Android自定义EditText去除边框并添加下划线

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<!--注意名称 -->
<com.marine.study.LineEditText     

    android:id="@+id/myEdit"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    style="?android:attr/textViewStyle"
    android:background="@null"
    android:textColor="@null"
/>
</LinearLayout> 

//请在这里添加您的包名
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.widget.EditText;  

public class LineEditText extends EditText {  

    private Paint mPaint;
    /**
     * @param context
     * @param attrs
     */
    public LineEditText(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        mPaint = new Paint();  

        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setColor(Color.BLUE);
    }  

    @Override
    public void onDraw(Canvas canvas)
    {
        super.onDraw(canvas);  

//      画底线
        canvas.drawLine(0,this.getHeight()-1,  this.getWidth()-1, this.getHeight()-1, mPaint);
    }
}  

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.text.InputFilter;
import android.util.AttributeSet;
import android.widget.EditText;  

public class LineEditTextTest extends Activity {
    /** Called when the activity is first created. */
    private EditText mEdit;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);  

        mEdit=(LineEditText)findViewById(R.id.myEdit);
        mEdit.setHint("从这里开始输入...");
        mEdit.setSingleLine();
        mEdit.setFilters(new InputFilter[]{new InputFilter.LengthFilter(20)});
    }  

}