Fragment在FrameLayout
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Fragment
- API11(Android3.0)中引入了Fragment，由FragmentManager来管理。
- Fragment extends object 。
- Fragment也是Activity中的一个普通控件而已，只不过它可以像Activity一样用于显示的同时还能用来盛装其它控件，并且有类似Activity的lifecycle。
- 可被多个Acitivity重用, 在Acitivity运行中动态地移除、加入、交换等。
- 兼容API11(Android3.0)以前版本使用 v4.app.Fragment，Acitivity需要继承AppCompatActivity，通过getSupportFragmentManager() 获得v4.app.FragmentManager 。
- API11(Android3.0)以后可使用 app.Fragment，通过getFragmentManager()获得app.FragmentManager 。
生命周期lifecycle
- 类似Acitivty，但是由Activity管理，由许多不同点。
简单添加到Activity方法
private void add() { OneFragment oneFragment = OneFragment.newInstance(""); FragmentTransaction transaction = mManager.beginTransaction(); transaction.add(R.id.fl_container, oneFragment, "one"); transaction.commit(); }- 将Fragment添加到Activity中，并生效。
- 重要的类有FragmentManager 和FragmentTransaction，在下面详细分析。
Fragment相关的类及其方法
FragmentManager
- FragmentManager是一个抽象类, getFragmentManager()获取的是FragmentManagerImpl ,是一个实现类
//调用层级 最后是FragmentManagerImpl getFragmentManager() -->FragmentController(Fragment's lifecycle) -->getFragmentManagerImpl() -->FragmentHostCallback -->final FragmentManagerImpl mFragmentManager = new FragmentManagerImpl();FragmentManager.java中 定义FragmentManager /FragmentManagerImpl / FragmentManagerState三个类/接口
beginTransaction() 获得FragmentTransaction,FragmentManagerImpl 中的Override的beginTransaction()
@Override public FragmentTransaction beginTransaction() { return new BackStackRecord(this); }- findFragmentById(@IdRes int id) 相同id ,取第一个找到的,一般就是最上面的。
- findFragmentByTag（String tag） 相同tag,取第一个找到的,一般就是最上面的。
- getFragments() 返回ArrayList< Fragment > mActive; 可能存在null
- 持有一个BackStackRecord的列表 ArrayList< BackStackRecord > mBackStackIndices
FragmentTransaction
add 和 replace 影响的只是界面，而控制回退的，是事务
FragmentTransaction 是一个抽象类, beginTransaction()获取的是BackStackRecord,是一个实现类
BackStackRecord extends FragmentTransaction
- add 和 replace 影响的只是界面，而控制回退的是事务,add 和 replace最后调用addOp(Op op)
addOp(Op op) 添加到队列mOps中,通过commit才会提交
void addOp(Op op) { mOps.add(op); op.enterAnim = mEnterAnim; op.exitAnim = mExitAnim; op.popEnterAnim = mPopEnterAnim; op.popExitAnim = mPopExitAnim; }addToBackStack(将事务添加到回退栈里)
@Override public FragmentTransaction addToBackStack(String name) { if (!mAllowAddToBackStack) { throw new IllegalStateException( "This FragmentTransaction is not allowed to be added to the back stack."); } mAddToBackStack = true; mName = name; return this; }commit (提交到处理队列里,默认不会添加到回退栈,默认等待执行),调用commitInternal(false)
int commitInternal(boolean allowStateLoss) { if (mCommitted) throw new IllegalStateException("commit already called"); if (FragmentManagerImpl.DEBUG) { Log.v(TAG, "Commit: " + this); LogWriter logw = new LogWriter(TAG); PrintWriter pw = new PrintWriter(logw); dump(" ", null, pw, null); pw.close(); } mCommitted = true; if (mAddToBackStack) { mIndex = mManager.allocBackStackIndex(this); } else { mIndex = -1; } mManager.enqueueAction(this, allowStateLoss); return mIndex; }
add
- add(@IdRes int containerViewId, Fragment fragment)
- 可能出现 Fragment already added 错误,原因:add 已经add的fragment(hashcode一样)
- lifecycle方法调用情况
10-23 17:01:58.737 13673-13673/com.wega.android E/Frag+Frame: OneFragment==null==OneFragment10-23 17:01:58.743 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onAttach10-23 17:01:58.744 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onCreate10-23 17:01:58.744 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onCreateView10-23 17:01:58.753 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onActivityCreated10-23 17:01:58.753 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onStart10-23 17:01:58.753 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onResume- 在add 前 需要new Fragment() ,但是new不会调起Framgent生命周期动作如:oncreate ,而 Acitivty不需要我们new的,是由系统创建的.
