1. if ( mBottomSheetDialog == null ){
2. mBottomSheetDialog = new BottomDialog ( that );
3. View specView = initSpecView (); // 这里只是用inflater将一个布局填充为了一View对象
4. . setContentView ( specView );
5. }
6. mBottomSheetDialog . show (); // 调用show方法就能展示了
7. mBottomSheetDialog . setOnDismissListener ( new DialogInterface . OnDismissListener () {
8. @Override
9. public void onDismiss ( DialogInterface dialog ) {
10. mBottomSheetDialog = null ;
11. }
12. });
13. private View initSpecView () {
14. View view = getLayoutInflater (). inflate ( R . layout . window_goods_choose , null );
15. ...... // 这里就是一些findViewById和对View 进行设置的操作
16. }

1. View bottomSheet = findViewById ( R . id . bottom_sheet ); //这里需要注意的是：view必须是CoordinatorLayout的子类
2. behavior = BottomSheetBehavior . from ( bottomSheet ); //该View需要配置Hehavior属性，Android 的默认实现为：app:layout_behavior="@string/bottom_sheet_behavior"
3. behavior . setBottomSheetCallback ( new BottomSheetBehavior . BottomSheetCallback () { //设置回调
4. @Override
5. public void onStateChanged ( @NonNull View bottomSheet , int newState ) {
6. // React to state change
7. }
9. @Override
10. public void onSlide ( @NonNull View bottomSheet , float slideOffset ) {
11. // React to dragging events
12. }
13. });

3、对状态的控制

1. behavior . setState ( BottomSheetBehavior . STATE_EXPANDED ); // 展开
2. behavior . setState ( BottomSheetBehavior . STATE_COLLAPSED ); //关闭

