android开发---简单购物商城(JAVA) （一）

包括：商品展示，商品详情，购物车，删除，一键清除，返回

运用sqllist

另外因为一篇写不下继续可看源码二

下面是目录

运行样子

下面是源码

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:name=".MyApplication"
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic"
        android:supportsRtl="true"
        android:theme="@style/Theme.Shop"
        tools:targetApi="31">
        <activity
            android:name=".ShoppingDetailActivity"
            android:exported="false" />
        <activity
            android:name=".ShoppingcartActivit"
            android:exported="false" />
        <activity
            android:name=".ShoppingChannelActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

/database/ShoppingDBHelper

package com.example.shop.database;

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

import com.example.shop.enity.CartInfo;
import com.example.shop.enity.GoodsInfo;

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

public class ShoppingDBHelper extends SQLiteOpenHelper {
    private static final String DB_NAME="shopping.db";
    public static final String TABLE_GOODS_INFO = "goods_info";
    public static final String TABLE_CART_INFO = "cart_info";
    public static final String CONTENT = "content";
    private static final String TAG="MyApplication";
    private static final int DB_VERSION=1;
    private static ShoppingDBHelper mHelper=null;
    private SQLiteDatabase mRDB=null;
    private SQLiteDatabase mWDB=null;
    public ShoppingDBHelper( Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }
    public static ShoppingDBHelper getInstance(Context context){
        if(mHelper==null)mHelper=new ShoppingDBHelper(context);
        return mHelper;
    }
    public SQLiteDatabase openReadLink(){
        if(mRDB==null||!mRDB.isOpen()){
            mRDB=mHelper.getReadableDatabase();
        }
        return mRDB;
    }
    public SQLiteDatabase openWriteLink(){
        if(mWDB==null||!mWDB.isOpen()){
            mWDB=mHelper.getWritableDatabase();
        }
        return mWDB;
    }
    public void closeLink(){
        if(mRDB!=null&&mRDB.isOpen()){
            mRDB.close();
            mRDB=null;
        }
        if(mWDB!=null&&mWDB.isOpen()){
            mWDB.close();
            mWDB=null;
        }
    }



    @Override
    //数据库第一次被创建时调用该方法
    public void onCreate(SQLiteDatabase db) {
        //初始化数据库的表结构，执行一条建表的SQL语句
        String sql ="create table if NOT EXISTS "+TABLE_GOODS_INFO+"(_id integer primary key autoincrement not null,"+"name varchar not null,"+"description varchar not null,"+
                "price float not null,"+
                "pic_path varchar not null);";

        db.execSQL(sql);

         sql ="create table if NOT EXISTS "+TABLE_CART_INFO+"(_id integer primary key autoincrement not null,"+
                "goods_id integer not null,"+
                "count integer not null);";

        db.execSQL(sql);
    }




    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
    public void insertGoodsInfos(List<GoodsInfo> list){//插入多条记录
        try {

            mWDB.beginTransaction();
            for(GoodsInfo info:list){
                ContentValues values=new ContentValues();
                values.put("name",info.name);
                values.put("description",info.description);
                values.put("price",info.price);
                values.put("pic_path",info.picPath);
                mWDB.insert(TABLE_GOODS_INFO,null,values);

            }
            mWDB.setTransactionSuccessful();
        } catch (Exception e){

        } finally {

            mWDB.endTransaction();
        }


    }
    //查询
    public List<GoodsInfo>queryAllGoodsInfo(){
        String sql="select * from "+TABLE_GOODS_INFO;
        List<GoodsInfo>list=new ArrayList<>();
       Cursor cursor= mRDB.rawQuery(sql,null);
       while (cursor.moveToNext()){
           GoodsInfo info=new GoodsInfo();
           info.id=cursor.getInt(0);
           info.name=cursor.getString(1);
           info.description=cursor.getString(2);
           info.price=cursor.getFloat(3);
           info.picPath=cursor.getString(4);
           list.add(info);
       }
       cursor.close();
       return list;
    }

    public void insertCartInfo(int gid) {//添加购物车
        //不存在
        CartInfo cartInfo=queryCartInfoByGoodsId(gid);
        ContentValues values=new ContentValues();
        values.put("goods_id",gid);
        if(cartInfo==null){
            values.put("count",1);
            mRDB.insert(TABLE_CART_INFO,null,values);
        }
        else{ //数量加一
            values.put("_id",cartInfo.id);
            values.put("count",++cartInfo.count);
            mWDB.update(TABLE_CART_INFO,values,"_id=?",new String[]{String.valueOf(cartInfo.id)});

