基于WiFi模块的Android WiFi通信

忘是亡心i 2022-02-12 11:45 511阅读 0赞

基于ESP8266的Android WiFi通信广泛应用于物联网领域，常用是通过局域网实现Android端和下位机的通信，达到控制目的。

此篇文章记录的内容，需要手机连接到WiFi模块，通过wifi让Android端和硬件部分处于同一个局域网内。Android网络通信通过socket编程实现网络的连接，通过IO流实现数据的发送与接收。

首先，创建一个Android项目，首先，需要给予APP网络权限：

<uses-permission android:name="android.permission.INTERNET" />  
<uses-permission android:name="android.permission.ACCESS\_NETWORK\_STATE" />  
<uses-permission android:name="android.permission.CHANGE\_NETWORK\_STATE" />  
第二步，创建一个类SendThead，内容为发送和接收的代码，首先定义IP，端口port，以及接收/发送’变量，打开套接字实现网络的连接，连接结束关闭套接字，采取多线程实现信息的发送与接收：

package com.example.a14942.smart\_see;  
  
/\*\*  
\* Created by 14942 on 2018/3/26.  
\*/  
  
import android.os.Handler;  
import android.os.Message;  
import android.util.Log;  
  
import java.io.BufferedReader;  
import java.io.BufferedWriter;  
import java.io.IOException;  
import java.io.InputStreamReader;  
import java.io.OutputStreamWriter;  
import java.io.PrintWriter;  
import java.net.Socket;  
import java.net.UnknownHostException;  
import java.util.ArrayList;  
  
class SendThread implements Runnable \{  
  
private String ip;  
private int port;  
BufferedReader in;  
PrintWriter out; //打印流  
Handler mainHandler;  
Socket s;  
private String receiveMsg;  
  
ArrayList<String> list = new ArrayList<String>();  
  
public SendThread(String ip,int port, Handler mainHandler) \{ //IP，端口，数据  
this.ip = ip;  
this.port=port;  
this.mainHandler = mainHandler;  
\}  
  
/\*\*  
\* 套接字的打开  
\*/  
void open()\{  
try \{  
s = new Socket(ip, port);  
//in收单片机发的数据  
in = new BufferedReader(new InputStreamReader(s.getInputStream()));  
out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(  
s.getOutputStream())), true);  
\} catch (IOException e) \{  
e.printStackTrace();  
\}  
\}  
  
/\*\*  
\* 套接字的关闭  
\*/  
void close()\{  
try \{  
s.close();  
\} catch (IOException e) \{  
e.printStackTrace();  
\}  
\}  
  
@Override  
public void run() \{  
  
//创建套接字  
open();  
  
//BufferedReader  
Thread thread = new Thread(new Runnable() \{  
@Override  
public void run() \{  
while (true) \{  
try \{  
Thread.sleep(200);  
close();  
open();  
\} catch (InterruptedException e1) \{  
e1.printStackTrace();  
\}  
if (!s.isClosed()) \{  
if (s.isConnected()) \{  
if (!s.isInputShutdown()) \{  
try \{  
Log.i("mr", "等待接收信息");  
  
char\[\] chars = new char\[1024\]; //byte\[\] bys = new byte\[1024\];  
int len = 0; //int len = 0;  
while((len = in.read(chars)) != -1)\{ //while((len = in.read(bys)) != -1) \{  
System.out.println("收到的消息： "+new String(chars, 0, len)); in.write(bys,0,len);  
receiveMsg = new String(chars, 0, len); // \}  
  
Message msg=mainHandler.obtainMessage();  
msg.what=0x00;  
msg.obj=receiveMsg;  
mainHandler.sendMessage(msg);  
\}  
  
\} catch (IOException e) \{  
Log.i("mr", e.getMessage());  
try \{  
s.shutdownInput();  
s.shutdownOutput();  
s.close();  
\} catch (IOException e1) \{  
e1.printStackTrace();  
\}  
e.printStackTrace();  
\}  
\}  
\}  
\}  
  
