android自定义Dialog实现底部弹窗

拿到这个需求，很多人都是直接想用popWindow 实现，但是这样的效果我们完全可以根据系统的Dialog 自定义一个。

AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setTitle("SSS");
builder.show();

这样就直接显示出一个对话框，但是，这个对话框在屏幕的中间，然后，我们去查看dialog的源码：
看dialog.show()里面判断了是否正在显示中，并没有和根布局有关系，看这个类的父类。里面的show()中：

public void show() {
    if (mShowing) {
        if (mDecor != null) {
            if (mWindow.hasFeature(Window.FEATURE_ACTION_BAR)) {
                mWindow.invalidatePanelMenu(Window.FEATURE_ACTION_BAR);
            }
            mDecor.setVisibility(View.VISIBLE);
        }
        return;
    }

    mCanceled = false;

    if (!mCreated) {
        dispatchOnCreate(null);
    } else {
        // Fill the DecorView in on any configuration changes that
        // may have occured while it was removed from the WindowManager.
        final Configuration config = mContext.getResources().getConfiguration();
        mWindow.getDecorView().dispatchConfigurationChanged(config);
    }

    onStart();
    mDecor = mWindow.getDecorView();

    if (mActionBar == null && mWindow.hasFeature(Window.FEATURE_ACTION_BAR)) {
        final ApplicationInfo info = mContext.getApplicationInfo();
        mWindow.setDefaultIcon(info.icon);
        mWindow.setDefaultLogo(info.logo);
        mActionBar = new WindowDecorActionBar(this);
    }

    WindowManager.LayoutParams l = mWindow.getAttributes();
    if ((l.softInputMode
            & WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION) == 0) {
        WindowManager.LayoutParams nl = new WindowManager.LayoutParams();
        nl.copyFrom(l);
        nl.softInputMode |=
                WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION;
        l = nl;
    }

    mWindowManager.addView(mDecor, l);
    mShowing = true;

    sendShowMessage();
}

这个调用addView 进去，我们Dialog就是这样加进去的；
可以看到Dialog的源码中的方法，也有onCreate( ) 他也是初始化 对话框的

/**
 * Similar to {@link Activity#onCreate}, you should initialize your dialog
 * in this method, including calling {@link #setContentView}.
 * @param savedInstanceState If this dialog is being reinitialized after a
 *     the hosting activity was previously shut down, holds the result from
 *     the most recent call to {@link #onSaveInstanceState}, or null if this
 *     is the first time.
 */
protected void onCreate(Bundle savedInstanceState) {
}

看Dialog 的实现类。里面有个日期弹窗的实现类，效果如下，更多时间筛选的对话框可以看我的另一个自定义的 文章：

系统的效果如下：
[图片上传失败...(image-ceb45e-1511342382391)]

自定义Dialog实现

1.创建一个自定义类继承dialog类，创建布局，当成Activity 重写onCreate()看效果

public class SmartDialog extends Dialog {
    public SmartDialog(@NonNull Context context) {
        super(context);
    }

    public SmartDialog(@NonNull Context context, @StyleRes int themeResId) {
        super(context, themeResId);
    }

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.smartlayout);
}

}

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView
      android:layout_width="match_parent"
      android:layout_margin="10dp"
      android:layout_height="wrap_content"
      android:id="@+id/title"
      android:text="自定义风格弹窗"
        />
    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

点击事件调用：

SmartDialog smartDialog = new SmartDialog(DialogShowActivity.this);
smartDialog.setTitle("我是Title");
smartDialog.show();

image.png

设置View的 属性，让弹窗到底部

requestWindowFeature(Window.FEATURE_NO_TITLE);//事情定需不需要加
setContentView(R.layout.smartlayout);
WindowManager.LayoutParams params = getWindow().getAttributes();
if(params!=null){
    //获取属性可能失败 为空
    params.gravity= Gravity.CENTER_HORIZONTAL|Gravity.BOTTOM;
    getWindow().setAttributes(params);
}

image.png

更改布局，添加数据

这里我们简单做一个ListView

image.png

.显示效果你会发现没有完全填充，这个时候，再去看我们调用Dialog 默认的构造函数，

查看源码。更改style

public Dialog(@NonNull Context context) {
    this(context, 0, true);
}
if (createContextThemeWrapper) {
    if (themeResId == 0) {
        final TypedValue outValue = new TypedValue();
        context.getTheme().resolveAttribute(R.attr.dialogTheme, outValue, true);
        themeResId = outValue.resourceId;
    }
    mContext = new ContextThemeWrapper(context, themeResId);
} else {
    mContext = context;
}