        }


    }

    private CartInfo queryCartInfoByGoodsId(int gid) {
        //查询
        Cursor cursor=mRDB.query(TABLE_CART_INFO,null,"goods_id=?",new String[]{String.valueOf(gid)},null,null,null);
        CartInfo info=null;
        if(cursor.moveToNext()){
            info=new CartInfo();
            info.id=cursor.getInt(0);
            info.goodsid=cursor.getInt(1);
            info.count=cursor.getInt(2);
        }
        return info;
    }

    public int countCartInfo() {
        int count=0;
       // String sql="select sum(count) from"+TABLE_CART_INFO;
       // List<CartInfo>list=new ArrayList<>();
      //  Cursor cursor= mRDB.rawQuery(sql,null);
     //   count=cursor.getInt(0);
//
//       // Cursor cursor=mRDB.rawQuery(sql,null);
//        if(cursor.moveToNext()){
   //        count=cursor.getInt(0);
    //    Log.d(TAG,String.valueOf(count));
//        }
        return count;
    }

    public List<CartInfo> queryAllCartInfo() {//查询购物车信息
        List<CartInfo>list=new ArrayList<>();
        Cursor cursor=mRDB.query(TABLE_CART_INFO,null,null,null,null,null,null,null);
        while(cursor.moveToNext()){
            CartInfo info=new CartInfo();
            info.id=cursor.getInt(0);
            info.goodsid=cursor.getInt(1);
            info.count=cursor.getInt(2);
            list.add(info);
        }
        return list;
    }

    public GoodsInfo queryGoodsInfoById(int goodsid) {
        GoodsInfo info=null;
        Cursor cursor=mRDB.query(TABLE_GOODS_INFO,null,"_id=?",new String[]{String.valueOf(goodsid)},null,null,null);
        if(cursor.moveToNext()){
            info=new GoodsInfo();
            info.id=cursor.getInt(0);
            info.name=cursor.getString(1);
            info.description=cursor.getString(2);
            info.price=cursor.getFloat(3);
            info.picPath=cursor.getString(4);

        }

        return info;
    }

    public void deleteCartinfobygoodsid(int goodsid) {//delete one
        mWDB.delete(TABLE_CART_INFO,"goods_id=?",new String[]{String.valueOf(goodsid)});
    }
    public void deleteallcartinfo(){
        mWDB.delete(TABLE_CART_INFO,"1=1",null);//条件
    }
}

/enity/CartInfo 购物车数据

package com.example.shop.enity;

public class CartInfo {
    public int id;
    public int count;
    public int goodsid;
    public CartInfo(){}
    public CartInfo(int id,int goodsid,int count){
        this.goodsid=goodsid;
        this.id=id;
        this.count=count;
    }
}

/enity/GoodsInfo 商品数据

package com.example.shop.enity;

import com.example.shop.R;

import java.util.ArrayList;

public class GoodsInfo {
    public int id;
    public String name;
    public String description;
    public float price;
    public String picPath;
    public int pic;
    private static String[ ]mNameArray={
            "iPhone 11","mate 30","mi30","huawei 2","rongyao30s","vivo x30"
    };
    private static String[]mDescArray={
            "Apple iphone 256D|G",
            "mate30 iphone 256D|G",
            "mi30 iphone 256D|G",
            "huawei 2 iphone 256D|G",
            "rongyao30s iphone 256D|G",
            "vivo x30 iphone 256D|G",
    };
    private static float[]mPriceArray={100,200,31,221,22,40};

    private static int[]mPicArray={
            R.drawable.no1,R.drawable.no2,R.drawable.no3,R.drawable.no4,R.drawable.no5,R.drawable.no6
    };
    public static ArrayList<GoodsInfo>getDefaultList(){
        ArrayList<GoodsInfo>goodsList=new ArrayList<>();
        for(int i=0;i<mNameArray.length;i++){
            GoodsInfo info=new GoodsInfo();
            info.id=i;
            info.name=mNameArray[i];
            info.description=mDescArray[i];
            info.price=  mPriceArray[i];
            info.pic=mPicArray[i];
            goodsList.add(info);

        }
        return goodsList;
    }
}

/util/FilUtil 读取数据库数据并显示

package com.example.shop.util;

import android.graphics.Bitmap;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;

public class FilUtil {
    //保存
    public static void saveText(String path,String txt){
        BufferedWriter os=null;
        try{
            os=new BufferedWriter(new FileWriter(path));
            os.write(txt);
        }catch (Exception e){
            e.printStackTrace();
        }
        finally {
            if(os!=null){
                try{
                    os.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        }
    }
    //读取
    public static String openText(String path){
        BufferedReader is=null;
        StringBuilder sb=new StringBuilder();
        try{
            is= new BufferedReader(new FileReader(path));
            String line=null;
            while((line=is.readLine())!=null){
                sb.append(line);
            }

