效果图如下：

两个类，一个继承Activity的类，一个继承EditText的类，一个xml文件

继承Activity的类：

public class EditTestActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.edittest);
}
}

继承EditText的类：

package com.mrzhu.edittest;

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 EditTextTest extends EditText {

public EditTextTest(Context context) {
super(context);
}

public EditTextTest(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}

public EditTextTest(Context context, AttributeSet attrs) {
super(context, attrs);
}

@Override
protected void onDraw(Canvas canvas) {
Paint paint = new Paint();
paint.setTextSize(20);
paint.setColor(Color.GRAY);
canvas.drawText("输入提示文本:", 10, getHeight() / 2 + 5, paint);
super.onDraw(canvas);
}
}

edittext.xml文件：

< xml version="1.0" encoding="utf-8" >
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingLeft="100dp"
android:text="从此处输入文本"
android:id="@+id/test"
/>