viewpagerDemo

修改了recyclerview的页面 刚开始进入的话 会自动把指示器顶上去的问题  但是下面的gif图没换新的  最新效果可以下载运行查看

这几天 朋友问我了个问题 有个特别的需求 页面如下

就是当viewpager里面的当前页面内容足够多的时候 要去能滑上去 并且指示器吸顶 但是当内容不多的时候 能滑到哪就停在哪 当时第一反应是用coordinatelayout 结果不行 内容少的时候 也直接滑到顶部了

activity的xml文件

<com.example.wenlaisu.myapplication.MyScrollview
    android:id="@+id/scroll"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <ImageView
            android:layout_width="match_parent"
            android:layout_height="200dp"
            android:background="?attr/colorPrimary"
            android:scaleType="fitXY"
            android:id="@+id/iv"
            android:src="@drawable/tangyan" />

        <LinearLayout
            android:id="@+id/layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <android.support.design.widget.TabLayout
                android:id="@+id/tabs"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="?attr/colorPrimary" />
        </LinearLayout>


        <com.example.wenlaisu.myapplication.CustomViewPager
            android:id="@+id/viewpager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </LinearLayout>
</com.example.wenlaisu.myapplication.MyScrollview>

<RelativeLayout
    android:id="@+id/rl_layout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

</RelativeLayout>

后来就直接用scrollView包裹来实现了 自定义scrollView实现滚动监听 用来实现指示器吸顶效果

public class MyScrollview extends ScrollView {

private ScrollViewListener scrollViewListener = null;

public MyScrollview(Context context) {
    super(context);
}

public MyScrollview(Context context, AttributeSet attrs) {
    super(context, attrs);
}

public MyScrollview(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
}

public void setScrollViewListener(ScrollViewListener scrollViewListener) {
    this.scrollViewListener = scrollViewListener;
}

@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
    super.onScrollChanged(l, t, oldl, oldt);
    if (scrollViewListener != null) {
        scrollViewListener.onScrollChanged(this, l, t, oldl, oldt);
    }
}

public interface ScrollViewListener {
    void onScrollChanged(MyScrollview scrollView, int l, int t, int oldl, int oldt);
}

}

在activity里面设置监听

scroll.setScrollViewListener(new MyScrollview.ScrollViewListener() { @Override public void onScrollChanged(MyScrollview scrollView, int l, int t, int oldl, int oldt) { if (t >iv.getHeight() && mTabLayout.getParent() == layout) { layout.removeView(mTabLayout); rl_layout.addView(mTabLayout); } else if (t < iv.getHeight() && mTabLayout.getParent() == rl_layout) { rl_layout.removeView(mTabLayout); layout.addView(mTabLayout); } } });

然后就是实现viewpager的每个页面的内容高度适配了 从写viewpager

public class CustomViewPager extends ViewPager {

private int current;  
private int height = 0;  
/**  
 * 保存position与对于的View  
 */  
private HashMap<Integer, View> mChildrenViews = new LinkedHashMap<Integer, View>();

private boolean scrollble = true;  

public CustomViewPager(Context context) {
    super(context);  
}  

public CustomViewPager(Context context, AttributeSet attrs) {
    super(context, attrs);  
}  


@Override  
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  
    if (mChildrenViews.size() > current) {  
        View child = mChildrenViews.get(current);  
        if (child != null) {  
            child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));  
            height = child.getMeasuredHeight();  
        }  
    }  

    heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);  

    super.onMeasure(widthMeasureSpec, heightMeasureSpec);  
}  

public void resetHeight(int current) {  
    this.current = current;  
    if (mChildrenViews.size() > current) {  

        LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) getLayoutParams();
        if (layoutParams == null) {  
            layoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, height);
        } else {  
            layoutParams.height = height;  
        }  
        setLayoutParams(layoutParams);  
    }  
}  

/**  
 * 保存position与对于的View  
 */  
public void setObjectForPosition(View view, int position) {  
    mChildrenViews.put(position, view);  
}  


@Override  
public boolean onTouchEvent(MotionEvent ev) {
    if (!scrollble) {  
        return true;  
    }  
    return super.onTouchEvent(ev);  
}  


public boolean isScrollble() {  
    return scrollble;  
}  

public void setScrollble(boolean scrollble) {  
    this.scrollble = scrollble;  
}  

}
用法是在每个fragment 的onCreatView里面添加一行代码就行 然后在viewpager所在的activity里面设置监听 就可以了

mViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() { @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { }

@Override
public void onPageSelected(int position) {
    mViewPager.resetHeight(position);
}

@Override
public void onPageScrollStateChanged(int state) {
}

});

下面是整个activity的代码

package com.example.wenlaisu.myapplication;

import android.os.Bundle; import android.support.design.widget.TabLayout; import android.support.v4.app.Fragment; import android.support.v4.view.ViewPager; import android.support.v7.app.AppCompatActivity; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.RelativeLayout; import java.util.ArrayList; import java.util.List; /**

• Created by wenlaisu on 2018/4/12. */ public class ViewPagerSample extends AppCompatActivity {

  CustomViewPager mViewPager; List mFragments;

  String[] mTitles = new String[]{ "主页", "微博", "相册" }; private TabLayout mTabLayout; private MyScrollview scroll; private LinearLayout layout; private RelativeLayout rl_layout; private ImageView iv;

  @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_third); // 第一步，初始化ViewPager和TabLayout mViewPager = (CustomViewPager) findViewById(R.id.viewpager); mTabLayout = (TabLayout) findViewById(R.id.tabs); layout = (LinearLayout) findViewById(R.id.layout); rl_layout = (RelativeLayout) findViewById(R.id.rl_layout); scroll = (MyScrollview) findViewById(R.id.scroll); iv = (ImageView) findViewById(R.id.iv); setupViewPager(); }

  private void setupViewPager() { mFragments = new ArrayList<>(); ListFragment listFragment = new ListFragment(mViewPager, 0); ListFragment2 listFragment2 = new ListFragment2(mViewPager, 1); ListFragment3 listFragment3 = new ListFragment3(mViewPager, 2); mFragments.add(listFragment); mFragments.add(listFragment2); mFragments.add(listFragment3);

   // 第二步：为ViewPager设置适配器
   BaseFragmentAdapter adapter =
           new BaseFragmentAdapter(getSupportFragmentManager(), mFragments, mTitles);
  
   mViewPager.setAdapter(adapter);
   //  第三步：将ViewPager与TableLayout 绑定在一起
   mTabLayout.setupWithViewPager(mViewPager);
  
   mViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
       @Override
       public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
       }
  
       @Override
       public void onPageSelected(int position) {
           mViewPager.resetHeight(position);
       }
  
       @Override
       public void onPageScrollStateChanged(int state) {
       }
   });
  
   scroll.setScrollViewListener(new MyScrollview.ScrollViewListener() {
       @Override
       public void onScrollChanged(MyScrollview scrollView, int l, int t, int oldl, int oldt) {
           if (t >iv.getHeight() && mTabLayout.getParent() == layout) {
               layout.removeView(mTabLayout);
               rl_layout.addView(mTabLayout);
           } else if (t < iv.getHeight() && mTabLayout.getParent() == rl_layout) {
               rl_layout.removeView(mTabLayout);
               layout.addView(mTabLayout);
           }
       }
   });
  

  } }

就可以了