ViewPager动态替换数据源------Fragment

鸣谢：参考博客：http://blog.csdn.net/z13759561330/article/details/40737381

现在就直接上代码吧，其实原理我也没太懂，刚好实现了，急用的话可以拿去直接用，空闲了去看看我上面鸣谢的博客吧

适配器Adapter

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.view.ViewGroup;

import java.util.List;

/**
* Created by PersonalFolder on 17/4/1.
*/
public class FragAdapter extends FragmentPagerAdapter {

private FragmentManager mFm;
private List<Fragment> mFragments;
private Fragment replaceFragment;
private int mPosition;
private boolean canReplace;

public FragAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
// TODO Auto-generated constructor stub
this.mFm=fm;
this.mFragments=fragments;

}

/**
* 动态替换fragment,可直接调用
* @param position 指定替换已有fragment的position,第一个是0;
* @param fragment 待替换的新的Fragment;
*/
public void replaceFragment(int position,Fragment fragment){
if (position>=0&&position<mFragments.size()) {
this.replaceFragment = fragment;
this.mPosition = position;
canReplace = true;
this.notifyDataSetChanged();
}
}

@Override
public int getItemPosition(Object object) {
//TODO 这是重点继续研究
//return super.getItemPosition(object);//默认是不改变
return POSITION_NONE;//可以即时刷新看源码
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
//得到缓存的fragment
Fragment fragment = (Fragment) super.instantiateItem(container,
position);
//得到tag，这点很重要
String fragmentTag = fragment.getTag();
if (canReplace&&mPosition==position) {
//如果这个fragment需要更新
FragmentTransaction ft = mFm.beginTransaction();
//移除旧的fragment
ft.remove(fragment);
//换成新的fragment
fragment = replaceFragment;
//添加新fragment时必须用前面获得的tag，这点很重要
ft.add(container.getId(), fragment, fragmentTag);
ft.attach(fragment);
ft.commit();
//复位更新标志
canReplace=false;
}
return fragment;
}

@Override
public Fragment getItem(int arg0) {
// TODO Auto-generated method stub
return mFragments.get(arg0);
}

@Override
public int getCount() {
// TODO Auto-generated method stub
return mFragments.size();
}

}

多说一句，适配器里面的重点代码是getItemPosition()和instantiateItem()这两个方法是原理核心部分。replaceFragment()方法已封装可直接调用；

接下来，看看怎么封装调用的

import android.os.Handler;
import android.os.Message;
import android.support.v4.app.Fragment;
import android.support.v4.app.ListFragment;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

private Button mainReplace;
private ViewPager mainViewPager;
private List<Fragment> fragmentList;
private FragAdapter fragAdapter;
private static final int REPLACE_TAG = 0X12;

private Handler mainHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
// TODO 自动生成的方法存根
super.handleMessage(msg);
switch (msg.what) {
case REPLACE_TAG:
fragAdapter.replaceFragment(1, new ThirdFragment());
break;
default:
}
}
};

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
mainReplace = (Button) findViewById(R.id.main_replace);
mainViewPager = (ViewPager) findViewById(R.id.main_viewpager);
mainViewPager.setAdapter(fragAdapter = new FragAdapter(getSupportFragmentManager(), fragmentList));

mainReplace.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//如果操作比较耗时使用handler   //mainHandler.sendEmptyMessage(REPLACE_TAG);
//一般的操作直接执行
fragAdapter.replaceFragment(1, new ThirdFragment());
}
});

}

private void initView() {
fragmentList = new ArrayList<>();
fragmentList.add(new FirstFragment());
fragmentList.add(new SecondFragment());
}
}

就这样，有问题欢迎留言