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<!DOCTYPE html><html lang="zh-CN" data-theme="light"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no"><title>树莓派Wifi小车(二) | 王恒's Blog</title><meta name="keywords" content="Java,Hadoop,Linux,Shell,C#,PHP,Python,Coder,Arduino,Raspberry pi"><meta name="author" content="王恒"><meta name="copyright" content="王恒"><meta name="format-detection" content="telephone=no"><meta name="theme-color" content="#ffffff"><meta name="description" content="上篇文章 之后，继续折腾我的小车，又用C#和Android 写了两个控制客户端。 思路比较直接，使用POST请求去发送小车转向参数，然后就动起来了。C#不说了，很熟练写起来也非常简单，使用钩子捕获全局键盘，这样及时程序不在前台也能控制小车。 核心代码如下： using System; using System.Collections.Generic; using System.Componen">
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<a title="树莓派Wifi小车(一)" href="http://wangheng.org/raspberry-wifi-car-1.html" target="_blank">上篇文章 </a>之后，继续折腾我的小车，又用C#和Android 写了两个控制客户端。
<p>思路比较直接，使用POST请求去发送小车转向参数，然后就动起来了。C#不说了，很熟练写起来也非常简单，使用钩子捕获全局键盘，这样及时程序不在前台也能控制小车。</p>
<p>核心代码如下：</p>
<pre class="brush: csharp; gutter: true">using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Security;
using System.Runtime.InteropServices;
using System.Text;
using System.Windows.Forms;
namespace WangHeng.Org.PiCar
{
public partial class MainFrm : Form
{
public MainFrm()
{
InitializeComponent();
InitControl();
KeyHookUtils.Hook_Start();
}
private void InitControl()
{
this.StartPosition = FormStartPosition.CenterScreen;
this.Text = "PiCar Control v" + this.ProductVersion;
this.MaximizeBox = false;
this.MinimizeBox = true;
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
this.btnDown.Tag = "t_down";
this.btnLeft.Tag = "t_left";
this.btnRight.Tag = "t_right";
this.btnUp.Tag = "t_up";
this.btnStop.Tag = "t_stop";
this.statusStrip1.SizingGrip = false;
this.lblPostResultInfo.Text = "启动成功！";
}
protected override bool ProcessDialogKey(Keys keyData)
{
if (keyData == Keys.Left)
{
lblPostResultInfo.Text = "left";
}
return base.ProcessDialogKey(keyData);
}
private void ctlButton_Click(object sender, EventArgs e)
{
var btn = sender as Button;
var result = CarCtl.TurnFunc(btn.Tag.ToString());
this.lblPostResultInfo.Text = "请求成功 - " + result;
}
}
public static class CarCtl
{
public enum CarStatus
{
Left,
Right,
Up,
Down,
Stop,
Unknown
}
public static CarStatus CurrentStatus = CarStatus.Unknown;
public static string TurnFunc(string direcID)
{
try
{
var requestUrl = "http://192.168.1.171:2000/ctl";
var requestData = new Dictionary<string, string>() { { "id", direcID } };
var requestUserAgent = "WangHeng PiCar/v1.0";
var requestEncoding = Encoding.Default;
var result = HttpUtility.CreatePostHttpResponse(
requestUrl,
requestData,
5000,
requestUserAgent,
requestEncoding,
null);
using (var sr = new StreamReader(result.GetResponseStream(), requestEncoding))
{
return sr.ReadToEnd();
}
}
catch (Exception ex)
{
return null;
}
}
}
public class KeyHookUtils
{
[StructLayout(LayoutKind.Sequential)]
public class KeyBoardHookStruct
{
public int vkCode;
public int scanCode;
public int flags;
public int time;
public int dwExtraInfo;
}
//委托
public delegate int HookProc(int nCode, int wParam, IntPtr lParam);
static int hHook = 0;
public const int WH_KEYBOARD_LL = 13;
//LowLevel键盘截获，如果是WH_KEYBOARD＝2，并不能对系统键盘截取，Acrobat Reader会在你截取之前获得键盘。
static HookProc KeyBoardHookProcedure;
//设置钩子
[DllImport("user32.dll")]
public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);
//抽掉钩子
[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern bool UnhookWindowsHookEx(int idHook);
//调用下一个钩子
[DllImport("user32.dll")]
public static extern int CallNextHookEx(int idHook, int nCode, int wParam, IntPtr lParam);
[DllImport("kernel32.dll")]
public static extern int GetCurrentThreadId();
[DllImport("kernel32.dll")]
public static extern IntPtr GetModuleHandle(string name);
public static void Hook_Start()
{
if (hHook == 0)
{
KeyBoardHookProcedure = new HookProc(KeyBoardHookProc);
hHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyBoardHookProcedure,
GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName), 0);
//如果设置钩子失败.
