解析，網絡判斷，上下拉加載及數據庫緩存

原創 MaMaiPi000 2020-02-24 02:53
佈局文件需要導依賴：
pulltorefresh

佈局爲：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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="com.example.com.zhangjinlong41.MainActivity"
 xmlns:ptr="http://schemas.android.com/apk/res-auto"
 android:orientation="vertical">
<com.handmark.pulltorefresh.library.PullToRefreshListView
 android:layout_height="match_parent"
 android:layout_width="match_parent"
 android:id="@+id/lv"
 ptr:ptrDrawable="@drawable/default_ptr_flip"
 ptr:ptrAnimationStyle="flip"
 ptr:ptrHeaderBackground="#383838"

 ptr:ptrHeaderTextColor="#FFFFFF"/>
</LinearLayout>




mainActivity:
package com.example.com.zhangjinlong41;

import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ListView;
import android.widget.Toast;

import com.example.com.zhangjinlong41.db.jsonshujudao;
import com.google.gson.Gson;
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshListView;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
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 int num=10;
    private int type=1;
    private int pageIndex=1;
    private  MyAdapter adapter;
    private PullToRefreshListView lv;
    private List<ReqBean.DataBean> list=new ArrayList<>();
    private String urldata="http://www.93.gov.cn/93app/data.do?channelId=0&startNum="+num;

   private Handler myHandler=new Handler(){
       @Override
       public void handleMessage(Message msg) {
           List<ReqBean.DataBean> data=(List<ReqBean.DataBean>)msg.obj;
           /*if (type==1){
               list.clear();
           }
           list.addAll(data);
           seadaper();
           lv.onRefreshComplete();*/
           showdata(data);
       }
   };
    private com.example.com.zhangjinlong41.db.jsonshujudao jsonshujudao;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv = findViewById(R.id.lv);
        jsonshujudao = new jsonshujudao(this);

        intoptlv();
        getlDate();



    }



    private void getlDate() {
        if (NetStateUtil.isConn(this)){


        new Thread(){
            @Override
            public void run() {
//創建url對象
                try {
                    URL url = new URL(urldata);
                    HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
                    urlConnection.setRequestMethod("GET");
                    urlConnection.setReadTimeout(5000);
                    urlConnection.setConnectTimeout(5000);
                    //4.獲取響應碼進行判斷
                    int responseCode = urlConnection.getResponseCode();
                    if (responseCode==200){
                        InputStream inputStream = urlConnection.getInputStream();
                        String content=statemstring(inputStream);
                        jsonshujudao.inserdata(urldata,content);
                        Gson gson = new Gson();
                        ReqBean reqBean = gson.fromJson(content, ReqBean.class);
                        List<ReqBean.DataBean> data = reqBean.getData();
                        Message obtain = Message.obtain();
                        obtain.obj=data;
                        myHandler.sendMessage(obtain);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }.start();
    }else {
            Log.d("zzz","無網絡，查詢數據庫中的數據");
            Toast.makeText(this,"沒有網絡，稍後重試",Toast.LENGTH_SHORT).show();
            String querydata = jsonshujudao.querydata(urldata);
            List<ReqBean.DataBean> beans=asyncJson(querydata);
            showdata(beans);
        }
    }
public  List<ReqBean.DataBean> asyncJson(String json){
    Gson gson = new Gson();
    ReqBean reqBean = gson.fromJson(json, ReqBean.class);
    List<ReqBean.DataBean> datas=reqBean.getData();
    return datas;
}

public void showdata( List<ReqBean.DataBean> data){
    if (type==1) {
        list.clear();
    }
    list.addAll(data);
    seadaper();
    lv.onRefreshComplete();
}
    //設置適配器
    private void seadaper(){
        if (adapter==null){
           adapter=new MyAdapter(MainActivity.this,list);
           lv.setAdapter(adapter);
        }else {
            adapter.notifyDataSetChanged();
        }
    }
    //將流轉換成字符串
    public String statemstring(InputStream stream){
    StringBuilder builder=new StringBuilder();
        BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
        String str;
        try {
            while ((str=reader.readLine())!=null){
            builder.append(str);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return builder.toString();
    }
    private void intoptlv() {
        lv.setMode(PullToRefreshBase.Mode.BOTH);

        lv.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener2<ListView>() {
            @Override
            public void onPullDownToRefresh(PullToRefreshBase<ListView> refreshView) {
                type =1;
                //pageIndex=1;
                num=10;
                urldata="http://www.93.gov.cn/93app/data.do?channelId=0&startNum="+num;
                getlDate();

            }

            @Override
            public void onPullUpToRefresh(PullToRefreshBase<ListView> refreshView) {
                type=2;
                num +=20;
               // pageIndex++;
                urldata="http://www.93.gov.cn/93app/data.do?channelId=0&startNum="+num;
                getlDate();

            }
        });
    }
}

適配器：
package com.example.com.zhangjinlong41;

import android.content.Context;
import android.graphics.Bitmap;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.assist.ImageScaleType;
import com.nostra13.universalimageloader.core.display.RoundedBitmapDisplayer;

import java.util.List;

