掃碼槍是如何工作的，安卓如何怎么獲取掃碼槍的內容。本文將介紹安卓獲取和處理商米收銀機掃碼槍掃描后的內容。包括：“安卓開發獲取掃碼槍掃描后的內容”、“處理掃碼槍掃描后的內容”、“在Fragment中使用ScanGun類”。

1、安卓開發獲取掃碼槍掃描后的內容。

掃碼槍會將掃描出來的內容轉化為鍵盤事件KeyEvent，所以我們在fragment類中重寫onKeyDownChild方法，就可以捕獲掃碼事件，進而獲取掃碼內容：

public void onKeyDownChild(int keyCode, KeyEvent event) {log.info("---------------------------------onKeyDown: KeyCode:" + keyCode + "------event:" + event + "------------------------------------");scanGun.isMaybeScanning(keyCode, event); }

2、處理掃碼槍掃描后的內容。

SanGun類定義一個isMayBeScanning方法，掃碼槍掃描后觸發鍵盤事件，在鍵盤事件中調用isMayBeScanning方法，進而解析獲取掃碼內容：

查看代碼 package com.bx.erp.helper;import android.view.KeyEvent;import org.apache.log4j.Logger;public class ScanGun {private Logger log = Logger.getLogger(this.getClass());/*** 默認按鍵之間時間間隔*/public final static int MAX_KEYS_INTERVAL_DEFAULT = 200;private long currentTime = 0;private boolean isKeySHIFT = false;private StringBuilder stringBuilder = new StringBuilder();private ScanGunCallBack callBack = null;private static int maxKeysInterval = MAX_KEYS_INTERVAL_DEFAULT;/*** 設置按鍵事件的最大時間間隔(部分掃描槍稍大，建議范圍20--100)** @param interval 時間間隔*/public static void setMaxKeysInterval(int interval) {maxKeysInterval = interval;}public ScanGun(ScanGunCallBack callBack) {this.callBack = callBack;}public ScanGun() {}public boolean isMaybeScanning(int keyCode, KeyEvent event) {log.info("isMaybeScanning--");log.info("event.getFlags:" + event.getFlags());if (event.getFlags() != 0x8 && event.getFlags() != 0x6) {return false;}if (currentTime == 0) {if (stringBuilder.length() > 0) {stringBuilder = stringBuilder.delete(0, stringBuilder.length());}currentTime = System.currentTimeMillis();} else {if ((System.currentTimeMillis() - currentTime) > maxKeysInterval) {if (stringBuilder.length() > 0) {stringBuilder = stringBuilder.delete(0,stringBuilder.length());}}currentTime = System.currentTimeMillis();}// Shiftif (keyCode == KeyEvent.KEYCODE_SHIFT_RIGHT || keyCode == KeyEvent.KEYCODE_SHIFT_LEFT) {if (event.getAction() == KeyEvent.ACTION_DOWN) {//按著shift鍵，表示大寫isKeySHIFT = true;} else {//松開shift鍵，表示小寫isKeySHIFT = false;}}// Enterif (keyCode == KeyEvent.KEYCODE_ENTER) {isKeySHIFT = false;currentTime = 0;if (callBack != null) {log.info("stringBuilder:" + stringBuilder);callBack.onScanFinish(stringBuilder.toString());}return true;}if (keyCode >= KeyEvent.KEYCODE_0 && keyCode <= KeyEvent.KEYCODE_9) {// 數字鍵(鍵盤上方橫條數字，需要考慮Shift)handleTopNumKeys(keyCode);} else if (keyCode >= 29 && keyCode <= 54) {// 字母鍵(需要考慮Shift)wwcheckShift((char) (keyCode + 68), (char) (keyCode + 36));} else if (keyCode >= 144 && keyCode <= 158) {// 數字鍵盤區handleNumPadKeys(keyCode);log.info("數字：" + stringBuilder);} else {// 鍵盤主鍵區其他雙字符鍵位switch (keyCode) {case KeyEvent.KEYCODE_GRAVE: {checkShift(ASCII.CHAR_SIGN_BACKTICK, ASCII.CHAR_SIGN_TILDE);break;}case KeyEvent.KEYCODE_MINUS: {checkShift(ASCII.CHAR_SIGN_MINUS, ASCII.CHAR_SIGN_UNDERSCORE);break;}case KeyEvent.KEYCODE_EQUALS: {checkShift(ASCII.CHAR_SIGN_EQUALS, ASCII.CHAR_SIGN_PLUS);break;}case KeyEvent.KEYCODE_LEFT_BRACKET: {checkShift(ASCII.CHAR_SIGN_BRACKET_LEFT,ASCII.CHAR_SIGN_BRACE_LEFT);break;}case KeyEvent.KEYCODE_RIGHT_BRACKET: {checkShift(ASCII.CHAR_SIGN_BRACKET_RIGHT,ASCII.CHAR_SIGN_BRACE_RIGHT);break;}case KeyEvent.KEYCODE_BACKSLASH: {checkShift(ASCII.CHAR_SIGN_BACKSLASH, ASCII.CHAR_SIGN_BAR);break;}case KeyEvent.KEYCODE_SEMICOLON: {checkShift(ASCII.CHAR_SIGN_SEMICOLON, ASCII.CHAR_SIGN_COLON);break;}case KeyEvent.KEYCODE_APOSTROPHE: {checkShift(ASCII.CHAR_SIGN_QUOTE, ASCII.CHAR_SIGN_DOUBLE_QUOTE);break;}case KeyEvent.KEYCODE_COMMA: {checkShift(ASCII.CHAR_SIGN_COMMA, ASCII.CHAR_SIGN_LESS);break;}case KeyEvent.KEYCODE_PERIOD: {checkShift(ASCII.CHAR_SIGN_PERIOD, ASCII.CHAR_SIGN_GREATER);break;}case KeyEvent.KEYCODE_SLASH: {checkShift(ASCII.CHAR_SIGN_SLASH, ASCII.CHAR_SIGN_QUESTION);break;}// 其他單字符鍵位case KeyEvent.KEYCODE_SPACE: {stringBuilder.append(ASCII.CHAR_SIGN_SPACE);log.info("Other StringBuilder:" + stringBuilder);break;}default: {return false;}}return true;}return true;}/*** 判斷是否同時按下Shift鍵** @param ascallNoShift* @param ascallOnShift*/private void checkShift(char ascallNoShift, char ascallOnShift) {if (isKeySHIFT) {stringBuilder.append(ascallOnShift);isKeySHIFT = false;} else {stringBuilder.append(ascallNoShift);}}/*** 數字鍵盤區按鍵** @param keyCode*/public void handleNumPadKeys(int keyCode) {if (keyCode <= 153) {stringBuilder.append((char) (keyCode - 96));} else if (keyCode == KeyEvent.KEYCODE_NUMPAD_DIVIDE) {stringBuilder.append(ASCII.CHAR_SIGN_SLASH);} else if (keyCode == KeyEvent.KEYCODE_NUMPAD_MULTIPLY) {stringBuilder.append(ASCII.CHAR_SIGN_STAR);} else if (keyCode == KeyEvent.KEYCODE_NUMPAD_SUBTRACT) {stringBuilder.append(ASCII.CHAR_SIGN_MINUS);} else if (keyCode == KeyEvent.KEYCODE_NUMPAD_ADD) {stringBuilder.append(ASCII.CHAR_SIGN_PLUS);} else if (keyCode == KeyEvent.KEYCODE_NUMPAD_DOT) {stringBuilder.append(ASCII.CHAR_SIGN_PERIOD);}}/*** 鍵盤上方數字鍵** @param keyCode*/private void handleTopNumKeys(int keyCode) {if (keyCode < 7 || keyCode > 16) {return;}switch (keyCode) {case KeyEvent.KEYCODE_0:checkShift(ASCII.CHAR_NUM_0, ASCII.CHAR_SIGN_PAREN_RIGHT);break;case KeyEvent.KEYCODE_1:checkShift(ASCII.CHAR_NUM_1, ASCII.CHAR_SIGN_EXCLAM);break;case KeyEvent.KEYCODE_2:checkShift(ASCII.CHAR_NUM_2, ASCII.CHAR_SIGN_AT);break;case KeyEvent.KEYCODE_3:checkShift(ASCII.CHAR_NUM_3, ASCII.CHAR_SIGN_HASH);break;case KeyEvent.KEYCODE_4:checkShift(ASCII.CHAR_NUM_4, ASCII.CHAR_SIGN_DOLLAR);break;case KeyEvent.KEYCODE_5:checkShift(ASCII.CHAR_NUM_5, ASCII.CHAR_SIGN_PERCENT);break;case KeyEvent.KEYCODE_6:checkShift(ASCII.CHAR_NUM_6, ASCII.CHAR_SIGN_CARET);break;case KeyEvent.KEYCODE_7:checkShift(ASCII.CHAR_NUM_7, ASCII.CHAR_SIGN_AMPERSAND);break;case KeyEvent.KEYCODE_8:checkShift(ASCII.CHAR_NUM_8, ASCII.CHAR_SIGN_STAR);break;case KeyEvent.KEYCODE_9:checkShift(ASCII.CHAR_NUM_9, ASCII.CHAR_SIGN_PAREN_LEFT);break;default:break;}}public interface ScanGunCallBack {public void onScanFinish(String data);} }

