Android namespaces and custom attributes

Often seen in layout files

xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"

This is to declare the namespace. If you want the attributes of your own life to be meaningful in the View, you need to add a namespace prefix to the attribute, such as "android" or "app".

We can define our own namespace to use custom attributes
Steps :
1 Declare the namespace:

xmlns:zsg="http://schemas.android.com/apk/res-auto"

Note here:
If you want to use your custom attributes in eclipse, you cannot use res-auto,
you must replace it with the package to which your custom view belongs (xmlns:myxmlns=""http://schemas.android.com/ apk/res/<package name of your application>"), if the custom attribute you just used is made into lib, you can only use res-auto, and in android-studio, whether you are You can only use res-auto if you write your own custom view or the custom view in the referenced lib. The previous way of writing the package name was abandoned in android-studio.

2 Custom attributes are
in attrs. xml file to define custom attributes

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="TestView">
        <!--Attribute name attribute type -->
        <attr name="text" format="string" />
        <attr name="textColor" format="color" />
    </declare-styleable>
</resources>

3 Use custom attributes in the layout file
where MyView is a custom view

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:zsg="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.zsg.mytextview.MyView
        android:layout_width="match_parent"
        android:layout_height="30dp"
        zsg:text="This is a custom attribute"
        zsg:textColor="#ff0000"/>

</RelativeLayout>

4 Get the value in the custom attribute in MyView

public class MyView extends View {
    public MyView(Context context) {
        super(context);
    }

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
        //get TypedArray
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TestView);

        String text = (String)a.getText(R.styleable.TestView_text);

        int textColor = a.getColor(R.styleable.TestView_textColor, 0xff000000);

        Log.d("test", "text:" + text);

        Log.d("test", "textColor:" + textColor);

        a.recycle();
    }
}

Output:

For the usage of TypeArray and AttributeSet, please refer to
http://blog.csdn.net/lmj623565791/article/details/45022631

Android namespaces and custom attributes

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