在列表视图中仅加载10个项目 [英] Loading only 10 items in listview

问题描述

该列表视图使用线程池从Internet加载了100张图片.如何仅将元素10加载到必要的程度?向下滚动时再加载10个项目?我正在为此使用Lru缓存

The listview is loaded 100 pictures from the internet using a thread pool. How load only elements 10 to the extent necessary? And when scrolldown loading another 10 items? I'm using Lru cache for this

推荐答案

您可以为此使用limit和offset:

示例:

假设我要获取10条记录，结束后滚动将获取另外10条记录:

suppose i want to fetch 10 records and after end the scroll will fetch another 10 records:

定义偏移量变量

private static int offset = 0;

在绑定适配器时传递了offset变量:

when you bind the adapter at that pass the offset variable:

Select * from table limit 10 offset 0

因此，在为listview编写以下代码之后，这将仅从0-9获取10条记录:

So this will fetch only 10 records from 0-9 after that write below code for listview:

    listview.setOnScrollListener(new OnScrollListener() {
        private int mLastFirstVisibleItem;

        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {

        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {

            mLastFirstVisibleItem = firstVisibleItem;

            final int lastItem = firstVisibleItem + visibleItemCount;
            if (lastItem == totalItemCount) {

                if (preLast != lastItem) { 
                    preLast = lastItem;

                    offset = offset + 10;

                    new fetchrecords().execute();

                } else {

                }
            }
        }

    });

因此，当您当时转到列表视图项的最后一个位置时，它将调用方法fetchrecords()和您的offset value is 10.

so when go you to last position of list view item at that time it will call the method fetchrecords() and your offset value is 10.

因此，当该方法在那时调用时，偏移值是10.

So when this method calls at that time your offset value is 10.

因此下一次您的查询如下:

so for next time your query is like:

select * from table limit 10 offset 10

因此它将获取其他接下来的10条记录.

So it will fetch other next 10 records.

完成了！

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