Android开发实践：用PopupWindow实现自定义Dailog

Android的PopupWindow是个很有用的widget，利用它可以实现悬浮窗体的效果，比如实现一个悬浮的菜单，最常见的应用就是在视频播放界面里，做一个工具栏，用来控制播放进度。本文利用PopupWindow来实现一个通用的Dailog，类似Android系统的AlertDailog，从中学习和掌握有关PopupWindow和Dailog的使用和实现细节。

界面效果如图所示，点击 Click 按钮后，弹出对话框提示。

1. CustomDailog的布局

首先定义 CustDailog的布局文件，由系统的AlertDailog可以知道，一个对话框包含了三个要素，一个是Title，即标题，一个是Message，即主体内容，还有一个是Button，即确定和取消的按钮，用来与用户交互。因此，布局设计如下：

<?xml version="1.0" encoding="utf-8"?>

其中，shap_bg.xml 是Dailog的背景的定义文件，你可以修改此文件，来改变Dailog的背景：

<?xml version="1.0" encoding="UTF-8"?>

（2） CustomDailog的定义

CustomDailog的接口，可以类比AlertDailg的接口定义，主要包括如下一些方法：

1. setTitle 设置标题

2. setMessage 设置主体内容

3. setPositiveButton 设置 “确定” 按钮

4. setNegativeButton 设置 “取消” 按钮

5. show 显示

6. dimiss 消失

其定义如下：

package com.ticktick.popdailog;                                                                                                                                                import android.content.Context;import android.view.Gravity;import android.view.LayoutInflater;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup.LayoutParams;import android.widget.Button;import android.widget.LinearLayout;import android.widget.PopupWindow;import android.widget.TextView;                                                                                                                                                    public class CustomDailog {                                                                                                                                                   private View mParent;    private PopupWindow mPopupWindow;    private LinearLayout mRootLayout;      private LayoutParams mLayoutParams;                                                                                                                                                    //PopupWindow必须有一个ParentView，所以必须添加这个参数    public CustomDailog(Context context, View parent) {                                                                                                                                                           mParent = parent;                                                                                                                                                           LayoutInflater mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);                                                                                                                                                                 //加载布局文件        mRootLayout = (LinearLayout)mInflater.inflate(R.layout.custom_dailog, null);                                                                                                                                                                    mLayoutParams = new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);    }                                                                                                                                                     //设置Dailog的标题    public void setTitle(String title) {        TextView mTitle = (TextView)mRootLayout.findViewById(R.id.CustomDlgTitle);        mTitle.setText(title);    }                                                                                                                                                   //设置Dailog的主体内容    public void setMessage(String message) {        TextView mMessage = (TextView)mRootLayout.findViewById(R.id.CustomDlgContentText);        mMessage.setText(message);    }                                                                                                                                                   //设置Dailog的“确定”按钮    public void setPositiveButton(String text,OnClickListener listener ) {        final Button buttonOK = (Button)mRootLayout.findViewById(R.id.CustomDlgButtonOK);        buttonOK.setText(text);        buttonOK.setOnClickListener(listener);        buttonOK.setVisibility(View.VISIBLE);    }                                                                                                                                                   //设置Dailog的“取消”按钮    public void setNegativeButton(String text,OnClickListener listener ) {        final Button buttonCancel = (Button)mRootLayout.findViewById(R.id.CustomDlgButtonCancel);        buttonCancel.setText(text);        buttonCancel.setOnClickListener(listener);        buttonCancel.setVisibility(View.VISIBLE);    }                                                                                                                                                   //替换Dailog的“主体”布局    public void setContentLayout(View layout) {                                                                                                                                                           TextView mMessage = (TextView)mRootLayout.findViewById(R.id.CustomDlgContentText);        mMessage.setVisibility(View.GONE);                                                                                                                                                           LinearLayout contentLayout = (LinearLayout)mRootLayout.findViewById(R.id.CustomDlgContentView);              contentLayout.addView(layout);                  }                                                                                                                                                   //设置Dailog的长宽    public void setLayoutParams(int width, int height) {        mLayoutParams.width  = width;        mLayoutParams.height = height;    }                                                                                                                                                   //显示Dailog    public void show() {                                                                                                                                                       if(mPopupWindow == null) {            mPopupWindow = new PopupWindow(mRootLayout, mLayoutParams.width,mLayoutParams.height);            mPopupWindow.setFocusable(true);        }                                                                                                                                                           mPopupWindow.showAtLocation(mParent, Gravity.CENTER, Gravity.CENTER, Gravity.CENTER);    }                                                                                                                                                   //取消Dailog的显示    public void dismiss() {                                                                                                                                                           if(mPopupWindow == null) {            return;        }                                                                                                                                                           mPopupWindow.dismiss();    }}

（3）在Activity中的使用方法

由于 PopupWindow 的显示必须给一个ParentView，在Activity中使用的话，最简单的方法就是将整个activity的“根View”传递给这个PopupWindow，这样就可以在整个屏幕的正中央来显示Dailog，获取Acitivity的根View的方法如下：

findViewById(android.R.id.content)).getChildAt(0);

因此，上面定义的 CunstomDailog的使用方法如下所示：

final CustomDailog dailog = new CustomDailog(this,getRootLayout());dailog.setTitle("Warning");dailog.setMessage("This is ticktick's blog!");dailog.setPositiveButton("OK", new OnClickListener() {            @Override    public void onClick(View v) {        dailog.dismiss();             }});dailog.setNegativeButton("Cancel", new OnClickListener() {            @Override    public void onClick(View v) {    dailog.dismiss();             }});dailog.show();

到此为止，整个Dailog的实现就介绍到这里了，工程文件可以在博客后面的附件中下载，你可以通过修改CustomDailog的定义以及custom_dailog.xml文件来改变Dailog的界面和效果，有不清楚的地方，欢迎留言或者来信lujun.hust@gmail.com交流，或者关注我的新浪微博 @卢_俊获取最新的文章和资讯。

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