自定义FragmentTabHost--实现View重复加载问题
1,接着上篇的Fragment+FragmentTabHost搭建简单的底部功能切换框架,效果如下:
结果在项目中用到的时候发现Fragment+FragmentTabHost实现的时候每一次切换底部菜单的时候都要重新加载数据,然后点进去FragmentTabHost发现与Fragment每次切换都是对新的Fragment执行Attach,而对上一个Fragment执行UnAttach,就相当于FragmentManager中的Add和Remove方法,这样的话我们每次切换的话都会重新走Fragmnet的OnCreateView()方法,数据和UI都要重新的刷新,这样用户体验极其的差,所以现在要解决这个问题,在网上找了挺久的都没有找到好的解决方法,最后在群里面问了一下,其实也挺简单的,就是相当于把Add和Remove方法变成show和hide方法,这样的话就有点思路了,代码也挺简单的,如下:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 | /** * Created by monkey * on 2014/9/24 * 功能描述:修改过的FragmentTabHost,保存fragment实例不销毁 */ /* * Copyright (C) 2012 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.util.ArrayList; import android.content.Context; import android.content.res.TypedArray; import android.os.Bundle; import android.os.Parcel; import android.os.Parcelable; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentTransaction; import android.util.AttributeSet; import android.view.View; import android.view.ViewGroup; import android.widget.FrameLayout; import android.widget.LinearLayout; import android.widget.TabHost; import android.widget.TabWidget; /** * Special TabHost that allows the use of {@link Fragment} objects for its tab * content. When placing this in a view hierarchy, after inflating the hierarchy * you must call {@link #setup(Context, FragmentManager, int)} to complete the * initialization of the tab host. * * <p> * Here is a simple example of using a FragmentTabHost in an Activity: * * {@sample * development/samples/Support4Demos/src/com/example/android/supportv4/app/ * FragmentTabs.java complete} * * <p> * This can also be used inside of a fragment through fragment nesting: * * {@sample * development/samples/Support4Demos/src/com/example/android/supportv4/app/ * FragmentTabsFragmentSupport.java complete} */ public class FragmentTabHost extends TabHost implements TabHost.OnTabChangeListener { private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>(); private FrameLayout mRealTabContent; private Context mContext; private FragmentManager mFragmentManager; private int mContainerId; private OnTabChangeListener mOnTabChangeListener; private TabInfo mLastTab; private boolean mAttached; static final class TabInfo { private final String tag; private final Class<?> clss; private final Bundle args; private Fragment fragment; TabInfo(String _tag, Class<?> _class, Bundle _args) { tag = _tag; clss = _class; args = _args; } } static class DummyTabFactory implements TabContentFactory { private final Context mContext; public DummyTabFactory(Context context) { mContext = context; } @Override public View createTabContent(String tag) { View v = new View(mContext); v.setMinimumWidth( 0 ); v.setMinimumHeight( 0 ); return v; } } static class SavedState extends BaseSavedState { String curTab; SavedState(Parcelable superState) { super (superState); } private SavedState(Parcel in) { super (in); curTab = in.readString(); } @Override public void writeToParcel(Parcel out, int flags) { super .writeToParcel(out, flags); out.writeString(curTab); } @Override public String toString() { return "FragmentTabHost.SavedState{" + Integer.toHexString(System.identityHashCode( this )) + " curTab=" + curTab + "}" ; } public static final Creator<SavedState> CREATOR = new Creator<SavedState>() { public SavedState createFromParcel(Parcel in) { return new SavedState(in); } public SavedState[] newArray( int size) { return new SavedState[size]; } }; } public FragmentTabHost(Context context) { // Note that we call through to the version that takes an AttributeSet, // because the simple Context construct can result in a broken object! super (context, null ); initFragmentTabHost(context, null ); } public FragmentTabHost(Context context, AttributeSet attrs) { super (context, attrs); initFragmentTabHost(context, attrs); } private void initFragmentTabHost(Context context, AttributeSet attrs) { TypedArray a = context.obtainStyledAttributes(attrs, new int [] { android.R.attr.inflatedId }, 0 , 0 ); mContainerId = a.getResourceId( 0 , 0 ); a.recycle(); super .setOnTabChangedListener( this ); } private void ensureHierarchy(Context context) { // If owner hasn't made its own view hierarchy, then as a convenience // we will construct a standard one here. if (findViewById(android.R.id.tabs) == null ) { LinearLayout ll = new LinearLayout(context); ll.setOrientation(LinearLayout.VERTICAL); addView(ll, new LayoutParams( ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); TabWidget tw = new TabWidget(context); tw.setId(android.R.id.tabs); tw.setOrientation(TabWidget.HORIZONTAL); ll.addView(tw, new LinearLayout.LayoutParams( ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT, 0 )); FrameLayout fl = new FrameLayout(context); fl.setId(android.R.id.tabcontent); ll.addView(fl, new LinearLayout.LayoutParams( 0 , 0 , 0 )); mRealTabContent = fl = new