从Android Launcher源码学习自定义标签

res/values/attrs.xml
<declare-styleable name="CellLayout">
<!-- The width of a single cell -->
<attr name="cellWidth" format="dimension"  />
<!-- The height of a single cell -->
<attr name="cellHeight" format="dimension"  />
.....
</declare-styleable>


res/layout-port/workspace_screen.xml
<com.android.launcher.CellLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:launcher="http://schemas.android.com/apk/res/com.android.launcher"

android:layout_width="fill_parent"
android:layout_height="fill_parent"

launcher:cellWidth="80dip"
launcher:cellHeight="96dip"
....
/>


src/com.android.launcher.CellLayout.java
public CellLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CellLayout, defStyle, 0);

mCellWidth = a.getDimensionPixelSize(R.styleable.CellLayout_cellWidth, 10);
mCellHeight = a.getDimensionPixelSize(R.styleable.CellLayout_cellHeight, 10);
.....
}


根据颜色看, 应该很清晰:
1. 蓝色部分是自己定义的styleable和attr的名称, 代码和XML里要一致;
2. 绿色部分是自定义的命名空间名称, 也只要上下保持一致即可;
3. 红色部分是View所在的包名, 不允许有误.

参考:http://blog.csdn.net/Android_Tutor/archive/2010/04/21/5508615.aspx