扣丁学堂——Fragments
一丶源码见本文
二丶课程讲解
方法一：布局文件添加（用得多一些）
1.添加布局文件
两个Fragement，注意layout_weight和name属性
<fragment android:layout_width="0dip" android:layout_height="match_parent" android:id="@+id/title_fragment" android:layout_weight="1" android:name="com.jin.administrator.my1220application.TitleFragment"/> <fragment android:layout_width="0dip" android:layout_height="match_parent" android:layout_weight="3" android:name="com.jin.administrator.my1220application.ContentFragment" android:id="@+id/content_fragment" />这里name分别对应的是相应的fragement的class
public class ContentFragment extends Fragment { @Nullable @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.content_layout, container, false); return view; } }
public class TitleFragment extends Fragment { @Nullable @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.title_layout,container,false); return view; } }而每一个class对应一个布局
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:background="#00ff00"> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="时间" android:id="@+id/button" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="地点" android:id="@+id/button2" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="人物" android:id="@+id/button3" /> </LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#00ddff"> <TextView android:layout_width="match_parent" android:layout_height="571dp" android:text="没有数据" android:gravity="center" android:id="@+id/textView" /> </LinearLayout>
MainActivity，主要将Fragement放入：
public class MainActivity extends AppCompatActivity { TitleFragment titleFragment; ContentFragment contentFragment; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //通过 getFragmentManager(管理器获取fragment来获取实例) titleFragment = (TitleFragment) getFragmentManager().findFragmentById(R.id.title_fragment); contentFragment = (ContentFragment) getFragmentManager().findFragmentById(R.id.content_fragment); } }演示效果：
方法二：代码添加
看一下MainActivity就行
public class MainActivity2Activity extends Activity {
ContentFragment contentFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_activity2);
addContentLayout();
}
/***
*
* 通过代码添加Fragment
*
* @param
*/
private void addContentLayout(){
FragmentManager fm = getFragmentManager();
//开启一个事务
FragmentTransaction ft = fm.beginTransaction();
//创建fragment实例对象
contentFragment = new ContentFragment();
//添加fragment到指定布局的中中显示
ft.add(R.id.content_layout,contentFragment);
//ft.remove(); 删除
//ft.replace(); 替换
Log.i("Layout","添加frament");
ft.commit();//提交事务
}
}
新建一个Activity
布局文件：
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="one"
android:id="@+id/button4"
android:layout_below="@+id/textView2"
android:layout_alignParentStart="true"
android:onClick="oneClick"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="two"
android:id="@+id/button5"
android:layout_below="@+id/textView2"
android:layout_alignParentEnd="true"
android:layout_marginEnd="25dp"
android:onClick="twoClick"
/>
<FrameLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_below="@+id/button4"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:id="@+id/content"
></FrameLayout>
Activity.mian
public class PopBackTaskActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pop_back_task);
}
//当单击的时候显示不同的fragment内容
public void oneClick(View v){
PopBackFragment p1 = new PopBackFragment("two");
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.content,p1);
//把当前fragment添加到Activity栈中
ft.addToBackStack(null);
ft.commit();
}
public void twoClick(View v){
PopBackFragment p2 = new PopBackFragment("one");//创建fragment类
//开启事务
FragmentTransaction ft = getFragmentManager().beginTransaction();
//替换activity中的组件，
//参数：要替换的id, fragment组件（这里通过代码的方式来添加fragment组件）
ft.replace(R.id.content,p2);
//把当前fragment添加到Activity栈中
ft.addToBackStack(null);
ft.commit();
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_BACK){
if(getFragmentManager().getBackStackEntryCount() == 0){
finish();
}else {
getFragmentManager().popBackStack();//出栈的动作
}
return true;
}
return super.onKeyDown(keyCode,event);
}
}
鼠标右键创建一个空白frament,会自动生成继承fragment类和xml文件
public class PopBackFragment extends Fragment {
String title;
public PopBackFragment() {
}
public PopBackFragment(String title){//传入字符，用于区分不同的显示
this.title = title;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_pop_back, container, false);
//获取布局中的textView组件
TextView tx = (TextView) view.findViewById(R.id.textViw_text);
//设置字符串
tx.setText(title);
return view;
}
}这里演示的效果就是，显示两Fragement的切换退栈效果，因为加了onKeyDowm，按返回也是退栈效果
优化上面的方法：原因：fragment传参问题，上面的结果导致手机屏幕旋转时，frangment会丢失传入的参数
public class PopBackFragment extends Fragment {
public PopBackFragment() {
}
//正确的给 fragment传递参数
public static PopBackFragment getInstance(String title){
