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Android中的PopupWindow详解

 
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Android的对话框有两种:PopupWindow和AlertDialog。它们的不同点在于:

  • AlertDialog的位置固定,而PopupWindow的位置可以随意
  • AlertDialog是非阻塞线程的,而PopupWindow是阻塞线程的

PopupWindow的位置按照有无偏移分,可以分为偏移和无偏移两种;按照参照物的不同,可以分为相对于某个控件(Anchor锚)和相对于父控件。具体如下

  • showAsDropDown(View anchor):相对某个控件的位置(正左下方),无偏移
  • showAsDropDown(View anchor, int xoff, int yoff):相对某个控件的位置,有偏移
  • showAtLocation(View parent, int gravity, int x, int y):相对于父控件的位置(例如正中央Gravity.CENTER,下方Gravity.BOTTOM等),可以设置偏移或无偏移

下面通过一个Demo讲解(解释看注释):

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />

    <Button
        android:id="@+id/button01"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="以自己为Anchor,不偏移" />

    <Button
        android:id="@+id/button02"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="以自己为Anchor,有偏移" />

    <Button
        android:id="@+id/button03"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="以屏幕中心为参照,不偏移(正中间)" />

    <Button
        android:id="@+id/button04"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="以屏幕下方为参照,下方中间" />

</LinearLayout>

popup_window.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="#00FF00"
    android:orientation="vertical" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="选择状态:"
        android:textColor="@android:color/white"
        android:textSize="20px" />

    <RadioGroup
        android:id="@+id/radioGroup"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

        <RadioButton android:text="在线" />

        <RadioButton android:text="离线" />

        <RadioButton android:text="隐身" />
    </RadioGroup>

</LinearLayout>

PopupWindowDemoActivity.java

package com.tianjf;

import android.app.Activity;
import android.os.Bundle;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.PopupWindow;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;

public class PopupWindowDemoActivity extends Activity implements OnClickListener,
		OnCheckedChangeListener {

	private Button mbutton01;
	private Button mbutton02;
	private Button mbutton03;
	private Button mbutton04;
	private PopupWindow mPopupWindow;
	// 屏幕的width
	private int mScreenWidth;
	// 屏幕的height
	private int mScreenHeight;
	// PopupWindow的width
	private int mPopupWindowWidth;
	// PopupWindow的height
	private int mPopupWindowHeight;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		mbutton01 = (Button) findViewById(R.id.button01);
		mbutton02 = (Button) findViewById(R.id.button02);
		mbutton03 = (Button) findViewById(R.id.button03);
		mbutton04 = (Button) findViewById(R.id.button04);

		mbutton01.setOnClickListener(this);
		mbutton02.setOnClickListener(this);
		mbutton03.setOnClickListener(this);
		mbutton04.setOnClickListener(this);
	}

	@Override
	public void onClick(View v) {
		switch (v.getId()) {
		// 相对某个控件的位置(正左下方),无偏移
		case R.id.button01:
			getPopupWindowInstance();
			mPopupWindow.showAsDropDown(v);
			break;

		// 相对某个控件的位置(正左下方),有偏移
		case R.id.button02:
			getPopupWindowInstance();
			mPopupWindow.showAsDropDown(v, 50, 50);// X、Y方向各偏移50
			break;

		// 相对于父控件的位置,无偏移
		case R.id.button03:
			getPopupWindowInstance();
			mPopupWindow.showAtLocation(v, Gravity.CENTER, 0, 0);
			break;

		// 相对于父控件的位置,有偏移
		case R.id.button04:
			getPopupWindowInstance();
			mPopupWindow.showAtLocation(v, Gravity.BOTTOM, 0, 50);
			break;

		default:
			break;
		}
	}

	@Override
	public void onCheckedChanged(RadioGroup group, int checkedId) {
		mPopupWindow.dismiss();
	}

	/*
	 * 获取PopupWindow实例
	 */
	private void getPopupWindowInstance() {
		if (null != mPopupWindow) {
			mPopupWindow.dismiss();
			return;
		} else {
			initPopuptWindow();
		}
	}

	/*
	 * 创建PopupWindow
	 */
	private void initPopuptWindow() {
		LayoutInflater layoutInflater = LayoutInflater.from(this);
		View popupWindow = layoutInflater.inflate(R.layout.popup_window, null);
		RadioGroup radioGroup = (RadioGroup) popupWindow.findViewById(R.id.radioGroup);
		radioGroup.setOnCheckedChangeListener(this);

		// 创建一个PopupWindow
		// 参数1:contentView 指定PopupWindow的内容
		// 参数2:width 指定PopupWindow的width
		// 参数3:height 指定PopupWindow的height
		mPopupWindow = new PopupWindow(popupWindow, 100, 130);

		// 获取屏幕和PopupWindow的width和height
		mScreenWidth = getWindowManager().getDefaultDisplay().getWidth();
		mScreenWidth = getWindowManager().getDefaultDisplay().getHeight();
		mPopupWindowWidth = mPopupWindow.getWidth();
		mPopupWindowHeight = mPopupWindow.getHeight();
	}
}



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