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

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来代替这些私有变量
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     @Override
103     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;//创建一个button对象
19     MyApplication app = MyApplication.getInstance();
20      protected void onCreate(Bundle savedInstanceState) {
21             super.onCreate(savedInstanceState);//父类操作
22             setContentView(R.layout.activity_main);//引入名为activity_main的界面
23             btn_openActivty=(Button) findViewById(R.id.btn_openActivity);//找id为btn_openActivity的button
24             btn_openActivty.setOnClickListener(new OnClickListener() {//设置button点击监听
25
26                 @Override
27                 public void onClick(View v) {//onclick事件
28                     // TODO Auto-generated method stub
29                     Intent intent=new Intent(MainActivity.this,Activity01.class);//初始化intent
30                     //Application域的访问
31                     //MyApplication app=(MyApplication) getApplication();
32                     app.setName("fry");
33                     app.setAge(22);
34
35                     //HashMap的应用
36                     app.getMap().put("data1", "data1");
37                     app.getMap().put("data2", 2.2);
38                     startActivity(intent);//打开activity
39                 }
40             });
41         }
42      @Override
43     protected void onDestroy() {
44         // TODO Auto-generated method stub
45         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

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     <application
11         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         <activity
17             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>