Hi3861的代码实例库中，介绍了http的连接，但是没有说明如何解析。当然，解析http返回值的方法是一个通用方法，不只限于在openharmony中使用。

1、http_parser库

http-parser是一个用C编写的HTTP消息解析器，可以解析请求和响应，被设计用于高性能HTTP应用程序。它不会进行任何系统调用及内存分配，它不会缓冲数据，它可以被随时中断。

2、源代码

/*
 * Copyright (c) 2020 HiSilicon (Shanghai) Technologies CO., LIMITED.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "hi_stdlib.h"
#include "lwip/sockets.h"
#include "lwip/netdb.h"
#include "lwip/sockets.h"
#include "lwip/netifapi.h"
#include "lwip/netdb.h"
#include "lwip/netifapi.h"
#include <string.h>
#include <stdlib.h>
#include "lwip/sockets.h"
#include "hi_mem.h"
#include "hi_config.h"
#include "audio_http_client.h"
#include "../http_parser/http_parser.h"
#include "hi_i2s.h"
#include "hi_time.h"

#define HTTPC_DEMO_RECV_BUFSIZE 2048*2
#define SOCK_TARGET_PORT  80

//#define ADDRESS "192.168.1.91" //"192.168.0.200"
#define ADDRESS "121.36.121.226"

bool bParsed = false;
int total_len = 10902;
int frame_len = 2560;

char current_header_key[64];

void audio_http_parser_init();
void audio_http_parser_exec(char *buf,int len);
/*****************************************************************************
* Func description: demo for http get action
*****************************************************************************/
unsigned int audio_http_clienti_get()
{
    struct sockaddr_in addr = {0};
    int s, r;
    char recv_buf[HTTPC_DEMO_RECV_BUFSIZE];
    addr.sin_family = AF_INET;
    addr.sin_port = PP_HTONS(SOCK_TARGET_PORT);
    //addr.sin_port =  my_htons(SOCK_TARGET_PORT);
    addr.sin_addr.s_addr = ipaddr_addr(ADDRESS);
    printf("addr=%d,%d,%d\r\n",addr.sin_family,addr.sin_port,addr.sin_addr.s_addr);
    s = my_socket(AF_INET, SOCK_STREAM, 0);
    if (s < 0) {
        return 1;
    }
    DEBUG_printf("... allocated socket %d\r\n",s);
    if (my_connect(s, (struct sockaddr*)&addr, sizeof(addr)) != 0) {
        DEBUG_printf("... socket connect failed.\r\n");
        my_closesocket(s);
        return 1;
    }
    DEBUG_printf("... connected\r\n");

    int start = 0;
    int length = frame_len -1;
    int end = start + length;

    char get_request[512];
    char header_bytes[256];

    int body_recv_len = 0;

    int down_start_time = hi_get_milli_seconds();
    while (1)
    {
        //DEBUG_printf("******start********\r\n");
        sprintf(header_bytes,"Range:bytes=%d-%d\r\n",start,end);
        sprintf(get_request,"GET /sis/tts/test02.pcm HTTP/1.1\r\nContent-Type: application/x-www-form-urlencoded;charset=UTF-8\r\nConnection: Keep-Alive\r\nHost: hqx-default-sis.obs.cn-north-4.myhuaweicloud.com\r\n%s\r\n",
        header_bytes);

        if (lwip_write(s, get_request, strlen(get_request)) < 0) {
            my_closesocket(s);
            DEBUG_printf("my_closesocket\r\n");
            return 1;
        }
        //DEBUG_printf("... socket send success. %s\r\n",header_bytes);
        struct timeval receiving_timeout;
        