3、在Fragment中使用ScanGun類。

ScanGun類定義了一個內部類接口，data就是掃描完成后的內容：

public interface ScanGunCallBack {public void onScanFinish(String data); }

掃碼完成后，調用該接口的onScanFinish方法：

// Enter if (keyCode == KeyEvent.KEYCODE_ENTER) {isKeySHIFT = false;currentTime = 0;if (callBack != null) {log.info("stringBuilder:" + stringBuilder);callBack.onScanFinish(stringBuilder.toString());}return true; }

所以在Fragment獲取掃描結果，需要創建Scan的實例，并且實現這個onScanFinish方法：

/* 初始化掃碼槍 */ private void initScanGun() {// 設置key事件最大間隔，默認20ms，部分低端掃碼槍效率低ScanGun.setMaxKeysInterval(50);scanGun = new ScanGun(new ScanGun.ScanGunCallBack() {@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR1)@Overridepublic void onScanFinish(String scanResult) {if (payment.getVisibility() != View.GONE) { // 支付頁面沒關閉loadingDailog = createWaitingUI(loadingDailog, LOADING_MSG_Paying);// 判斷優惠券是否可用if (!validateCouponCodeAvailable()) {return;}if (choosePaymentType.getCheckedRadioButtonId() == wechatPay.getId()) {……

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