remove
- remove(Fragment fragment)
- Remove an existing fragment
- 先获得已存在fragment才能remove 不能传空值
- 通过findFragmentById() findFragmentByTag()获得已存在fragment
- lifecycle方法调用情况
10-23 17:02:55.873 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onPause10-23 17:02:55.874 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onStop10-23 17:02:55.874 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onDestroyView10-23 17:02:55.874 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onDestroy10-23 17:02:55.874 13673-13673/com.wega.android E/Frag+Frame: OneFragment==0==onDetachreplace
- replace(@IdRes int containerViewId, Fragment fragment)
- 不能传空值
- 先remove掉相同id的所有fragment，然后在add当前的这个fragment
- add 和 remove 结合
- lifecycle方法调用情况
10-23 17:07:11.092 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==OneFragment10-23 17:07:11.098 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onAttach10-23 17:07:11.098 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onCreate10-23 17:07:11.099 24280-24280/com.wega.android E/Frag+Frame: OneFragment==0==onPause10-23 17:07:11.099 24280-24280/com.wega.android E/Frag+Frame: OneFragment==0==onStop10-23 17:07:11.099 24280-24280/com.wega.android E/Frag+Frame: OneFragment==0==onDestroyView10-23 17:07:11.099 24280-24280/com.wega.android E/Frag+Frame: OneFragment==0==onDestroy10-23 17:07:11.099 24280-24280/com.wega.android E/Frag+Frame: OneFragment==0==onDetach10-23 17:07:11.099 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onCreateView10-23 17:07:11.099 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onActivityCreated10-23 17:07:11.100 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onStart10-23 17:07:11.100 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onResumehide
- hide(Fragment fragment)
- 与show一起作用
- hide 已经添加的fragment 不能传空值
- hide fragment 不会调用生命周期
show
- show(Fragment fragment)
- 与hide一起作用
- This is only relevant for fragments whose views have been added to a container
- show已经hide的fragment
- show fragment 不会调用生命周期
detach
- detach(Fragment fragment)
- 与attach一起作用
- 不能传空值
- lifecycle方法调用情况
10-23 17:07:41.687 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onPause10-23 17:07:41.687 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onStop10-23 17:07:41.687 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onDestroyViewattach
-attach(Fragment fragment)
- 与detach一起作用
- 不能传空值
- lifecycle方法调用情况
10-23 17:07:56.420 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onCreateView10-23 17:07:56.420 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onActivityCreated10-23 17:07:56.421 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onStart10-23 17:07:56.421 24280-24280/com.wega.android E/Frag+Frame: OneFragment==null==onResume重建 切屏
- Fragment也有onSaveInstanceState的方法，在此方法中进行保存数据，然后在onCreate或者onCreateView或者onActivityCreated进行恢复都可以。
@Override public void onSaveInstanceState(Bundle outState) { outState.putString("name", "save"); super.onSaveInstanceState(outState); Log.e("Activity", TAG +"=="+mTag1+"=="+"onSaveInstanceState"+"=="+outState.getString("name")); } @Override public void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); if(savedInstanceState!=null) { Log.e("Activity", TAG +"=="+mTag1+"=="+"onCreate"+"=="+savedInstanceState.getString("name")); } Bundle arguments = getArguments(); if(arguments!=null) { mTag1 = arguments.getString("tag"); } Log.e("Activity", TAG +"=="+mTag1+"=="+"onCreate"); }demo源码
FragmentActivity
package com.wega.android.fragment;import android.content.DialogInterface;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentManager;import android.support.v4.app.FragmentTransaction;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.view.View;import com.wega.android.R;import java.util.List;public class FragmentActivity extends AppCompatActivity implements View.OnClickListener { private String LOG_TAG="Frag+Frame"; private FragmentManager mManager; private OneFragment mOneFragment; private String TAG; private int num; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_fragment); mManager = getSupportFragmentManager(); TAG = this.getClass().getSimpleName(); if (savedInstanceState == null) { Log.e(LOG_TAG, TAG + "==onCreate"); } else { String name = savedInstanceState.getString("name"); Log.e(LOG_TAG, TAG + "==onCreate==name==" + name); } findViewById(R.id.add).setOnClickListener(this); findViewById(R.id.remove).setOnClickListener(this); findViewById(R.id.replace).setOnClickListener(this); findViewById(R.id.log).setOnClickListener(this); findViewById(R.id.show).setOnClickListener(this); findViewById(R.id.hide).setOnClickListener(this); findViewById(R.id.attach).setOnClickListener(this); findViewById(R.id.detach).setOnClickListener(this); } @Override public void onClick(View view) { switch (view.getId()) { case R.id.add: add(); break; case R.id.remove: remove(); break; case R.id.replace: replace(); break; case R.id.show: show(); break; case R.id.hide: hide(); break; case R.id.log: getFragmentList(); break; case R.id.attach: attach(); break; case R.id.detach: detach(); break; } } private void add() { OneFragment oneFragment = OneFragment.newInstance("" + num++); FragmentTransaction transaction = mManager.beginTransaction(); transaction.add(R.id.fl_container, oneFragment, "one"); transaction.commit(); } private void remove(){ Fragment fragmentById = mManager.findFragmentById(R.id.fl_container); FragmentTransaction transaction = mManager.beginTransaction(); if(fragmentById!