使用WebClient&tls获取实时天气

发布于 2018-08-27 10:44:48 浏览：4083 订阅该版

* 本帖最后由 slyant 于 2018-9-12 23:08 编辑 *

修改自组件自带的webclient_get_sample.c例子如果运行失败，注意修改lwip\opt.h文件的MEMP_NUM_NETDB宏定义值为>1的值，否则https的URL的解析会失败，MEMP_NUM_NETDB的大概意思是lwip_addrinfo()占用的内存释放前能够被并发调用的数量。

app_httpclient.c
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```#include <rtthread.h>
#include <webclient.h>
#include <url_code.h>
#include <string.h>
#include "cJSON_util.h"

#define GET_HEADER_BUFSZ        1024
#define GET_RESP_BUFSZ                1024
#define GET_RESP_CONTENTSZ        4096
#define URL_LEN_MAX                        1024

#define GET_LOCAL_URI                "https://www.apiopen.top/weatherApi?city=%s"
#define LOCAL_CITY                        "%E6%AD%A6%E6%B1%89"        //urlencode("武汉")

static void weather_data_parse(char* data)
{
 cJSON *root = RT_NULL, *object = RT_NULL, *list = RT_NULL, *item = RT_NULL, *weatheritem = RT_NULL;
 int index, list_size = 0;
 root = cJSON_Parse((const char *)data);
 if (!root)
 {
 rt_kprintf("No memory for cJSON root! ");
 return;
 }
 item = cJSON_GetObjectItem(root, "code"); 
 if(item->valueint != 200)
 {
 item = cJSON_GetObjectItem(root, "msg");
 rt_kprintf(" %s", item->valuestring);
 goto __EXIT;
 }
 object = cJSON_GetObjectItem(root, "data");
 item = cJSON_GetObjectItem(object, "city");
 rt_kprintf(" city:\t%s", item->valuestring);
 list = cJSON_GetObjectItem(object, "forecast");
 list_size = cJSON_GetArraySize(list);
 for(index=0;index<list_size;index++)
 {
 weatheritem = cJSON_GetArrayItem(list, index); 
 rt_kprintf(" Data:\t%s", cJSON_item_get_string(weatheritem, "date"));
 rt_kprintf(" type:\t%s", cJSON_item_get_string(weatheritem, "type"));
 rt_kprintf(" wendu:\t%s-%s", cJSON_item_get_string(weatheritem, "low"), cJSON_item_get_string(weatheritem, "high"));
 rt_kprintf(" fengxiang:%s %s", cJSON_item_get_string(weatheritem, "fengxiang"), cJSON_item_get_string(weatheritem, "fengli"));
 rt_kprintf(" ");
 } 
 rt_kprintf(" ");
__EXIT:
 if (root != RT_NULL)
 cJSON_Delete(root); 
}

int get_weather(int argc, char **argv)
{
 struct webclient_session* session = RT_NULL;
 unsigned char *buffer = RT_NULL;
 char *URI = RT_NULL;
 int index, ret = 0;
 int bytes_read, resp_status;
 int content_length = -1;
 char *city_name = rt_calloc(1,255);
 if(argc == 1)
 {
 strcpy(city_name, LOCAL_CITY);
 }
 else if (argc == 2)
 {
 strcpy(city_name, argv[1]);
 urlencode(city_name);//对中文编码
 }
 else if(argc > 2)
 {
 rt_kprintf("wt [CityName] - webclient GET request test. ");
 return -1;
 }
 URI = rt_calloc(1, URL_LEN_MAX); 
 rt_snprintf(URI, URL_LEN_MAX, GET_LOCAL_URI, city_name);
 buffer = (unsigned char *) web_malloc(GET_RESP_CONTENTSZ);
 if (buffer == RT_NULL)
 {
 rt_kprintf("no memory for receive buffer. ");
 ret = -RT_ENOMEM;
 goto __exit;
 }

/* create webclient session and set header response size */
    session = webclient_session_create(GET_HEADER_BUFSZ);
    if (session == RT_NULL)
    {
        ret = -RT_ENOMEM;
        goto __exit;
    }

