数据库调用于Pulltorefresh+网络判断

最新推荐文章于 2019-01-20 20:55:08 发布

whatfuck_

最新推荐文章于 2019-01-20 20:55:08 发布

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本文链接：https://blog.youkuaiyun.com/whatfuck_/article/details/79824213

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本示例展示了一个使用PullToRefreshListView实现下拉刷新和上拉加载更多功能的应用。该应用通过AsyncTask发起网络请求获取新闻数据，并使用Gson进行JSON解析。同时，应用具备离线模式，当网络不可用时，会从SQLite数据库中读取已缓存的数据。

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package com.example.app2;

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.view.StandaloneActionMode;
import android.view.View;
import android.widget.ListView;
import android.widget.Toast;

import com.google.gson.Gson;
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshListView;

import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private List<Bean.NewslistBean> list=new ArrayList<>();
    private PullToRefreshListView pl;
    private int page=1;
    private MyBase base;
    private SqliteDao dao;
    private String path="https://api.tianapi.com/wxnew/?key=48a7d7193e11bd2dd4a683b6e2f90a4f&num=10&page=1";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        pl = findViewById(R.id.pl);
        dao = new SqliteDao(new MySqlite(this));
        Request();
        Init();
    }

    private void Request() {
        if (NerWorkUtil.isConn(this)){
        MyTask task=new MyTask(new MyTask.IcallBack(){
            @Override
            public void updateUiByjson(String string) {
                dao.insert(path,string);
                Gson gson=new Gson();
                Bean bean = gson.fromJson(string, Bean.class);
                if (page==1){
                    list.clear();
                }
                list.addAll(bean.getNewslist());
                SetAdap();
                pl.onRefreshComplete();
            }
        });
        task.execute(path);
    }

    else {
            Toast.makeText(this,"没有网络，从数据库查询",Toast.LENGTH_SHORT).show();
            String select = dao.select(path);
            Gson gson=new Gson();
            Bean bean = gson.fromJson(select, Bean.class);
            if (page==1){
                list.clear();
            }
            list.addAll(bean.getNewslist());
            SetAdap();
            pl.onRefreshComplete();
        }
    }
    private void SetAdap() {
        if (base==null){
            base = new MyBase(this,list);
            pl.setAdapter(base);
        }
            else {
            base.notifyDataSetChanged();
        }
    }
    private void Init() {
        pl.setMode(PullToRefreshBase.Mode.BOTH);
        pl.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener2<ListView>() {
            @Override
            public void onPullDownToRefresh(PullToRefreshBase<ListView> refreshView) {
                page=1;
                Request();
            }

            @Override
            public void onPullUpToRefresh(PullToRefreshBase<ListView> refreshView) {
                page++;
                Request();
            }
        });
    }
}