        }catch (Exception e){
            e.printStackTrace();
        }
        finally {
            if(is!=null){
                try{
                    is.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        }
        return path;
    }
    public static void saveImage(String path, Bitmap bitmap){
        FileOutputStream fos=null;
        try{
            fos=new FileOutputStream(path);
            bitmap.compress(Bitmap.CompressFormat.JPEG,100,fos);
        }catch (Exception e){
            e.printStackTrace();
        }
        finally {
            if(fos!=null){
                try{
                    fos.close();
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        }

    }
}

/util/SharedUtil 轻量级存储

package com.example.shop.util;

import android.content.Context;
import android.content.SharedPreferences;

import java.util.Calendar;

public class SharedUtil {
    private static SharedUtil mUtil;
    private SharedPreferences preferences;
    public static SharedUtil getInstance(Context ctx){
        if(mUtil==null){
            mUtil=new SharedUtil();
            mUtil.preferences=ctx.getSharedPreferences("shopping",Context.MODE_PRIVATE);
        }
        return mUtil;
    }

    public void writeBoolean(String key,boolean value){//快捷方法
        SharedPreferences.Editor editor=preferences.edit();
        editor.putBoolean(key,value);
        editor.commit();
    }
    public boolean reaadBoolean(String key,Boolean de){
        return preferences.getBoolean(key,de);
    }

}

AppWriteActivity

package com.example.shop;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

public class AppWriteActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_app_write);
    }
}

MainActivity

package com.example.shop;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;

import java.lang.ref.Cleaner;

import okhttp3.OkHttpClient;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class MainActivity extends AppCompatActivity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    }
    
}

MyApplication

package com.example.shop;

import android.app.Application;
import android.content.res.Configuration;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Environment;

import androidx.annotation.NonNull;

import com.example.shop.database.ShoppingDBHelper;
import com.example.shop.enity.GoodsInfo;
import com.example.shop.util.FilUtil;
import com.example.shop.util.SharedUtil;

import java.io.File;
import java.util.HashMap;
import java.util.List;

public class MyApplication extends Application {
    private static MyApplication mApp;
    public HashMap<String,String>infoMap=new HashMap<>();
    public int goodsCount;
    public static MyApplication getInstance(){//外部调用
        return mApp;
    }

    @Override
    public void onCreate() {

        super.onCreate();
        mApp=this;
        initGoodsInfo();
    }

    private void initGoodsInfo() {//第一次打开
        Boolean isFirst=SharedUtil.getInstance(this).reaadBoolean("first",true);
        String directory=getExternalFilesDir(Environment.DIRECTORY_DOCUMENTS).toString()+ File.separatorChar;

        if(isFirst){//打开数据库
            List<GoodsInfo>list=GoodsInfo.getDefaultList();
            for(GoodsInfo info:list){
                Bitmap bitmap=BitmapFactory.decodeResource(getResources(),info.pic);
                String path=directory+info.id+".jpg";
                FilUtil.saveImage(path,bitmap);

                bitmap.recycle();
                info.picPath=path;
            }

            //存储
            ShoppingDBHelper dbHelper=ShoppingDBHelper.getInstance(this);
            dbHelper.openWriteLink();
            dbHelper.insertGoodsInfos(list);
            dbHelper.closeLink();
            SharedUtil.getInstance(this).writeBoolean("frist",false);

        }

    }

    @Override
    public void onTerminate() {

        super.onTerminate();
    }

    @Override
    public void onConfigurationChanged(@NonNull Configuration newCondig) {

        super.onConfigurationChanged(newCondig);

    }
}

ShoppingcartActivit

package com.example.shop;

import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

import com.example.shop.database.ShoppingDBHelper;
import com.example.shop.enity.CartInfo;
import com.example.shop.enity.GoodsInfo;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class ShoppingcartActivit extends AppCompatActivity implements View.OnClickListener {
    private TextView tv_count;
    private LinearLayout ll_cart;
    private ShoppingDBHelper mDBHelper;
    public List<CartInfo> mCartList;//购物车
    private TextView tv_total_price;
    //声明缓存
    private Map<Integer,GoodsInfo>mGoodsMap=new HashMap<>();
    private LinearLayout ll_empty;
    private LinearLayout ll_content;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_shoppingcart);
        TextView tv_title=findViewById(R.id.tv_title);
         tv_count=findViewById(R.id.tv_count);
         tv_title.setText("购物车");
         tv_count.setText(String.valueOf(MyApplication.getInstance().goodsCount));
         ll_cart=findViewById(R.id.ll_cart);

         tv_total_price=findViewById(R.id.tv_total_price);
        mDBHelper= ShoppingDBHelper.getInstance(this);

        findViewById(R.id.iv_back).setOnClickListener(this);
        findViewById(R.id.btn_shopping_channel).setOnClickListener(this);
        findViewById(R.id.btn_clear).setOnClickListener(this);
        findViewById(R.id.btn_settle).setOnClickListener(this);

        ll_empty=findViewById(R.id.ll_empty);
        ll_content=findViewById(R.id.ll_content);