=null) { transaction.remove(fragmentById); } transaction.commit(); } private void replace() { if (mOneFragment == null) { mOneFragment = new OneFragment(); } FragmentTransaction transaction = mManager.beginTransaction(); transaction.replace(R.id.fl_container, mOneFragment); transaction.commit(); } private void show() { Fragment fragmentById = mManager.findFragmentById(R.id.fl_container); FragmentTransaction transaction = mManager.beginTransaction(); transaction.show(fragmentById); transaction.commit(); } private void hide() { Fragment fragmentById = mManager.findFragmentById(R.id.fl_container); FragmentTransaction transaction = mManager.beginTransaction(); transaction.hide(fragmentById); transaction.commit(); } private void attach() { Fragment fragmentById = mManager.findFragmentById(R.id.fl_container); FragmentTransaction transaction = mManager.beginTransaction(); transaction.attach(fragmentById); transaction.commit(); } private void detach() { Fragment fragmentById = mManager.findFragmentById(R.id.fl_container); FragmentTransaction transaction = mManager.beginTransaction(); transaction.detach(fragmentById); transaction.commit(); } private void getFragmentList() { Fragment fragment = mManager.findFragmentById(R.id.fl_container); Fragment fragment1 = mManager.findFragmentByTag("one"); if (fragment != null) { Log.e("fragment", "findFragmentById=" + fragment.toString()); } if (fragment1 != null) { Log.e("fragments1", "findFragmentByTag=" + fragment1.toString()); } List<Fragment> fragments = mManager.getFragments(); if (fragments == null) { return; } for (int i = 0; i < fragments.size(); i++) { if (fragments.get(i) == null) { Log.e("fragments", "null"); } else { Log.e("fragments", fragments.get(i).toString()); } } Log.e("fragments", "=========="); }}OneFragment
package com.wega.android.fragment;import android.content.Context;import android.os.Bundle;import android.support.annotation.Nullable;import android.support.v4.app.Fragment;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;import com.wega.android.R;/** * A simple {@link Fragment} subclass. */public class OneFragment extends Fragment { private String TAG; private String LOG_TAG="Frag+Frame"; private String mTag1; public OneFragment() { TAG =this.getClass().getSimpleName(); Bundle arguments = getArguments(); if(arguments!=null) { mTag1 = arguments.getString("tag"); } Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"OneFragment"); } public static OneFragment newInstance(String tag) { Bundle args = new Bundle(); args.putString("tag",tag); OneFragment fragment = new OneFragment(); fragment.setArguments(args); return fragment; } @Override public void onAttach(Context context) { super.onAttach(context); Bundle arguments = getArguments(); if(arguments!=null) { mTag1 = arguments.getString("tag"); } Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onAttach"); } @Override public void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); if(savedInstanceState!=null) { Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onCreate"+"=="+savedInstanceState.getString("name")); } Bundle arguments = getArguments(); if(arguments!=null) { mTag1 = arguments.getString("tag"); } Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onCreate"); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { TAG =this.getClass().getSimpleName(); Bundle arguments = getArguments(); if(arguments!=null) { mTag1 = arguments.getString("tag"); } Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onCreateView"); View inflate = inflater.inflate(R.layout.fragment_one, container, false); TextView viewById = (TextView) inflate.findViewById(R.id.tv_hashcode); viewById.setText(this.toString()+"tag=="+mTag1); return inflate; } @Override public void onActivityCreated(@Nullable Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onActivityCreated"); } @Override public void onStart() { super.onStart(); Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onStart"); } @Override public void onResume() { super.onResume(); Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onResume"); } @Override public void onPause() { super.onPause(); Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onPause"); } @Override public void onStop() { super.onStop(); Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onStop"); } @Override public void onDestroyView() { super.onDestroyView(); Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onDestroyView"); } @Override public void onDestroy() { super.onDestroy(); Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onDestroy"); } @Override public void onDetach() { super.onDetach(); Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onDetach"); } @Override public void onSaveInstanceState(Bundle outState) { outState.putString("name", "save"); super.onSaveInstanceState(outState); Log.e(LOG_TAG, TAG +"=="+mTag1+"=="+"onSaveInstanceState"+"=="+outState.getString("name")); }}demo源码地址
demo源码地址：https://github.com/LinweiJ/Android
backStack
未完待续
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