本篇使用的是lwip编写udp客户端。需要提前准备好一个PARAM_HOTSPOT_SSID宏定义的热点，并且密码为PARAM_HOTSPOT_PSK。还需要准备一个udp服务，服务ip为PARAM_SERVER_ADDR宏定义，端口为PARAM_SERVER_PORT宏定义。
修改网络参数
在Hi3861开发板上运行上述四个测试程序之前，需要根据你的无线路由、Linux系统IP修改 net_params.h文件的相关代码：
- PARAM_HOTSPOT_SSID 修改为你的热点名称
- PARAM_HOTSPOT_PSK 修改为你的热点密码；
- PARAM_SERVER_ADDR 修改为你的服务器IP地址；
- PARAM_SERVER_PORT 修改为你的服务器端口号；
LwIP Socket API编程udp客户端主要步骤
创建Socket socket()
设置目标服务器地址和端口 sockaddr_in
发送和接收数据 sendto() recvfrom()
关闭Socket close()
代码编写
修改D:\DevEcoProjects\test\src\vendor\rtplay\rt_hi3861\demo\BUILD.gn文件
# Copyright (c) 2023 Beijing HuaQing YuanJian Education Technology Co., Ltd
# 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. import("//build/lite/config/component/lite_component.gni")lite_component("demo") {features = [#"base_00_helloworld:base_helloworld_example",#"base_01_led:base_led_example",#"base_02_loopkey:base_loopkey_example",#"base_03_irqkey:base_irqkey_example",#"base_04_adc:base_adc_example",#"base_05_pwm:base_pwm_example",#"base_06_ssd1306:base_ssd1306_example",#"kernel_01_task:kernel_task_example",#"kernel_02_timer:kernel_timer_example",#"kernel_03_event:kernel_event_example",#"kernel_04_mutex:kernel_mutex_example",#"kernel_05_semaphore_as_mutex:kernel_semaphore_as_mutex_example",#"kernel_06_semaphore_for_sync:kernel_semaphore_for_sync_example",#"kernel_07_semaphore_for_count:kernel_semaphore_for_count_example",#"kernel_08_message_queue:kernel_message_queue_example",#"wifi_09_hotspot:wifi_hotspot_example",#"wifi_10_sta:wifi_sta_example",#"tcp_11_server:tcp_server_example",#"tcp_12_client:tcp_client_example",#"udp_13_server:udp_server_example","udp_14_client:udp_client_example",]
}创建D:\DevEcoProjects\test\src\vendor\rtplay\rt_hi3861\demo\udp_14_client文件夹
文件夹中创建D:\DevEcoProjects\test\src\vendor\rtplay\rt_hi3861\demo\udp_14_client\BUILD.gn文件
#Copyright (C) 2021 HiHope Open Source Organization .
#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.static_library("udp_client_example") {# uncomment one of following line, to enable one test:sources = ["udp_client_example.c"]sources += ["wifi_connecter.c"]include_dirs = ["//utils/native/lite/include","//kernel/liteos_m/kal","//foundation/communication/wifi_lite/interfaces/wifiservice",]
}文件夹中创建D:\DevEcoProjects\test\src\vendor\rtplay\rt_hi3861\demo\udp_14_client\net_common.h文件，文件主要引入一些头文件。文件同tcp_12_client\net_common.h
文件夹中创建D:\DevEcoProjects\test\src\vendor\rtplay\rt_hi3861\demo\udp_14_client\wifi_connecter.h文件，该头文件包含wifi连接的宏。文件同tcp_12_client\wifi_connecter.h
文件夹中创建D:\DevEcoProjects\test\src\vendor\rtplay\rt_hi3861\demo\udp_14_client\wifi_connecter.c文件，文件同tcp_12_client\wifi_connecter.c
文件夹中创建D:\DevEcoProjects\test\src\vendor\rtplay\rt_hi3861\demo\udp_14_client\udp_client_example.c文件
/** Copyright (C) 2021 HiHope Open Source Organization .* 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 <stdio.h>
// #include <string.h>
#include <unistd.h>
#include "ohos_init.h"
#include "cmsis_os2.h"#include "net_common.h"
#include "wifi_connecter.h"static char request[] = "Hello.";
static char response[128] = "";#define DELAY_TICKS_10 (10)void UdpClientTest(void)
{WifiDeviceConfig config = {0};// 准备AP的配置参数// strcpy(config.ssid, PARAM_HOTSPOT_SSID);// strcpy(config.preSharedKey, PARAM_HOTSPOT_PSK);strcpy_s(config.ssid, WIFI_MAX_SSID_LEN, PARAM_HOTSPOT_SSID);strcpy_s(config.preSharedKey, WIFI_MAX_KEY_LEN, PARAM_HOTSPOT_PSK);config.securityType = PARAM_HOTSPOT_TYPE;osDelay(DELAY_TICKS_10);int netId = ConnectToHotspot(&config);ssize_t retval = 0;int sockfd = socket(AF_INET, SOCK_DGRAM, 0); // UDP socketstruct sockaddr_in toAddr = {0};toAddr.sin_family = AF_INET;toAddr.sin_port = htons(PARAM_SERVER_PORT); // 端口号，从主机字节序转为网络字节序if (inet_pton(AF_INET, PARAM_SERVER_ADDR, &toAddr.sin_addr) <= 0) { // 将主机IP地址从“点分十进制”字符串 转化为 标准格式（32位整数）printf("inet_pton failed!\r\n");goto do_cleanup;}// UDP socket 是 “无连接的” ，因此每次发送都必须先指定目标主机和端口，主机可以是多播地址retval = sendto(sockfd, request, sizeof(request), 0, (struct sockaddr *)&toAddr, sizeof(toAddr));if (retval < 0) {printf("sendto failed!\r\n");goto do_cleanup;}printf("send UDP message {%s} %ld done!\r\n", request, retval);struct sockaddr_in fromAddr = {0};socklen_t fromLen = sizeof(fromAddr);// UDP socket 是 “无连接的” ，因此每次接收时前并不知道消息来自何处，通过 fromAddr 参数可以得到发送方的信息（主机、端口号）retval = recvfrom(sockfd, &response, sizeof(response), 0, (struct sockaddr *)&fromAddr, &fromLen);if (retval <= 0) {printf("recvfrom failed or abort, %ld, %d!\r\n", retval, errno);goto do_cleanup;}response[retval] = '\0';printf("recv UDP message {%s} %ld done!\r\n", response, retval);printf("peer info: ipaddr = %s, port = %hu\r\n", inet_ntoa(fromAddr.sin_addr), ntohs(fromAddr.sin_port));do_cleanup:printf("do_cleanup...\r\n");close(sockfd);DisconnectWithHotspot(netId);
}SYS_RUN(UdpClientTest);
使用build，编译成功后，使用upload进行烧录。
