SharedPreferences类的使用

SharedPreferences，用xml文件保存用户的偏好设置，是一个轻量级的存储类。

效果图：

代码:

activity_main

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:gravity="center"    tools:context=".MainActivity">

<TextView    android:id="@+id/textview"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="@string/Hello_World" />

</LinearLayout>

activity_settings

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

    <fragment        xmlns:android="http://schemas.android.com/apk/res/android"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:name="com.example.admin.sharedpreferences.SettingsActivity$preferenceFragment"        android:id="@+id/preference"/>

menu.menu

<?xml version="1.0" encoding="utf-8"?><menu    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto">    <item        android:id="@+id/menu_settings"        android:title="@string/menu_title"        app:showAsAction="never"/></menu>

arrays

<?xml version="1.0" encoding="utf-8"?><resources>    <string-array name="color_show">        <item>@string/black</item>        <item>@string/red</item>        <item>@string/blue</item>        <item>@string/green</item>    </string-array></resources>

preferences_settings

<?xml version="1.0" encoding="utf-8"?><PreferenceScreen    xmlns:android="http://schemas.android.com/apk/res/android">

    <CheckBoxPreference        android:title="@string/CheckBoxPreference_title"        android:defaultValue="false"        android:summaryOn="@string/CheckBoxPreference_summaryOn"        android:summaryOff="@string/CheckBceoxPreferen_summaryOff"        android:key="@string/CheckBceoxPreferen_key"/>

    <EditTextPreference        android:title="@string/EditTextPreference_title"        android:defaultValue="@string/EditTextPreference_defaultValue"        android:inputType="numberDecimal"        android:selectAllOnFocus="true"        android:key="@string/EditTextPreference_key"/>

    <ListPreference        android:title="@string/ListPreference_title"        android:defaultValue="@string/ListPreference_defaultValue"        android:entries="@array/color_show"        android:entryValues="@array/color_show"        android:key="@string/ListPreference_key"/></PreferenceScreen>

AndroidMainFest

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.admin.sharedpreferences">

    <application        android:allowBackup="true"        android:icon="@mipmap/ic_launcher"        android:label="@string/app_name"        android:roundIcon="@mipmap/ic_launcher_round"        android:supportsRtl="true"        android:theme="@style/AppTheme">        <activity android:name=".MainActivity">            <intent-filter>                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>

        <activity            android:name=".SettingsActivity"            android:parentActivityName=".MainActivity">            <meta-data                android:name="android.support.PARENT_ACTIVITY"                android:value=".MainActivity"/>        </activity>    </application>

</manifest>

MainActivity.java

package com.example.admin.sharedpreferences;

import android.content.Intent;import android.content.SharedPreferences;import android.graphics.Color;import android.preference.PreferenceManager;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private TextView textView;

    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        textView = findViewById(R.id.textview);    }

    @Override    public boolean onCreateOptionsMenu(Menu menu) {        getMenuInflater().inflate(R.menu.menu, menu);        return super.onCreateOptionsMenu(menu);    }

    @Override    public boolean onOptionsItemSelected(MenuItem item) {        int id = item.getItemId();        switch (id) {            case R.id.menu_settings:                Intent intent = new Intent(this, SettingsActivity.class);                startActivity(intent);                break;        }        return true;    }

    @Override    protected void onStart() {        super.onStart();        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);

        if (sharedPreferences.getBoolean(getString(R.string.CheckBceoxPreferen_key), false)) {            textView.setText(R.string.Bye);        }

        String colorText = sharedPreferences.getString(getString(R.string.ListPreference_key), getString(R.string.ListPreference_defaultValue));        String[] color_array = getResources().getStringArray(R.array.color_show);

        for (int i = 0; i < color_array.length; i++) {

            if (color_array[i] .equals(colorText)){                setTextColor(i);                break;            }        }

        String sizeText = sharedPreferences.getString(getString(R.string.EditTextPreference_key), getString(R.string.EditTextPreference_defaultValue));        int size = Integer.parseInt(sizeText);        textView.setTextSize(size);    }

    public void setTextColor(int number) {        switch (number) {            default:                textView.setTextColor(Color.BLACK);            case 0:                textView.setTextColor(Color.BLACK);                break;            case 1:                textView.setTextColor(Color.RED);                break;            case 2:                textView.setTextColor(Color.BLUE);                break;            case 3:                textView.setTextColor(Color.GREEN);                break;

        }    }}

SettingsActivity.java

package com.example.admin.sharedpreferences;

import android.content.SharedPreferences;import android.os.Bundle;import android.preference.ListPreference;import android.preference.Preference;import android.preference.PreferenceFragment;import android.preference.PreferenceManager;import android.support.v4.app.NavUtils;import android.support.v7.app.AppCompatActivity;

public class SettingsActivity extends AppCompatActivity {    @Override    public void onCreate( Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_settings);    }

    @Override    public void onBackPressed() {        super.onBackPressed();        NavUtils.navigateUpFromSameTask(this);    }

    public static class  preferenceFragment extends PreferenceFragment implements Preference.OnPreferenceChangeListener {

        @Override        public void onCreate( Bundle savedInstanceState) {            super.onCreate(savedInstanceState);            addPreferencesFromResource(R.xml.preferences_settings);            Preference preference_size = findPreference(getString(R.string.EditTextPreference_key));            preferenceSummary(preference_size);            Preference preference_color = findPreference(getString(R.string.ListPreference_key));            preferenceSummary(preference_color);        }

        @Override        public boolean onPreferenceChange(Preference preference, Object newValue) {            String value=String.valueOf(newValue);            if (preference instanceof ListPreference){                ListPreference listPreference=(ListPreference) preference;                int index=listPreference.findIndexOfValue(value);                if (index >=0){                    CharSequence[] text=listPreference.getEntries();                    preference.setSummary(text[index]);                }            }else {                preference.setSummary(value);            }            return true;        }

        public void preferenceSummary(Preference preference) {            preference.setOnPreferenceChangeListener(this );            SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(preference.getContext());            String text = sharedPreferences.getString(preference.getKey(), "");            onPreferenceChange(preference,text);        }    }

}

github项目源码: https://github.com/NeoWu55/Android-Sharedpreferences