当主线程sendMessage后，子线程便会调用handleMessage来获取你所发送的Message。我的主线程向子线程发送消息时携带了数据，子线程根据主线程发送来的数据进行数据库查询，并将查询后的结果返回给该主线程：
1public class UpdataPeople extends Activity {
2
3EditText updata_name;
4EditText updata_phone;
5EditText updata_address;
6Button updata_quxiao;
7Button updata_baocun;
8
9String name;
10String phone;
11
12//创建一个子线程对象
13UpdataThread updataThread ;
14
15//定义一个全局变量，该Handler在主线程中重写HandleMessage。
16//若不定义成为全局变量，则在子线程中无发用到该Handler
17private Handler mainHandler = null;
18
19//创建一个非UI线程
20class UpdataThread extends Thread {
21
22public Handler mhandler;
23
24public void run() {
25Looper.prepare();
26mhandler = new Handler() {
27
28//定义处理消息的方法
29@Override
30public voidhandleMessage(Message msg) {
31//---这里面做一些耗时操作
32if (msg.what == 0x123) {
33//获取msg所携带的数据
34Bundle bundle =msg.getData();
35if (bundle != null) {
36String name =bundle.getString("name");
37String phone =bundle.getString("phone");
38Toast.makeText(getApplication(), "传值成功" +name + phone, Toast.LENGTH_LONG).show();
39} else {
40name = "";
41phone = "";
42}
43//创建并连接数据库，若该数据库已经存在，则打开该数据库
44CreateDatabaseHelpercdh = new CreateDatabaseHelper(getApplication(), "myPeople.db3", 1);
45//使用游标查询数据库，并返回结果集
46Cursor cursor =cdh.getReadableDatabase().rawQuery("select * from people where name = ?and phone = ?", new String[]{name, phone});
47//创建一个Bundle存储查询出来的结果
48Bundle dataAll = newBundle();
49//遍历cursor，并将结果赋值给Bundle
50while(cursor.moveToNext()) {
51dataAll.putString("name", cursor.getString(1));
52dataAll.putString("phone", cursor.getString(2));
53dataAll.putString("address",cursor.getString(3));
54}
55//↓↓↓↓↓↓↓这一块便是子线程将查询的结果返回给主线程↓↓↓↓↓↓↓
56//创建Message
57Message msg_main = newMessage();
58msg_main.what = 0x456;
59//为Message添加数据
60msg_main.setData(dataAll);
61//向主线程发送消息
62mainHandler.sendMessage(msg_main);
63
64}
65}
66};
67Looper.loop();
68}
69}
70
71@Override
72protected void onCreate(BundlesavedInstanceState) {
73super.onCreate(savedInstanceState);
74//实例化Thread
75updataThread = new UpdataThread();
76//启动新线程
77updataThread.start();
78setContentView(R.layout.updatapeople);
79//获取布局文件里的控件
80updata_name = (EditText)findViewById(R.id.updata_name);
81updata_phone = (EditText)findViewById(R.id.updata_phone);
82updata_address = (EditText)findViewById(R.id.updata_address);
83updata_quxiao = (Button)findViewById(R.id.updata_quxiao);
84updata_baocun = (Button)findViewById(R.id.updata_baocun);
85
86//获取启动该Activity的Intent
87Intent intent = getIntent();
88//取出Intent所携带的数据包
89Bundle datas = intent.getExtras();
90//取出包中所携带的各种数据
91if (datas != null) {
92name =datas.getString("name");
93phone =datas.getString("phone");
94} else {
95name = "空";
96phone = "空";
97}
98 //↓↓↓↓↓↓↓这一块便是主线程向子线程发送消息↓↓↓↓↓↓↓↓
99//创建消息
100Message msg = new Message();
101//为msg标记一下(类似与--key--)
102msg.what = 0x123;
103//创建一个Bundle,并存放数据
104Bundle bundle = new Bundle();
105bundle.putString("name", name);
106bundle.putString("phone", phone);
107//将数据添加到msg
108msg.setData(bundle);
109//向新线程发送消息
110updataThread.mhandler.sendMessage(msg);
111
112//接受子线程返回的消息和子线程那边的用法一样
113mainHandler = new Handler() {
114@Override
115public void handleMessage(Message msg_main) {
116if (msg_main.what == 0x456){
117//更新UI(因为在UI线程中可以进行UI的更新。。。)
118updata_name.setText(msg_main.getData().getString("name"));
119}
120}
121};
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