19 Handler 子线程向主线程发送信息

package com.example.day19_handler_demo1;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.widget.TextView;

public class MainActivity extends Activity {

private TextView tv;

private int count =0;

private Handler handler = new Handler(){
public void handleMessage(android.os.Message msg) {

Log.e("AAA", "=handleMessage=>"+Thread.currentThread().getName());
//处理消息
//获取消息
int num = msg.arg1;
//更新数据
tv.setText(num+"");

};
};

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

tv = (TextView) findViewById(R.id.tv);

//       android.view.ViewRootImpl$CalledFromWrongThreadException:
//           Only the original thread that created a view hierarchy
//           can touch its views.

new Thread(){
public void run() {
while(true){

if(count<100){
count++;
}
Log.e("AAA", "=Thread=>"+Thread.currentThread().getName());
//  tv.setText(count+"");
//方式一获取Message对象  不建议使用
//Message msg = new Message(); 如果用sendToTarget想要setTarget
//方式二获取Message对象
//Message msg = Message.obtain(); 方便后面用sendToTarget
//方式三获取Message对象
Message msg = handler.obtainMessage();
//msg携带数据
msg.arg1 = count;
//使用Handler发送数据
handler.sendMessage(msg);

try {
sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
}.start();
}

}

package com.qf.day19_handler_demo2;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;

public class MainActivity extends Activity {

private Handler handler = new Handler(){
public void handleMessage(android.os.Message msg) {
//接收和处理消息的
switch (msg.what) {//根据标记进行处理数据
case 1:
int a = msg.arg1;
int a2 = msg.arg2;
String str = (String) msg.obj;
int flag = msg.what;

Log.e("AAA", "==a=="+a);
Log.e("AAA", "==a2=="+a2);
Log.e("AAA", "==str=="+str);
Log.e("AAA", "==flag=="+flag);

break;
case 2:
Log.e("AAAA", "AAAAAAAAAAAAAAAA");

break;

default:
break;
}
};
};

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

//子线程里的数据发送到主线程
public void OnMyClick(View v){

new Thread(){
public void run() {

//获取消息的载体对象
Message msg = Message.obtain();
msg.arg1 = 100;
msg.arg2 = 200;//arg1,arg2:都是int类型数据
msg.obj = "我是大数据"; //Object对象   string   Bitmap   List<T>
msg.what = 1;//int 类型   标记

handler.sendMessage(msg);

};
}.start();

}

}

package com.qf.day19_handler_demo4;

import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;

public class MainActivity extends Activity {

private ImageView ivShow;

Handler handler = new Handler();

Handler handler2 = new Handler(){
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case 1:
pDialog.show();
break;
case 2:

Bitmap bitmap = (Bitmap) msg.obj;
ivShow.setImageBitmap(bitmap);

pDialog.dismiss();

break;

default:
break;
}

};
};

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

ivShow = (ImageView) findViewById(R.id.iv_show);

pDialog = new ProgressDialog(MainActivity.this);
pDialog.setTitle("下载图片");
pDialog.setIcon(R.drawable.ic_launcher);
pDialog.setMessage("正在下载中,请稍后...");
}

public void MyLoadClick(View v) {
//pDialog.show();
//开启子线程下载图片
new Thread(){
public void run() {
//在子线程展示

//发送null消息  只设置一个标记
handler2.sendEmptyMessage(1);

byte[] data = HttpUtil.getHttpResult("https://ss2.baidu.com/6ONYsjip0QIZ8tyhnq/it/u=2507878052,3446525205&fm=58");
final Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);

//第一种方式   将代码块发送到主线程 在内部直接一个匿名内部类runnable 可以直接更新UI（主线程）
//              handler.post(new Runnable() {
//
//                  @Override
//                  public void run() {
//                      // TODO Auto-generated method stub
//                      Log.e("AAA", "=handler=>"+Thread.currentThread().getName());
//
//                      //更新Ui
//                      ivShow.setImageBitmap(bitmap);
//                      pDialog.dismiss();
//                  }
//              });

//延迟发送 在内部直接一个匿名内部类runnable 可以直接更新UI（主线程）
//              handler.postDelayed(r, delayMillis)

//第二种方式     使用msg  携带数据到主线程
//              Message msg = Message.obtain();
//              msg.obj = bitmap;
//              msg.what = 2;
//              handler2.sendMessage(msg);

//              延迟发送一个msg
//handler2.sendMessageDelayed(msg, delayMillis)

//第三种   sendToTarget  发送到那个Handler
//              Message msg = handler2.obtainMessage();
//              msg.obj = bitmap;
//              msg.what = 2;
//              msg.sendToTarget();//发送给那个Handler

//第四种方式
Message msg = Message.obtain();
msg.obj = bitmap;
msg.what = 2;
msg.setTarget(handler2);//指明是那个Handler
msg.sendToTarget();//发送给那个Handler

};
}.start();

}

}