objective-c post json

先看同步，默认服务器接受json数据，返回json数据

//同步post
-(NSString *)postSyn:(NSString *)urlStr jsonData:(NSString *)jsonData{
    NSLog(@"post_begin");
    
    NSData* postData = [jsonData dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];//数据转码;
    NSString *length = [NSString stringWithFormat:@"%d", [postData length]];
    
    NSMutableURLRequest* request = [[NSMutableURLRequest alloc]init];
    [request setURL:[NSURL URLWithString:urlStr]]; //设置地址
    [request setHTTPMethod:@"POST"]; //设置发送方式
    [request setTimeoutInterval: 20]; //设置连接超时
    [request setValue:length forHTTPHeaderField:@"Content-Length"]; //设置数据长度
    [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"]; //设置发送数据的格式
    [request setValue:@"application/json" forHTTPHeaderField:@"Accept"]; //设置预期接收数据的格式
    [request setHTTPBody:postData]; //设置编码后的数据
    
    //发起连接，接受响应
    NSHTTPURLResponse* urlResponse = nil;
    NSError *error = [[NSError alloc] init] ;  
    NSData *responseData = [NSURLConnection sendSynchronousRequest:request
                                                 returningResponse:&urlResponse 
                                                             error:&error];  
    NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding]; //返回数据，转码
    
    NSLog(responseString);
    NSLog(@"post_end");
    return responseString;
}

将下面的代码加入到某个类中，然后调用httpPost方法就可以了，这个是异步的

-(void)httpPost:(NSString*)strcontext URL:(NSString*)urlstr{
    strcontext = nil;
    NSLog(@"url--%@",urlstr);
    NSLog(@"param--%@",strcontext);
    assert(strcontext!=NULL);
    assert(urlstr!=NULL);
    NSData* postData = [strcontext dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];//转码
    NSString* postLength = [NSString stringWithFormat:@"%d",[postData length]];
    NSMutableURLRequest* request = [[[NSMutableURLRequest alloc]init]autorelease];
    [request setURL:[NSURL URLWithString:urlstr]]; //设置地址
    [request setHTTPMethod:@"POST"]; //设置发送方式
    [request setTimeoutInterval: 20]; //设置连接超时
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"]; //设置数据长度
    [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"]; //设置发送数据的格式
    [request setValue:@"application/json" forHTTPHeaderField:@"Accept"]; //设置预期接收数据的格式
    [request setHTTPBody:postData]; //设置编码后的数据
    NSURLConnection*conn=[[NSURLConnection alloc]initWithRequest:request delegate:self];  //设置类代理,注意要是self哦
    if(conn)
    {
        NSLog(@"ConnectionSuccess");
        [UIApplication sharedApplication].networkActivityIndicatorVisible=YES;
        [conn retain];
    }
    else
    {
        NSLog(@"ConnectionFailed");
        //informtheuserthatthedownloadcouldnotbemade
    }
}

#pragma mark------------------以下为相应的回调函数-------------------------------
//收到响应时,会触发
-(void)connection:(NSURLConnection*)connection didReceiveResponse:(NSURLResponse*)response{
    //注意这里将NSURLResponse对象转换成NSHTTPURLResponse对象才能去
    NSHTTPURLResponse*httpResponse=(NSHTTPURLResponse*)response;
    if([response respondsToSelector:@selector(allHeaderFields)]){
        NSDictionary*dictionary=[httpResponse allHeaderFields];
        NSLog(@"didReceiveResponse1:%@",[dictionary description]);
        NSLog(@"didReceiveResponse2:%d",[response statusCode]);
    }
}
//链接错误
-(void)connection:(NSURLConnection*)connection didFailWithError:(NSError*)error{
    //[selfperformSelectorOnMainThread:@selector(httpConnectEnd)withObject:nil waitUntilDone:NO];
    NSLog(@"didFailWithError:%@",[error localizedDescription]);
}
//Calledwhenachunkofdatahasbeendownloaded.
//接收数据每收到一次数据,会调用一次
-(void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data{
    //Processthedownloadedchunkofdata.
    NSLog(@"didReceiveData_length:%d",[data length]);
    // NSLog(@"didReceiveData_data:%d",[data description]);
    [[self responseData] appendData:data];
    NSLog(@"didReceiveData_data%@",[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]);
    //[selfperformSelectorOnMainThread:@selector(updateProgress)withObject:nil waitUntilDone:NO];
}
//接收结束
-(void)connectionDidFinishLoading:(NSURLConnection*)connection{
    NSLog(@"connectionDidFinishLoading：%@",connection);
    //NSLog(@"%lld",received_);
    //[selfperformSelectorOnMainThread:@selector(httpConnectEnd)withObject:nil waitUntilDone:NO];
    //Settheconditionwhichendstherunloop.
    
    
    
    
    NSString *responseString = [[NSString alloc] initWithData:[self responseData] encoding:NSUTF8StringEncoding];
    [responseData release];
    
    NSLog(@"responseString：%@",responseString);
}