写一个背景渐变的TextView输入框

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
    <!-- 设置圆角 -->
    <corners android:radius="5dip"/>
    <!-- 设置渐变色 -->
    <gradient android:startColor="@android:color/white"
        android:endColor="@android:color/holo_blue_bright"/>
    <!-- 设置边框颜色和宽度 -->
    <stroke android:width="1dp"
        android:color="@android:color/black"
        />
</shape>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >
    <EditText 
        android:layout_width="match_parent"
        android:gravity="center|right"
        android:layout_height="60dp"
        android:id="@+id/et_input"
        android:background="@drawable/writebg"
        android:editable="false"
        />
</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.thinker.caculatordemo"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.thinker.caculatordemo.MainActivity"
            android:label="@string/app_name" 
            <!-- 设置页面的主题背景 -->
            android:theme="@android:style/Theme.Black.NoTitleBar"
            >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>