用Androidx的方式使用Preference

起因

可能是因为targetApi=29的原因，在使用传统的PreferenceActivity的时候AS提醒我里面的一些方法已经被弃用，作为一个非常激进的业余菜鸟开发者，我的强迫症促使我去寻找其解决方案
近期收到我的小软件AndroCode有些用户反馈设置的第二级打不开，点击没有反应

找轮子

我开始百度找轮子，得知android10使用androidx全面替代，看了一下迁移的对应关系migrate，于是又百度androidx.preference，但结果寥寥无几，只有androidx PreferenceDialogFragmentCompat 和 DialogPreference的配合应用这一篇有一些记载，但对于我们这样的菜鸟很不友好，没有讲基础的使用方法或贴代码，里面的参考文档还被墙打不开。

不得已去看官方API，终于找到了使用方法指南，竟然有中文！！！还这么简洁，我大喜过望，赶紧上手操作

导入依赖

implementation 'androidx.preference:preference:1.1.0'
implementation 'androidx.core:core:1.2.0-beta01'
implementation 'androidx.fragment:fragment:1.2.0-rc01'

官方Demo

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

    <SwitchPreferenceCompat
        app:key="notifications"
        app:title="Enable message notifications"/>

    <Preference
        app:key="feedback"
        app:title="Send feedback"
        app:summary="Report technical issues or suggest new features"/>

</PreferenceScreen>

public class MySettingsFragment extends PreferenceFragmentCompat {
    @Override
    public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
        setPreferencesFromResource(R.xml.preferences, rootKey);
    }
}

public class MySettingsActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.settings_container, new MySettingsFragment())
                .commit();
    }
}

首先是没有了header的方式，但我的APP暂时还是需要这种布局，于是用RecyclerView模拟了一个

activity_settings_item.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?android:attr/selectableItemBackground"
    android:clickable="true"
    android:focusable="true"
    android:orientation="vertical"
    android:paddingStart="15dp"
    android:paddingTop="10dp"
    android:paddingEnd="15dp"
    android:paddingBottom="10dp">
    <!--actionBarItemBackground -->
    <TextView
        android:id="@+id/activity_settings_label"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAllCaps="true"
        android:textStyle="bold"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium" />

    <TextView
        android:id="@+id/activity_settings_message"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="@style/TextAppearance.AppCompat.Small" />
</LinearLayout>

activity_settings.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:id="@+id/activity_settings_layout"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/activity_settings_recyclerv"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <FrameLayout
        android:id="@+id/activity_settings_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

这里偷了个懒，用显示隐藏RecycerView的方式来给Fragment腾地方

由于PreferenceScreen还要用Fragment显示，于是在AppCompatActivity中用recyclerview来触发事件显示fragment

onCreate:

headers.add(new SettingHeader("应用", "配置应用主题、会话", new SettingFragment(R.xml.settings_app)));
        headers.add(new SettingHeader("编辑器", "配置编辑器、代码、保存", new SettingFragment(R.xml.settings_editor)));
        headers.add(new SettingHeader("构建、运行", "配置工程构建和运行设置", new SettingFragment(R.xml.settings_build)));
        headers.add(new SettingHeader("关于", "介绍等", new SettingFragment(R.xml.settings_about)));
        recyclerv.setAdapter(new BaseRecyclerAdapter<SettingHeader>(headers) {
            @Override
            protected int getItemLayoutId(int viewType) {
                return R.layout.activity_settings_item;
            }

            @Override
            protected void bindData(@NonNull RecyclerViewHolder holder, int position, SettingHeader item) {
                holder.getTextView(R.id.activity_settings_label).setText(item.label);
                holder.getTextView(R.id.activity_settings_message).setText(item.message);
                holder.itemView.setOnClickListener(v -> {
                    getSupportFragmentManager()
                            .beginTransaction()
                            .replace(R.id.activity_settings_container, item.fragmentCompat)
                            .commit();
                    recyclerv.setVisibility(View.GONE);
                });
            }
        });
        recyclerv.setLayoutManager(new LinearLayoutManager(this, RecyclerView.VERTICAL, false));

为了减少代码，我机智地复用一个SettingFragment来加载不同xml

 public static class SettingHeader {
        public String label;
        public String message;
        public PreferenceFragmentCompat fragmentCompat;

        public SettingHeader(String label, String message, PreferenceFragmentCompat fragmentCompat) {
            this.label = label;
            this.message = message;
            this.fragmentCompat = fragmentCompat;
        }
    }

    public static class SettingFragment extends PreferenceFragmentCompat {
        private final int id;

        public SettingFragment(int xmlId) {
            super();
            this.id = xmlId;
        }

        @Override
        public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
            setPreferencesFromResource(id, rootKey);
        }

        @Override
        public void onDisplayPreferenceDialog(Preference preference) {
            if (preference instanceof GenKeystorePreference) {
                ((GenKeystorePreference) preference).showDialog();
            } else
                super.onDisplayPreferenceDialog(preference);
        }
    }