Android USB编程


一、什么是USB

USB就是通用串行总线（Universal Serial Bus）的缩写，用于规范主从通信。USB接口支持设备的即插即用和热插拔功能。

与USB有关的OTG既是On-The-Go，主要用于各种不同的设备或移动设备件间的链接和数据交换。

二、Android的USB相关API

包：android.hardware.usb

类：UsbManager/UsbDevice/UsbInterface/UsbEndPoint/UsbDeviceConnection/UsbRequest/UsbConstants/UsbAccessory

获取UsbManager:UsbManager manager = (UsbManager)getSystemService(Context.USB_SERVICE);

三、Android设备与USB设备

第一种模式Host Mode：Android设备作为Host,向Usb设备供电，并进行数据传输；

第一种模式Accessory Mode：Usb设备作为Host,向Android设备供电，并进行数据传输；

四、例子（可以枚举设备/点击设备建立连接/接收数据/发送数据）

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.example.usbhelper"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk

android:minSdkVersion="8"

android:targetSdkVersion="21" />

<uses-feature android:name="android.hardware.usb.host" />

<application

android:allowBackup="true"

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name=".MainActivity"

android:label="@string/app_name" >

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

<receiver android:name=".UsbReceiver" >

<intent-filter android:priority="1000" >

<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />

</intent-filter>

</receiver>

</application>

</manifest>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.example.usbhelper"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk

android:minSdkVersion="8"

android:targetSdkVersion="21" />

<uses-feature android:name="android.hardware.usb.host" />

<application

android:allowBackup="true"

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name=".MainActivity"

android:label="@string/app_name" >

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

<receiver android:name=".UsbReceiver" >

<intent-filter android:priority="1000" >

<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />

</intent-filter>

</receiver>

</application>

</manifest>

item.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.example.usbhelper"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk

android:minSdkVersion="8"

android:targetSdkVersion="21" />

<uses-feature android:name="android.hardware.usb.host" />

<application

android:allowBackup="true"

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name=".MainActivity"

android:label="@string/app_name" >

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

<receiver android:name=".UsbReceiver" >

<intent-filter android:priority="1000" >

<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />

</intent-filter>

</receiver>

</application>

</manifest>

MainActivity.java

package com.example.usbhelper;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Iterator;

import android.annotation.SuppressLint;

import android.app.Activity;

import android.app.PendingIntent;

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.content.IntentFilter;

import android.hardware.usb.UsbDevice;

import android.hardware.usb.UsbDeviceConnection;

import android.hardware.usb.UsbEndpoint;

import android.hardware.usb.UsbInterface;

import android.hardware.usb.UsbManager;

import android.os.Bundle;

import android.os.Handler;

import android.os.Message;

import android.util.Log;

import android.view.View;

import android.widget.AdapterView;

import android.widget.AdapterView.OnItemClickListener;

import android.widget.Button;

import android.widget.EditText;

import android.widget.ListView;

import android.widget.SimpleAdapter;

import android.widget.TextView;

import android.widget.Toast;

@SuppressLint("NewApi")

public class MainActivity extends Activity {

private Button send = null;

private Button receive = null;

private Button list = null;

private ListView information = null;

private EditText content = null;

private TextView result = null;

private Handler mHandler = null;

private ArrayList<UsbDevice> devicesList = null;

private ArrayList<HashMap<String, Object>> showDevices = null;

private SimpleAdapter adapter = null;

private boolean isRunning = false;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

mHandler = new Handler() {

@Override

public void handleMessage(Message msg) {

// TODO Auto-generated method stub

// super.handleMessage(msg);

int what = msg.what;

switch (what) {

case 0: {

String string = msg.obj.toString();

result.setText(result.getText().toString() + "\n" + string);

}

break;

default:

break;

}

}

};

initData();

}

private UsbManager mUsbManager = null;

private void initData() {

findViewsById();

showDevices = new ArrayList<HashMap<String, Object>>();

devicesList = new ArrayList<UsbDevice>();

mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);

registerUsbReceiver();

initListView();

}

private PendingIntent mPermissionIntent = null;

private void registerUsbReceiver() {

mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(

ACTION_USB_PERMISSION), 0);

IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);

registerReceiver(mUsbReceiver, filter);

}

private void findViewsById() {

send = (Button) findViewById(R.id.btn_send_main);

receive = (Button) findViewById(R.id.btn_receive_main);

content = (EditText) findViewById(R.id.et_content_main);

result = (TextView) findViewById(R.id.tv_result_main);

list = (Button) findViewById(R.id.btn_list_main);

information = (ListView) findViewById(R.id.lv_devices_main);

send.setOnClickListener(mOnClickListener);

receive.setOnClickListener(mOnClickListener);

list.setOnClickListener(mOnClickListener);

information.setOnItemClickListener(new OnItemClickListener() {

@Override

public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,

long arg3) {

// TODO Auto-generated method stub

mUsbManager.requestPermission(devicesList.get(arg2),

mPermissionIntent);

