android学习14#--Handler消息传递机制实例应用

上一篇android学习13#–Handler消息传递机制讲了它的原理，本文写两个例子来巩固下。例子比较简单。

主线程创建Handler

功能：UI线程创建一个handler，通过定时器周期性发送消息给UI线程，UI线程收到消息调整文字字体大小。
xml布局：

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.uudou.study.handleronuithread.MainActivity">


    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="测试文字"
            android:id="@+id/textView"
            android:layout_gravity="center_horizontal" />
    </LinearLayout>
</RelativeLayout>

activity源码：

public class MainActivity extends AppCompatActivity {

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


        final TextView tText = (TextView) findViewById(R.id.textView);

        /*主线程创建handler*/
        final Handler tHandle = new Handler() {
            public float tSize=32;

            @Override
            public void handleMessage(Message msg) {
                if (msg.what == 0x123) {
                    super.handleMessage(msg);
                    this.tSize++;
                    if (this.tSize > 100) this.tSize = 32;
                    tText.setText("测试文字[size：" + (int) this.tSize + "]");
                    tText.setTextSize(this.tSize);
                }
            }
        };

        /*创建一个定时器，周期性执行指定任务*/
        new Timer().schedule(new TimerTask() {
            @Override
            public void run() {
                tHandle.sendEmptyMessage(0x123);
            }
        }, 0, 1000);
    }
}

效果图：

在新线程中创建handler

功能：创建一个线程类，在新线程中创建一个handler，UI线程往新线程发送消息，新线程收到消息打印收到一个消息。打印出来
xml布局：

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.uudou.study.handleronnewthread.MainActivity">

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true">

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="发送消息"
            android:id="@+id/button"
            android:layout_gravity="center_horizontal"
            android:onClick="onClickButton"
            android:textSize="32dp" />
    </LinearLayout>
</RelativeLayout>

activity源码：

//NewThread.java
/**
 * Created by jindg on 16-7-11.
 */
public class NewThread extends Thread {

    protected Handler tHandler;

    Handler gettHandler() {
        return tHandler;
    }

    @Override
    public void run() {
        Looper.prepare();
        this.tHandler = new Handler() {
            float tSize = 32;
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                if(msg.what == 0x123) {
                    Log.d("NewThread", "NewThread接收Handler消息");
                }
            }
        };

        Looper.loop();
    }
}
//MainActivity.java
public class MainActivity extends AppCompatActivity {
    Handler tHandler;
    NewThread tThread;

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

        tThread = new NewThread();
        tThread.start();

    }

    public void onClickButton(View source) {
        this.tHandler = tThread.gettHandler();
        this.tHandler.sendEmptyMessage(0x123);
        Log.d("NewThread", "UI线程发送Handler消息");
    }
}

效果图：