android学习笔记26——Activity

Activity

==>

android中四大组件：Activity、Service、BroadcastReceiver、ContentProvider

Activity组件用于对用户呈现操作界面，不同的Activity呈现的UI不同，添加新的Activity需要在AndroidMainfest.xml添加对应的配置——否则新添加的activity将无法正常使用。

android应用要求所有应用程序组件(Activity、Service、BroadcastReceiver、ContentProvider)都必须显式进行配置。

配置Activity通常需要指定如下三个属性：

　　1.name:指定Activity的实现类

　　2.icon:指定该Activity对应的图标

　　3.lalbe:指定Activity的标签

注意：除此之外，配置Activity时，通常还需要指定一个或多个<intent-filter/>元素，该元素用于指定activity可响应的Intent.

配置方式如下图所示：

新添加的XXActivity需要继承Activity.

Activity

ListActivity——实现列表

TabActivity——实现标签页

LaucherActivity

==》

继承LaucherActivity时通常应该重写Intent intentForPosition(int position)方法，该方法根据不同列表项返回不同的Intent(用于启动不同的Activity).

实例：

操作步骤：

　　1.res下添加xml文件夹，添加preference.xml

　　2.添加OtherActivity、PreferenceActivityTest、ExpandableListActivityTest

　　3.values下添加array.xml

　　4.AndroidMainfest.xml添加Activity配置

资源文件==》

<?xml version="1.0" encoding="utf-8"?>

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >

    <!-- 设置系统铃声 -->

    <RingtonePreference

        android:key="ring_key"

        android:ringtoneType="all"

        android:showDefault="true"

        android:showSilent="true"

        android:summary="选择铃声"

        android:title="设置铃声" >

    </RingtonePreference>

    <PreferenceCategory android:title="个人信息设置组" >

        <!-- 通过输入框填写用户名 -->

        <EditTextPreference

            android:dialogTitle="您所使用的用户名为: "

            android:key="name"

            android:summary="填写你的用户名"

            android:title="用户名" />

        <!-- 通过列表框选择性别 -->

        <ListPreference

            android:dialogTitle="ListPreference"

            android:entries="@array/gender_name_list"

            android:entryValues="@array/gender_value_list"

            android:key="gender"

            android:summary="选择您的性别"

            android:title="性别" />

    </PreferenceCategory>

    <PreferenceCategory android:title="系统功能设置组" >

        <CheckBoxPreference

            android:defaultValue="true"

            android:key="autoSave"

            android:summaryOff="自动保存：关闭"

            android:summaryOn="自动保存 ：开启"

            android:title="自动保存进度" />

    </PreferenceCategory>

</PreferenceScreen>

<?xml version="1.0" encoding="utf-8"?>

<resources>

    <string-array name="gender_name_list">

        <item>男</item>

        <item>女</item>

    </string-array>

    <string-array name="gender_value_list">

        <item>male</item>

        <item>female</item>

    </string-array>

</resources>

代码实现==》

package com.example.mylauncheractivity;

import android.app.LauncherActivity;

import android.content.Intent;

import android.os.Bundle;

import android.widget.ArrayAdapter;

public class OtherActivity extends LauncherActivity

{

	// 定义两个Activity的名称

	String[] names = { "设置程序参数", "查看星际兵种" };

	// 定义两个Activity对应的实现类

	Class<?>[] clazzs = { PreferenceActivityTest.class, ExpandableListActivityTest.class };

	@Override

	public void onCreate(Bundle savedInstanceState)

	{

		super.onCreate(savedInstanceState);

		ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,

				android.R.layout.simple_list_item_1, names);

		// 设置该窗口显示的列表所需的Adapter

		setListAdapter(adapter);

	}

	// 根据列表项返回指定Activity对应的Intent

	@Override

	protected Intent intentForPosition(int position)

	{

		// TODO Auto-generated method stub

		return new Intent(OtherActivity.this, clazzs[position]);

	}

}

package com.example.mylauncheractivity;

import android.app.ExpandableListActivity;

import android.os.Bundle;

import android.view.Gravity;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AbsListView;

import android.widget.BaseExpandableListAdapter;

import android.widget.ExpandableListAdapter;

import android.widget.ImageView;

import android.widget.LinearLayout;

import android.widget.TextView;

public class ExpandableListActivityTest extends ExpandableListActivity

{

	@Override

	protected void onCreate(Bundle savedInstanceState)

	{

		// TODO Auto-generated method stub

		super.onCreate(savedInstanceState);

		ExpandableListAdapter adapter = new BaseExpandableListAdapter()

