近期开发一个功能的时候发生一个故事,其情节例如以下:
功能事实上不复杂,当中须要一个EditText来获取用户输入的信息.于是,我做了一个Dialog来显示我的输入界面(代码例如以下):
mAlertDialog = new AlertDialog.Builder(this)//, android.R.style.Theme_Holo_Light
.setIcon(R.drawable.ic_dialog_info_light)
.setTitle(R.string.model_rename_device)
.setView(createDialogView(deviceName))
.setPositiveButton(android.R.string.ok,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
//String deviceName = mDeviceNameView.getText().toString();
reset_success=false;
reset_model_name(mDeviceNameView.getText().toString());
//finish();
}
})
.setNegativeButton(android.R.string.cancel,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
//finish();
}
})
.setOnDismissListener(new DialogInterface.OnDismissListener() {
@Override
public void onDismiss(DialogInterface arg0) {
if(reset_success){
start_confir_ResetPhone();
}else{
finish();
}
}
}) .create(); mAlertDialog.getWindow().setSoftInputMode(
WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
mAlertDialog.show();
private View createDialogView(String deviceName) {
final LayoutInflater layoutInflater = (LayoutInflater)this
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = layoutInflater.inflate(R.layout.dialog_edittext, null);
mDeviceNameView = (EditText) view.findViewById(R.id.edittext);
mDeviceNameView.setFilters(new InputFilter[] {
new Utf8ByteLengthFilter(MODEL_NAME_MAX_LENGTH_BYTES)
});
mDeviceNameView.setText(deviceName); // set initial value before adding listener
mDeviceNameView.addTextChangedListener(this);
mDeviceNameView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
if (actionId == EditorInfo.IME_ACTION_DONE) {
reset_model_name(v.getText().toString());
mAlertDialog.dismiss();
//finish();
return true; // action handled
} else {
//finish();
return false; // not handled
}
}
});
mDeviceNameView.setSelection(mDeviceNameView.length());
return view;
}
实现起来非常easy!只是当我把用户输入的字符串存储起来时候,问题就来了!
原来这个用户输入的字符串须要存储在一段我们自己配置的nv里面,重要的是,分给我存储的字符串的空间仅仅有20个byte,没有错就是byte. 所以非常easy,输入的字符最多不能超过20个字符,因为是byte类型,所以对于输入的字符必须做检測,其字符必须在一个byte取值空间(0-127)里面.实际上就是asic码.
所以须要对输入的字符检測.
为了可以实时检測EditText输入的字符你须要EditText.addTextChangedListener()来加入一个TextWatcher的检測器,而且实现当中的方法:
public void afterTextChanged(Editable s)
public void beforeTextChanged(CharSequence s, int start, int count, int after)
public void onTextChanged(CharSequence s, int start, int before, int count)
首当其冲想到的办法是在afterTextChanged方法里面推断当前输入的字符是否时正确的字符,假设不是就通过Editable s来更改:s.delete()来删除.或者直接使用这个EditText的去从新设置输入的字符:setText();
事实上,这两个办法都不行,当高速输入不正确的字符时候就会出现异常,非常显然时同步的问题.
非常快我给出来另个解决方法:在onTextChanged()里面检測是否有异常的字符,假设有则通过Handler发送消息的形式来处理.
public void onTextChanged(CharSequence s, int start, int before, int count) {
for(int i=0; i < count; i++){
if(s.charAt(i+start) > 127 || s.charAt(i+start) < 0){
Message msg = mHandler.obtainMessage(handleMessage_detection_MG);
msg.obj = s;
mHandler.sendMessage(msg);
break;
}
}
//Log.d(DEBUG_STR,"onTextChanged str="+s.toString()+"start="+start+"; before="+before+"; count="+count);
}
Handler mHandler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case handleMessage_detection_MG:
InptText_Error_correction((CharSequence) msg.obj);
break;
case handleMessage_blue_name_MG:
InptText_rename_blue((String) msg.obj);
break;
default:
break;
}
}
};
private void InptText_Error_correction(CharSequence chars){
if(chars != null){
StringBuilder str_b = new StringBuilder(chars);
char temp;
int start_indx = -1;
for(int i = 0; i < str_b.length(); i++){
temp = str_b.charAt(i);
if(temp > 127 || temp < 0){
if(start_indx < 0){
start_indx = i;
}
str_b.deleteCharAt(i);
}
}
mDeviceNameView.setText(str_b.toString());
if(start_indx < 0){
start_indx = mDeviceNameView.length();
}
mDeviceNameView.setSelection(start_indx);
Toast.makeText(Rename_model_activity.this, getString(R.string.set_name_Error_Character_notice),
Toast.LENGTH_SHORT).show();
}
}
最后要说的是:对于输入字符的限制能够通过EditText.setFilters()来配置:
mDeviceNameView.setFilters(new InputFilter[] {
new Utf8ByteLengthFilter(MODEL_NAME_MAX_LENGTH_BYTES)
});
MODEL_NAME_MAX_LENGTH_BYTES时输入字符的最大长度,Utf8ByteLengthFilter是InputFilter的子类.这里就是对输入长度的适配.
事实上你会非常快发现!InputFilter就是一个对输入字符的检測器.所以对于输入字符错误检測事实上不用那么麻烦,事实上InputFilter全然能够解决.实现他的方法:
public CharSequence filter(CharSequence source, int start, int end,
Spanned dest, int dstart, int dend)
对于输入的错误字符,字节返回""就能够:
for (int i = start; i < end; i++) {
char c = source.charAt(i);
if(c > 127 || c < 0){
return "";
}
}