Android 之 设置EditText最大可输入字符

转自：http://blog.csdn.net/liujianminghero/article/details/7092236

Android 中的EditText最大可输入字符数可以通过xml文件中为EditText设置maxLength属性或者在代码中为EditText设置LengthFilter来设置。

例如要设置EditText只能输入10个字符

xml中：

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<EditText android:layout_width = "fill_parent"

android:layout_height = "wrap_content"

android:id = "@+id/mEdit"

android:maxLength = "10"/>

代码中：

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EditText mEdit = (EditText)findViewById(R.id.mEdit);

InputFilter[] filters = {new LengthFilter(10)};

mEdit.setFilters(filters);

以上任意一种方法都可以满足需求，但这种方法只能为EditText设置统一的最大可输入字符，如果碰到根据实际情况限制不同的可输入字符数时，这种方法就不能用了。

比如SIM卡上的电话本姓名字段长度，纯英文下允许输入17个字符，而中文则只可以输入6个字符。此时可以重写InputFilter类来实现。

即：

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EditText mEdit = (EditText)findViewById(R.id.mEdit);

InputFilter[] filters = {new AdnNameLengthFilter()};

mEdit.setFilters(filters);

public static class AdnNameLengthFilter implements InputFilter

{

private int nMax;



public CharSequence filter (CharSequence source, int start, int end, Spanned dest, int dstart, int dend)

{

Log.w("Android_12", "source("+start+","+end+")="+source+",dest("+dstart+","+dend+")="+dest);



if(isChinese(dest.toString())|| isChinese(source.toString()))

{

nMax = LENGTH_ZNAME;

}else

{

nMax =LENGTH_ENAME;

}



int keep = nMax - (dest.length() - (dend - dstart));



if (keep <= 0) {

return "";

} else if (keep >= end - start) {

return null; // keep original

} else {

return source.subSequence(start, start + keep);

}



}

}

[java] view
plaincopy

EditText mEdit = (EditText)findViewById(R.id.mEdit);

InputFilter[] filters = {new AdnNameLengthFilter()};

mEdit.setFilters(filters);

public static class AdnNameLengthFilter implements InputFilter

{

private int nMax;



public CharSequence filter (CharSequence source, int start, int end, Spanned dest, int dstart, int dend)

{

Log.w("Android_12", "source("+start+","+end+")="+source+",dest("+dstart+","+dend+")="+dest);



if(isChinese(dest.toString())|| isChinese(source.toString()))

{

nMax = LENGTH_ZNAME;

}else

{

nMax =LENGTH_ENAME;

}



int keep = nMax - (dest.length() - (dend - dstart));



if (keep <= 0) {

return "";

} else if (keep >= end - start) {

return null; // keep original

} else {

return source.subSequence(start, start + keep);

}



}

}

其中的isChinese函数是判断是否字符串中是否包含中文字符，具体实现方法就不再赘述了。

LENGTH_ZNAME : 是中文模式下允许输入的最大字符数。

LENGTH_ENAME：是纯英文模式下允许输入的最大字符数。

android怎样判断EditText输入的值是数字还是汉字 ，并限定输入字数

2011-11-25 10:37

判断汉字的方法

private boolean isChinese(char c) {
        Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
        if (ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS
             || ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS
            || ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A
            || ub == Character.UnicodeBlock.GENERAL_PUNCTUATION
            || ub == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION
            || ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS) {
            return true;
        }
        return false;
    }

数字就根据unicode的范围判断吧！



方法一：利用TextWatcher

editText.addTextChangedListener(new TextWatcher() {   
           private CharSequence temp;   
           private boolean isEdit = true;   
           private int selectionStart ;   
           private int selectionEnd ;   
           @Override  
           public void beforeTextChanged(CharSequence s, int arg1, int arg2,   
                   int arg3) {   
               temp = s;   
           }   
              
           @Override  
           public void onTextChanged(CharSequence s, int arg1, int arg2,   
                   int arg3) {   
           }   
              
           @Override  
           public void afterTextChanged(Editable s) {   
                selectionStart = editText.getSelectionStart();   
               selectionEnd = editText.getSelectionEnd();   
               Log.i("gongbiao1",""+selectionStart);   
               if (temp.length() > Constant.TEXT_MAX) {   
                   Toast.makeText(KaguHomeActivity.this,   
                           R.string.edit_content_limit, Toast.LENGTH_SHORT)   
                           .show();   
                   s.delete(selectionStart-1, selectionEnd);   
                   int tempSelection = selectionStart;   
                   editText.setText(s);   
                   editText.setSelection(tempSelection);   
               }   
           }   
  
  
       });

private TextWatcher mTextWatcher = new TextWatcher(){
  Toast mToast = null;
  public void beforeTextChanged(CharSequence s, int start, 
    int count,int after) {
  }
  public void onTextChanged(CharSequence s, int start, 
    int before,int count) {
  }
  
  public void afterTextChanged(Editable s) {
   int nSelStart = 0;
   int nSelEnd = 0;
   boolean nOverMaxLength = false;
   
   nSelStart = mEditText.getSelectionStart();
   nSelEnd   = mEditText.getSelectionEnd();
   
   nOverMaxLength = (s.length() > Constants.MAX_TEXT_INPUT_LENGTH) ? true : false;
   if(nOverMaxLength){
    if(null == mToast){
     mToast = Toast.makeText(mContext, 
       R.string.IDS_MSG_TEXT_OVER_MAXLENGTH, 
       Toast.LENGTH_SHORT);
    }
    mToast.show();
    
    s.delete(nSelStart - 1, nSelEnd);
    mEditText.setTextKeepState(s);//请读者注意这一行，保持光标原先的位置，而 mEditText.setText(s)会让光标跑到最前面，
                                                     //就算是再加mEditText.setSelection(nSelStart) 也不起作用
    }
  }
 };

方法二：利用InputFilter



editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(100)}); //其中100最大输入字数

editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(100)}); //其中100最大输入字数

方法三：在XML中设定

Xml代码

<EditText

.

.

.

Android:maxLength="100"

/>



=========================================================

方法二：

利用EditText可以设置filter的特性，自定义一个LengthFilter，当输入字数超过限制时 ，做出自定义的提示

// 输入框限制输入字数

InputFilter[] filters = new InputFilter[1];
        filters[0] = new InputFilter.LengthFilter(Constant.TEXT_MAX) {
            @Override
            public CharSequence filter(CharSequence source, int start, int end,
                    Spanned dest, int dstart, int dend) {
                if (source.length() > 0 && dest.length() == Constant.TEXT_MAX) {
                    if ((System.currentTimeMillis() - toastTime) > interval) {
                        toastTime = System.currentTimeMillis();
                        Toast
                                .makeText(KaguHomeActivity.this,
                                        R.string.edit_content_limit,
                                        Toast.LENGTH_SHORT).show();
                    }
                }
                if (dest.toString().equals(
                        getResources().getString(R.string.input_default_txt))) {
                    Bundle data = new Bundle();
                    data.putCharSequence("source", source);
                    Message message = textHandler.obtainMessage();
                    message.setData(data);
                    message.sendToTarget();
                }

                return super.filter(source, start, end, dest, dstart, dend);
            }
        };
        editText.setFilters(filters);
private Handler textHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {

            Bundle data = msg.getData();
            CharSequence source = data.getCharSequence("source");
            editText.setTextColor(Color.BLACK);
            editText.setText(source);
            editText.setSelection(source.length());
        }
    };