1.Thread
Android中有三种开启Thread的方式
1.继承Thread
class MyTherad extends Thread{
@Override
public void run() {
super.run();
//耗时操作
try {
sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
//子线程内一旦有耗时操作就，就不能在子线程内进行UI修改
String a="123";
Log.i("接收到的值",a);
}
}
//开启线程
MyTherad myTherad=new MyTherad();
myTherad.start();
2.实现Runnable接口
class MyRunnable implements Runnable{
@Override
public void run() {
try {
Thread.sleep(3000);
Log.i("实现接口创建子线程","123");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
MyRunnable myRunnable=new MyRunnable();
Thread thread=new Thread(myRunnable);
thread.start();
3.Thread和Runnable综合使用（最常见的）
new Thread(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(3000);
Log.i("匿名","333");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}).start();
2.Handler
1.特点
从服务器接收到用户的昵称，并将昵称设置在textview对应的text属性上
连接服务器的功能，是属于耗时任务，所以必须放在子线程
子线程中是没有办法修改页面,借助Handler给主线程传递消息
主线程接收到消息后，开始执行修改UI
2.代码实现
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
tv_age = findViewById(R.id.tv_age);
new Thread(new Runnable() {
@Override
public void run() {
try {
//模拟在连接服务器的耗时
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
Message message=new Message();
message.what=1;
message.obj=ac;
handler.sendMessage(message);
}
}).start();
}
private Handler handler=new Handler(Looper.getMainLooper()){
@Override
public void handleMessage(@NonNull Message msg) {
super.handleMessage(msg);
if (msg.what==1){
tv_age.setText(ac);
}
}
};
3. 给Handler传值有两种方式
1.new Message这种方式
Message message=new Message();
message.what=1;
message.obj=ac;
handler.sendMessage(message);
2.通过handler.hasMessages()这种方式
3.通过学习了以上知识做了一个进度条案例
代码实现
public class MainActivity3 extends AppCompatActivity {
private ProgressBar progressBar;
private int aa=0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main3);
progressBar = findViewById(R.id.progressBar);
new Thread(new Runnable() {
@Override
public void run() {
try {
while (aa<100){
Thread.sleep(100);
aa++;
handler.hasMessages(1);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}).start();
}
private Handler handler=new Handler(Looper.getMainLooper()){
@Override
public void handleMessage(@NonNull Message msg) {
super.handleMessage(msg);
if (msg.what==1){
progressBar.setProgress(aa);
}
}
};
}
4.Seriver中使用Handler
1.特点
Seriver中不会自动开启线程，也不会自动停止线程
2. 代码实现
public class MyService extends Service {
public MyService() {
}
@Override
public void onCreate() {
Log.i("onCreate","服务已创建");
super.onCreate();
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i("onCreate","服务已开启");
new Thread(new Runnable() {
@Override
public void run() {
long ac=System.currentTimeMillis()+20*1000;
while (System.currentTimeMillis()<ac){
synchronized (this){
try {
wait(ac-System.currentTimeMillis());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
stopSelf();
}
}).start();
return super.onStartCommand(intent, flags, startId);
}
@Override
public void onDestroy() {
Log.i("onCreate","服务已销毁");
super.onDestroy();
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
}
5.IntentService
1.如何创建IntentService
1.new 一个Java文件
2.继承IntentService
3.实现onHandleIntent方法和构造方法
4.创建一个无参的构造方法
5.注册
2.特点
IntentService 自动开启线程，并在执行完毕后，关闭线程
3.代码实现
public class MyIntentService extends IntentService {
/**
* @param name
* @deprecated
*/
public MyIntentService(String name) {
super(name);
}
public MyIntentService(){
super("MyIntentService");
}
@Override
protected void onHandleIntent(@Nullable Intent intent) {
Log.i("IntentSerivce","IntentSerivce已启动");
long ac=System.currentTimeMillis()+20*1000;
while (System.currentTimeMillis()<ac){
synchronized (this){
try {
wait(ac-System.currentTimeMillis());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
@Override
public void onDestroy() {
Log.i("IntentSerivce","IntentSerivce已销毁");
super.onDestroy();
}
}