AndroidStudio模板工程（六）

一、Scrolling Activity

此模板下的运行截图如下所示：

这个模式下的工程创建完成之后，ScrollingActivity和AndroidStudio模板工程（五）中的ItemDetailActivity类似，所以此处就不再做详细介绍。

二、Setting Activity

此模板下的运行截图如下所示：

                          

这个模式下的工程创建完成之后，AppCompatPreferenceActivity.java和SettingsActivity.java将会被创建。
AppCompatPreferenceActivity.java源码如下所示：

package org.chromium.chrome.browser.androidstudio12demo;

import android.content.res.Configuration;
import android.os.Bundle;
import android.preference.PreferenceActivity;
import android.support.annotation.LayoutRes;
import android.support.annotation.Nullable;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatDelegate;
import android.support.v7.widget.Toolbar;
import android.view.MenuInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * A {@link android.preference.PreferenceActivity} which implements and proxies the necessary calls
 * to be used with AppCompat.
 */
public abstract class AppCompatPreferenceActivity extends PreferenceActivity {

    /**
     * 通过AppCompatDelegate来为Activity添加ActionBar
     */
    private AppCompatDelegate mDelegate;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        getDelegate().installViewFactory();
        getDelegate().onCreate(savedInstanceState);
        super.onCreate(savedInstanceState);
    }

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        getDelegate().onPostCreate(savedInstanceState);
    }

    public ActionBar getSupportActionBar() {
        return getDelegate().getSupportActionBar();
    }

    public void setSupportActionBar(@Nullable Toolbar toolbar) {
        getDelegate().setSupportActionBar(toolbar);
    }

    @Override
    public MenuInflater getMenuInflater() {
        return getDelegate().getMenuInflater();
    }

    @Override
    public void setContentView(@LayoutRes int layoutResID) {
        getDelegate().setContentView(layoutResID);
    }

    @Override
    public void setContentView(View view) {
        getDelegate().setContentView(view);
    }

    @Override
    public void setContentView(View view, ViewGroup.LayoutParams params) {
        getDelegate().setContentView(view, params);
    }

    @Override
    public void addContentView(View view, ViewGroup.LayoutParams params) {
        getDelegate().addContentView(view, params);
    }

    @Override
    protected void onPostResume() {
        super.onPostResume();
        getDelegate().onPostResume();
    }

    @Override
    protected void onTitleChanged(CharSequence title, int color) {
        super.onTitleChanged(title, color);
        getDelegate().setTitle(title);
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        getDelegate().onConfigurationChanged(newConfig);
    }

    @Override
    protected void onStop() {
        super.onStop();
        getDelegate().onStop();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        getDelegate().onDestroy();
    }

    public void invalidateOptionsMenu() {
        getDelegate().invalidateOptionsMenu();
    }

    private AppCompatDelegate getDelegate() {
        if (mDelegate == null) {
            mDelegate = AppCompatDelegate.create(this, null);
        }
        return mDelegate;
    }
}

SettingsActivity.java源码如下所示：

package org.chromium.chrome.browser.androidstudio12demo;

import android.annotation.TargetApi;
import android.content.Context;
import android.content.Intent;
import android.content.res.Configuration;
import android.media.Ringtone;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.preference.ListPreference;
import android.preference.Preference;
import android.preference.PreferenceActivity;
import android.support.v7.app.ActionBar;
import android.preference.PreferenceFragment;
import android.preference.PreferenceManager;
import android.preference.RingtonePreference;
import android.text.TextUtils;
import android.view.MenuItem;

import java.util.List;


public class SettingsActivity extends AppCompatPreferenceActivity {

    /**
     * A preference value change listener that updates the preference's summary
     * to reflect its new value.
     * 首选项改变的监听
     */
    private static Preference.OnPreferenceChangeListener sBindPreferenceSummaryToValueListener = new Preference.OnPreferenceChangeListener() {
        @Override
        public boolean onPreferenceChange(Preference preference, Object value) {
            String stringValue = value.toString();

            if (preference instanceof ListPreference) {
                // For list preferences, look up the correct display value in
                // the preference's 'entries' list.
                ListPreference listPreference = (ListPreference) preference;
                int index = listPreference.findIndexOfValue(stringValue);

                // Set the summary to reflect the new value.
                preference.setSummary(
                        index >= 0
                                ? listPreference.getEntries()[index]
                                : null);

            } else if (preference instanceof RingtonePreference) {
                // For ringtone preferences, look up the correct display value
                // using RingtoneManager.
                if (TextUtils.isEmpty(stringValue)) {
                    // Empty values correspond to 'silent' (no ringtone).
                    preference.setSummary(R.string.pref_ringtone_silent);

                } else {
                    Ringtone ringtone = RingtoneManager.getRingtone(
                            preference.getContext(), Uri.parse(stringValue));

                    if (ringtone == null) {
                        // Clear the summary if there was a lookup error.
                        preference.setSummary(null);
                    } else {
                        // Set the summary to reflect the new ringtone display
                        // name.
                        String name = ringtone.getTitle(preference.getContext());
                        preference.setSummary(name);
                    }
                }

            } else {
                // For all other preferences, set the summary to the value's
                // simple string representation.
                preference.setSummary(stringValue);
            }
            return true;
        }
    };

    /**
     * Helper method to determine if the device has an extra-large screen. For
     * example, 10" tablets are extra-large.
     * 是否是大型屏幕设备
     */
    private static boolean isXLargeTablet(Context context) {
        return (context.getResources().getConfiguration().screenLayout
                & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_XLARGE;
    }