if (hHook == 0)
{
Hook_Clear();
}
}
}
/// <summary>
/// 取消钩子事件
/// </summary>
public static void Hook_Clear()
{
bool retKeyboard = true;
if (hHook != 0)
{
retKeyboard = UnhookWindowsHookEx(hHook);
hHook = 0;
}
}
public static int KeyBoardHookProc(int nCode, int wParam, IntPtr lParam)
{
if (nCode >= 0)
{
KeyBoardHookStruct kbh = (KeyBoardHookStruct)Marshal.PtrToStructure(lParam, typeof(KeyBoardHookStruct));
Keys k = (Keys)Enum.Parse(typeof(Keys), kbh.vkCode.ToString());
switch (k)
{
case Keys.Left:
if (kbh.flags == 1)
{
// 这里写按下后做什么事
if (CarCtl.CurrentStatus != CarCtl.CarStatus.Up)
{
CarCtl.TurnFunc("t_left");
CarCtl.CurrentStatus = CarCtl.CarStatus.Up;
}
}
else if (kbh.flags == 129)
{
//放开后做什么事
CarCtl.TurnFunc("t_stop");
CarCtl.CurrentStatus = CarCtl.CarStatus.Stop;
}
return 1;
case Keys.Up:
if (kbh.flags == 1)
{
// 这里写按下后做什么事
if (CarCtl.CurrentStatus != CarCtl.CarStatus.Up)
{
CarCtl.TurnFunc("t_up");
CarCtl.CurrentStatus = CarCtl.CarStatus.Up;
}
}
else if (kbh.flags == 129)
{
//放开后做什么事
CarCtl.TurnFunc("t_stop");
CarCtl.CurrentStatus = CarCtl.CarStatus.Stop;
}
return 1;
case Keys.Right:
if (kbh.flags == 1)
{
if (CarCtl.CurrentStatus != CarCtl.CarStatus.Up)
{
CarCtl.TurnFunc("t_right");
CarCtl.CurrentStatus = CarCtl.CarStatus.Up;
}
}
else if (kbh.flags == 129)
{
//放开后做什么事
CarCtl.TurnFunc("t_stop");
CarCtl.CurrentStatus = CarCtl.CarStatus.Stop;
}
return 1;
case Keys.Down:
if (kbh.flags == 1)
{
if (CarCtl.CurrentStatus != CarCtl.CarStatus.Up)
{
CarCtl.TurnFunc("t_down");
CarCtl.CurrentStatus = CarCtl.CarStatus.Up;
}
}
else if (kbh.flags == 129)
{
//放开后做什么事
CarCtl.TurnFunc("t_stop");
CarCtl.CurrentStatus = CarCtl.CarStatus.Stop;
}
return 1;
default:
break;
}
}
return CallNextHookEx(hHook, nCode, wParam, lParam);
}
}
}
</pre>
<p>这里主要说一下Android 的客户端<span id="more"></span></p>
<p>Android之前虽没怎么接触过，但凭着自己一些基础，还是慢慢摸索到了门路。唯一比较坑的是，在获取Wifi权限的时候，照着网上的介绍改了AndroidManifest.xml 加入</p>
<pre class="brush: java; gutter: true"> <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WAKE_LOCK"/>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/></pre>
<p>依然没有访问网络的权限 :(</p>
<p>为此还特意加了几个Android的开发群，但是群里一个个爱答不理，趾高气扬的态度，我就呵呵了。果断退群，还是得靠自己，扶梯子上Google，一顿搜搜搜，果然有同病相怜的朋友。</p>
<p>原因竟然是一个小问题目标SDK版本不对。。。好吧，果然弱爆了。</p>
<p><a href="uploads/2015/01/android_target_sdk_version_error.png"><img class="alignleft size-medium wp-image-95041" src= "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" data-lazy-src="uploads/2015/01/android_target_sdk_version_error-300x76.png" alt="android_target_sdk_version_error" width="300" height="76" /></a></p>
<p> </p>
<p> </p>
<p> </p>
<p>按上图将Target SDK Version 从18改成19，运行，测试，这次果然可以了。如下：</p>
<p><a href="uploads/2015/01/piCar_screenshot.png"><img class="alignleft size-medium wp-image-95042" src= "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" data-lazy-src="uploads/2015/01/piCar_screenshot-168x300.png" alt="piCar截图" width="168" height="300" /></a></p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p>代码也比较简单，核心代码如下：</p>
<pre class="brush: java; gutter: true">package com.apiof.picar;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.InetAddress;
import java.net.MalformedURLException;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.os.StrictMode;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import android.view.View.OnClickListener;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 禁止屏幕锁屏，也可以用View.setKeepScreenOn(boolean)来实现
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
InitHandler();
TestNetWork();
}
public void DisplayToast(String str)
{
Toast.makeText(this, str, Toast.LENGTH_SHORT).show();
}
public boolean onKeyDown(int KeyCode, KeyEvent event) {
switch (KeyCode) {
case KeyEvent.KEYCODE_0:
DisplayToast("按下数字0");
break;
}
return super.onKeyDown(KeyCode, event);
}
@Override
public boolean onKeyUp(int keyCode,KeyEvent event){
switch(keyCode){
case KeyEvent.KEYCODE_0:
DisplayToast("松开数字0");
break;
}
return super.onKeyUp(keyCode, event);
}
public void TestNetWork() {
String strUrl = "http://nas.apiof.com:2000";
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
.detectDiskReads().detectDiskWrites().detectNetwork()
.penaltyLog().build());
URL url = null;
try {
url = new URL(strUrl);
System.out.println(url.getPort());
HttpURLConnection urlConn = (HttpURLConnection) url
.openConnection();
InputStreamReader in = new InputStreamReader(
urlConn.getInputStream());
BufferedReader br = new BufferedReader(in);
String result = "";
String readerLine = null;
while ((readerLine = br.readLine()) != null) {
result += readerLine;
}
in.close();
urlConn.disconnect();
System.out.println("r:" + result);
TextView textView = (TextView) this.findViewById(R.id.textView2);
textView.setText(result);
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void onBackPressed() {
new AlertDialog.Builder(this).setTitle("确认退出吗？")
.setIcon(android.R.drawable.ic_dialog_info)
.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// 点击“确认”后的操作
MainActivity.this.finish();
}
})
.setNegativeButton("返回", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// 点击“返回”后的操作,这里不设置没有任何操作
}
}).show();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private String intToIp(int i) {
return (i & 0xFF) + "." + ((i >> 8) & 0xFF) + "." + ((i >> 16) & 0xFF)
+ "." + (i >> 24 & 0xFF);
}
public String getLocalIpAddress() {
try {
for (Enumeration<NetworkInterface> en = NetworkInterface
.getNetworkInterfaces(); en.hasMoreElements();) {
NetworkInterface intf = en.nextElement();
for (Enumeration<InetAddress> enumIpAddr = intf
.getInetAddresses(); enumIpAddr.hasMoreElements();) {
InetAddress inetAddress = enumIpAddr.nextElement();
if (!inetAddress.isLoopbackAddress()) {
return inetAddress.getHostAddress().toString();
}
}
}
} catch (SocketException ex) {
Log.e("WifiPreference IpAddress", ex.toString());
}
return null;
}
public void InitHandler() {
// 获取wifi服务
WifiManager wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
// 判断wifi是否开启
if (!wifiManager.isWifiEnabled()) {
wifiManager.setWifiEnabled(true);
}
WifiInfo wifiInfo = wifiManager.getConnectionInfo();
int ipAddress = wifiInfo.getIpAddress();
String ip = intToIp(ipAddress);
TextView txt1 = (TextView) findViewById(R.id.textView1);
txt1.setText(txt1.getText() + "\r\nLocal IP: " + ip);
((Button)findViewById(R.id.btnStop)).setOnClickListener(stopHandler);
((Button)findViewById(R.id.btnForward)).setOnClickListener(upHandler);
((Button)findViewById(R.id.btnBackward)).setOnClickListener(downHandler);
((Button)findViewById(R.id.btnTurnLeft)).setOnClickListener(leftHandler);
((Button)findViewById(R.id.btnTurnRight)).setOnClickListener(rightHandler);
}
private void Trun(String id) {
TextView txt = (TextView) findViewById(R.id.textView2);
try {
String requestUrl = "http://192.168.1.171:2000/ctl";
Map<String, String> requestParams = new HashMap<String, String>();
requestParams.put("id", id);
String result = HttpUtils.submitPostData(requestUrl,
requestParams, "utf-8");
txt.setText("turn to: "+result);
} catch (Throwable e) {
e.printStackTrace();
}
}
private OnClickListener stopHandler=new OnClickListener() {
public void onClick(View v) {
Trun("t_stop");
}
};
private OnClickListener leftHandler=new OnClickListener() {
public void onClick(View v) {
Trun("t_left");
}
};
private OnClickListener rightHandler=new OnClickListener() {
public void onClick(View v) {
Trun("t_right");
}
};
private OnClickListener upHandler=new OnClickListener() {
public void onClick(View v) {
Trun("t_up");
}
};
