前言
相信每位Android开发者都用过
ToastalertMesageBoxdialogdialogtoastToast先看下源码：
public class Toast {
public static final int LENGTH_SHORT = 0;
public static final int LENGTH_LONG = 1;
public Toast(Context context) {
...
//获取系统内置的toast_y_offset常量值
mTN.mY = context.getResources().getDimensionPixelSize(
com.android.internal.R.dimen.toast_y_offset);
mTN.mGravity = context.getResources().getInteger(
com.android.internal.R.integer.config_toastDefaultGravity);
}
public void show() {
//如果mNextView为空，即没有设置view
if (mNextView == null) {
throw new RuntimeException("setView must have been called");
}
//通过系统服务，获取通知管理器。看来这是使用系统通知？
INotificationManager service = getService();
String pkg = mContext.getOpPackageName();
TN tn = mTN;
tn.mNextView = mNextView;
try {
service.enqueueToast(pkg, tn, mDuration);
} catch (RemoteException e) {
// Empty
}
}
public void cancel() {
mTN.hide();
try {
getService().cancelToast(mContext.getPackageName(), mTN);
} catch (RemoteException e) {
// Empty
}
}
public void setView(View view) {
mNextView = view;
}
public void setDuration(@Duration int duration) {
mDuration = duration;
}
public void setMargin(float horizontalMargin, float verticalMargin) {
mTN.mHorizontalMargin = horizontalMargin;
mTN.mVerticalMargin = verticalMargin;
}
public void setGravity(int gravity, int xOffset, int yOffset) {
mTN.mGravity = gravity;
mTN.mX = xOffset;
mTN.mY = yOffset;
}
public static Toast makeText(Context context, CharSequence text, @Duration int duration) {
Toast result = new Toast(context);
LayoutInflater inflate = (LayoutInflater)
context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
//包含了一个默认的TextView，这个textview的布局位置在
com.android.internal.R.layout.transient_notification，可以去查看下内容
View v = inflate.inflate(com.android.internal.R.layout.transient_notification, null);
TextView tv = (TextView)v.findViewById(com.android.internal.R.id.message);
tv.setText(text);
result.mNextView = v;
result.mDuration = duration;
return result;
}
public void setText(CharSequence s) {
if (mNextView == null) {
throw new RuntimeException("This Toast was not created with Toast.makeText()");
}
TextView tv = (TextView) mNextView.findViewById(com.android.internal.R.id.message);
if (tv == null) {
throw new RuntimeException("This Toast was not created with Toast.makeText()");
}
tv.setText(s);
}
static private INotificationManager getService() {
if (sService != null) {
return sService;
}
//获取远程的通知服务
sService = INotificationManager.Stub.asInterface(ServiceManager.getService("notification"));
return sService;
}
//TN是一个瞬态通知的子类，里面包含显示和隐藏两个任务对象
private static class TN extends ITransientNotification.Stub {
final Runnable mShow = new Runnable() {
@Override
public void run() {
handleShow();
}
};
final Runnable mHide = new Runnable() {
@Override
public void run() {
handleHide();
// Don't do this in handleHide() because it is also invoked by handleShow()
mNextView = null;
}
};
//出现Handler了哦
final Handler mHandler = new Handler();
@Override
public void show() {
if (localLOGV) Log.v(TAG, "SHOW: " + this);
//handler发送异步任务了
mHandler.post(mShow);
}
@Override
public void hide() {
if (localLOGV) Log.v(TAG, "HIDE: " + this);
mHandler.post(mHide);
}
//...
}
} 通过上面的源码解读，了解到有远程通知，
handler重点是toast的用法：
1、直接调用makeText静态方法即可，返回的是Toast对象，最后别忘了调用show方法显示：
Toast.makeText(context, text, duration).show(); 或
Toast toast = Toast.makeText(context, text, duration);
pre name="code" class="html"> toast.setView(view);
toast.setText(s);
toast.setGravity(gravity, xOffset, yOffset);
toast.setDuration(duration);
toast.show();2、还可以使用new的方式创建，别忘了setView()方法：
Toast toast = new Toast();
toast.setView(view);
toast.setText(s);
toast.setGravity(gravity, xOffset, yOffset);
toast.setDuration(duration);
toast.show(); 以上这些都不值得一提，很简单。
在开发过程中，有这样的需求：在项目总，我们偷懒，想连串
toasttoasttoast
public class T {
private static Toast toast;
public static void show(Context context, String msg) {
if (toast == null) {
toast = Toast.makeText(context, msg, Toast.LENGTH_SHORT);
} else {
toast.setText(msg);
}
toast.show();
}
} 单例模式，每次创建
toastshowToastshowcancelmakeTextnewtoasthandler结束语
以上就是Android中Toast提示框优化的全部内容，希望对大家开发Android能有所帮助，如果有大家有疑问可以留言交流。
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