Android 获取扫码枪的扫描内容

思路：

重写Activity的dispatchKeyEvent()方法  将获取到的内容自定义处理  然后再回调得到扫描内容

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements ScannerKeyEventHelper.OnScanSuccessListener {
    private ScannerKeyEventHelper mScannerKeyEventHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mScannerKeyEventHelper = new ScannerKeyEventHelper(this);

    }
    /**
     * 截取按键事件 分发给扫描枪解析类
     * 这里没有返回true进行事件拦截是由于 业务需要在HTML中input有焦点时自动查询
     * @param event
     * @return
     */
    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        mScannerKeyEventHelper.analysisKeyEvent(event);
        return super.dispatchKeyEvent(event);
    }

    /**
     * 扫描成功回调
     * @param barcode
     */
    @Override
    public void onScanSuccess(String barcode) {
        Toast.makeText(MainActivity.this,"扫描枪内容："+barcode,Toast.LENGTH_SHORT).show();
        //根据业务需求处理扫描到的内容
    }

    @Override
    protected void onDestroy() {
        mScannerKeyEventHelper.onDestroy();
        super.onDestroy();
    }
}

扫描枪解析类：

public class ScannerKeyEventHelper {

    private StringBuffer mStringBufferResult;           //扫描内容
    private boolean mCaps;                              //大小写
    private final Handler mHandler;
    private final Runnable mScanningFinishedRunnable;
    private OnScanSuccessListener mOnScanSuccessListener;

    public ScannerKeyEventHelper(OnScanSuccessListener onScanSuccessListener){
        mOnScanSuccessListener = onScanSuccessListener;
        mStringBufferResult = new StringBuffer();
        mHandler = new Handler();
        mScanningFinishedRunnable = new Runnable() {
            @Override
            public void run() {
                performScanSuccess();
            }
        };
    }

    /**
     * 扫描成功结果
     */
    private void performScanSuccess(){
        String barcode = mStringBufferResult.toString();
        if(mOnScanSuccessListener != null)
            mOnScanSuccessListener.onScanSuccess(barcode);
        mStringBufferResult.setLength(0);
    }

    /**
     * 扫描事件解析
     * @param event
     */
    public void analysisKeyEvent(KeyEvent event){
        int keyCode = event.getKeyCode();
        //判断字母大小写
        checkLetterStatus(event);
        if(event.getAction() == KeyEvent.ACTION_DOWN)
        {
            char aChar  = getInputCode(event);
            if(aChar != 0)
            {
                mStringBufferResult.append(aChar);
            }
            if(keyCode == KeyEvent.KEYCODE_ENTER)
            {
                //回车键 返回
                mHandler.removeCallbacks(mScanningFinishedRunnable);
                mHandler.post(mScanningFinishedRunnable);
            }

        }
    }

    /**
     * shift键
     * @param keyEvent
     */
    private void checkLetterStatus(KeyEvent keyEvent){
        int keyCode = keyEvent.getKeyCode();
        if(keyCode == KeyEvent.KEYCODE_SHIFT_LEFT || keyCode == KeyEvent.KEYCODE_SHIFT_RIGHT)
        {
            if(keyEvent.getAction() == KeyEvent.ACTION_DOWN)
            {
                //按住shift键 大写
                mCaps = true;
            }
            else
            {
                //小写
                mCaps = false;
            }
        }
    }

    /**
     * 获取扫描内容
     * @param keyEvent
     * @return
     */
    private char getInputCode(KeyEvent keyEvent){
        char aChar;
        int keyCode = keyEvent.getKeyCode();
        Log.i("TAGKEYCODE",keyCode+"");
        if(keyCode >= KeyEvent.KEYCODE_A && keyCode <= keyEvent.KEYCODE_Z)//29< keycode <54
        {
            //字母
            aChar = (char)((mCaps?'A':'a')+keyCode - KeyEvent.KEYCODE_A);//
        }
        else if (keyCode >= KeyEvent.KEYCODE_0 && keyCode <= KeyEvent.KEYCODE_9)
        {
            //数字
            if(mCaps)//是否按住了shift键
            {
                //按住了 需要将数字转换为对应的字符
                switch (keyCode)
                {
                    case KeyEvent.KEYCODE_0:
                        aChar = ')';
                        break;
                    case KeyEvent.KEYCODE_1:
                        aChar = '!';
                        break;
                    case KeyEvent.KEYCODE_2:
                        aChar = '@';
                        break;
                    case KeyEvent.KEYCODE_3:
                        aChar = '#';
                        break;
                    case KeyEvent.KEYCODE_4:
                        aChar = '$';
                        break;
                    case KeyEvent.KEYCODE_5:
                        aChar = '%';
                        break;
                    case KeyEvent.KEYCODE_6:
                        aChar = '^';
                        break;
                    case KeyEvent.KEYCODE_7:
                        aChar = '&';
                        break;
                    case KeyEvent.KEYCODE_8:
                        aChar = '*';
                        break;
                    case KeyEvent.KEYCODE_9:
                        aChar = '(';
                        break;
                    default:
                        aChar = ' ';
                        break;
                }
            }
            else
            {
                aChar = (char)('0'+keyCode- KeyEvent.KEYCODE_0);
            }

        }
        else
        {
            //其他符号
            switch (keyCode)
            {
                case KeyEvent.KEYCODE_PERIOD:
                    aChar = '.';
                    break;
                case KeyEvent.KEYCODE_MINUS:
                    aChar = mCaps?'_':'-';
                    break;
                case KeyEvent.KEYCODE_SLASH:
                    aChar = '/';
                    break;
                case KeyEvent.KEYCODE_STAR:
                    aChar = '*';
                    break;
                case KeyEvent.KEYCODE_POUND:
                    aChar = '#';
                    break;
                case KeyEvent.KEYCODE_SEMICOLON:
                    aChar = mCaps?':':';';
                    break;
                case KeyEvent.KEYCODE_AT:
                    aChar = '@';
                    break;
                case KeyEvent.KEYCODE_BACKSLASH:
                    aChar = mCaps?'|':'\\';
                    break;
                default:
                    aChar = ' ';
                    break;
            }
        }

        return aChar;
    }

    public interface OnScanSuccessListener{
        void onScanSuccess(String barcode);
    }

    public void onDestroy(){
        mHandler.removeCallbacks(mScanningFinishedRunnable);
        mOnScanSuccessListener = null;
    }

}