我正在创建一个Android USB主机应用程序包含登录页面，当我第一次登录成功登录时，当我按下后退按钮并再次进入登录页面时我按下登录按钮然后我的应用程序崩溃。 ..请帮我解决这个问题......
这是我的java代码：
import java.nio.ByteBuffer;
import java.util.HashMap;
import android.annotation.SuppressLint;
import android.app.ActionBar;
import android.app.Activity;
import android.content.Intent;
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.hardware.usb.UsbRequest;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import com.example.demo2c1testpanel.LifeTest;
import com.example.demo2c1testpanel.DriveResponseTest;
public class Loginpage extends Activity
{
public static final int targetVendorID = 1155;
public static final int targetProductID = 22336;
public UsbManager manager;
public UsbDeviceConnection usbDeviceConnection;
public UsbInterface usbInterfaceFound = null;
public UsbEndpoint endpointOut = null;
public UsbEndpoint endpointIn = null;
public UsbDevice usbdevice,device_details;
public UsbEndpoint listusbendpoint;
public LifeTest Life_Test_child;
HashMap<String, UsbDevice> devicelist= null;
int selectedendpoint;
static int Coil_No;
private static final int VID = 1155;
private static final int PID = 22336;
private static UsbDriver Usb_Driver_class;
ActionBar actionbar;
UsbConnectionHandler connectionHandler;
public static UsbDriver USB_Driver_Child;
public static boolean Communication_Failed,Frame_Ok,Total_Frame_Decoded;
static byte[] Communication_Byte;
Button clear,signin;
EditText username,password;
String i = "";
Intent i2;
String User_Name=null;
TextView title;
ByteBuffer buffer;
static byte[] sample;
static boolean Communication_Ok;
public static float []Wave_Form_Data=new float[1500];
public static float []Wave_Form_Data_1=new float[1500];
public static float Respsonse_Time,Drive_Voltage;
static int Sequence_No,Response_Time;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.loginpage);
actionbar = getActionBar();
actionbar.hide();
username = (EditText)findViewById(R.id.edt_username);
password = (EditText)findViewById(R.id.edt_password);
title = (TextView)findViewById(R.id.textView1);
title.setSelected(true);
signin = (Button)findViewById(R.id.btn_signin);
signin.setOnClickListener(new View.OnClickListener() {
@SuppressWarnings("static-access")
@Override
public void onClick(View v)
{
{
Communication_Byte=new byte[1];
User_Name=username.getText().toString();
if(User_Name.toLowerCase().equals("medequip") && password.getText().toString().equals("medequip"))
{
if(Check_Devices_Available()==true)
{
int Packet_Size = USB_Driver_Child.Data_In_End_Point.getMaxPacketSize();
Toast.makeText(Loginpage.this,""+Packet_Size, Toast.LENGTH_LONG).show();
Receive.start();
Communication_Ok=false;
for(int i=0;(i<5 && Communication_Ok!=true);i++)
Send_Communication_Check_Command();
if(Communication_Ok)
Toast.makeText(Loginpage.this, "Communication Successfully Established", 1000).show();
else
Toast.makeText(Loginpage.this, "Communication Failure", 10000).show();
i2 = new Intent(Loginpage.this,TestsPage.class);
startActivity(i2);
}
}
else
{
Toast.makeText(Loginpage.this,"Invalid username and password", Toast.LENGTH_LONG).show();
}
}
}
});
clear = (Button)findViewById(R.id.btn_clear);
clear.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
username.setText("");
password.setText("");
}
});
}
@SuppressLint("ShowToast") @SuppressWarnings({ "static-access" })
public boolean Check_Devices_Available()
{
Usb_Driver_class = new UsbDriver(this, connectionHandler, VID, PID);
if(USB_Driver_Child.Device_Exception==0)
{
if(USB_Driver_Child.USB_Device_Connection==null || USB_Driver_Child.Data_Out_End_Point==null)
return false;
Toast.makeText(Loginpage.this,"Device Found", 1000).show();
return true;
}
else if(USB_Driver_Child.Device_Exception==1)
{
Toast.makeText(Loginpage.this,"No Devices Attached ", Toast.LENGTH_LONG).show();
return false;
}
else if(USB_Driver_Child.Device_Exception==2)
{
Toast.makeText(Loginpage.this,"Device Found,But No End Points", Toast.LENGTH_LONG).show();
return false;
}
else if(USB_Driver_Child.Device_Exception==3)
{
Toast.makeText(Loginpage.this,"Unable to Open Device", Toast.LENGTH_LONG).show();
return false;
}
return false; //un known exception
}