如果走默认的构造就不显示，去SDK中找到 R.attr.dialogTheme 先找到自己对应版本的SDK 到自己项目 的build.gradle 中找到
进到自己的安装目录下找对于的 dialogTheme 发现只是定义了 类型，并没具体定义。然后去themes 里面找到：

 <!-- Dialog attributes -->
        <item name="dialogTheme">@style/Theme.Dialog</item>
        <item name="dialogTitleIconsDecorLayout">@layout/dialog_title_icons</item>
        <item name="dialogCustomTitleDecorLayout">@layout/dialog_custom_title</item>
        <item name="dialogTitleDecorLayout">@layout/dialog_title</item>
        <item name="dialogPreferredPadding">@dimen/dialog_padding</item>

因为并没有找到具体的定义属性，再去搜索 Theme.Dialog 去 style 中找下 没找到，发现这个文件就在 themes 中,如下：

  <style name="Theme.Dialog">
        <item name="windowFrame">@null</item>
        <item name="windowTitleStyle">@style/DialogWindowTitle</item>
        <item name="windowBackground">@drawable/panel_background</item>
        <item name="windowIsFloating">true</item>
        <item name="windowContentOverlay">@null</item>
        <item name="windowAnimationStyle">@style/Animation.Dialog</item>
        <item name="windowSoftInputMode">stateUnspecified|adjustPan</item>
        <item name="windowCloseOnTouchOutside">@bool/config_closeDialogWhenTouchOutside</item>
        <item name="windowActionModeOverlay">true</item>

        <item name="colorBackgroundCacheHint">@null</item>

        <item name="textAppearance">@style/TextAppearance</item>
        <item name="textAppearanceInverse">@style/TextAppearance.Inverse</item>

        <item name="textColorPrimary">@color/primary_text_dark</item>
        <item name="textColorSecondary">@color/secondary_text_dark</item>
        <item name="textColorTertiary">@color/tertiary_text_dark</item>
        <item name="textColorPrimaryInverse">@color/primary_text_light</item>
        <item name="textColorSecondaryInverse">@color/secondary_text_light</item>
        <item name="textColorTertiaryInverse">@color/tertiary_text_light</item>
        <item name="textColorPrimaryDisableOnly">@color/primary_text_dark_disable_only</item>
        <item name="textColorPrimaryInverseDisableOnly">@color/primary_text_light_disable_only</item>
        <item name="textColorPrimaryNoDisable">@color/primary_text_dark_nodisable</item>
        <item name="textColorSecondaryNoDisable">@color/secondary_text_dark_nodisable</item>
        <item name="textColorPrimaryInverseNoDisable">@color/primary_text_light_nodisable</item>
        <item name="textColorSecondaryInverseNoDisable">@color/secondary_text_light_nodisable</item>
        <item name="textColorHint">@color/hint_foreground_dark</item>
        <item name="textColorHintInverse">@color/hint_foreground_light</item>
        <item name="textColorSearchUrl">@color/search_url_text</item>

        <item name="textAppearanceLarge">@style/TextAppearance.Large</item>
        <item name="textAppearanceMedium">@style/TextAppearance.Medium</item>
        <item name="textAppearanceSmall">@style/TextAppearance.Small</item>
        <item name="textAppearanceLargeInverse">@style/TextAppearance.Large.Inverse</item>
        <item name="textAppearanceMediumInverse">@style/TextAppearance.Medium.Inverse</item>
        <item name="textAppearanceSmallInverse">@style/TextAppearance.Small.Inverse</item>

        <item name="listPreferredItemPaddingLeft">10dip</item>
        <item name="listPreferredItemPaddingRight">10dip</item>
        <item name="listPreferredItemPaddingStart">10dip</item>
        <item name="listPreferredItemPaddingEnd">10dip</item>

        <item name="preferencePanelStyle">@style/PreferencePanel.Dialog</item>
    </style>

我们重点看这个属性： <item name="windowBackground">@drawable/panel_background</item>
在资源文件中搜索这个panel_background,打开你会发现是一张 .9图片如下：

image.png

我们自己在项目中实现一个style 去重写这个background 属性，去覆盖

    <!--自定义对话框-->
    <style name="MtStyle" parent="@style/Theme.AppCompat.Dialog">
        <!-- Customize your theme here. -->
        <item name="android:windowBackground">@android:color/white</item>
    </style>

然后在代码中去使用就直接多传递一个参数去设置：

 public Smartdialog(@NonNull Context context) {
        super(context,R.style.MtStyle);
    }

这样就实现我们要的效果，和PopWindow 一样，但是注意了，在一些新的版本上该效果还是有间隙，这个就要去研究对应SDK的刚才那个属性 中的参数影响了。试了两个版本都不行。。。。只有在老版本上可以，不过也给大家提供了一个思路！