从主线程发送消息到子线程（准确地说应该是非ui线程）
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package com.zhuozhuo;
import android.app.activity;
import android.os.bundle;
import android.os.handler;
import android.os.looper;
import android.os.message;
import android.util.log;
import android.view.view;
import android.view.view.onclicklistener;
public class looperthreadactivity extends activity{
/** called when the activity is first created. */
private final int msg_hello = 0;
private handler mhandler;
@override
public void oncreate(bundle savedinstancestate) {
super.oncreate(savedinstancestate);
setcontentview(r.layout.main);
new customthread().start();//新建并启动customthread实例
findviewbyid(r.id.send_btn).setonclicklistener(new onclicklistener() {
@override
public void onclick(view v) {//点击界面时发送消息
string str = "hello";
log.d("test", "mainthread is ready to send msg:" + str);
mhandler.obtainmessage(msg_hello, str).sendtotarget();//发送消息到customthread实例
}
});
}
class customthread extends thread {
@override
public void run() {
//建立消息循环的步骤
looper.prepare();//1、初始化looper
mhandler = new handler(){//2、绑定handler到customthread实例的looper对象
public void handlemessage (message msg) {//3、定义处理消息的方法
switch(msg.what) {
case msg_hello:
log.d("test", "customthread receive msg:" + (string) msg.obj);
}
}
};
looper.loop();//4、启动消息循环
}
}
}
从非ui线程传递消息到ui线程(界面主线程），因为主界面已经有messagequeue，所以可以直接获取消息处理消息。而上面由主线程向非ui线程中处理消息的时候，非ui线程需要先添加消息队列，然后处理消息循环。
public class threadhandleractivity extends activity {
/** called when the activity is first created. */
private static final int msg_success = 0;//获取图片成功的标识
private static final int msg_failure = 1;//获取图片失败的标识
private imageview mimageview;
private button mbutton;
private thread mthread;
private handler mhandler = new handler() {
public void handlemessage (message msg) {//此方法在ui线程运行
switch(msg.what) {
case msg_success:
mimageview.setimagebitmap((bitmap) msg.obj);//imageview显示从网络获取到的logo
toast.maketext(getapplication(), getapplication().getstring(r.string.get_pic_success), toast.length_long).show();
break;
case msg_failure:
toast.maketext(getapplication(), getapplication().getstring(r.string.get_pic_failure), toast.length_long).show();
break;
}
}
};
@override
public void oncreate(bundle savedinstancestate) {
super.oncreate(savedinstancestate);
setcontentview(r.layout.main);
mimageview= (imageview) findviewbyid(r.id.imageview);//显示图片的imageview
mbutton = (button) findviewbyid(r.id.button);
mbutton.setonclicklistener(new onclicklistener() {
@override
public void onclick(view v) {
if(mthread == null) {
mthread = new thread(runnable);
mthread.start();//线程启动
}
else {
toast.maketext(getapplication(), getapplication().getstring(r.string.thread_started), toast.length_long).show();
}
}
});
}
runnable runnable = new runnable() {
@override
public void run() {//run()在新的线程中运行
httpclient hc = new defaulthttpclient();
httpget hg = new httpget("http://csdnimg.cn/www/images/csdnindex_logo.gif");//获取csdn的logo
final bitmap bm;
try {
httpresponse hr = hc.execute(hg);
bm = bitmapfactory.decodestream(hr.getentity().getcontent());
} catch (exception e) {
mhandler.obtainmessage(msg_failure).sendtotarget();//获取图片失败
return;
}
mhandler.obtainmessage(msg_success,bm).sendtotarget();//获取图片成功，向ui线程发送msg_success标识和bitmap对象
// mimageview.setimagebitmap(bm); //出错！不能在非ui线程操作ui元素
// mimageview.post(new runnable() {//另外一种更简洁的发送消息给ui线程的方法。
//
// @override
// public void run() {//run()方法会在ui线程执行
// mimageview.setimagebitmap(bm);
// }
// });
}
};
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