解决安卓自定义Dialog不能水平填满屏幕

问题描述：

UI设计，需要展示一个底部充满屏幕的弹出框，但是发现下面和左右都没有充满。
预期：

实际：

解决方案：

• 自定义的Dialog中调用父类构造函数时，需要设置style
• 完整自定义dialog代码如下：
  1.CustDialog.java

package com.cxyzy.simplebottomdialog;

import android.app.Dialog;
import android.content.Context;
import android.support.annotation.NonNull;
import android.view.Gravity;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;

public class CustDialog extends Dialog {
    public CustDialog(@NonNull Context context) {
        super(context,R.style.common_dialog);
        setContentView(R.layout.cust_dialog_layout);
        changeDialogStyle();
    }

    /**
     * 设置dialog居下占满屏幕
     */
    private void changeDialogStyle() {
        Window window = getWindow();
        if (window != null) {
            WindowManager.LayoutParams attr = window.getAttributes();
            if (attr != null) {
                attr.height = ViewGroup.LayoutParams.WRAP_CONTENT;
                attr.width = ViewGroup.LayoutParams.MATCH_PARENT;
                attr.gravity = Gravity.BOTTOM;
                window.setAttributes(attr);
            }
        }
    }
}

2.cust_dialog_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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="wrap_content"
    android:background="#FFFFFF"
    android:orientation="vertical">

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="21dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:text="测试dialog"
        android:textColor="@android:color/black"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/btn_cancel"
        android:layout_width="0dp"
        android:layout_height="40dp"
        android:layout_marginStart="12dp"
        android:layout_marginLeft="12dp"
        android:layout_marginTop="80dp"
        android:layout_marginEnd="12dp"
        android:layout_marginRight="12dp"
        android:background="#E9E9E9"
        android:gravity="center_vertical|center_horizontal"
        android:text="取消"
        android:textColor="#5B5B5B"
        android:textSize="14sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView2" />

</android.support.constraint.ConstraintLayout>

3.styles.xml中增加：

    <style name="common_dialog" parent="@android:style/Theme.Dialog">
        <item name="android:windowBackground">@android:color/transparent</item>
    </style>

Demo源代码：

https://gitee.com/cxyzy1/custom_dialog/tree/master/simpleBottomDialog