/**
 * Created by 聯想 on 2018/4/1.
 */

class MyAdapter extends BaseAdapter {
    private Context context;
    private List<ReqBean.DataBean> data;
    private final DisplayImageOptions options;
    public MyAdapter(Context context, List<ReqBean.DataBean> data) {
        this.context = context;
        this.data = data;
        options = new DisplayImageOptions.Builder()
                .cacheInMemory(true)//浣跨敤鍐呭瓨緙撳瓨
                .cacheOnDisk(true)//浣跨敤紓佺洏緙撳瓨
                .showImageOnLoading(R.mipmap.ic_launcher)//璁劇疆姝ｅ湪涓嬭澆鐨勫浘鐗?
                .showImageForEmptyUri(R.mipmap.ic_launcher)//url涓虹┖鎴栬奼傜殑璧勬簮涓嶅瓨鍦ㄦ椂
                .showImageOnFail(R.mipmap.ic_launcher)//涓嬭澆澶辮觸鏃舵樉紺虹殑鍥劇墖
                .bitmapConfig(Bitmap.Config.RGB_565)//璁劇疆鍥劇墖鑹插僵妯″紡 1px=2瀛楄妭
                .imageScaleType(ImageScaleType.EXACTLY)//璁劇疆鍥劇墖鐨勭緝鏀炬ā寮?
                .displayer(new RoundedBitmapDisplayer(100))//璁劇疆鍦嗚 30浠ｈ〃鍗婂緞 鑷畾涔?
                .build();

    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public Object getItem(int i) {
        return data.get(i);
    }

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

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        ViewHolder holder;
        if (view==null){
       view=View.inflate(context,R.layout.view,null);
            holder=new ViewHolder();
            holder.img=view.findViewById(R.id.img);
            holder.tv=view.findViewById(R.id.tv);
            view.setTag(holder);
        }else{
            holder= (ViewHolder) view.getTag();
        }
        holder.tv.setText(data.get(i).getTITLE());
        ImageLoader.getInstance().displayImage(data.get(i).getIMAGEURL(),holder.img,options);
        return view;
    }

    private class ViewHolder{
        ImageView img;
        TextView tv;
    }
}

子佈局：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">
<ImageView
    android:layout_width="80dp"
    android:layout_height="80dp"
    android:id="@+id/img"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/tv"/>
</LinearLayout>

Myhelper:
package com.example.com.zhangjinlong41.db;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

/**
 * Created by 聯想 on 2018/4/2.
 */

public class MyHelper extends SQLiteOpenHelper {
    public MyHelper(Context context) {
       //確定數據庫名稱以及版本號
        super(context, "mydb", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL("create table jsonshuju(id Integer primary key autoincrement,urlpath text,jsondata text)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
}

Dao類：
package com.example.com.zhangjinlong41.db;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;

/**
 * Created by 聯想 on 2018/4/2.
 */

public class jsonshujudao {

    private final MyHelper myHelper;

    public jsonshujudao (Context context){
        myHelper = new MyHelper(context);
    }

    //添加的方法
    public void inserdata(String path,String data){
        SQLiteDatabase db = myHelper.getWritableDatabase();
        db.delete("jsonshuju","urlpath=?", new String[]{path});
        ContentValues contentValues = new ContentValues();
        contentValues.put("urlpath",path);
        contentValues.put("jsondata",data);
        long jsonshuju = db.insert("jsonshuju", null, contentValues);
        Log.d("zzz","插入的數據jsonshuju"+jsonshuju);


    }

    //查詢的方法，根據url
    public  String querydata(String path){
        String data="";
        SQLiteDatabase database = myHelper.getWritableDatabase();
        Cursor cursor = database.query("jsonshuju", null, "urlpath=?", new String[]{path}, null, null, null);
while (cursor.moveToNext()){
   data = cursor.getString(cursor.getColumnIndex("jsondata"));

}
return data;
    }

}

網絡判斷：
package com.example.com.zhangjinlong41;

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;




/**
 * 得到網絡狀態的工具類
 * Created by e531 on 2017/10/16.
 */
public class NetStateUtil {

    /*
 * 判斷網絡連接是否已開
 * true 已打開  false 未打開
 * */
    public static boolean isConn(Context context){
        boolean bisConnFlag=false;
        ConnectivityManager conManager = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo network = conManager.getActiveNetworkInfo();
        if(network!=null){
            bisConnFlag=network.isAvailable();
        }
        return bisConnFlag;
    }

    /**
     * 當判斷當前手機沒有網絡時選擇是否打開網絡設置
     * @param context
     */
    public static void showNoNetWorkDlg(final Context context) {
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        builder.setIcon(R.mipmap.ic_launcher)         //
                .setTitle(R.string.app_name)            //
                .setMessage("當前無網絡").setPositiveButton("設置", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
                // 跳轉到系統的網絡設置界面
                Intent intent = null;
                // 先判斷當前系統版本
                if(android.os.Build.VERSION.SDK_INT > 10){  // 3.0以上
                    intent = new Intent(android.provider.Settings.ACTION_WIRELESS_SETTINGS);
                }else{
                    intent = new Intent();
                    intent.setClassName("com.android.settings", "com.android.settings.WirelessSettings");
                }
                context.startActivity(intent);

            }
        }).setNegativeButton("知道了", null).show();
    }
}

配置權限：
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET"></uses-permission>













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