/* send GET request by default header */
 rt_kprintf("send GET request to %s ", URI);
 if ((resp_status = webclient_get(session, URI)) != 200)
 {
 rt_kprintf("webclient GET request failed, response(%d) error. ", resp_status);
 ret = -RT_ERROR;
 goto __exit;
 }
 content_length = webclient_content_length_get(session);
 if (content_length < 0)
 {
 rt_kprintf("webclient GET request type is chunked. ");
 do
 {
 bytes_read = webclient_read(session, buffer, GET_RESP_BUFSZ);
 if (bytes_read <= 0)
 {
 break;
 }

for (index = 0; index < bytes_read; index++)
 {
 rt_kprintf("%c", buffer[index]);
 }
 } while (1);
 rt_kprintf(" ");
 }
 else
 {
 int content_pos = 0;
 do
 {
 bytes_read = webclient_read(session, buffer+content_pos, GET_RESP_BUFSZ);
 if (bytes_read <= 0)
 {
 break;
 }
 content_pos += bytes_read;
 } while (content_pos < content_length);
 weather_data_parse((char*)buffer);
 }

__exit:
    if (session)
    {
        webclient_close(session);
    }

if (buffer)
    {
        web_free(buffer);
    }

if (URI)
    {
        web_free(URI);
    }

return ret;
}

#ifdef FINSH_USING_MSH
#include <finsh.h>
MSH_CMD_EXPORT_ALIAS(get_weather, wt, wt [CityName] webclient GET request test);
#endif /* FINSH_USING_MSH */
```
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因中文地名需要URL转码，涉及文件url_code.c,url_code.h
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```#ifndef __URL_CODE_H__
#define __URL_CODE_H__

void urlencode(char *url);
void urldecode(char *url);

#endif``````#include <url_code.h>
//#include <stdio.h>
#include <string.h>
#include <rtthread.h>
 
#define BURSIZE 1024
 
static int hex2dec(char c)
{
 if ('0' <= c && c <= '9') {
 return c - '0';
 } else if ('a' <= c && c <= 'f') {
 return c - 'a' + 10;
 } else if ('A' <= c && c <= 'F') {
 return c - 'A' + 10;
 } else {
 return -1;
 }
}
 
static char dec2hex(short int c)
{
 if (0 <= c && c <= 9) {
 return c + '0';
 } else if (10 <= c && c <= 15) {
 return c + 'A' - 10;
 } else {
 return (char)-1;
 }
}
 
 
/*
 * 编码一个url
 */
void urlencode(char *url)
{
 int i = 0;
 int len = strlen(url);
 int res_len = 0;
 char *res = rt_calloc(1, BURSIZE);
 for (i = 0; i < len; ++i) {
 char c = url*;
 if (('0' <= c && c <= '9') ||
 ('a' <= c && c <= 'z') ||
 ('A' <= c && c <= 'Z') || c == '/' || c == '.') {
 res[res_len++] = c;
 } else {
 int j = (short int)c;
 if (j < 0)
 j += 256;
 int i1, i0;
 i1 = j / 16;
 i0 = j - i1 * 16;
 res[res_len++] = '%';
 res[res_len++] = dec2hex(i1);
 res[res_len++] = dec2hex(i0);
 }
 }
 res[res_len] = '\0';
 strcpy(url, res);
 rt_free(res);
}
 
/*
 * 解码url
 */
void urldecode(char *url)
{
 int i = 0;
 int len = strlen(url);
 int res_len = 0;
 char *res = rt_calloc(1, BURSIZE);
 for (i = 0; i < len; ++i) {
 char c = url*;
 if (c != '%') {
 res[res_len++] = c;
 } else {
 char c1 = url[++i];
 char c0 = url[++i];
 int num = 0;
 num = hex2dec(c1) * 16 + hex2dec(c0);
 res[res_len++] = num;
 }
 }
 res[res_len] = '\0';
 strcpy(url, res);
 rt_free(res);
}

```

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运行结果：
![wt.png](/uploads/201808/27/105226xkkq3gqg6xgea84s.png)