		{

			int[] logos = new int[] { R.drawable.plane, R.drawable.plane3, R.drawable.plane5 };

			private String[] armTypes = new String[] { "神族兵种", "虫族兵种", "人族兵种" };

			private String[][] arms = new String[][] { { "狂战士", "龙骑士", "黑暗圣堂", "点兵" },

					{ "小狗", "刺蛇", "飞龙", "自爆飞机" }, { "机枪兵", "护士MM", "幽灵" } };

			// 获取指定组位置、指定子列表项处的子列表项数据

			public Object getChild(int groupPosition, int childPosition)

			{

				// TODO Auto-generated method stub

				return arms[groupPosition][childPosition];

			}

			public long getChildId(int groupPosition, int childPosition)

			{

				return childPosition;

			};

			public int getChildrenCount(int groupPosition)

			{

				// TODO Auto-generated method stub

				return arms[groupPosition].length;

			}

			private TextView getTextView()

			{

				@SuppressWarnings("deprecation")

				AbsListView.LayoutParams lp = new AbsListView.LayoutParams(

						ViewGroup.LayoutParams.WRAP_CONTENT, 64);

				TextView tv = new TextView(ExpandableListActivityTest.this);

				tv.setLayoutParams(lp);

				tv.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);

				tv.setPadding(35, 0, 0, 0);

				tv.setHeight(500);

				tv.setTextSize(18);

				return tv;

			}

			public View getChildView(int groupPosition, int childPosition, boolean isLastChild,

					View convertView, ViewGroup parent)

			{

				// TODO Auto-generated method stub

				TextView textView = getTextView();

				textView.setText(getChild(groupPosition, childPosition).toString());

				return textView;

			}

			// 获取指定位置处的组数据

			public Object getGroup(int groupPosition)

			{

				return armTypes[groupPosition];

			};

			public int getGroupCount()

			{

				// TODO Auto-generated method stub

				return armTypes.length;

			}

			public long getGroupId(int groupPosition)

			{

				// TODO Auto-generated method stub

				return groupPosition;

			}

			public View getGroupView(int groupPosition, boolean isExpanded, View convertView,

					ViewGroup parent)

			{

				// TODO Auto-generated method stub

				LinearLayout ll = new LinearLayout(ExpandableListActivityTest.this);

				ll.setOrientation(0);

				ImageView logo = new ImageView(ExpandableListActivityTest.this);

				logo.setImageResource(logos[groupPosition]);

				ll.addView(logo);

				TextView textView = getTextView();

				textView.setText(getGroup(groupPosition).toString());

				ll.addView(textView);

				return ll;

			}

			public boolean hasStableIds()

			{

				// TODO Auto-generated method stub

				return true;

			}

			public boolean isChildSelectable(int groupPosition, int childPosition)

			{

				// TODO Auto-generated method stub

				return true;

			}

		};

		// 设置该窗口显示列表

		setListAdapter(adapter);

	}

}

package com.example.mylauncheractivity;

import android.os.Bundle;

import android.preference.PreferenceActivity;

public class PreferenceActivityTest extends PreferenceActivity {

    @SuppressWarnings("deprecation")

	@Override

    protected void onCreate(Bundle savedInstanceState) {

        // TODO Auto-generated method stub

        super.onCreate(savedInstanceState);

        //设置显示参数设置布局

        addPreferencesFromResource(R.xml.preference);

    }

}

AndroidMainfest.xml配置文件==》

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.mylauncheractivity"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="18" />

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name="com.example.mylauncheractivity.OtherActivity"

            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="com.example.mylauncheractivity.PreferenceActivityTest" />

        <activity android:name="com.example.mylauncheractivity.ExpandableListActivityTest" />

    </application>

</manifest>

资源文件：图片，略.

运行效果：

    

LauncherActivity可用于开发启动Activity列表。　　

LauncherActivity继承自ListActivity,因此其本质就用于开发列表界面的Activity,其开发的列表界面中的每个列表项都对应一个Intent对象，因此当用户单击不同的列表项时，应用程序会自动启动对应的Activity.

LauncherActivity同样需要设置Adapter(可使用简单的ArrayAdapter/SimpleAdapter/扩展BaseAdapter实现自己的Adapter).与普通的ListActivity,不同的是，继承LauncherActivity时——通常应该重写Intent

intentForPosition(int position)方法，该方法根据不同列表返回不同的Intent——用于启动不同的Activity.

ExpandableListActivity,用于显示一个可展开的列表窗口。

PreferenceActivity,用于显示一个显示设置选项参数并进行保存的窗口。