近期自学到了线程这一块，用了一上午的时间终于搞出来了主、子线程间的相互通信。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：
1 public class UpdataPeople extends Activity { 2 3 EditText updata_name; 4 EditText updata_phone; 5 EditText updata_address; 6 Button updata_quxiao; 7 Button updata_baocun; 8 9 String name; 10 String phone; 11 12 //创建一个子线程对象 13 UpdataThread 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 17 private Handler mainHandler = null; 18 19 //创建一个非UI线程 20 class UpdataThread extends Thread { 21 22 public Handler mhandler; 23 24 public void run() { 25 Looper.prepare(); 26 mhandler = new Handler() { 27 28 //定义处理消息的方法 29 @Override 30 public void handleMessage(Message msg) { 31 //---这里面做一些耗时操作 32 if (msg.what == 0x123) { 33 //获取msg所携带的数据 34 Bundle bundle = msg.getData(); 35 if (bundle != null) { 36 String name = bundle.getString("name"); 37 String phone = bundle.getString("phone"); 38 Toast.makeText(getApplication(), "传值成功" + name + phone, Toast.LENGTH_LONG).show(); 39 } else { 40 name = " "; 41 phone = " "; 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 44 CreateDatabaseHelper cdh = new CreateDatabaseHelper(getApplication(), "myPeople.db3", 1); 45 //使用游标查询数据库，并返回结果集 46 Cursor 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 48 Bundle dataAll = new Bundle(); 49 //遍历cursor，并将结果赋值给Bundle 50 while (cursor.moveToNext()) { 51 dataAll.putString("name", cursor.getString(1)); 52 dataAll.putString("phone", cursor.getString(2)); 53 dataAll.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 57 Message msg_main = new Message(); 58 msg_main.what = 0x456; 59 //为Message添加数据 60 msg_main.setData(dataAll); 61 //向主线程发送消息 62 mainHandler.sendMessage(msg_main); 63 64 } 65 } 66 }; 67 Looper.loop(); 68 } 69 } 70 71 @Override 72 protected void onCreate(Bundle savedInstanceState) { 73 super.onCreate(savedInstanceState); 74 //实例化Thread 75 updataThread = new UpdataThread(); 76 //启动新线程 77 updataThread.start(); 78 setContentView(R.layout.updatapeople); 79 //获取布局文件里的控件 80 updata_name = (EditText) findViewById(R.id.updata_name); 81 updata_phone = (EditText) findViewById(R.id.updata_phone); 82 updata_address = (EditText) findViewById(R.id.updata_address); 83 updata_quxiao = (Button) findViewById(R.id.updata_quxiao); 84 updata_baocun = (Button) findViewById(R.id.updata_baocun); 85 86 //获取启动该Activity的Intent 87 Intent intent = getIntent(); 88 //取出Intent所携带的数据包 89 Bundle datas = intent.getExtras(); 90 //取出包中所携带的各种数据 91 if (datas != null) { 92 name = datas.getString("name"); 93 phone = datas.getString("phone"); 94 } else { 95 name = "空"; 96 phone = "空"; 97 } 98 //↓↓↓↓↓↓↓这一块便是主线程向子线程发送消息↓↓↓↓↓↓↓↓ 99 //创建消息100 Message msg = new Message();101 //为msg标记一下(类似与--key--)102 msg.what = 0x123;103 //创建一个Bundle,并存放数据104 Bundle bundle = new Bundle();105 bundle.putString("name", name);106 bundle.putString("phone", phone);107 //将数据添加到msg108 msg.setData(bundle);109 //向新线程发送消息110 updataThread.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113 mainHandler = new Handler() {114 @Override115 public void handleMessage(Message msg_main) {116 if (msg_main.what == 0x456){117 //更新UI(因为在UI 线程中可以进行UI的更新。。。)118 updata_name.setText(msg_main.getData().getString("name"));119 }120 }121 };