Arduino网络编程实战-Ethernet篇-Ethernet篇-Web客户端数据请求

Web客户端数据请求

Arduino Ethernet Shield V1 允许 Arduino 板连接到互联网。它基于 Wiznet W5100ethernet 芯片（数据表）。 Wiznet W5100 提供支持 TCP 和 UDP 的网络 (IP) 堆栈。它最多支持四个同时套接字连接。

本次实例将演示如何实现如何进行HTTP请求。

1、硬件准备

Arduino Mega 2560
Arduino Ethernet Shield
路由器（推荐可以上网、开启DHCP）
网线一条
电脑一台

2、软件准备

Arduino IDE
网络调试软件（推荐使用通信猫)

3、代码实现

#include <SPI.h>
#include <Ethernet.h>


#define USE\_STATIC 0

byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
#if USE\_STATIC
IPAddress ip(192, 168, 0, 177);
#endif

char server[] = "jsonplaceholder.typicode.com";

EthernetClient client;
int byteCount = 0;
void setup() {
  
   Serial.begin(9600);
   Serial.println("Ethernet Http Request Example");
   
#if USE\_STATIC
   Ethernet.begin(mac,ip);
#else
  Ethernet.begin(mac);
#endif

   if (Ethernet.hardwareStatus() == EthernetNoHardware) {
    Serial.println("Ethernet shield was not found. Sorry, can't run without hardware. :(");
    while (true) {
      delay(1); 
    }
  }
  if (Ethernet.linkStatus() == LinkOFF) {
    Serial.println("Ethernet cable is not connected.");
    while(true){
      delay(1);  
    }
  }

  Serial.print("IP:");
  Serial.println(Ethernet.localIP());
  Serial.print("Subnet Mask:");
  Serial.println(Ethernet.subnetMask());
  Serial.print("Gateway:");
  Serial.println(Ethernet.gatewayIP());
  Serial.print("DNS Server:");
  Serial.println(Ethernet.dnsServerIP());


  if (client.connect(server, 80)) {
    Serial.print("connected to ");
    Serial.println(client.remoteIP());
    // Make a HTTP request:
    client.println("GET /comments?id=10 HTTP/1.1");
    client.println("Host: jsonplaceholder.typicode.com");
    client.println("Connection: close");
    client.println();
  } else {
    Serial.println("connection failed");
  }
  
}

void loop() {
  int len = client.available();
  if (len > 0) {
    byte buffer[80];
    if (len > 80) len = 80;
    client.read(buffer, len);
  
   Serial.write(buffer, len); 
  
    byteCount = byteCount + len;
  }

  
  if (!client.connected()) {
   
    Serial.println();
    Serial.println("disconnecting.");
    client.stop();
    Serial.print("Received ");
    Serial.print(byteCount);
   
    // do nothing forevermore:
    while (true) {
      delay(1);
    }
  }
}