android ViewPager 自适应高度

很多Android开发者会遇到的问题，ViewPager无法自适应内容的高度
下面根据内容动态设置ViewPager的高度，总结给出2种方式：

第一种 :
取所有view中最大高度作为ViewPager的高度，此方法试用所有page页高度相差不多的时候，否则下面会有空白的部分，代码如下：

public class AutoHeightViewPager extends ViewPager {         public AutoHeightViewPager (Context context) {          super(context);      }         public AutoHeightViewPager (Context context, AttributeSet attrs) {          super(context, attrs);      }         @Override      protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {             int height = 0;          for (int i = 0; i < getChildCount(); i++) {              View child = getChildAt(i);              child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));              int h = child.getMeasuredHeight();              if (h > height)                  height = h;          }             heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);          super.onMeasure(widthMeasureSpec, heightMeasureSpec);      }  }

使用方法也很简单，直接在xml布局里面替换原来的ViewPager就行：

  xxx.xxx.xxx代表路径

第二种
在遇到不是所有界面高度一样的情况下，会导致高度低的页面中出现空白，下面就介绍第二种方式动态设置高度：

public class AutoHeightViewPager extends ViewPager {        public AutoHeightViewPager(Context context, AttributeSet attrs) {        super(context, attrs);    }        @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        // find the current child view        // and you must cache all the child view        // use setOffscreenPageLimit(adapter.getCount())        View view = getChildAt(getCurrentItem());        if (view != null) {            // measure the current child view with the specified measure spec            view.measure(widthMeasureSpec, heightMeasureSpec);        }                setMeasuredDimension(getMeasuredWidth(), measureHeight(heightMeasureSpec, view));    }        /**     * Determines the height of this view     *     * @param measureSpec A measureSpec packed into an int     * @param view the base view with already measured height     *     * @return The height of the view, honoring constraints from measureSpec     */    private int measureHeight(int measureSpec, View view) {        int result = 0;        int specMode = MeasureSpec.getMode(measureSpec);        int specSize = MeasureSpec.getSize(measureSpec);                if (specMode == MeasureSpec.EXACTLY) {            result = specSize;        } else {            // set the height from the base view if available            if (view != null) {                result = view.getMeasuredHeight();            }            if (specMode == MeasureSpec.AT_MOST) {                result = Math.min(result, specSize);            }        }        return result;    }        /**     * 单独测量view获取尺寸     *     * @param view     */    public void measeureView(View view) {                int intw = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);        int inth = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);        // 重新测量view        view.measure(intw, inth);                // 以上3句可简写成下面一句        //view.measure(0,0);                // 获取测量后的view尺寸        int intwidth = view.getMeasuredWidth();        int intheight = view.getMeasuredHeight();    }}

注释中有详细解释，使用方法如下：

xml布局中配置

xxx.xxx.xxx代表路径

代码中调用

mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {            @Override            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {            }            @Override            public void onPageSelected(final int position) {            // 切换到当前页面，重置高度               mViewPager.requestLayout();            }            @Override            public void onPageScrollStateChanged(int state) {            }        });

设置offset属性，预先加载全部view，防止下面的方法获取到没有加载的view是高度为0
// View view = getChildAt(getCurrentItem());

// 如果不设置，可能第三个页面以后就显示不出来了，因为offset就是默认值1了mViewPager.setOffscreenPageLimit(adapter.getCount());

以上就是总结的2种ViewPager自适应高度的方式，希望对你有帮助，不足之处还望大佬指教

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