    /**
     * Binds a preference's summary to its value. More specifically, when the
     * preference's value is changed, its summary (line of text below the
     * preference title) is updated to reflect the value. The summary is also
     * immediately updated upon calling this method. The exact display format is
     * dependent on the type of preference.
     *
     * @see #sBindPreferenceSummaryToValueListener
     * 给对应的首选项添加任务改变事件
     */
    private static void bindPreferenceSummaryToValue(Preference preference) {
        // Set the listener to watch for value changes.
        //给当前的preference添加内容改变事件
        preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);

        // Trigger the listener immediately with the preference's
        // current value.
        //处理preference的初始化
        sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
                PreferenceManager
                        .getDefaultSharedPreferences(preference.getContext())
                        .getString(preference.getKey(), ""));
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setupActionBar();
    }

    /**
     * Set up the {@link android.app.ActionBar}, if the API is available.
     * 设置ActionBar
     */
    private void setupActionBar() {
        ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            // Show the Up button in the action bar.
            actionBar.setDisplayHomeAsUpEnabled(true);
        }
    }

    /**
     * {@inheritDoc}
     * 当前多窗口-------------被PreferenceActivity调用
     */
    @Override
    public boolean onIsMultiPane() {
        return isXLargeTablet(this);
    }

    /**
     * {@inheritDoc}
     * 构建头资源-------------被PreferenceActivity调用
     */
    @Override
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public void onBuildHeaders(List<Header> target) {
        /**
         * 加载头资源
         */
        loadHeadersFromResource(R.xml.pref_headers, target);
    }

    /**
     * This method stops fragment injection in malicious applications.
     * Make sure to deny any unknown fragments here.
     * 判断当前的Fragment是否有效----------被PreferenceActivity调用
     */
    protected boolean isValidFragment(String fragmentName) {
        return PreferenceFragment.class.getName().equals(fragmentName)
                || GeneralPreferenceFragment.class.getName().equals(fragmentName)
                || DataSyncPreferenceFragment.class.getName().equals(fragmentName)
                || NotificationPreferenceFragment.class.getName().equals(fragmentName);
    }

    /**
     * This fragment shows general preferences only. It is used when the
     * activity is showing a two-pane settings UI.
     * 显示处理普通的首选项，当activity正在显示一个二级的设置UI时使用
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public static class GeneralPreferenceFragment extends PreferenceFragment {
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            //从资源添加设置资源
            addPreferencesFromResource(R.xml.pref_general);
            //在onCreate()中调用 setHasOptionsMenu(true)。
            //Android Framework会调用Fragement中的
            //onCreateOptionsMenu()来向Activity的Menu中添加item。
            setHasOptionsMenu(true);

            // Bind the summaries of EditText/List/Dialog/Ringtone preferences
            // to their values. When their values change, their summaries are
            // updated to reflect the new value, per the Android Design
            // guidelines.
            //初始化
            bindPreferenceSummaryToValue(findPreference("example_text"));
            bindPreferenceSummaryToValue(findPreference("example_list"));
        }

        /**
         * 点击ActionBar的返回按钮
         * @param item
         * @return
         */
        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            int id = item.getItemId();
            if (id == android.R.id.home) {
                startActivity(new Intent(getActivity(), SettingsActivity.class));
                return true;
            }
            return super.onOptionsItemSelected(item);
        }
    }

    /**
     * This fragment shows notification preferences only. It is used when the
     * activity is showing a two-pane settings UI.
     * 显示处理通知的首选项，当activity正在显示一个二级的设置UI时使用
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public static class NotificationPreferenceFragment extends PreferenceFragment {
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.pref_notification);
            setHasOptionsMenu(true);

            // Bind the summaries of EditText/List/Dialog/Ringtone preferences
            // to their values. When their values change, their summaries are
            // updated to reflect the new value, per the Android Design
            // guidelines.
            //初始化
            bindPreferenceSummaryToValue(findPreference("notifications_new_message_ringtone"));
        }

        /**
         * 点击ActionBar的返回按钮
         * @param item
         * @return
         */
        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            int id = item.getItemId();
            if (id == android.R.id.home) {
                startActivity(new Intent(getActivity(), SettingsActivity.class));
                return true;
            }
            return super.onOptionsItemSelected(item);
        }
    }

    /**
     * This fragment shows data and sync preferences only. It is used when the
     * activity is showing a two-pane settings UI.
     * 显示处理数据同步的首选项，当activity正在显示一个二级的设置UI时使用
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public static class DataSyncPreferenceFragment extends PreferenceFragment {
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.pref_data_sync);
            setHasOptionsMenu(true);

            // Bind the summaries of EditText/List/Dialog/Ringtone preferences
            // to their values. When their values change, their summaries are
            // updated to reflect the new value, per the Android Design
            // guidelines.
            //初始化
            bindPreferenceSummaryToValue(findPreference("sync_frequency"));
        }

        /**
         * 点击ActionBar的返回按钮
         * @param item
         * @return
         */
        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            int id = item.getItemId();
            if (id == android.R.id.home) {
                startActivity(new Intent(getActivity(), SettingsActivity.class));
                return true;
            }
            return super.onOptionsItemSelected(item);
        }
    }
}

由上面两个文件的源代码可以看出SettingsActivity是继承至AppCompatPreferenceActivity的。
AppCompatPreferenceActivity主要使用的是AppCompatDelegate来进行兼容性处理的。
综上所述，上面所提到的资源文件都是由AndroidStudio自动创建的，此处就不做详细介绍了。