\}  
\}  
  
\});  
thread.start();  
  
while (true) \{  
  
//连接中  
if (!s.isClosed()&&s.isConnected()&&!s.isInputShutdown()) \{  
  
// 如果消息集合有东西，并且发送线程在工作。  
if (list.size() > 0 && !s.isOutputShutdown()) \{  
out.println(list.get(0));  
list.remove(0);  
\}  
  
Message msg=mainHandler.obtainMessage();  
msg.what=0x01;  
mainHandler.sendMessage(msg);  
\} else \{  
//连接中断了  
Log.i("mr", "连接断开了");  
Message msg=mainHandler.obtainMessage();  
msg.what=0x02;  
mainHandler.sendMessage(msg);  
\}  
try \{  
Thread.sleep(200);  
\} catch (InterruptedException e) \{  
try \{  
out.close();  
in.close();  
s.close();  
\} catch (IOException e1) \{  
e1.printStackTrace();  
\}  
e.printStackTrace();  
\}  
\}  
  
\}  
  
public void send(String msg) \{  
System.out.println("msg的值为： " + msg);  
list.add(msg);  
\}  
  
\}  
  
第三步，创建主活动，编写布局（xml）文件，这里我创建了一个温度显示框，和两个开关控制按钮（switch控件）：

<?xml version="1.0" encoding="utf-8"?>  
<AbsoluteLayout xmlns:android="http://schemas.android.com/apk/res/android"  
android:id="@+id/screen"  
android:layout\_width="match\_parent"  
android:layout\_height="match\_parent"  
android:orientation="vertical"  
android:background="@drawable/bb"  
>  
  
<LinearLayout  
android:layout\_width="match\_parent"  
android:layout\_height="wrap\_content"  
android:layout\_margin="10dp"  
android:layout\_x="30dp"  
android:layout\_y="130dp"  
android:orientation="horizontal">  
  
  
<TextView  
android:id="@+id/textView2"  
android:layout\_width="50sp"  
android:layout\_height="wrap\_content"  
android:layout\_marginLeft="33px"  
android:text="湿度"  
android:textColor="\#000000"  
android:textSize="18sp" />  
  
<TextView  
android:id="@+id/ttv2"  
android:layout\_width="160sp"  
android:layout\_height="wrap\_content"  
android:background="\#FFFFFF"  
android:text=""  
android:textSize="18sp" />  
  
<TextView  
android:layout\_width="60sp"  
android:layout\_height="wrap\_content"  
android:gravity="center"  
android:paddingLeft="10px"  
android:text="%rh"  
android:textColor="\#000000"  
android:textSize="18sp" />  
  
</LinearLayout>  
  
<TextView  
android:layout\_width="wrap\_content"  
android:layout\_height="wrap\_content"  
android:text="开 关"  
android:textColor="\#000000"  
android:textSize="18sp"  
android:layout\_x="50dp"  
android:layout\_y="200dp"  
/>  
  
<Switch  
android:id="@+id/Switch2"  
android:layout\_width="50sp"  
android:layout\_height="wrap\_content"  
android:layout\_weight="1.01"  
android:layout\_x="210dp"  
android:layout\_y="270dp" />  
  
<TextView  
android:layout\_width="wrap\_content"  
android:layout\_height="wrap\_content"  
android:text="自动手动"  
android:textColor="\#000000"  
android:textSize="18sp"  
android:layout\_x="50dp"  
android:layout\_y="270dp"  
/>  
  
<Switch  
android:id="@+id/Switch1"  
android:layout\_width="50sp"  
android:layout\_height="wrap\_content"  
android:layout\_x="210dp"  
android:layout\_y="200dp" />  
  