        /* 5S Timeout */
        /*
        receiving_timeout.tv_sec = 1;
        receiving_timeout.tv_usec = 0;
        if (my_setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &receiving_timeout, sizeof(receiving_timeout)) < 0) {
            printf("setsockopt = %d,%d,%d\r\n",s,SOL_SOCKET,SO_RCVTIMEO);
            DEBUG_printf("... failed to set socket receiving timeout\r\n");
            my_closesocket(s);
            return 1;
        }
        DEBUG_printf("... set socket receiving timeout success\r\n");
        */
        audio_http_parser_init();
        /* Read HTTP response */
        do {
            (void)memset_s(recv_buf, sizeof(recv_buf), 0, sizeof(recv_buf));
            r = lwip_read(s, recv_buf, sizeof(recv_buf) - 1);
            
            //for (int i = 0; i < r; i++) {
            //    putchar(recv_buf[i]);
            //}
            DEBUG_printf("-%d-",r);
            audio_http_parser_exec(recv_buf,r);
            if (bParsed)
            {
                bParsed = false;
                break;
            }
        } while (r > 0);

        start = start + length + 1;
        end = start + length;
        if(end > total_len - 1)
            end = total_len - 1;
        if(start > total_len - 1)
            break;
    }
    //DEBUG_printf("... done reading from socket. Last read return=%d\r\n", r);
    my_closesocket(s);
    int down_end_time = hi_get_milli_seconds();
    DEBUG_printf("down load time = %d ms\r\n",down_end_time - down_start_time);
    return 0;
}

int on_header_field(http_parser* _, const char* at, size_t length) {
    (void)_;
    //DEBUG_printf("Header field: %.*s\n", (int)length, at);
    strncpy(current_header_key,at,length);
    current_header_key[length] = '\0';
    return 0;
}
int on_header_value(http_parser* _, const char* at, size_t length) {
    (void)_;
    //DEBUG_printf("Header %s value: %.*s\n",current_header_key, (int)length, at);
    if (strcmp(current_header_key, "Content-Range") == 0) 
    {
        int s=0,e=0,t=0;
        sscanf(at,"bytes %d-%d/%d",&s,&e,&t);
        //DEBUG_printf("parser=%d,%d,%d\r\n",s,e,t);
        total_len = t;
    }
    return 0;
}

unsigned char audio_data_buff[2048];
int audio_data_len = 0;

int on_body(http_parser* _, const char* at, size_t length) {
  (void)_;
  //DEBUG_printf("Body: %.*s\n", (int)length, at);
  memcpy(audio_data_buff,at,length);
  audio_data_len = length;
  //DEBUG_printf("Body: %d\n", (int)length);
  return 0;
}
int on_message_begin(http_parser* _) {
  (void)_;
  //DEBUG_printf("\n***MESSAGE BEGIN***\n\n");
  return 0;
}

int on_message_complete(http_parser* _) {
  (void)_;
  //DEBUG_printf("\n***MESSAGE COMPLETE***\n\n");
  bParsed = true;
  return 0;
}

int on_headers_complete(http_parser* _) {
  (void)_;
  //DEBUG_printf("\n***HEADERS COMPLETE***\n\n");
  return 0;
}

http_parser_settings settings;
http_parser parser;  
void audio_http_parser_init(char *buf,int len)
{
    http_parser_settings_init(&settings);
    settings.on_header_field = on_header_field;
    settings.on_header_value = on_header_value;
    settings.on_body = on_body;
    settings.on_headers_complete = on_headers_complete;
	settings.on_message_complete = on_message_complete;

    http_parser_init(&parser, HTTP_RESPONSE);
}

void audio_http_parser_exec(char *buf,int len)
{
    http_parser_execute(&parser, &settings, buf,len);  //执行解析过程
    if (bParsed)
    {
        DEBUG_printf("#");
        audio_data_len = frame_len;
        
        hi_u32 ret = hi_i2s_write(audio_data_buff,audio_data_len,1000);
        if (ret != HI_ERR_SUCCESS) {
            DEBUG_printf("hi_i2s_write fail, err = %X\n", ret);
        }

        //bParsed = false;
    }
}

3、代码概要说明

http_parser库使用的时候，需要先初始化，audio_http_parser_init();需要在函数中实现回调。这样就可以解析数据了。