Thread Receive = new Thread(new Runnable()
{
@SuppressWarnings("unused")
@Override
public void run()
{
Sequence_No=0;
buffer = ByteBuffer.allocate(1500);
sample = new byte[1500];
int Frame_Size;
UsbRequest request = new UsbRequest();
int i,j;
byte [] datarx=new byte[1];
char q;
while (true)
{
request.initialize(UsbDriver.USB_Device_Connection, UsbDriver.Data_In_End_Point);
request.queue(buffer, 1500);
if (UsbDriver.USB_Device_Connection.requestWait() == request)
{
sample=buffer.array();
for(i=0;i<1500;i++)
{
if(sample[i]=='&')
{
Communication_Ok=true;
break;
}
else if(sample[i]==0x03)
{
if(sample[0]==0x02)
Frame_Ok=true;
break;
}
}
if(Frame_Ok==true)
{
Frame_Ok=false;
if(sample[1]==1)
Coil_No=1;
else
Coil_No=2;
Response_Time= (int)(((sample[2]&0x00FF)<<8) + (sample[3]&0x00FF));
Total_Frame_Decoded=true;
sample = null;
}
}
}
}
});
private static void Send_Communication_Check_Command()
{
long i,j;
Communication_Byte[0]='&';
UsbDriver.USB_Device_Connection.bulkTransfer(UsbDriver.Data_Out_End_Point,Communication_Byte, 1, 0);
for(i=0;(i<1000 && Communication_Ok!=true) ;i++)
for(j=0;(j<1000 && Communication_Ok!=true);j++);
}
//Test_Name=1; For Drive Response Test
//Test_Name=2; For Drive Life Test
//Test_Name=3; To Stop test
public static void Send_Command_For_Drive_Response_Test(int Test_Name)
{
int i;
byte []Command_To_Transfer= new byte[5];
Communication_Ok=false;
for(i=0;i<5;i++)
{
Send_Communication_Check_Command();
if(Communication_Ok==true)
break;
}
if(Communication_Ok==true)
{
Command_To_Transfer[0]='*';
if(Test_Name==1)
{
Command_To_Transfer[1]=Command_To_Transfer[2]=(byte) 0xA1;
}
else if(Test_Name==2)
{
Command_To_Transfer[1]=Command_To_Transfer[2]=(byte) 0xA2;
}
else if(Test_Name==3)
{
Command_To_Transfer[1]=Command_To_Transfer[2]=(byte) 0xA3;
}
Command_To_Transfer[3]=0; //For Future Reference
Command_To_Transfer[4]='#';
UsbDriver.USB_Device_Connection.bulkTransfer(UsbDriver.Data_Out_End_Point,Command_To_Transfer, 5, 0);
Communication_Failed=true;
}
else
{
Communication_Failed=false;
}
}
}
这是我的USB驱动程序：
/*
* UsbController.java
* This file is part of UsbController
*
* Copyright (C) 2012 - Manuel Di Cerbo
*
* UsbController is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* UsbController is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with UsbController. If not, see <http://www.gnu.org/licenses/>.
*/
import java.util.HashMap;
import java.util.Iterator;
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.UsbConstants;
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.util.Log;
public class UsbDriver
{
private final Context mApplicationContext;
private final UsbManager mUsbManager;
@SuppressWarnings("unused")
private final UsbConnectionHandler mConnectionHandler;
private final int VID;
private final int PID;
protected static final String ACTION_USB_PERMISSION = "ch.serverbox.android.USB";
public static int Device_Exception;
public static UsbDevice Device_Details;
public static UsbEndpoint Data_In_End_Point = null;
public static UsbEndpoint Data_Out_End_Point = null;
public static UsbDeviceConnection USB_Device_Connection;
public UsbDriver(Activity parentActivity,UsbConnectionHandler connectionHandler, int vid, int pid)
{
mApplicationContext = parentActivity.getApplicationContext();
mConnectionHandler = connectionHandler;
mUsbManager = (UsbManager) mApplicationContext.getSystemService(Context.USB_SERVICE);
VID = 1155;
PID = 22336;
Device_Exception = 0;
// init();
Check_Devices();
}
public void Check_Devices()
{
@SuppressWarnings("unused")
int j=0;
HashMap<String, UsbDevice> devlist = mUsbManager.getDeviceList();
Iterator<UsbDevice> deviter = devlist.values().iterator();
Device_Details = null;
if (devlist.size() != 0)
{
while (deviter.hasNext())
{
Device_Details = deviter.next();
if (Device_Details.getVendorId() == VID && Device_Details.getProductId() == PID)
{
if (!mUsbManager.hasPermission(Device_Details))
{
onPermissionDenied(Device_Details);
}
else
{
UsbDeviceConnection conn = mUsbManager.openDevice(Device_Details);
if (!conn.claimInterface(Device_Details.getInterface(1), true))
{
return;
}
conn.controlTransfer(0x21, 34, 0, 0, null, 0, 0);
