Writing in the front

  • Record the use of BroadCast learning
  • IDE: Android-Studio SDK version: API30

About the previous foundation:

  • About what isBroadCastPlease refer to this articleAndroid BroadcastReceiver
  • aboutServiceRefer to this articleAndroid four components of the Service

This paper mainly uses Service and BroadCast to realize a stopwatch with start, pause, return to zero three functions

Without further ado, let’s start coding

activity_receive.xml


      
<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"
    tools:context=".ReceiveActivity"
    android:orientation="vertical">

    <TextView
        android:id="@+id/text1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="35sp">
    </TextView>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="200dp"
        android:layout_marginTop="100dp"
        android:orientation="vertical">

        <Button
            android:id="@+id/btn1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="Start">
        </Button>

        <Button
            android:id="@+id/btn2"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="Pause">
        </Button>

        <Button
            android:id="@+id/btn3"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="Zero">
        </Button>
    </LinearLayout>
    <TextView
        android:id="@+id/timeView"
        android:layout_marginTop="50dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="">
    </TextView>
</LinearLayout>
Copy the code

Preview the interface. It’s easy

1. Define BroadCastSender

package com.czie.service;

import android.content.Intent;

/** ** Broadcast transmitter */
public class BroadCastSender {
    // Define constants
    public static final String BROADACTION = "CZIE";
    Intent intent = new Intent();

    public void send(String name, String value) {
        // Add a theme
        intent.setAction(BROADACTION);
        intent.putExtra(name, value);
        // Send a broadcast
        MyApplication.getContext().sendBroadcast(intent);
    }

    public void send(String name, int value) {
        // Add a theme
        intent.setAction(BROADACTION);
        intent.putExtra(name, value);
        MyApplication.getContext().sendBroadcast(intent);
    }

    public void send(String name, Long value) {
        // Add a theme
        intent.setAction(BROADACTION);
        intent.putExtra(name, value);
        MyApplication.getContext().sendBroadcast(intent);
    }

    public void send(String name, Byte value) {
        // Add a themeintent.setAction(BROADACTION); intent.putExtra(name, value); MyApplication.getContext().sendBroadcast(intent); }}Copy the code

2. Define a Service to send messages

Keep sending messages through a while loop

TestService3

package com.czie.service;

import android.app.IntentService;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;

import androidx.annotation.Nullable;

import static com.czie.service.ReceiveActivity.istime;

public class TestService3 extends IntentService {
    BroadCastSender sender = new BroadCastSender();
    // The parent class constructor must be implemented
    public TestService3(a) {
        super("TestService3");
        // TODO Auto-generated constructor stub
    }

    // Core methods that must be overridden
    @Override
    protected void onHandleIntent(@Nullable Intent intent) {
      
        int i = 0;
        while (true) {
            if (istime == 0) {
                i++;
            } else if (istime == 1) {
                i = 0;
            }
            sender.send("HelloWorld",i);
            try {
                    Thread.sleep(1000);
                } catch(InterruptedException e) { e.printStackTrace(); }}}}Copy the code

3. MyApplication

This class is used to get the context

MyApplication

package com.czie.service;

import android.app.Application;
import android.content.Context;

public class MyApplication extends Application {
    private static Context context;

    @Override
    public void onCreate(a) {
        super.onCreate();
        context=this;
    }

    public static Context getContext(a) {
        returncontext; }}Copy the code

4. ReceiveActivity on the home screen

  • Set button listening events
  • Radio reception
  • Creating a Broadcast receiver

ReceiveActivity

package com.czie.service;

import androidx.appcompat.app.AppCompatActivity;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.text.SimpleDateFormat;
import java.util.Date;
@SuppressWarnings({"all"})
public class ReceiveActivity extends AppCompatActivity implements View.OnClickListener {
    public static int istime;
    MyBroadReceiver myBroadReceiver;
    private TextView textView;
    private TextView timeView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_receive);
        Button btn1 = findViewById(R.id.btn1);
        Button btn2 = findViewById(R.id.btn2);
        Button btn3 = findViewById(R.id.btn3);
        textView = findViewById(R.id.text1);
        timeView=findViewById(R.id.timeView);
        btn1.setOnClickListener(this);
        btn2.setOnClickListener(this);
        btn3.setOnClickListener(this);

        // Broadcast acceptance
        myBroadReceiver=new MyBroadReceiver();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(BroadCastSender.BROADACTION);
        registerReceiver(myBroadReceiver,intentFilter);
      // startService(new Intent(ReceiveActivity.this,TestService3.class));
    }
    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.btn1:
                istime=0;
                startService(new Intent(ReceiveActivity.this,TestService3.class));
              // startService(Intent.makeMainActivity(startService(new Intent(ReceiveActivity.this, TestService3.class))));
            break;
            case R.id.btn2:
                istime=2;
                break;
            case R.id.btn3:
                istime=1;
                break; }}// Create a broadcast receiver
    class MyBroadReceiver extends BroadcastReceiver{
        @Override
        public void onReceive(Context context, Intent intent) {
            // Get parameters
            int time = intent.getIntExtra("HelloWorld".0);
            / / minute
            int min =time/60;
            / / second
            int second=time%60;
            String times=String.format("%02d",min)+":"+String.format("%02d",second);

            textView.setText(String.valueOf(times));
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
            String clockTime = simpleDateFormat.format(newDate()); timeView.setText(clockTime); }}}Copy the code

Preview the results

Write in the last

  • Master the basic knowledge of BroadCast and how to send and receive messages, and realize the functions 👍
  • Continue exploring BroadCast’s other features 💪
  • If you found this article useful, please like 👍
  • If you have any questions about this article, please point to ❤️ in the comments section