三、需要注意的问题（遇到的坑）

1. import android . content . Context ;
2. import android . os . Build ;
3. import android . os . Bundle ;
4. import android . support . annotation . LayoutRes ;
5. import android . support . annotation . NonNull ;
6. import android . support . annotation . StyleRes ;
7. import android . support . design . widget . BottomSheetBehavior ;
8. import android . support . design . widget . CoordinatorLayout ;
9. import android . support . v7 . app . AppCompatDialog ;
10. import android . util . Log ;
11. import android . util . TypedValue ;
12. import android . view . View ;
13. import android . view . ViewGroup ;
14. import android . view . Window ;
15. import android . widget . FrameLayout ;
17. import java . lang . reflect . Field ;
19. /**
20. * Base class for {@link android.app.Dialog}s styled as a bottom sheet.
21. */
22. public class MyDialog extends AppCompatDialog {
24. private BottomSheetBehavior bottomSheetBehavior ;
26. public MyDialog ( @NonNull Context context ) {
27. this ( context , 0 );
28. }
30. public MyDialog ( @NonNull Context context , @StyleRes int theme ) {
31. super ( context , getThemeResId ( context , theme ));
32. // We hide the title bar for any style configuration. Otherwise, there will be a gap
33. // above the bottom sheet when it is expanded.
34. supportRequestWindowFeature ( Window . FEATURE_NO_TITLE );
35. }
37. protected MyDialog ( @NonNull Context context , boolean cancelable ,
38. OnCancelListener cancelListener ) {
39. super ( context , cancelable , cancelListener );
40. supportRequestWindowFeature ( Window . FEATURE_NO_TITLE );
41. }
43. @Override
44. public void setContentView ( @LayoutRes int layoutResId ) {
45. super . setContentView ( wrapInBottomSheet ( layoutResId , null , null ));
46. }
48. @Override
49. protected void onCreate ( Bundle savedInstanceState ) {
50. super . onCreate ( savedInstanceState );
51. getWindow (). setLayout (
52. ViewGroup . LayoutParams . MATCH_PARENT , ViewGroup . LayoutParams . MATCH_PARENT );
53. }
55. @Override
56. public void setContentView ( View view ) {
57. super . setContentView ( wrapInBottomSheet ( 0 , view , null ));
58. }
60. @Override
61. public void setContentView ( View view , ViewGroup . LayoutParams params ) {
62. super . setContentView ( wrapInBottomSheet ( 0 , view , params ));
63. }
65. private View wrapInBottomSheet ( int layoutResId , View view , ViewGroup . LayoutParams params ) {
66. final CoordinatorLayout coordinator = ( CoordinatorLayout ) View . inflate ( getContext (),
67. android . support . design . R . layout . design_bottom_sheet_dialog , null );
68. if ( layoutResId != 0 && view == null ) {
69. view = getLayoutInflater (). inflate ( layoutResId , coordinator , false );
70. }
71. FrameLayout bottomSheet = ( FrameLayout ) coordinator . findViewById ( android . support . design . R . id . design_bottom_sheet );
72. bottomSheetBehavior = BottomSheetBehavior . from ( bottomSheet );
73. bottomSheetBehavior . setBottomSheetCallback ( mBottomSheetCallback );
74. if ( params == null ) {
75. bottomSheet . addView ( view );
76. } else {
77. bottomSheet . addView ( view , params );
78. }
79. // We treat the CoordinatorLayout as outside the dialog though it is technically inside
80. if ( shouldWindowCloseOnTouchOutside ()) {
81. coordinator . findViewById ( android . support . design . R . id . touch_outside ). setOnClickListener (
82. new View . OnClickListener () {
83. @Override
84. public void onClick ( View view ) {
85. if ( isShowing ()) {
86. cancel ();
87. }
88. }
89. });
90. }
91. return coordinator ;
92. }
94. private boolean shouldWindowCloseOnTouchOutside () {
95. if ( Build . VERSION . SDK_INT < 11 ) {
96. return true ;
97. }
98. TypedValue value = new TypedValue ();
99. //noinspection SimplifiableIfStatement
100. if ( getContext (). getTheme ()
101. . resolveAttribute ( android . R . attr . windowCloseOnTouchOutside , value , true )) {
102. return value . data != 0 ;
103. }
104. return false ;
105. }
107. private static int getThemeResId ( Context context , int themeId ) {
108. if ( themeId == 0 ) {
109. // If the provided theme is 0, then retrieve the dialogTheme from our theme
110. TypedValue outValue = new TypedValue ();
111. if ( context . getTheme (). resolveAttribute (
112. android . support . design . R . attr . bottomSheetDialogTheme , outValue , true )) {
113. themeId = outValue . resourceId ;
114. } else {
115. // bottomSheetDialogTheme is not provided; we default to our light theme
116. themeId = android . support . design . R . style . Theme_Design_Light_BottomSheetDialog ;
117. }
118. }
119. return themeId ;
120. }
122. private BottomSheetBehavior . BottomSheetCallback mBottomSheetCallback
123. = new BottomSheetBehavior . BottomSheetCallback () {
124. @Override
125. public void onStateChanged ( @NonNull View bottomSheet ,
126. @BottomSheetBehavior . State int newState ) {
127. if ( newState == BottomSheetBehavior . STATE_HIDDEN ) {
128. dismiss ();
129. }
130. }
132. @Override
133. public void onSlide ( @NonNull View bottomSheet , float slideOffset ) {
134. }
135. };
137. @Override
138. protected void onStart () {
139. super . onStart ();
140. // 会有异常
141. // if (bottomSheetBehavior != null)
142. // bottomSheetBehavior.setState(BottomSheetBehavior.STATE_EXPANDED);
144. //暂时解决方法
145. try {
146. Field field = BottomSheetBehavior . class . getDeclaredField ( "mState" );
147. field . setAccessible ( true );
148. field . setInt ( bottomSheetBehavior , BottomSheetBehavior . STATE_EXPANDED );
149. } catch ( NoSuchFieldException e ) {
150. Log . e ( "BottomSheetBehavior" , "Error setting BottomSheetBehavior initial state (1)" , e );
151. } catch ( IllegalAccessException e ) {
152. Log . e ( "BottomSheetBehavior" , "Error setting BottomSheetBehavior initial state (2)" , e );
153. }
154. }
155. }