自己设计的Android简易版本Handler 框架及实现源码，对了解Android Handler原理有一定的参考价值

package com.example.android_architecture; import com.example.android_architecture.core.CustomHandler; import com.example.android_architecture.core.CustomLooper; import com.example.android_architecture.core.CustomMessage; import org.junit.Test; import static org.junit.Assert.*; /** * Example local unit test, which will execute on the development machine (host). * * @see <a href="http://d.android.com/tools/testing">Testing documentation</a> */ public class ExampleUnitTest { @Test public void addition_isCorrect() { assertEquals(4, 2 + 2); } @Test public void testHandler(){ // - 子线程中存，子线程中取 new Thread("thread-1"){ @Override public void run() { ThreadLocal<String> mThread_A = new ThreadLocal(); mThread_A.set("thread-1"); System.out.println("mThread_A :"+mThread_A.get()); } }.start(); // - 主线程中存，子线程取 final ThreadLocal<String> mThread_B = new ThreadLocal(); mThread_B.set("thread_B"); new Thread(){ @Override public void run() { System.out.println("mThread_B :"+mThread_B.get()); } }.start(); // - 主线程存，主线程取 ThreadLocal<String> mThread_C = new ThreadLocal(); mThread_C.set("thread_C"); System.out.println("mThread_C :"+mThread_C.get()); CustomLooper.prepare(); CustomHandler customHandler = new CustomHandler(){ @Override public void handleMessage(CustomMessage msg) { super.handleMessage(msg); String mes = (String) msg.obj; System.out.println("收到消息---》"+ mes); } }; CustomMessage customMessage = new CustomMessage(); customMessage.obj = "哈哈，简易 Handler 架构实现"; customHandler.sendMessage(customMessage); //开始循环获取消息 - 》 分发消息 CustomLooper.loop(); } }