Android 二维码扫码枪内容识别

项目中有一个扫码枪扫描二维码识别内容的需求，扫码枪其实相当于一个外接键盘，会把扫描二维码后识别的内容通过键盘的方式输出到输入框中。

首先我尝试的第一种方法是在页面上放一个高度为0的EditText，然后监听EditText的内容变化，这种方法是可以获取到识别到的内容，但是会有软键盘闪现、焦点获取等一些问题，所以放弃了。

目前使用的方法是在Activity中监听onKeyDown方法，代码如下：

1. 重写onKeyDown方法，扫码枪一般最后以回车符结束，所以只用判断最后输入的一个键是不是ENTER键就可以知道二维码识别是否结束：

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

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
//        Log.d("onKeyDown","keyCode:"+keyCode);
        if(keyCode!= KeyEvent.KEYCODE_ENTER){ //扫码枪以回车为结束
            scannedCodes.add(keyCode);
        }else{ //结束
            handleKeyCodes();
        }
//
        return super.onKeyDown(keyCode, event);
    }

2. 处理接收到的keyCode值，这里主要是把keyCode转换为对应的字符：

   private void handleKeyCodes(){
        String result = "";
        boolean hasShift = false;
        for(int keyCode : scannedCodes){
            result += keyCodeToChar(keyCode, hasShift);
            hasShift = (keyCode == KeyEvent.KEYCODE_SHIFT_LEFT || keyCode == KeyEvent.KEYCODE_SHIFT_RIGHT);
        }
        Log.d("handleKeyCodes","result:"+result);
        Toast.makeText(this, "result:"+result, Toast.LENGTH_LONG).show();
        scannedCodes.clear();
    }

    /** keyCode转换为字符 */
    public String keyCodeToChar(int code, boolean isShift){
        switch(code){

            case KeyEvent.KEYCODE_SHIFT_LEFT: return "";
            case KeyEvent.KEYCODE_SHIFT_RIGHT: return "";

            //数字键10个 + 符号10个
            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";

            //字母键26个小写 + 26个大写
            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";

            //符号键11个 + 11个
            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 "";
        }
    }

以上就是实现的全部步骤和代码，是不是很简单！

参考：
Android 读取扫码枪内容（条形码)