private OnClickListener downHandler=new OnClickListener() {
public void onClick(View v) {
Trun("t_down");
}
};
}</pre>
<p>完整的代码放到了我的Github 共享，需要的朋友可以参考下载：</p>
<p><a title="pi小车 Android 源码" href="https://github.com/wujiwh/piCar/tree/master/client/android" target="_blank">https://github.com/wujiwh/piCar/tree/master/client/android</a><br></content></p>
</article><div class="post-copyright"><div class="post-copyright__author"><span class="post-copyright-meta">文章作者: </span><span class="post-copyright-info"><a href="http://wangheng.org">王恒</a></span></div><div class="post-copyright__type"><span class="post-copyright-meta">文章链接: </span><span class="post-copyright-info"><a href="http://wangheng.org/raspberry-wifi-car-2.html">http://wangheng.org/raspberry-wifi-car-2.html</a></span></div><div class="post-copyright__notice"><span class="post-copyright-meta">版权声明: </span><span class="post-copyright-info">本博客所有文章除特别声明外，均采用 <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" target="_blank">CC BY-NC-SA 4.0</a> 许可协议。转载请注明来自 <a href="http://wangheng.org" target="_blank">王恒's Blog</a>！</span></div></div><div class="tag_share"><div class="post-meta__tag-list"></div><div class="post_share"><div class="social-share" data-image="https://i.loli.net/2020/05/01/gkihqEjXxJ5UZ1C.jpg" data-sites="wechat,weibo,qq"></div><link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/butterfly-extsrc/sharejs/dist/css/share.min.css" media="print" onload="this.media='all'"><script src="https://cdn.jsdelivr.net/npm/butterfly-extsrc/sharejs/dist/js/social-share.min.js" defer></script></div></div><nav class="pagination-post" id="pagination"><div class="prev-post pull-left"><a href="/raspberry-wifi-car-3.html"><img class="prev-cover" src= "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" data-lazy-src="https://i.loli.net/2020/05/01/gkihqEjXxJ5UZ1C.jpg" onerror="onerror=null;src='/img/404.jpg'" alt="cover of previous post"><div class="pagination-info"><div class="label">上一篇</div><div class="prev_info">树莓派Wifi小车(三)</div></div></a></div><div class="next-post pull-right"><a href="/raspberry-wifi-car-1.html"><img class="next-cover" src= "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" data-lazy-src="https://i.loli.net/2020/05/01/gkihqEjXxJ5UZ1C.jpg" onerror="onerror=null;src='/img/404.jpg'" alt="cover of next post"><div class="pagination-info"><div class="label">下一篇</div><div class="next_info">树莓派Wifi小车(一)</div></div></a></div></nav><hr/><div id="post-comment"><div class="comment-head"><div class="comment-headline"><i class="fas fa-comments fa-fw"></i><span> 评论</span></div></div><div class="comment-wrap"><div><div id="disqus_thread"></div></div></div></div></div><div class="aside-content" id="aside-content"><div class="card-widget card-info"><div class="is-center"><div class="avatar-img"><img src= "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" data-lazy-src="/img/avatar.png" onerror="this.onerror=null;this.src='/img/friend_404.gif'" alt="avatar"/></div><div class="author-info__name">王恒</div><div class="author-info__description">make progress little day by day.</div></div><div class="card-info-data site-data is-center"><a href="/archives/"><div class="headline">文章</div><div class="length-num">86</div></a><a href="/tags/"><div class="headline">标签</div><div class="length-num">132</div></a><a href="/categories/"><div class="headline">分类</div><div class="length-num">7</div></a></div><a id="card-info-btn" target="_blank" rel="noopener" href="https://github.com/all4fun"><i class="fab fa-github"></i><span>关注</span></a></div><div class="sticky_layout"></div></div></main><footer id="footer"><div id="footer-wrap"><div class="copyright">©2020 - 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