PopBackFragment p = new PopBackFragment();
Bundle bundle = new Bundle();
bundle.putString("title",title);
p.setArguments(bundle);//保存传入的参数
return p;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_pop_back, container, false);
TextView tx = (TextView) view.findViewById(R.id.textViw_text);
tx.setText(getArguments().getString("title"));
return view;
}
}
public class PopBackTaskActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pop_back_task);
}
public void oneClick(View v){
PopBackFragment p1 =PopBackFragment.getInstance("one");
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.content,p1);
//把当前fragment添加到Activity栈中
ft.addToBackStack(null);
ft.commit();
}
public void twoClick(View v){
PopBackFragment p2 = PopBackFragment.getInstance("two");
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.content,p2);
//把当前fragment添加到Activity栈中
ft.addToBackStack(null);
ft.commit();
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_BACK){
if(getFragmentManager().getBackStackEntryCount() == 0){
finish();
}else {
getFragmentManager().popBackStack();//出栈的动作
}
return true;
}
return super.onKeyDown(keyCode,event);
}
}
//fragment与activity之间的交互
1.创建两个 fragment
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="新闻"
android:id="@+id/button1"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="音乐"
android:id="@+id/button2"
android:layout_gravity="left|top"
/>
-------------------------
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/value"
android:text="no data"
android:layout_gravity="center"
/>
----fragment事件源中创建一个回调接口,得到activity并调用实现接口的方法-------
public class MainFragment extends Fragment implements View.OnClickListener {
private MainLister mainLister;
public MainFragment() {
// Required empty public constructor
}
//获取activity，也就是宿主
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
mainLister = (MainLister) activity;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View V = inflater.inflate(R.layout.fragment_main, container, false);
V.findViewById(R.id.button1).setOnClickListener(this);
V.findViewById(R.id.button2).setOnClickListener(this);
return V;
}
//单击按钮更新另一个fragment中的值，fragment之间产生交互
@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.button1:
mainLister.changeValue("news");
break;
case R.id.button2:
mainLister.changeValue("music");
break;
}
}
//定义一个回调接口
public static interface MainLister{
public void changeValue(String value);
}
}
------要改变的fragmen---------
public class MentFragment extends Fragment {
private TextView textView_value;
public MentFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_ment, container, false);
textView_value= (TextView) v.findViewById(R.id.value);
return v;
}
public void changeTextValue(String value){
textView_value.setText(value);
}
}
---------activity,并实现接口------------
public class MainActivity extends ActionBarActivity implements MainFragment.MainLister {
private MentFragment mentFragment;
private MainFragment mainFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//获取两个fragment对象
mainFragment = (MainFragment) getFragmentManager().findFragmentById(R.id.main);
mentFragment = (MentFragment) getFragmentManager().findFragmentById(R.id.ment);
}
@Override
public void changeValue(String value) {
mentFragment.changeTextValue(value);
}
}
1.preferences.xml
<?xml version="1.0" encoding="utf-8"?> <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"> <PreferenceCategory android:title="打开声音"> <CheckBoxPreference android:key="checkbox_preference" android:title="打开" android:summary="声音设置" /> </PreferenceCategory> <PreferenceCategory android:title="城市"> <EditTextPreference android:key="edittext_preference" android:title="城市名称" android:summary="请输入城市" android:dialogTitle="城市标题" /> <ListPreference android:key="list_preference" android:title="城市名称1" android:summary="请选择城市名称" android:entries="@array/city" android:entryValues="@array/city" android:dialogTitle="城市名称" /> </PreferenceCategory> </PreferenceScreen>string.xml
<string-array name="city"> <item>北京</item> <item>上海</item> <item>武汉</item> <item>深圳</item> </string-array>mainActivity
public class Main2Activity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main2); SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this); String name = sp.getString("checkbox_preference",""); Log.i("msg", name); } }main布局
<fragment android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/perfs_fragment" android:name="com.jin.administrator.my1220application.PreFragment" ></fragment>定义一个fragment
public class PreFragment extends PreferenceFragment { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //加载Preferences.xml文件 addPreferencesFromResource(R.xml.preference); } }演示效果：
