学步园

一．“初次邂逅”
我们构建的应用程序经常会需要一个设置界面，用来设置应用程序的各个参数，就如同Android系统本身的设置界面一样。
Android中提供了专门的方法来构建自己的设置界面

二．“先看外表”
首先创建一个项目

在工程的res目录下添加xml文件夹，并添加构建设置界面的xml文件

我们先来编辑布局文件setting_demo.xml
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
	android:key="setting_demo_preference" android:title="@string/title_setting_demo_preference"
	android:summary="@string/summary_setting_demo_preference">
	
	<PreferenceCategory xmlns:android="http://schemas.android.com/apk/res/android"
		android:key="common_settings" android:title="@string/common_settings">
		
		<CheckBoxPreference android:key="check_box"
			android:title="@string/title_check_box" android:summary="@string/summary_check_box"
			android:persistent="false" />
		<ListPreference android:key="string_list_preference"
			android:title="@string/title_list_preference" android:summary="@string/summary_list_preference"
			android:entries="@array/entries_list_preference" android:entryValues="@array/entryvalues_list_preference"
			android:dialogTitle="@string/dialog_title_list_preference" />
		<EditTextPreference android:key="edit_text_preference"
			android:title="@string/title_edit_text_preference" android:summary="@string/summary_edit_text_preference"
			android:dialogTitle="@string/dialog_title_edit_text_preference" />
			
	</PreferenceCategory>

	<PreferenceCategory xmlns:android="http://schemas.android.com/apk/res/android"
		android:key="advanced_settings" android:title="@string/advanced_settings">

		<VolumePreference android:key="media_volume"
			android:title="@string/media_volume_title" android:summary="@string/media_volume_summary"
			android:dialogTitle="@string/media_volume_title" android:persistent="false"
			android:order="3" android:streamType="music" />
		<SeekBarPreference android:key="seek_bar_preference"
			android:title="@string/seek_bar_preference_title"></SeekBarPreference>

	</PreferenceCategory>
	
</PreferenceScreen>


其中的字符串定义：
<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello World, SettingDemo!</string>
    <string name="app_name">SettingDemo</string>
    <string name="title_setting_demo_preference">Setting Demo</string>
    <string name="summary_setting_demo_preference">setting demo summary</string>
    <string name="title_check_box">Title Check Box</string>
    <string name="summary_check_box">summary check box</string>
    <string name="title_list_preference">title_list_preference</string>
    <string name="summary_list_preference">summary_list_preference</string>
    <string name="dialog_title_list_preference">dialog_title_list_preference</string>
    
    
    <string name="title_edit_text_preference">title_edit_text_preference</string>
    <string name="summary_edit_text_preference">summary_edit_text_preference</string>
    <string name="dialog_title_edit_text_preference">dialog_title_edit_text_preference</string>
    <string name="common_settings">普通设置</string>
    <string name="advanced_settings">高级设置</string>
    <string name="media_volume_title">media_volume_title</string>
    <string name="media_volume_summary">media_volume_summary</string>
    <string name="seek_bar_preference_title">seek_bar_preference</string>
</resources>

编辑完这两个文件，我们在SettingDemo.java中的onCreate中加入下面一句话就可以看到效果了
public class SettingDemo extends PreferenceActivity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        addPreferencesFromResource(R.xml.setting_demo);
    }

	
}

效果如下图所示，根据效果图大家很容易的理解布局文件中的各个标签的用途了

三.“深入了解”

现在我们点击设置中的选项还没有实质的效果，首先我们先来了解一下设置中的CheckBox控件

private static final String CHECK_BOX_PRE = "check_box";//和xml中的key值对应
private CheckBoxPreference mCheckBoxPre; //声明一个用来控制checkbox的对象

mCheckBoxPre = (CheckBoxPreference) findPreference(CHECK_BOX_PRE);//findPreference通过在xml中控件的key值找到该控件

<CheckBoxPreference 
			
		    android:key="check_box"
			android:title="@string/title_check_box" android:summary="@string/summary_check_box"
			android:persistent="false" />


mCheckBoxPre.setOnPreferenceChangeListener(this);//设置监听器

我们将在onPreferenceChange中处理设置变化时的操作

详细代码如下：

public class SettingDemo extends PreferenceActivity implements
		OnPreferenceChangeListener {

	private static final String CHECK_BOX_PRE = "check_box";

	private CheckBoxPreference mCheckBoxPre;

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		addPreferencesFromResource(R.xml.setting_demo);

		mCheckBoxPre = (CheckBoxPreference) findPreference(CHECK_BOX_PRE);
		mCheckBoxPre.setOnPreferenceChangeListener(this);

	}
	
	@Override
	public boolean onPreferenceChange(Preference preference, Object newValue) {
		// TODO Auto-generated method stub
		if (preference.getKey().equals(CHECK_BOX_PRE)) {
			mCheckBoxPre.setChecked((Boolean) newValue);
			mCheckBoxPre.setSummary((Boolean) newValue ? "checked"
					: "unchecked");
			doSomething((Boolean) newValue ? 1 : 0);
		}
		return false;
	}

	

	private void doSomething(int i) {
		// TODO Auto-generated method stub
		if (i == 1) {
			Toast.makeText(this, "checked!", Toast.LENGTH_SHORT).show();
		} else if (i == 0) {
			Toast.makeText(this, "unchecked!", Toast.LENGTH_SHORT).show();
		}

	}

}

运行起来看看效果吧！

在程序中我们也可以动态的控制设置中内容的显示

 Preference yourSetting = findPreference(KEY_YOUR_SETTING);

 getPreferenceScreen().removePreference(yourSetting );

在xml中我们也可以通过Intent来启动另外的Activity

 <PreferenceScreen

            android:title="@string/manageapplications_settings_title"

            android:summary="@string/manageapplications_settings_summary">

        <intent android:action="android.intent.action.MAIN"

                android:targetPackage="com.android.settings"

                android:targetClass="com.android.settings.ManageApplications" />

    </PreferenceScreen>

通过指定包名和类名来启动指定的Activity

当然也可以隐式的通过指定Action来启动能接收该Intent的Activity，大家搜索Intent会找到详细的解释，这里就不累述了