] resume];
}
/// 获取文件的 mime type
/// @param fileExtension 文件扩展名
- (NSString *)getMimeType:(NSString *)fileExtension{
NSString *UTI = (__bridge_transfer NSString *)UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)fileExtension, NULL);
NSString *mimeType = (__bridge_transfer NSString *)UTTypeCopyPreferredTagWithClass((__bridge CFStringRef)UTI, kUTTagClassMIMEType);
return mimeType;
}
@end
调用示例
NSString *url = @"http://localhost";
HttpPostMultipart *request = [[HttpPostMultipart alloc]initWithUrl:url];
// 添加 user-agent
[request addHeader:@"User-Agent" value:@"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.132 Safari/537.36"];
// 添加 请求参数
[request addFormField:@"username" value:@"test"];
// 添加 图片
[request addFormFile:@"pictures" path:@"/Users/apple/Downloads/201228bli.bmp"];
void (^completionHandler)(NSData *, NSURLResponse *, NSError *) = ^(NSData *data, NSURLResponse *response, NSError *error) {
if (data == nil || data.length == 0 || response == nil || [(NSHTTPURLResponse *)response statusCode] != 200) {
NSLog(@"error");
return;
}
NSLog(@"success: %@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
};
[request finish:completionHandler];