FrameLayout(context); mRealTabContent.setId(mContainerId); ll.addView(fl, new LinearLayout.LayoutParams( LinearLayout.LayoutParams.MATCH_PARENT, 0 , 1 )); } } /** * @deprecated Don't call the original TabHost setup, you must instead call * {@link #setup(Context, FragmentManager)} or * {@link #setup(Context, FragmentManager, int)}. */ @Override @Deprecated public void setup() { throw new IllegalStateException( "Must call setup() that takes a Context and FragmentManager" ); } public void setup(Context context, FragmentManager manager) { ensureHierarchy(context); // Ensure views required by super.setup() super .setup(); mContext = context; mFragmentManager = manager; ensureContent(); } public void setup(Context context, FragmentManager manager, int containerId) { ensureHierarchy(context); // Ensure views required by super.setup() super .setup(); mContext = context; mFragmentManager = manager; mContainerId = containerId; ensureContent(); mRealTabContent.setId(containerId); // We must have an ID to be able to save/restore our state. If // the owner hasn't set one at this point, we will set it ourself. if (getId() == View.NO_ID) { setId(android.R.id.tabhost); } } private void ensureContent() { if (mRealTabContent == null ) { mRealTabContent = (FrameLayout) findViewById(mContainerId); if (mRealTabContent == null ) { throw new IllegalStateException( "No tab content FrameLayout found for id " + mContainerId); } } } @Override public void setOnTabChangedListener(OnTabChangeListener l) { mOnTabChangeListener = l; } public void addTab(TabSpec tabSpec, Class<?> clss, Bundle args) { tabSpec.setContent( new DummyTabFactory(mContext)); String tag = tabSpec.getTag(); TabInfo info = new TabInfo(tag, clss, args); if (mAttached) { // If we are already attached to the window, then check to make // sure this tab's fragment is inactive if it exists. This shouldn't // normally happen. info.fragment = mFragmentManager.findFragmentByTag(tag); if (info.fragment != null && !info.fragment.isDetached()) { FragmentTransaction ft = mFragmentManager.beginTransaction(); // ft.detach(info.fragment); ft.hide(info.fragment); ft.commit(); } } mTabs.add(info); addTab(tabSpec); } @Override protected void onAttachedToWindow() { super .onAttachedToWindow(); String currentTab = getCurrentTabTag(); // Go through all tabs and make sure their fragments match // the correct state. FragmentTransaction ft = null ; for ( int i = 0 ; i < mTabs.size(); i++) { TabInfo tab = mTabs.get(i); tab.fragment = mFragmentManager.findFragmentByTag(tab.tag); // if (tab.fragment != null && !tab.fragment.isDetached()) { if (tab.fragment != null ) { if (tab.tag.equals(currentTab)) { // The fragment for this tab is already there and // active, and it is what we really want to have // as the current tab. Nothing to do. mLastTab = tab; } else { // This fragment was restored in the active state, // but is not the current tab. Deactivate it. if (ft == null ) { ft = mFragmentManager.beginTransaction(); } // ft.detach(tab.fragment); ft.hide(tab.fragment); } } } // We are now ready to go. Make sure we are switched to the // correct tab. mAttached = true ; ft = doTabChanged(currentTab, ft); if (ft != null ) { ft.commitAllowingStateLoss(); mFragmentManager.executePendingTransactions(); } } @Override protected void onDetachedFromWindow() { super .onDetachedFromWindow(); mAttached = false ; } @Override protected Parcelable onSaveInstanceState() { Parcelable superState = super .onSaveInstanceState(); SavedState ss = new SavedState(superState); ss.curTab = getCurrentTabTag(); return ss; } @Override protected void onRestoreInstanceState(Parcelable state) { SavedState ss = (SavedState) state; super .onRestoreInstanceState(ss.getSuperState()); setCurrentTabByTag(ss.curTab); } @Override public void onTabChanged(String tabId) { if (mAttached) { FragmentTransaction ft = doTabChanged(tabId, null ); if (ft != null ) { ft.commit(); } } if (mOnTabChangeListener != null ) { mOnTabChangeListener.onTabChanged(tabId); } } private FragmentTransaction doTabChanged(String tabId, FragmentTransaction ft) { TabInfo newTab = null ; for ( int i = 0 ; i < mTabs.size(); i++) { TabInfo tab = mTabs.get(i); if (tab.tag.equals(tabId)) { newTab = tab; } } if (newTab == null ) { throw new IllegalStateException( "No tab known for tag " + tabId); } if (mLastTab != newTab) { if (ft == null ) { ft = mFragmentManager.beginTransaction(); } if (mLastTab != null ) { if (mLastTab.fragment != null ) { // ft.detach(mLastTab.fragment); ft.hide(mLastTab.fragment); } } if (newTab != null ) { if (newTab.fragment == null ) { newTab.fragment = Fragment.instantiate(mContext, newTab.clss.getName(), newTab.args); ft.add(mContainerId, newTab.fragment, newTab.tag); } else { // ft.attach(newTab.fragment); ft.show(newTab.fragment); } } mLastTab = newTab; } return ft; } } |
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