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微信支持下面四个Tab滑动，之前做的demo，遇到两个问题，1：Fragment会预加载，2：创建过的Fragment，来回滑动，会销毁重新创建。今天我这个demo，就要解决这两个问题。第一个问题需要导入一个新的V4包，最后我会提供，ViewPage要设置 mViewPager .setOffscreenPageLimit(0);这样的就能解决预加载的问题。第二个问题：我贴上代码：
package com.example.fragmentviewpage;
import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.Window;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.widget.TextView;
public class MainActivity extends FragmentActivity implements OnClickListener
{
private ViewPager mViewPager;
private FragmentStatePagerAdapter mAdapter;//没用到
private List<Fragment> mFragments;
private LinearLayout mTabWeixin;
private LinearLayout mTabContact;
private LinearLayout mTabFind;
private LinearLayout mTabSettings;
private ImageButton mImgWeixin;
private ImageButton mImgContact;
private ImageButton mImgFind;
private ImageButton mImgSettings;
private TextView mWeixintxt;
private TextView mContacttxt;
private TextView mFindtxt;
private TextView mSettingtxt;
Fragment mTab01 ;
Fragment mTab02 ;
Fragment mTab03;
Fragment mTab04 ;
FragmentTransaction transaction ;
private PagerAdapter myPageAdapter;
FragmentManager fm ;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main);
initView();
initEvent();
setSelect(0);
}
private void initEvent()
{
mTabWeixin.setOnClickListener(this);
mTabContact.setOnClickListener(this);
mTabFind.setOnClickListener(this);
mTabSettings.setOnClickListener(this);
}
private void initView()
{
mViewPager = (ViewPager) findViewById(R.id.id_viewpager);
mTabWeixin = (LinearLayout) findViewById(R.id.id_tab_weixin);
mTabContact = (LinearLayout) findViewById(R.id.id_tab_frd);
mTabFind = (LinearLayout) findViewById(R.id.id_tab_address);
mTabSettings = (LinearLayout) findViewById(R.id.id_tab_settings);
mImgWeixin = (ImageButton) findViewById(R.id.id_tab_weixin_img);
mImgContact = (ImageButton) findViewById(R.id.id_tab_frd_img);
mImgFind = (ImageButton) findViewById(R.id.id_tab_address_img);
mImgSettings = (ImageButton) findViewById(R.id.id_tab_settings_img);
mWeixintxt = (TextView)findViewById(R.id.id_tab_weixin_txt);
mContacttxt = (TextView) findViewById(R.id.id_tab_frd_txt);
mFindtxt = (TextView) findViewById(R.id.id_tab_address_txt);
mSettingtxt = (TextView) findViewById(R.id.id_tab_settings_txt);
fm = getSupportFragmentManager();
transaction = fm.beginTransaction();
mFragments = new ArrayList<Fragment>();
mTab01 = new MessageFragment();
mTab02 = new ContactFragment();
mTab03 = new FindFragment();
mTab04 = new SettingFragment();
mFragments.add(mTab01);
mFragments.add(mTab02);
mFragments.add(mTab03);
mFragments.add(mTab04);
mAdapter = new FragmentStatePagerAdapter(getSupportFragmentManager())
{
@Override
public int getCount()
{
return mFragments.size();
}
@Override
public Fragment getItem(int arg0)
{
return mFragments.get(arg0);
}
};
myPageAdapter = new PagerAdapter()
{
@Override
public void destroyItem(ViewGroup container, int position,
Object object)
{
container.removeView(mFragments.get(position).getView());
}
@Override
public Object instantiateItem(ViewGroup container, int position)
{
/*View view = mViews.get(position);
container.addView(view);*/
Fragment fragment = mFragments.get(position);
if(!fragment.isAdded()){ // 如果fragment还没有added
FragmentTransaction ft = fm.beginTransaction();
ft.add(fragment, fragment.getClass().getSimpleName());
ft.commit();
/**
* 在用FragmentTransaction.commit()方法提交FragmentTransaction对象后
* 会在进程的主线程中，用异步的方式来执行。
* 如果想要立即执行这个等待中的操作，就要调用这个方法（只能在主线程中调用）。
* 要注意的是，所有的回调和相关的行为都会在这个调用中被执行完成，因此要仔细确认这个方法的调用位置。
*/
fm.executePendingTransactions();
}
if(fragment.getView().getParent() == null){
container.addView(fragment.getView()); // 为viewpager增加布局
}
return fragment.getView();
//return view;
}
@Override
public boolean isViewFromObject(View arg0, Object arg1)
{
return arg0 == arg1;
}
@Override
public int getCount()
{
return mFragments.size();
}
};
//设置缓存数，我们这里不需要预加载
mViewPager .setOffscreenPageLimit(0);
mViewPager.setAdapter(myPageAdapter);
mViewPager.setOnPageChangeListener(new OnPageChangeListener()
{
@Override
public void onPageSelected(int arg0)
{
int currentItem = mViewPager.getCurrentItem();
setTab(currentItem);
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2)
{
// TODO Auto-generated method stub
}
@Override
public void onPageScrollStateChanged(int arg0)
{
// TODO Auto-generated method stub
}
});
}
@Override
public void onClick(View v)
{
switch (v.getId())
{
case R.id.id_tab_weixin:
setSelect(0);
break;
case R.id.id_tab_frd:
setSelect(1);
break;
case R.id.id_tab_address:
setSelect(2);
break;
case R.id.id_tab_settings:
setSelect(3);
break;
default:
break;
}
}
private void setSelect(int i)
{
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction transaction = fm.beginTransaction();
hideFragment(transaction);
switch (i)
{
case 0:
//mImgWeixin.setImageResource(R.drawable.tab_weixin_pressed);
break;
case 1:
//transaction.show(mTab02);
mTab02.onResume();
// mImgFrd.setImageResource(R.drawable.tab_find_frd_pressed);
break;
case 2:
//mImgAddress.setImageResource(R.drawable.tab_address_pressed);
break;
case 3:
//mImgSettings.setImageResource(R.drawable.tab_settings_pressed);
break;
default:
break;
}
setTab(i);
mViewPager.setCurrentItem(i);
}
private void setTab(int i)
{
resetImgs();
// 设置图片为亮色
// 切换内容区域
setBottom(i);
}
/**
* 切换图片至暗色，不选中
*/
private void resetImgs()
{
mImgWeixin.setSelected(false);
mImgContact.setSelected(false);
mImgFind.setSelected(false);
mImgSettings.setSelected(false);
mContacttxt.setSelected(false);
mWeixintxt.setSelected(false);
mFindtxt.setSelected(false);
mSettingtxt.setSelected(false);
}
//选中
private void setBottom(int position)
{
switch (position) {
case 0:
mImgWeixin.setSelected(true);
mWeixintxt.setSelected(true);
break;
case 1:
mImgContact.setSelected(true);
mContacttxt.setSelected(true);
break;
case 2:
mImgFind.setSelected(true);
mFindtxt.setSelected(true);
break;
case 3:
mImgSettings.setSelected(true);
mSettingtxt.setSelected(true);
break;
default:
break;
}
}
private void hideFragment(FragmentTransaction transaction)
{
if (mTab01 != null)
{
transaction.hide(mTab01);
}
if (mTab02 != null)
{
transaction.hide(mTab02);
}
if (mTab03 != null)
{
transaction.hide(mTab03);
}
if (mTab04 != null)
{
transaction.hide(mTab04);
}
}
}
高仿微信主界面：ViewPage+Fragment 不预加载Fragment 也不会销毁Fragment
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原文地址：http://blog.csdn.net/dhl_1986/article/details/51364511