</AbsoluteLayout>  
第四步，编写主活动，包括实现网络连接（SendThead），实现消息的发送和接收，对开关控件（switch）定义点击事件：

package com.example.a14942.smart\_see;  
  
import android.os.Bundle;  
import android.os.Handler;  
import android.os.Message;  
import android.support.v4.app.Fragment;  
import android.support.v4.app.FragmentManager;  
import android.support.v4.app.FragmentPagerAdapter;  
import android.support.v7.app.AppCompatActivity;  
import android.util.Log;  
import android.view.View;  
import android.widget.Button;  
import android.widget.CompoundButton;  
import android.widget.Switch;  
import android.widget.TextView;  
  
import java.io.BufferedReader;  
import java.io.PrintWriter;  
import java.util.ArrayList;  
import java.util.List;  
  
public class MainActivity extends AppCompatActivity\{  
  
/\*接收发送定义的常量\*/  
private String mIp = "192.168.4.1";  
private int mPort = 9000;  
private SendThread sendthread;  
String receive\_Msg;  
String l;  
String total0,total1,total2,total3;  
private Button button0;  
private Button button1;  
static PrintWriter mPrintWriterClient = null;  
static BufferedReader mBufferedReaderClient = null;  
Switch switch1,switch2;  
/\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*/  
  
  
@Override  
protected void onCreate(Bundle savedInstanceState) \{  
super.onCreate(savedInstanceState);  
//getSupportActionBar().hide();  
setContentView(R.layout.activity\_main);  
// button0= (Button)findViewById(R.id.Water\_W\_N);  
// button0.setOnClickListener(button0ClickListener);  
// button1= (Button)findViewById(R.id.Water\_W\_O);  
// button1.setOnClickListener(button1ClickListener);  
  
/\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*连接\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*/  
sendthread = new SendThread(mIp, mPort, mHandler);  
Thread1();  
new Thread().start();  
/\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*/  
  
switch1 = (Switch) findViewById(R.id.Switch1);  
switch1.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() \{  
  
@Override  
public void onCheckedChanged(CompoundButton buttonView,  
boolean isChecked) \{  
// TODO Auto-generated method stub  
if (isChecked) \{  
sendthread.send("A");  
\} else \{  
sendthread.send("B");  
\}  
\}  
  
\});  
  
switch2 = (Switch) findViewById(R.id.Switch2);  
switch2.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() \{  
  
@Override  
public void onCheckedChanged(CompoundButton buttonView,  
boolean isChecked) \{  
// TODO Auto-generated method stub  
if (isChecked) \{  
sendthread.send("C");  
\} else \{  
sendthread.send("D");  
\}  
\}  
  
\});  
\}  
// private View.OnClickListener button0ClickListener = new View.OnClickListener() \{  
// public void onClick(View arg0) \{  
// mPrintWriterClient.print("j");  
// mPrintWriterClient.flush();  
//  
// \}  
// \};  
// private View.OnClickListener button1ClickListener = new View.OnClickListener() \{  
// public void onClick(View arg0) \{  
// mPrintWriterClient.print("m");  
// mPrintWriterClient.flush();  
// \}  
// \};  
  
  
private class FragmentAdapter extends FragmentPagerAdapter \{  
List<Fragment> fragmentList = new ArrayList<Fragment>();  
  
public FragmentAdapter(FragmentManager fm, List<Fragment> fragmentList) \{  
super(fm);  
this.fragmentList = fragmentList;  
\}  
  
@Override  
public Fragment getItem(int position) \{  
return fragmentList.get(position);  
\}  
  
@Override  
public int getCount() \{  
return fragmentList.size();  
\}  
  
\}  
  
  
/\*接收线程\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*/  
/\*\*  
\* 开启socket连接线程  
\*/  
void Thread1()\{  
// sendthread = new SendThread(mIp, mPort, mHandler);  
new Thread(sendthread).start();//创建一个新线程  
\}  
  
Handler mHandler = new Handler()  
\{  
public void handleMessage(Message msg)  
\{  
TextView text0 = (TextView)findViewById(R.id.ttv2);  
super.handleMessage(msg);  
if (msg.what == 0x00) \{  
  
Log.i("mr\_收到的数据： ", msg.obj.toString());  
receive\_Msg = msg.obj.toString();  
l = receive\_Msg;  
text0.setText(l);  
\}  
\}  
\};

原文：https://blog.csdn.net/weixin\_40042248/article/details/81099324