自定义xml属性attr

xmlns:android是XML命名空间，告诉Android开发工具你准备使用Android命名空间里的一些通用属性

在所有Android XML文件中最外层的标记必须使用这个命名空间

用户也可以自定义XML属性

1. values/attrs.xml定义属性

<?xml version="1.0" encoding="utf-8"?><resources>    <attr name="relative">        <enum name="icon_left" value="0" />        <enum name="icon_right" value="1" />        <enum name="icon_above" value="2" />        <enum name="icon_below" value="3" />    </attr>    <declare-styleable name="IconTextView">        <attr name="relative"/>        <attr name="my_icon" format="reference"/>        <attr name="my_text" format="string"/>        <attr name="text_size" format="dimension"/>        <attr name="text_color" format="color"/>        <attr name="padding" format="dimension"/>    </declare-styleable></resources>

2. IconTextView.java继承LinearLayout实现自定义的属性

package com.silion.userdefinedxmlattr;import android.content.Context;import android.content.res.TypedArray;import android.graphics.drawable.Drawable;import android.media.Image;import android.util.AttributeSet;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.TextView;/** * Created by silion on 2015/10/19. */public class IconTextView extends LinearLayout {    private final static int ICON_LEFT = 0;    private final static int ICON_RIGHT = 1;    private final static int ICON_ABOVE = 2;    private final static int ICON_BELOW = 3;    private int mRelative;    private Drawable mIcon;    private String mText;    private float mTextSize;    private Integer mTextColor;    private int mPadding;    private TextView mTextView;    private ImageView mImageView;    public IconTextView(Context context, AttributeSet attrs) {        super(context, attrs);        TypedArray a = null;        try {            a = context.obtainStyledAttributes(attrs, R.styleable.IconTextView);            mRelative = a.getInt(R.styleable.IconTextView_relative, 0);            mIcon = a.getDrawable(R.styleable.IconTextView_my_icon);            mText = a.getString(R.styleable.IconTextView_my_text);            mTextSize = a.getDimension(R.styleable.IconTextView_text_size, 15);            mTextColor = a.getInteger(R.styleable.IconTextView_text_color, 0);            mPadding = a.getInt(R.styleable.IconTextView_padding, 15);        } finally {            a.recycle();        }        mTextView = new TextView(context);        mTextView.setText(mText);        mTextView.setTextSize(mTextSize);        mTextView.setTextColor(mTextColor);        mImageView = new ImageView(context);        mImageView.setImageDrawable(mIcon);        int paddingLeft = 0;        int paddingRight = 0;        int paddingTop = 0;        int paddingBottom = 0;        int orientation = HORIZONTAL;        switch (mRelative) {            case ICON_LEFT: {                orientation = HORIZONTAL;                paddingLeft = mPadding;                break;            }            case ICON_RIGHT: {                orientation = HORIZONTAL;                paddingRight = mPadding;                break;            }            case ICON_ABOVE: {                orientation = VERTICAL;                paddingTop = mPadding;                break;            }            case ICON_BELOW: {                orientation = VERTICAL;                paddingBottom = mPadding;                break;            }            default:                break;        }        this.setOrientation(orientation);        mImageView.setPadding(paddingLeft, paddingTop, paddingRight, paddingBottom);        this.addView(mImageView);        this.addView(mTextView);    }}

3. 在layout/activity_main.xml中定义xmlns使用自定义的属性

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    xmlns:app="http://schemas.android.com/apk/res-auto"    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"    android:orientation="vertical"    tools:context=".MainActivity">    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/hello_world" />    <com.silion.userdefinedxmlattr.IconTextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        app:relative="icon_right"        app:my_icon="@mipmap/ic_launcher"        app:my_text="@string/hello_world"        app:text_size="19sp"        app:text_color="#0000ff"        android:padding="16dp"/></LinearLayout>

4.MainActivity.java

package com.silion.userdefinedxmlattr;import android.support.v7.app.ActionBarActivity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;public class MainActivity extends ActionBarActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.menu_main, menu);        return true;    }    @Override    public boolean onOptionsItemSelected(MenuItem item) {        // Handle action bar item clicks here. The action bar will        // automatically handle clicks on the Home/Up button, so long        // as you specify a parent activity in AndroidManifest.xml.        int id = item.getItemId();        //noinspection SimplifiableIfStatement        if (id == R.id.action_settings) {            return true;        }        return super.onOptionsItemSelected(item);    }}