Android線程---UI線程和非UI線程之間通信

當主線程sendMessage後，子線程便會調用handleMessage來獲取你所發送的Message。我的主線程向子線程發送消息時攜帶了數據，子線程根據主線程發送來的數據進行數據庫查詢，並將查詢後的結果返回給該主線程：  

  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     //創建一個子線程對象
 13     UpdataThread updataThread ;
 14 
 15     //定義一個全局變量，該Handler在主線程中重寫HandleMessage。
 16     //若不定義成為全局變量，則在子線程中無發用到該Handler
 17     private Handler mainHandler = null;
 18 
 19     //創建一個非UI線程
 20     class UpdataThread extends Thread {
 21 
 22         public Handler mhandler;
 23 
 24         public void run() {
 25             Looper.prepare();
 26             mhandler = new Handler() {
 27 
 28                 //定義處理消息的方法
 29                 @Override
 30                 public voidhandleMessage(Message msg) {
 31                     //---這裡面做一些耗時操作
 32                     if (msg.what == 0x123) {
 33                         //獲取msg所攜帶的數據
 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(), "傳值成功" +name + phone, Toast.LENGTH_LONG).show();
 39                         } else {
 40                             name = "";
 41                             phone = "";
 42                         }
 43                         //創建並連接數據庫，若該數據庫已經存在，則打開該數據庫
 44                         CreateDatabaseHelpercdh = new CreateDatabaseHelper(getApplication(), "myPeople.db3", 1);
 45                         //使用游標查詢數據庫，並返回結果集
 46                         Cursor cursor =cdh.getReadableDatabase().rawQuery("select * from people where name = ?and phone = ?", new String[]{name, phone});
 47                         //創建一個Bundle存儲查詢出來的結果
 48                         Bundle dataAll = newBundle();
 49                         //遍歷cursor，並將結果賦值給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     //↓↓↓↓↓↓↓這一塊便是子線程將查詢的結果返回給主線程↓↓↓↓↓↓↓
 56                         //創建Message
 57                         Message msg_main = newMessage();
 58                         msg_main.what = 0x456;
 59                         //為Message添加數據
 60                        msg_main.setData(dataAll);
 61                         //向主線程發送消息
 62                        mainHandler.sendMessage(msg_main);
 63 
 64                     }
 65                 }
 66             };
 67             Looper.loop();
 68         }
 69     }
 70 
 71     @Override
 72     protected void onCreate(BundlesavedInstanceState) {
 73         super.onCreate(savedInstanceState);
 74         //實例化Thread
 75         updataThread = new UpdataThread();
 76         //啟動新線程
 77         updataThread.start();
 78         setContentView(R.layout.updatapeople);
 79         //獲取布局文件裡的控件
 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         //獲取啟動該Activity的Intent
 87         Intent intent = getIntent();
 88         //取出Intent所攜帶的數據包
 89         Bundle datas = intent.getExtras();
 90         //取出包中所攜帶的各種數據
 91         if (datas != null) {
 92             name =datas.getString("name");
 93             phone =datas.getString("phone");
 94         } else {
 95             name = "空";
 96             phone = "空";
 97         }
 98 //↓↓↓↓↓↓↓這一塊便是主線程向子線程發送消息↓↓↓↓↓↓↓↓
 99         //創建消息
100        Message msg = new Message();
101        //為msg標記一下(類似與--key--)
102        msg.what = 0x123;
103        //創建一個Bundle,並存放數據
104        Bundle bundle = new Bundle();
105        bundle.putString("name", name);
106        bundle.putString("phone", phone);
107        //將數據添加到msg
108        msg.setData(bundle);
109        //向新線程發送消息
110        updataThread.mhandler.sendMessage(msg);
111 
112        //接受子線程返回的消息和子線程那邊的用法一樣
113         mainHandler = new Handler() {
114            @Override
115            public void handleMessage(Message msg_main) {
116                 if (msg_main.what == 0x456){
117                     //更新UI(因為在UI 線程中可以進行UI的更新。。。)
118                    updata_name.setText(msg_main.getData().getString("name"));
119                 }
120            }
121        };