Android listview 自动加载数据

实现ListView滑动到底部自动加载更多

原理：监听ListView的滑动事件,判断ListView是否滑动到底部,然后去加载数据。

布局文件：activity_test_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="cn.sizebook.activities.measure.userdefine.TestMainActivity">

    <ListView
        android:id="@+id/listview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></ListView>
</android.support.constraint.ConstraintLayout>

布局文件：item.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
    android:layout_height="match_parent">
<TextView
    android:layout_width="match_parent"
    android:layout_height="45dp"
    android:textSize="16sp"
    android:text="测试"
    android:gravity="center_vertical"
    android:id="@+id/tvContent"/>
</android.support.constraint.ConstraintLayout>

Activity文件

package cn.sizebook.activities.measure.userdefine;

import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.TextView;

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

import cn.sizebook.R;

public class TestMainActivity extends AppCompatActivity {

    private ListView listview;
    private LayoutInflater inflater;
    private MyAdapter adapter;
    private List<String> contents;
   
    private Handler handler = new Handler();
    int lastItem;
   
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test_main);
        initData();
        inflater = LayoutInflater.from(this);
        listview = (ListView) findViewById(R.id.listview);
        adapter = new MyAdapter();
        
        listview.setAdapter(adapter);
        //添加listview滚动监听
        listview.setOnScrollListener(new AbsListView.OnScrollListener() {
        
            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {
                if (scrollState == AbsListView.OnScrollListener.SCROLL_STATE_IDLE) {
                    if (view.getLastVisiblePosition() == view.getCount() - 1) {
                        loadData();
                    }
                }
            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem,
                                 int visibleItemCount, int totalItemCount) {
                lastItem = firstVisibleItem + visibleItemCount - 1;
            }
        });
    }

    protected void loadData() {
  
  
        load();
        adapter.notifyDataSetChanged();
      
    }

    protected void load() {
        int count = adapter.getCount() + 1;
        for (int i = count; i < count + 20; i++) {  //每次加载20条数据
            contents.add("加载数据..." + i);
        }
    }

    private void initData() {
        contents = new ArrayList<String>();
        for (int i = 1; i < 20; i++) {
            contents.add("加载数据..." + i);
        }
    }

    class MyAdapter extends BaseAdapter {
        @Override
        public int getCount() {
            return contents.size();
        }

        @Override
        public Object getItem(int position) {
            return contents.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder holder;
            if (convertView == null) {
                convertView = inflater.inflate(R.layout.item, parent, false);
                holder = new ViewHolder();
                holder.tvContent = (TextView) convertView.findViewById(R.id.tvContent);
                convertView.setTag(holder);
            } else {
                holder = (ViewHolder) convertView.getTag();
            }
            holder.tvContent.setText(contents.get(position));
            return convertView;
        }

        class ViewHolder {
            TextView tvContent;
        }
    }
}