android基础---->Toast的使用

简要说明　　

　　Toast是一种没有交点，显示时间有限，不能与用户进行交互，用于显示提示信息的显示机制，我们可以把它叫做提示框。Toast不依赖 于Activity，也就是说，没有Activity，依然可以使用Toast。
　　 Android的四大组件：Activity， Service， Broadcast Receiver， Contet
Provider，都是继承Context的（Context，现在大家称之为上下文，之前又被翻译为句柄），包括整个Application也是继承于Context的。Toast就是依赖于应用程序Application的Context。

项目结构

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" alt="" />

代码实现

• MainActivity.java:

package com.example.linux.customtoasttest;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;

/**
 * writer: 胡红翔
 * function: 自定义toast，以及toast的简单使用
 */
public class MainActivity extends AppCompatActivity {

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

    // toast:位置的改变
    public void toast1(View view) {
        Toast toast = Toast.makeText(MainActivity.this, "toast", Toast.LENGTH_LONG);
        toast.setGravity(Gravity.BOTTOM | Gravity.LEFT, 0, 0);
        toast.show();
    }

    //toast：自定义Toast
    public void customToast(View view) {
        LayoutInflater inflater = getLayoutInflater();
        ViewGroup viewGroup = (ViewGroup) findViewById(R.id.toast_layout_root);
        View layout = inflater.inflate(R.layout.toast_layout, viewGroup);

        TextView text = (TextView) layout.findViewById(R.id.textView);
        text.setText("This is a custom toast");

        Toast toast = new Toast(MainActivity.this);
        toast.setGravity(Gravity.CENTER_VERTICAL, 0, 0);
        toast.setDuration(Toast.LENGTH_LONG);
        toast.setView(layout); // 自定义View
        toast.show();
    }
}

• activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.linux.customtoasttest.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!" />

    <Button
        android:text="ToastPosition"
        android:onClick="toast1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Button
        android:text="CustomToast"
        android:onClick="customToast"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</LinearLayout>

• toast_layout.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/toast_layout_root"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#DAAA"
    android:orientation="horizontal"
    android:padding="8dp">

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginRight="8dp"
        android:src="@mipmap/ic_launcher" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#FFF" />
</LinearLayout>

实现原理

• toast的makeText方法：得到一些信息，生成一个View

Toast result = new Toast(context);
LayoutInflater inflate = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
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;

• toast的show方法：这个比较难，表示没怎么看懂，后续再做补充。大概的是add(view)让上述view显示，开启了一个线程不断轮询(估计是duration)，启动了一个通知服务。

// 窗口管理类
mWM = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
......
mWM.addView(mView, mParams);
// 绑定事件
trySendAccessibilityEvent(); 

友情链接