activity之間通過全域變數傳遞資料，activity全域變數

activity之間通過全域變數傳遞資料，activity全域變數
activity之間通過全域變數傳遞資料

一、簡介

Application域中的onCreate方法是Android程式的入口，Android程式啟動並執行時候就自動載入Application的對象，感覺Main方法應該是封裝在這個裡面的。 

activity中傳遞資料主要用intent方式和全域變數方式。

 

二、使用步驟

1、建立MyApplication類繼承Application類

public class MyApplication extends Application

繼承之後MyApplication類就是全域的了

2、在傳輸資料頁面調用MyApplication類並產生資料

MyApplication app=(MyApplication) getApplication();

app.setName("fry");
app.setAge(22);

3、在接收資料頁面調用MyApplication類並輸出資料

MyApplication app=(MyApplication) getApplication();

tv_answer.setText("app:" + app );

4、在AndroidManifest.xml設定檔中添加MyApplication類的Android啟動配置

android:name="activityGlobelVariable.MyApplication"

5、大功告成

 

三、具體代碼執行個體

代碼中進行了兩次最佳化：

一是對MyApplication類實現了單例化模式，便於在沒有繼承Activity的類裡面調用

調用：

MyApplication app = MyApplication.getInstance();

二是對於傳輸多組資料，使用了HashMap

private HashMap<String, Object> map=new HashMap<String, Object>();

 

結果圖：

activityGlobelVariable.MyApplication

  1 package activityGlobelVariable;  2   3 import java.util.HashMap;  4   5 import android.app.Application;  6   7 public class MyApplication extends Application{  8       9      10     //也可以用hashMap來代替這些私人變數 11     private HashMap<String, Object> map=new HashMap<String, Object>(); 12              13      14     private String name; 15     private int age; 16      17      18      19      20      21     public HashMap<String, Object> getMap() { 22         return map; 23     } 24  25     public void setMap(HashMap<String, Object> map) { 26         this.map = map; 27     } 28  29  30  31  32  33  34  35  36  37  38  39 private static MyApplication instance=null; 40 41 public static MyApplication getInstance(){ 42 return instance; 43 } 44      45     public String getName() { 46         return name; 47     } 48  49  50  51     public void setName(String name) { 52         this.name = name; 53     } 54      55      56  57  58     public int getAge() { 59         return age; 60     } 61  62  63  64     public void setAge(int age) { 65         this.age = age; 66     } 67      68      69  70  71     public MyApplication() { 72         super(); 73     } 74  75  76  77     public MyApplication(String name, int age) { 78         super(); 79         this.name = name; 80         this.age = age; 81     } 82  83  84  85     @Override 86 public void onCreate() { 87 // TODO Auto-generated method stub 88 super.onCreate(); 89 this.instance=this; 90 } 91  92      93  94      95  96      97  98      99 100 101 102     @Override103     public String toString() {104         return "MyApplication [name=" + name + ", age=" + age + "]";105     }106     107     108     109     110 }

activityGlobelVariable.MainActivity

 1 package activityGlobelVariable; 2  3  4  5  6 import com.example.activityGlobelVariable.R; 7  8 import android.app.Activity; 9 import android.content.Intent;10 import android.os.Bundle;11 import android.view.View;12 import android.view.View.OnClickListener;13 import android.widget.Button;14 15 16 17 public class MainActivity extends Activity{18     private Button btn_openActivty;//建立一個button對象19     MyApplication app = MyApplication.getInstance();20      protected void onCreate(Bundle savedInstanceState) {21             super.onCreate(savedInstanceState);//父類操作22             setContentView(R.layout.activity_main);//引入名為activity_main的介面23             btn_openActivty=(Button) findViewById(R.id.btn_openActivity);//找id為btn_openActivity的button24             btn_openActivty.setOnClickListener(new OnClickListener() {//設定button點擊監聽25                 26                 @Override27                 public void onClick(View v) {//onclick事件28                     // TODO Auto-generated method stub29                     Intent intent=new Intent(MainActivity.this,Activity01.class);//初始化intent30                     //Application域的訪問31                     //MyApplication app=(MyApplication) getApplication();32                     app.setName("fry");33                     app.setAge(22);34                     35                     //HashMap的應用36                     app.getMap().put("data1", "data1");37                     app.getMap().put("data2", 2.2);38                     startActivity(intent);//開啟activity39                 }40             });41         }42      @Override43     protected void onDestroy() {44         // TODO Auto-generated method stub45         super.onDestroy();46         app.getMap().remove("data1");47         app.getMap().remove("data2");48     }49 }

activityGlobelVariable.Activity01

package activityGlobelVariable;import com.example.activityGlobelVariable.R;import android.app.Activity;import android.os.Bundle;import android.widget.TextView;public class Activity01 extends Activity {    private static final MyApplication MyApplication = null;    private TextView tv_answer;    @Override    protected void onCreate(Bundle savedInstanceState) {        // TODO Auto-generated method stub        super.onCreate(savedInstanceState);        setContentView(R.layout.activity01);        tv_answer = (TextView) findViewById(R.id.tv_answer);        /*         * getApplication()是Activity類裡面的方法，別的類沒有         * 因為MyApplication繼承了Application，是全域的 在設定檔裡面要配MyApplication         * MyApplication app=(MyApplication) getApplication();         * 上面這句話就是訪問調用MyApplication         */        // MyApplication app=(MyApplication) getApplication();        MyApplication app = MyApplication.getInstance(); // HashMap的應用        String s1 = (String) app.getMap().get("data1");        double d1 = (Double) app.getMap().get("data2");        tv_answer.setText("app:" + app + "\ns1:" + s1 + "\nd1:" + d1);    }}

/activityGlobelVariable/AndroidManifest.xml

 1 <manifest xmlns:android="http://schemas.android.com/apk/res/android" 2     package="com.example.activityGlobelVariable" 3     android:versionCode="1" 4     android:versionName="1.0" > 5  6     <uses-sdk 7         android:minSdkVersion="8" 8         android:targetSdkVersion="19" /> 9 10     <application11         android:name="activityGlobelVariable.MyApplication"12         android:allowBackup="true"13         android:icon="@drawable/ic_launcher"14         android:label="@string/app_name"15         android:theme="@style/AppTheme" >16         <activity17             android:name="activityGlobelVariable.MainActivity"18             android:label="@string/app_name" >19             <intent-filter>20                 <action android:name="android.intent.action.MAIN" />21 22                 <category android:name="android.intent.category.LAUNCHER" />23             </intent-filter>24         </activity>25         <activity android:name="activityGlobelVariable.Activity01" android:exported="true"></activity>26     </application>27 28 </manifest>