Custom View-View constructor

Construction method that needs to be rewritten

• public CustomView(Context context) {super(context);}

• public CustomView(Context context, @Nullable AttributeSet attrs) {super(context, attrs); }//Get custom attributes through attrs

• public CustomView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);}

• Get custom attributes

  • Create attrs.xml under the res/values ​​folder, the content is as follows:

  <?xml version="1.0" encoding="utf-8"?>
  <resources>
  <!--所属的自定义的View-->
  <declare-styleable name="CicleView">
      <!--属性名称和类型-->
      <attr name="size" format="integer">
          <!--属性的指定的值，这个是可选的-->
          <enum name="normal" value="1" />
      </attr>
  </declare-styleable>
  </resources>
  

  • Use custom View and custom attributes in the xml file of the layout, as follows:

  <?xml version="1.0" encoding="utf-8"?>
  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:gravity="center"
  android:orientation="vertical">
  
  <com.example.administrator.aidldemo.anim.object.CicleView
      android:id="@+id/cv_demo"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      app:size="normal" />
  </LinearLayout>
  

  • Get custom attributes in custom View

    public CicleView(Context context) {
      super(context);
      init(context, null);
  }
  
  public CicleView(Context context, @Nullable AttributeSet attrs) {
      super(context, attrs);
      init(context, attrs);
  }
  
  public CicleView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
      super(context, attrs, defStyleAttr);
      init(context, attrs);
  }
  
  private void init(Context context, @Nullable AttributeSet attrs) {
      if (attrs != null) {
          TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.CicleView);
          int size = array.getInt(R.styleable.CicleView_size, 0);
          array.recycle();
      }
  }