树莓派与安卓手机app的WIFI通信（局域网通信）

参考：树莓派与安卓手机app的WIFI通信（局域网通信）
作者：图触靓
发布时间： 2020-07-29 10:18:12
网址：https://blog.csdn.net/bhbhhyg/article/details/107655967

树莓派作为服务器

与树莓派与wemos的无线通信类似，只不过这次我们将客户端变为安卓手机，树莓派作为服务器。

#include <sys/types.h>
#include <sys/socket.h>
#include<netinet/in.h>
#include <arpa/inet.h>
#include<stdio.h>
#include<stdlib.h>
#include <unistd.h>
#include<string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int initsocket(){int s_fd=socket(AF_INET, SOCK_STREAM,0);if (s_fd==-1){perror("socket");exit(-1);}struct sockaddr_in addr;memset(&addr,0,sizeof(struct sockaddr_in));addr.sin_family=AF_INET;addr.sin_port=htons(9001); //端口号inet_aton("192.168.200.XXX",&addr.sin_addr);//IP地址//        addr.sin_port=htons(atoi(argv[2]));//       inet_aton(argv[1],&addr.sin_addr);int bid=bind(s_fd,(struct sockaddr *)&addr,sizeof(struct sockaddr_in));listen(s_fd,10);int len=sizeof(struct sockaddr_in);return s_fd;
}int main(){char readbuf[2]={0};int s_fd=initsocket();  //初始化服务器printf("wait connect.....\n");while(1){int fd_a=accept(s_fd,NULL,NULL); //该函数用来接受连接，没有连接的时候也可以用来阻塞while（1）printf("connect\n");memset(readbuf,0,2);           //初始化字符串int r=read(fd_a,readbuf,2);   //读指令if(r==-1){perror("read");}else{printf("  cmd is %c \n",readbuf[0]);//打印安卓客户端发来的指令}

安卓端连接服务器的方法

package com.example.smarthome;import java.io.OutputStream;
import java.net.Socket;import android.os.Handler;public class NetUtils {public String message;public String reTurnMes;public Handler handler;public NetUtils(String message) {this.message = message;}public NetUtils(String message, Handler handler) {this.message = message;this.handler = handler;}public void sendMessage() {new Thread(new Runnable() {@Overridepublic void run() {try {Socket client = new Socket("192.168.XXX.XXX",9001);//与服务器对应的IP地址与端口号OutputStream out = client.getOutputStream(); out.write(message.getBytes());  //像服务器发送信息out.close();    //关闭输入流client.close();  //客户端的连接} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}}).start();}
}

安卓AndroidManifest中需要添加的权限：

     <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /><uses-permission android:name="android.permission.INTERNET" />

安卓按键发送的写法

Button kd=(Button)findViewById(R.id.kd);
kd.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View arg0) {new NetUtils("A").sendMessage();}});