conn.controlTransfer(0x21, 32, 0, 0,new byte[] { (byte) 0x80, 0x25 , 0x00, 0x00,0x00, 0x00, 0x08 }, 7, 0);
USB_Device_Connection=conn;
Data_In_End_Point = null;
Data_Out_End_Point = null;
UsbInterface usbIf = Device_Details.getInterface(1);
for (int i = 0; i < usbIf.getEndpointCount(); i++)
{
if (usbIf.getEndpoint(i).getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)
{
if (usbIf.getEndpoint(i).getDirection() == UsbConstants.USB_DIR_IN)
Data_In_End_Point = usbIf.getEndpoint(i);
else
Data_Out_End_Point = usbIf.getEndpoint(i);
}
}
if (Data_In_End_Point == null || Data_Out_End_Point == null)
Device_Exception = 2;
}
break;
}j++;
}
if (Device_Details == null)
{
Device_Exception = 3;
return;
}
}
else
{
Device_Exception = 1;
return;
}
}
public void onPermissionDenied(UsbDevice d)
{
UsbManager usbman = (UsbManager) mApplicationContext.getSystemService(Context.USB_SERVICE);
PendingIntent pi = PendingIntent.getBroadcast(mApplicationContext, 0, new Intent(ACTION_USB_PERMISSION), 0);
mApplicationContext.registerReceiver(mPermissionReceiver,new IntentFilter(ACTION_USB_PERMISSION));
usbman.requestPermission(d, pi);
}
private class PermissionReceiver extends BroadcastReceiver
{
private final IPermissionListener mPermissionListener;
public PermissionReceiver(IPermissionListener permissionListener)
{
mPermissionListener = permissionListener;
}
@Override
public void onReceive(Context context, Intent intent)
{
mApplicationContext.unregisterReceiver(this);
if (intent.getAction().equals(ACTION_USB_PERMISSION))
{
if (!intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false))
{
mPermissionListener.onPermissionDenied((UsbDevice) intent.getParcelableExtra(UsbManager.EXTRA_DEVICE));
}
else
{
l("Permission granted");
UsbDevice dev = (UsbDevice) intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (dev != null)
{
if (dev.getVendorId() == VID && dev.getProductId() == PID)
{
Check_Devices() ;
}
}
else
{
e("device not present!");
}
}
}
}
}
private BroadcastReceiver mPermissionReceiver = new PermissionReceiver(new IPermissionListener()
{
@Override
public void onPermissionDenied(UsbDevice d)
{
l("Permission denied on " + d.getDeviceId());
}
});
private static interface IPermissionListener
{
void onPermissionDenied(UsbDevice d);
}
public final static String TAG = "USBController";
private void l(Object msg)
{
Log.d(TAG, ">==<" + msg.toString() + " >==<");
}
private void e(Object msg)
{
Log.e(TAG, ">==< " + msg.toString() + " >==<");
}
}
这是我的Logcat：
01-05 06:17:51.794: W/dalvikvm(6120): threadid=1: thread exiting with uncaught exception (group=0x41994700)
01-05 06:17:51.804: E/AndroidRuntime(6120): FATAL EXCEPTION: main
01-05 06:17:51.804: E/AndroidRuntime(6120): java.lang.IllegalThreadStateException: Thread already started
01-05 06:17:51.804: E/AndroidRuntime(6120): at java.lang.Thread.checkNotStarted(Thread.java:871)
01-05 06:17:51.804: E/AndroidRuntime(6120): at java.lang.Thread.start(Thread.java:1025)
01-05 06:17:51.804: E/AndroidRuntime(6120): at com.example.demo2c1testpanel.Loginpage$2.onClick(Loginpage.java:89)
01-05 06:17:51.804: E/AndroidRuntime(6120): at android.view.View.performClick(View.java:4240)
01-05 06:17:51.804: E/AndroidRuntime(6120): at android.view.View$PerformClick.run(View.java:17721)
01-05 06:17:51.804: E/AndroidRuntime(6120): at android.os.Handler.handleCallback(Handler.java:730)
01-05 06:17:51.804: E/AndroidRuntime(6120): at android.os.Handler.dispatchMessage(Handler.java:92)
01-05 06:17:51.804: E/AndroidRuntime(6120): at android.os.Looper.loop(Looper.java:137)
01-05 06:17:51.804: E/AndroidRuntime(6120): at android.app.ActivityThread.main(ActivityThread.java:5103)
01-05 06:17:51.804: E/AndroidRuntime(6120): at java.lang.reflect.Method.invokeNative(Native Method)
01-05 06:17:51.804: E/AndroidRuntime(6120): at java.lang.reflect.Method.invoke(Method.java:525)
01-05 06:17:51.804: E/AndroidRuntime(6120): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
01-05 06:17:51.804: E/AndroidRuntime(6120): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
01-05 06:17:51.804: E/AndroidRuntime(6120): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
我必须检查线程状态。这是我在接收线程中的工作代码
if(!Receive.isAlive())
{
Receive.start();
}