Notification通知

测试账号 2021-01-07 04:47 684阅读 0赞

Notification：  
例子的NotificationCompat使用的是v4包下的，稍微有点老，如果大家使用的话，建议使用v7包下的，通知也没什么好介绍的，直接看代码  
MainActivity：

package com.fitsoft;
    
    import android.app.Notification;
    import android.app.NotificationManager;
    import android.app.PendingIntent;
    import android.content.Context;
    import android.content.Intent;
    import android.os.Bundle;
    import android.support.v4.app.NotificationCompat;
    import android.support.v7.app.AppCompatActivity;
    import android.view.View;
    import android.widget.Button;
    
    public class MainActivity extends AppCompatActivity {
    
        private int notificationId = 100;
        private static int times = 0;
        Button button;
        Context context;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            context = this;  //设置上下文对象
    
            button = findViewById(R.id.btn);
            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    times++;
                    if(times%2 == 1){
                        button.setText("销毁通知");
                        createNotification();  //创建通知
                    }else {
                        button.setText("创建通知");
                        destroyNotification(); //取消通知
                    }
                }
            });
        }
    
        /**
         * 创建通知
         */
        private void createNotification() {
            //创建builder
            NotificationCompat.Builder builder = new NotificationCompat.Builder(context, "my_notifications");
            //设置属性
            builder.setSmallIcon(R.mipmap.ic_launcher_round);  //设置图标
            builder.setContentTitle("这是通知的标题");     //设置标题
            builder.setContentText("这是通知的具体内容");  //设置内容
            builder.setNumber(1);    //设置通知次数
            builder.setAutoCancel(true);   //设置是否自动取消
            //构建启动意图
            PendingIntent pendingIntent = PendingIntent.getActivity(context, 1,
                    new Intent(this, SecondActivity.class), PendingIntent.FLAG_UPDATE_CURRENT);
            //设置启动意图
            builder.setContentIntent(pendingIntent);
            Notification notification = builder.build();
            //获取系统服务
            NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
            //系统创建通知
            notificationManager.notify(notificationId, notification);
        }
    
        /**
         * 取消通知
         */
        private void destroyNotification() {
            NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
            //取消通知
            notificationManager.cancel(notificationId);
        }
    }

布局文件使用的是上一次的只有一个按钮的状态选择器的布局，具体请查看上一篇。  
这里的方法都很好理解，只是其中有一个构建启动意图的时候的PendingIntent.getActivity()方法，我们具体看一下：

/**
     * Retrieve a PendingIntent that will start a new activity, like calling
     * {@link Context#startActivity(Intent) Context.startActivity(Intent)}.
     * Note that the activity will be started outside of the context of an
     * existing activity, so you must use the {@link Intent#FLAG_ACTIVITY_NEW_TASK
     * Intent.FLAG_ACTIVITY_NEW_TASK} launch flag in the Intent.
     *
     * <p class="note">For security reasons, the {@link android.content.Intent}
     * you supply here should almost always be an <em>explicit intent</em>,
     * that is specify an explicit component to be delivered to through
     * {@link Intent#setClass(android.content.Context, Class) Intent.setClass}</p>
     *
     * @param context The Context in which this PendingIntent should start
     * the activity.
     * @param requestCode Private request code for the sender
     * @param intent Intent of the activity to be launched.
     * @param flags May be {@link #FLAG_ONE_SHOT}, {@link #FLAG_NO_CREATE},
     * {@link #FLAG_CANCEL_CURRENT}, {@link #FLAG_UPDATE_CURRENT},
     * or any of the flags as supported by
     * {@link Intent#fillIn Intent.fillIn()} to control which unspecified parts
     * of the intent that can be supplied when the actual send happens.
     *
     * @return Returns an existing or new PendingIntent matching the given
     * parameters.  May return null only if {@link #FLAG_NO_CREATE} has been
     * supplied.
     */
    public static PendingIntent getActivity(Context context, int requestCode,
            Intent intent, @Flags int flags) {
        return getActivity(context, requestCode, intent, flags, null);
    }

这里的第四个参数flags值得注意，我们点击这个@Flags注解进行查看：

/** @hide */
    @IntDef(flag = true,
            value = {
                    FLAG_ONE_SHOT,
                    FLAG_NO_CREATE,
                    FLAG_CANCEL_CURRENT,
                    FLAG_UPDATE_CURRENT,
                    FLAG_IMMUTABLE,
    
                    Intent.FILL_IN_ACTION,
                    Intent.FILL_IN_DATA,
                    Intent.FILL_IN_CATEGORIES,
                    Intent.FILL_IN_COMPONENT,
                    Intent.FILL_IN_PACKAGE,
                    Intent.FILL_IN_SOURCE_BOUNDS,
                    Intent.FILL_IN_SELECTOR,
                    Intent.FILL_IN_CLIP_DATA
            })
    @Retention(RetentionPolicy.SOURCE)
    public @interface Flags {}

这是一个源码级的注解，有五个常用的值以及一些Intent的常用值，这五个值的含义大致如下：

1.  FLAG\_ONE\_SHOT：表明这里构建的PendingIntent只能使用一次
2.  FLAG\_NO\_CREATE：如果前一个PendingIntent已经不存在，将不再构建它
3.  FLAG\_CANCEL\_CURRENT：如果构建的PendingIntent已经存在，则取消前一个，重新构建一个
4.  FLAG\_UPDATE\_CURRENT：如果构建的PendingIntent已经存在，则替换它
5.  FLAG\_IMMUTABLE：已经构建的PendingIntent不可更改

这里我们使用第4个，因为它比较常用。