activity之间通过全局变量传递数据

activity之间通过全局变量传递数据

一、简介

Application域中的onCreate方法是Android程序的入口，Android程序运行的时候就自动加载Application的对象，感觉Main方法应该是封装在这个里面的。

activity中传递数据主要用intent方式和全局变量方式。

二、使用步骤

1、新建MyApplication类继承Application类

public class MyApplication extends Application

继承之后MyApplication类就是全局的了

2、在传输数据页面调用MyApplication类并生成数据

MyApplication app=(MyApplication) getApplication();

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

3、在接收数据页面调用MyApplication类并输出数据

MyApplication app=(MyApplication) getApplication();

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

4、在AndroidManifest.xml配置文件中添加MyApplication类的Android启动配置

android:name="activityGlobelVariable.MyApplication"

5、大功告成

三、具体代码实例

代码中进行了两次优化：

一是对MyApplication类实现了单例化模式，便于在没有继承Activity的类里面调用

调用：

MyApplication app = MyApplication.getInstance();

二是对于传输多组数据，使用了HashMap

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

结果图：

activityGlobelVariable.MyApplication

 package activityGlobelVariable;

 import java.util.HashMap;

 import android.app.Application;

 public class MyApplication extends Application{

     //也可以用hashMap来代替这些私有变量
     private HashMap<String, Object> map=new HashMap<String, Object>();
             

     private String name;
     private int age;

     public HashMap<String, Object> getMap() {
         return map;
     }

     public void setMap(HashMap<String, Object> map) {
         this.map = map;
     }

 39     private static MyApplication instance=null;
 40
 41     public static MyApplication getInstance(){
 42         return instance;
 43     }

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public int getAge() {
         return age;
     }

     public void setAge(int age) {
         this.age = age;
     }

     public MyApplication() {
         super();
     }

     public MyApplication(String name, int age) {
         super();
         this.name = name;
         this.age = age;
     }

     @Override
 86     public void onCreate() {
 87         // TODO Auto-generated method stub
 88         super.onCreate();
 89         this.instance=this;
 90     }
 

     @Override
     public String toString() {
         return "MyApplication [name=" + name + ", age=" + age + "]";
     }

 }

activityGlobelVariable.MainActivity

 package activityGlobelVariable;

 import com.example.activityGlobelVariable.R;

 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;

 public class MainActivity extends Activity{
     private Button btn_openActivty;//创建一个button对象
     MyApplication app = MyApplication.getInstance();
      protected void onCreate(Bundle savedInstanceState) {
             super.onCreate(savedInstanceState);//父类操作
             setContentView(R.layout.activity_main);//引入名为activity_main的界面
             btn_openActivty=(Button) findViewById(R.id.btn_openActivity);//找id为btn_openActivity的button
             btn_openActivty.setOnClickListener(new OnClickListener() {//设置button点击监听

                 @Override
                 public void onClick(View v) {//onclick事件
                     // TODO Auto-generated method stub
                     Intent intent=new Intent(MainActivity.this,Activity01.class);//初始化intent
                     //Application域的访问
                     //MyApplication app=(MyApplication) getApplication();
                     app.setName("fry");
                     app.setAge(22);

                     //HashMap的应用
                     app.getMap().put("data1", "data1");
                     app.getMap().put("data2", 2.2);
                     startActivity(intent);//打开activity
                 }
             });
         }
      @Override
     protected void onDestroy() {
         // TODO Auto-generated method stub
         super.onDestroy();
         app.getMap().remove("data1");
         app.getMap().remove("data2");
     }
 }

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类里面的方法，别的类没有
         * 因为MyApplication继承了Application，是全局的 在配置文件里面要配MyApplication
         * MyApplication app=(MyApplication) getApplication();
         * 上面这句话就是访问调用MyApplication
         */
        // MyApplication app=(MyApplication) getApplication();
        MyApplication app = MyApplication.getInstance();

        // HashMap的应用

        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

 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.example.activityGlobelVariable"
     android:versionCode="1"
     android:versionName="1.0" >

     <uses-sdk
         android:minSdkVersion="8"
         android:targetSdkVersion="19" />

     <application
         android:name="activityGlobelVariable.MyApplication"
         android:allowBackup="true"
         android:icon="@drawable/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/AppTheme" >
         <activity
             android:name="activityGlobelVariable.MainActivity"
             android:label="@string/app_name" >
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />

                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
         <activity android:name="activityGlobelVariable.Activity01" android:exported="true"></activity>
     </application>

 </manifest>