}

});

}

private void listTheDevice() {

if (mUsbManager == null) {

return;

}

HashMap<String, UsbDevice> devices = mUsbManager.getDeviceList();

Iterator<UsbDevice> iterator = devices.values().iterator();

showDevices.clear();

devicesList.clear();

while (iterator.hasNext()) {

UsbDevice device = iterator.next();

HashMap<String, Object> map = new HashMap<String, Object>();

map.put("device_id", device.getDeviceId());

map.put("device_name", device.getDeviceName());

showDevices.add(map);

devicesList.add(device);

}

if (showDevices.size() > 0) {

adapter = new SimpleAdapter(MainActivity.this, showDevices,

R.layout.item, new String[] { "device_id", "device_name" },

new int[] { R.id.device_id, R.id.device_name });

information.setAdapter(adapter);

}

Toast.makeText(this, "设备数：" + devicesList.size(), Toast.LENGTH_SHORT)

.show();

}

private void initListView() {

HashMap<String, Object> map = new HashMap<String, Object>();

map.put("device_id", "测试数据");

map.put("device_name", "测试数据");

showDevices.add(map);

adapter = new SimpleAdapter(MainActivity.this, showDevices,

R.layout.item, new String[] { "device_id", "device_name" },

new int[] { R.id.device_id, R.id.device_name });

information.setAdapter(adapter);

}

private View.OnClickListener mOnClickListener = new View.OnClickListener() {

@Override

public void onClick(View arg0) {

// TODO Auto-generated method stub

int id = arg0.getId();

switch (id) {

case R.id.btn_list_main:

listTheDevice();

break;

case R.id.btn_send_main: {

String message = content.getText().toString();

if (message != null && message.length() > 0) {

new Thread(new SendRunnable(message.getBytes()));

}

}

break;

case R.id.btn_receive_main: {

if (isRunning) {

isRunning = false;

} else {

isRunning = true;

new Thread(new ReceiveRunnable()).start();

}

}

break;

default:

Toast.makeText(MainActivity.this, "我真的不知道你对我做了什么",

Toast.LENGTH_SHORT).show();

break;

}

}

};

private class ReceiveRunnable implements Runnable {

public void run() {

byte[] buffer = new byte[64];

while (isRunning) {

mDeviceConnection.bulkTransfer(epin, buffer, buffer.length, 0);

Message msg = new Message();

msg.what = 0;

msg.obj = new String(buffer);

mHandler.sendMessage(msg);

System.out.println("received true");

}

}

}

private class SendRunnable implements Runnable {

private byte[] buffer;

public SendRunnable(byte[] buffer) {

this.buffer = buffer;

}

public void run() {

int length = mDeviceConnection.bulkTransfer(epout, buffer,

buffer.length, 0);

if (length > 0) {

mDeviceConnection.bulkTransfer(epin, buffer, buffer.length, 0);

Message msg = new Message();

msg.what = 0;

msg.obj = new String(buffer);

mHandler.sendMessage(msg);

}

}

}

// mUsbManager.requestPermission(device, mPermissionIntent);

private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";

private UsbDeviceConnection mDeviceConnection = null;

private UsbEndpoint epin = null;

private UsbEndpoint epout = null;

private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {

public void onReceive(Context context, Intent intent) {

String action = intent.getAction();

if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) {

} else if (ACTION_USB_PERMISSION.equals(action)) {

synchronized (this) {

UsbDevice mUsbDevice;

mUsbDevice = (UsbDevice) intent

.getParcelableExtra(UsbManager.EXTRA_DEVICE);

if (intent.getBooleanExtra(

UsbManager.EXTRA_PERMISSION_GRANTED, false)) {

if (mUsbDevice != null) {

// call method to set up device communication

UsbInterface intf = mUsbDevice.getInterface(0);

epin = intf.getEndpoint(0);

epout = intf.getEndpoint(1);

mDeviceConnection = mUsbManager

.openDevice(mUsbDevice);

mDeviceConnection.claimInterface(intf, true);

}

} else {

Log.d("UsbHelper", "permission denied for device "

+ mUsbDevice.getDeviceName());

}

}

}

}

};

}

UsbReceiver.java

package com.example.usbhelper;

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.sax.StartElementListener;

public class UsbReceiver extends BroadcastReceiver {

@Override

public void onReceive(Context arg0, Intent arg1) {

// TODO Auto-generated method stub

Intent intent = new Intent(arg0, MainActivity.class);

intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

arg0.startActivity(intent);

}

}

五、小结

USB通信是一种不会磨灭的通信，你懂的。随着物联网的到来和发展，WIFI/蓝牙/Zigbee火起来的，但随着物联网的进一步发展，USB或者类似的通信协议也将会得到空前的应用，因为，组件化会成为智能产品快速研发的关键，即插即用，安全可靠。