Android 輸入框限制字元輸入數，android輸入框字元

Android 輸入框限制字元輸入數，android輸入框字元

有時候對Android的輸入框有字元輸入數量的限制，並且顯示顯示字元輸入的數量。通過以下方式可以實現：

1.子定義LimitNumEditText繼承EditText

import android.content.Context;import android.content.res.TypedArray;import android.telephony.SmsMessage;import android.text.Editable;import android.text.InputFilter;import android.text.TextWatcher;import android.util.AttributeSet;import android.widget.EditText;import us.pinguo.cc.R;/** * Created by crab on 15-3-18. */public class LimitNumEditText extends EditText {    private int mMaxLength;    private OnTextCountChangeListener mTextCountChangeListener;    public LimitNumEditText(Context context) {        this(context, null);    }    public LimitNumEditText(Context context, AttributeSet attrs) {        super(context, attrs);        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.LimitNumEditText);        mMaxLength = typedArray.getInt(R.styleable.LimitNumEditText_maxLength, -1);        typedArray.recycle();        if (mMaxLength >= 0) {            setFilters(new InputFilter[]{new InputFilter.LengthFilter(mMaxLength)});        } else {            setFilters(new InputFilter[0]);        }        addTextChangedListener(null);    }    /**     * @return 返回限制輸入的最大字元數量     */    public int getLimitLength(){        return mMaxLength;    }    @Override    public void addTextChangedListener(final TextWatcher watcher) {        TextWatcher inner=new TextWatcher() {            @Override            public void beforeTextChanged(CharSequence s, int start, int count, int after) {                if(watcher!=null){                    watcher.beforeTextChanged(s,start,count,after);                }            }            @Override            public void onTextChanged(CharSequence s, int start, int before, int count) {                int[] params= SmsMessage.calculateLength(s,false);                int use=params[1];                if(mMaxLength>=0 && mTextCountChangeListener!=null){                    mTextCountChangeListener.onTextCountChange(use,mMaxLength);                }                if(watcher!=null){                    watcher.onTextChanged(s,start,before,count);                }            }            @Override            public void afterTextChanged(Editable s) {                if(watcher!=null){                    watcher.afterTextChanged(s);                }            }        };        super.addTextChangedListener(inner);    }    public LimitNumEditText(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);    }    public void setOnTextCountChangeListener(OnTextCountChangeListener listener){        mTextCountChangeListener=listener;    }    /**     * 監聽輸入框字元變化     */    public interface OnTextCountChangeListener{        /**         *         * @param use 輸入字元贊據的大小         * @param total 限制輸入數量的上線         */        public void onTextCountChange(int use, int total);    }

2.修改res/values/attrs.xml檔案，增加如下行  <declare-styleable name="LimitNumEditText">
        <attr name="maxLength" format="integer" />
    </declare-styleable>
3.在布局檔案中使用

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:algnText="http://schemas.android.com/apk/res-auto"    android:background="#FFFFFF"    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent">    <com.example.crab.mycameratest.LimitNumEditText        algnText:maxLength="20"        android:id="@+id/id_edit_text_test"        android:layout_width="match_parent"        android:layout_height="50dp"/></LinearLayout>