怎么在android-statusBar下添加字符显示

如何在android--statusBar上添加字符显示
最近修改statusBar,需要在上面添加自定义的字符。
版本：android-2.3.1
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1.先参考statusbar上时间的布局文件：
frameworks\base\packages\SystemUI\res\layout\status_bar.xml

 <LinearLayout android:id="@+id/statusIcons"            android:layout_width="wrap_content"            android:layout_height="match_parent"            android:layout_alignParentRight="true"            android:paddingRight="6dip"            android:gravity="center_vertical"            android:orientation="horizontal"/>            <com.android.systemui.statusbar.Clock              android:textAppearance="@*android:style/TextAppearance.StatusBar.Icon"            android:layout_width="wrap_content"            android:layout_height="match_parent"            android:singleLine="true"            android:paddingRight="6dip"            android:gravity="center_vertical|left"            />        <com.android.systemui.statusbar.HandSetNum  //我们所需要显示的字符android:textAppearance="@*android:style/TextAppearance.StatusBar.Icon"android:layout_width="wrap_content"android:layout_height="match_parent"android:textSize="14sp"android:gravity="center_vertical"android:paddingLeft="10dip"android:paddingRight="10dip"/>

注释： <com.android.systemui.statusbar.Clock 
       <com.android.systemui.statusbar.HandSetNum 
意思很明确，就是在statusbar目录下添加一个类名文件，我们参考closk，在
\frameworks\base\packages\SystemUI\src\com\android\systemui\statusbar\下创建一个HandSetNum.java 文件，里面内容基本跟clock.java一样。
android:gravity="center_vertical" ：意思就是在组件里面的位置
android:layout_gravity="center_vertical" :指组件在layout的位置。

android:paddingLeft="10dip"  ：离组件边距
android:paddingRight="10dip"

2.编写HandSetNum.java

public class HandSetNum extends TextView {    private boolean mAttached;    public HandSetNum(Context context) {        this(context, null);    }    public HandSetNum(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public HandSetNum(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);    }    @Override    protected void onAttachedToWindow() {        super.onAttachedToWindow();        if (!mAttached) {            mAttached = true;            IntentFilter filter = new IntentFilter();            filter.addAction(Intent.ACTION_HANDSET_NUM);            getContext().registerReceiver(mIntentReceiver, filter, null, getHandler());        }           updateHandSetNum();    }    @Override    protected void onDetachedFromWindow() {        super.onDetachedFromWindow();        if (mAttached) {            getContext().unregisterReceiver(mIntentReceiver);            mAttached = false;        }    }    private final BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {        @Override        public void onReceive(Context context, Intent intent) {            String action = intent.getAction();            if (action.equals(Intent.ACTION_HANDSET_NUM)) {updateHandSetNum();            }                    }    };    final void updateHandSetNum() {        setText("Hs:1");    }}//end HandSetNum

基本跟clock.java代码相同，主要以setText();来实现字符的显示。
3.编译android源码