Recently, there is a demand that the Android device is connected with a code scanning gun, and the system reads the scanning content of the code scanning gun.

I checked some examples on the Internet, but it was not easy to use them. Finally, I realized one by myself (only English letters and symbols are supported at present).

The code is as follows:

1. Rewrite the onKeyDown method of Activity to collect the keycode returned by the code scanning gun.

ArrayList<Integer> scannedCodes = new ArrayList<Integer>();

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {

	if(keyCode!= KeyEvent.KEYCODE_ENTER){ //Code scanning gun ends with carriage return
		scannedCodes.add(keyCode);
	}else{ //End
		handleKeyCodes();
	}
		
	return super.onKeyDown(keyCode, event);
}

2. Handle the received keycode, handleKeyCodes() method.

private void handleKeyCodes(){
	FnString fnString = new FnString();
	String result = "";
	boolean hasShift = false;
	for(int keyCode : scannedCodes){
		result += fnString.keyCodeToChar(keyCode, hasShift);
		hasShift = (keyCode == KeyEvent.KEYCODE_SHIFT_LEFT);	
	}
	Toast.makeText(context, result, Toast.LENGTH_LONG).show();
	scannedCodes.clear();
}

3. Method of converting keycode to character

/** keyCode Convert to character */
public String keyCodeToChar(int code, boolean isShift){
	switch(code){
		
		case KeyEvent.KEYCODE_SHIFT_LEFT: return "";
		
		//10 number keys + 10 symbols
		case KeyEvent.KEYCODE_0: return isShift ? ")" : "0";
		case KeyEvent.KEYCODE_1: return isShift ? "!" : "1";
		case KeyEvent.KEYCODE_2: return isShift ? "@" : "2";
		case KeyEvent.KEYCODE_3: return isShift ? "#" : "3";
		case KeyEvent.KEYCODE_4: return isShift ? "$" : "4";
		case KeyEvent.KEYCODE_5: return isShift ? "%" : "5";
		case KeyEvent.KEYCODE_6: return isShift ? "^" : "6";
		case KeyEvent.KEYCODE_7: return isShift ? "&" : "7";
		case KeyEvent.KEYCODE_8: return isShift ? "*" : "8";
		case KeyEvent.KEYCODE_9: return isShift ? "(" : "9";
		
		//Letter keys 26 lowercase + 26 uppercase
		case KeyEvent.KEYCODE_A: return isShift ? "A" : "a";
		case KeyEvent.KEYCODE_B: return isShift ? "B" : "b";
		case KeyEvent.KEYCODE_C: return isShift ? "C" : "c";
		case KeyEvent.KEYCODE_D: return isShift ? "D" : "d";
		case KeyEvent.KEYCODE_E: return isShift ? "E" : "e";
		case KeyEvent.KEYCODE_F: return isShift ? "F" : "f";
		case KeyEvent.KEYCODE_G: return isShift ? "G" : "g";
		case KeyEvent.KEYCODE_H: return isShift ? "H" : "h";
		case KeyEvent.KEYCODE_I: return isShift ? "I" : "i";
		case KeyEvent.KEYCODE_J: return isShift ? "J" : "j";
		case KeyEvent.KEYCODE_K: return isShift ? "K" : "k";
		case KeyEvent.KEYCODE_L: return isShift ? "L" : "l";
		case KeyEvent.KEYCODE_M: return isShift ? "M" : "m";
		case KeyEvent.KEYCODE_N: return isShift ? "N" : "n";
		case KeyEvent.KEYCODE_O: return isShift ? "O" : "o";
		case KeyEvent.KEYCODE_P: return isShift ? "P" : "p";
		case KeyEvent.KEYCODE_Q: return isShift ? "Q" : "q";
		case KeyEvent.KEYCODE_R: return isShift ? "R" : "r";
		case KeyEvent.KEYCODE_S: return isShift ? "S" : "s";
		case KeyEvent.KEYCODE_T: return isShift ? "T" : "t";
		case KeyEvent.KEYCODE_U: return isShift ? "U" : "u";
		case KeyEvent.KEYCODE_V: return isShift ? "V" : "v";
		case KeyEvent.KEYCODE_W: return isShift ? "W" : "w";
		case KeyEvent.KEYCODE_X: return isShift ? "X" : "x";
		case KeyEvent.KEYCODE_Y: return isShift ? "Y" : "y";
		case KeyEvent.KEYCODE_Z: return isShift ? "Z" : "z";
		
		//Symbol keys 11 + 11
		case KeyEvent.KEYCODE_COMMA: return isShift ? "<" : ",";
		case KeyEvent.KEYCODE_PERIOD: return isShift ? ">" : ".";
		case KeyEvent.KEYCODE_SLASH: return isShift ? "?" : "/";
		case KeyEvent.KEYCODE_BACKSLASH: return isShift ? "|" : "\\";
		case KeyEvent.KEYCODE_APOSTROPHE: return isShift ? "\"" : "'";
		case KeyEvent.KEYCODE_SEMICOLON: return isShift ? ":" : ";";
		case KeyEvent.KEYCODE_LEFT_BRACKET: return isShift ? "{" : "[";
		case KeyEvent.KEYCODE_RIGHT_BRACKET: return isShift ? "}" : "]";
		case KeyEvent.KEYCODE_GRAVE: return isShift ? "~" : "`";
		case KeyEvent.KEYCODE_EQUALS: return isShift ? "+" : "=";
		case KeyEvent.KEYCODE_MINUS: return isShift ? "_" : "-";
		
		default: return "?";
	}
}

Effect 1:

Effect 2: