Toast

Toast的基本原理其实就是将一个View添加到WindowManager中，让WindowManager来把View显示出来。（WindowManager可以将View显示在任何地方，任何Activity之上）


Toast的默认属性

Java代码

1. //对其方式为：水平居中，并在底部
2. mGravity=Gravtiy.CENTER_HORIZONTAL|Gravtiy.BOTTOM;
4. mX=0;
5. mY=context.getResources().getDimensionPixelSize(com.android.internal.R.dimen.toast_y_offset);
7. mHorizontalMargin=0;
8. mVerticalMargin=0;
10. 所以用Toast.makeText(getApplicationContext(),R.string.text,Toast.LENGTH_SHORT).show();生成的Toast总是处在底部水平居中的位置

在指定x, y处显示Toast

Java代码

1. //在(50,100)处显示Toast
2. Toasttoast=Toast.makeText(getApplicationContext(),"toastuse",Toast.LENGTH_SHORT);
3. toast.setGravity(Gravity.TOP|Gravity.LEFT,50,100);
4. toast.show();
6. //如果使用Gravity.NO_GRAVITY，后面的x,y就是相对于屏幕的中心点的（估计android是默认这么处理的）
7. Toasttoast=Toast.makeText(getApplicationContext(),"toastuse",Toast.LENGTH_SHORT);
8. toast.setGravity(Gravity.NO_GRAVITY,50,100);
9. toast.show();
11. //用margin来控制toast的位置
12. Toasttoast=Toast.makeText(getApplicationContext(),"toastuse",Toast.LENGTH_SHORT);
13. toast.setGravity(Gravity.LEFT|Gravity.TOP,0,0);
14. //leftMargin,topMargin分别是容器width,height的%多少(这里是10%和20%)
15. toast.setMargin(0.1F,0.2F);
16. toast.show();

指定View的Toast

Java代码

1. //布局xml：R.layout.toast
2. <Button
3. xmlns:android="http://schemas.android.com/apk/res/android"
4. android:id="@android:id/message"
5. android:layout_width="fill_parent"
6. android:layout_height="wrap_content"/>
9. Toasttoast=newToast(getApplicationContext());
10. toast.setView(LayoutInflater.from(getApplicationContext()).inflate(R.layout.toast,null));
11. toast.setText("toastuse");
12. //Button是否fill_parent是由gravity控制的,xml中的不起任何作用
13. toast.setGravity(toast.getGravity()|Gravity.FILL_HORIZONTAL,
14. toast.getXOffset(),toast.getYOffset());
15. toast.setDuration(Toast.LENGTH_SHORT);
16. toast.show();

Toast部分源码

Java代码

1. //Toast的构造器只设置了mY这个属性。mNextView,mDuration都没有设置(用makeText的话，这两个属性会设置)
2. publicToast(Contextcontext){
3. mContext=context;
4. mTN=newTN();
5. mY=context.getResources().getDimensionPixelSize(com.android.internal.R.dimen.toast_y_offset);
6. }
8. //setText方法，需要将显示text的view的id设为@android:id/message，否则会抛RuntimeException
9. publicvoidsetText(CharSequences){
10. if(mNextView==null){
11. thrownewRuntimeException("ThisToastwasnotcreatedwithToast.makeText()");
12. }
13. TextViewtv=(TextView)mNextView.findViewById(com.android.internal.R.id.message);
14. if(tv==null){
15. thrownewRuntimeException("ThisToastwasnotcreatedwithToast.makeText()");
16. }
17. tv.setText(s);
18. }

一直显示的Toast
实现原理是：在Toast隐藏之前，再show一个相同的Toast，来实现长显示的假象

Java代码

1. privateclassToastWrapper{
2. privateToastmToast;
4. privateHandlermHandler;
6. privateRunnablemShowToast=newRunnable(){
7. @Override
8. publicvoidrun(){
9. continueShow();
10. }
11. };
13. privatebooleanmCancelled=true;
15. publicToastWrapper(Contextctxt){
16. this(ctxt,newHandler());
17. }
19. publicToastWrapper(Contextctxt,Handlerhandler){
20. mToast=Toast.makeText(ctxt,null,Toast.LENGTH_SHORT);
21. mHandler=handler;
22. }
24. publicToastgetToast(){
25. returnmToast;
26. }
28. publicvoidshowUntilCancel(){
29. if(mCancelled){
30. mCancelled=false;
31. mToast.setDuration(Toast.LENGTH_LONG);
32. continueShow();
33. }
34. }
36. publicvoidcancel(){
37. mCancelled=true;
38. mToast.cancel();
39. }
41. privatevoidcontinueShow(){
42. if(mCancelled){
43. return;
44. }
45. mToast.show();
46. mHandler.postDelayed(mShowToast,3000);
47. }
48. }

使用ToastWrapper

Java代码

1. //一直显示的toast
2. toastWrapper=newToastWrapper(getApplicationContext());
3. Toasttoast=toastWrapper.getToast();
4. toast.setText("toastwrapper");
6. //...
8. Buttonbutton=newButton(getApplicationContext());
9. button.setText("一直显示toast");
10. button.setOnClickListener(newView.OnClickListener(){
11. @Override
12. publicvoidonClick(Viewview){
13. toastWrapper.showUntilCancel();
14. }
15. });
17. Buttonbutton=newButton(getApplicationContext());
18. button.setText("隐藏toast");
19. button.setOnClickListener(newView.OnClickListener(){
20. @Override
21. publicvoidonClick(Viewview){
22. toastWrapper.cancel();
23. }
24. });
28. //一搬的toast
29. Buttonbutton=newButton(getApplicationContext());
30. button.setText("一般的toast");
31. button.setOnClickListener(newView.OnClickListener(){
32. @Override
33. publicvoidonClick(Viewview){
34. Toasttoast=toastWrapper.getToast();
35. toast.setDuration(Toast.LENGTH_SHORT);
36. toast.show();
37. }
38. });

Android服务service里面出Toast：

1. if(phoneIsInUse())
2. {
3. newThread(newRunnable(){
4. publicvoidrun(){
5. Looper.prepare();
6. Toast
7. .makeText(
8. VuiService.this,
9. "请结束通话后再试",Toast.LENGTH_LONG).show();
10. Looper.loop();
11. }
12. }).start();
13. return;
14. }