    }
    protected void onResume() {

        super.onResume();
        showCart();
    }

    private void showCart() {//展示
        ll_cart.removeAllViews();//先移除
        mCartList=mDBHelper.queryAllCartInfo();
        if(mCartList.size()==0)return;
        else{
            for(CartInfo info:mCartList){
              GoodsInfo goods= mDBHelper.queryGoodsInfoById(info.goodsid);
              mGoodsMap.put(info.goodsid,goods);//缓存
                View view= LayoutInflater.from(this).inflate(R.layout.item_cart,null);
                @SuppressLint({"MissingInflatedId", "LocalSuppress"})
                ImageView iv_thumb= view.findViewById(R.id.iv_thumb);
                @SuppressLint({"MissingInflatedId", "LocalSuppress"})
                TextView tv_name=view.findViewById(R.id.tv_name);
                @SuppressLint({"MissingInflatedId", "LocalSuppress"})
                TextView tv_desc=view.findViewById(R.id.tv_desc);
                @SuppressLint({"MissingInflatedId", "LocalSuppress"})
                TextView tv_count=view.findViewById(R.id.tv_count);
                @SuppressLint({"MissingInflatedId", "LocalSuppress"})
                TextView tv_price=view.findViewById(R.id.tv_price);
                @SuppressLint({"MissingInflatedId", "LocalSuppress"})
                TextView tv_sum=view.findViewById(R.id.tv_sum);

                iv_thumb.setImageURI(Uri.parse(goods.picPath));
                tv_name.setText(goods.name);
                tv_price.setText(String.valueOf((int)goods.price));
                tv_count.setText(String.valueOf(info.count));
                tv_desc.setText(goods.description);
                tv_sum.setText(String.valueOf((int)(info.count*goods.price)));


                view.setOnLongClickListener(v -> {//clear 长安删除
                    AlertDialog.Builder builder=new AlertDialog.Builder(ShoppingcartActivit.this);//长安
                    builder.setMessage("是否从购物车中删除"+goods.name+"?");

                    builder.setPositiveButton("是",(dialog, which) -> {
                        ll_cart.removeView(v);//delete
                        deleteGoods(info);
                    });
                    builder.setNegativeButton("否",null);
                    builder.create().show();
                    return true;
                });



            ll_cart.addView(view);
            }
            refreshtotalprice();
        }
    }

    private void deleteGoods(CartInfo info) {
        MyApplication.getInstance().goodsCount-=info.count;
        mDBHelper.deleteCartinfobygoodsid(info.goodsid);//从detebse
        CartInfo removed=null;//从list from cart
        for(CartInfo cartInfo:mCartList){
            if(cartInfo.goodsid==info.goodsid){
                removed=cartInfo;
                break;
            }
        }
        mCartList.remove(removed);
        showCount();
        Toast.makeText(this,"已从购物车中删除"+mGoodsMap.get(info.goodsid).name,Toast.LENGTH_SHORT).show();
        mGoodsMap.remove(info.goodsid);
        refreshtotalprice();

    }

    private void showCount() {//显示购物车数据
        tv_count.setText(String.valueOf(MyApplication.getInstance().goodsCount));
        if(MyApplication.getInstance().goodsCount==0){
            ll_empty.setVisibility(View.VISIBLE);
            ll_content.setVisibility(View.GONE);
            ll_cart.removeAllViews();
        }
        else{
            ll_content.setVisibility(View.VISIBLE);
            ll_empty.setVisibility(View.GONE);
        }

    }

    private void refreshtotalprice() {//重新可计算
        int totalPrice=0;
        for(CartInfo info:mCartList){
            GoodsInfo goods=mGoodsMap.get(info.goodsid);
            totalPrice+=goods.price*info.count;
        }
        tv_total_price.setText(String.valueOf(totalPrice));

    }

    @Override
    public void onClick(View v) {
        if(v.getId()==R.id.iv_back){
            finish();
        } else if (v.getId()==R.id.btn_shopping_channel) {
            Intent intent=new Intent(this,ShoppingChannelActivity.class);
            intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
            startActivity(intent);

        } else if (v.getId()==R.id.btn_clear) {
            mDBHelper.deleteallcartinfo();
            MyApplication.getInstance().goodsCount=0;
            showCount();
            Toast.makeText(this,"购物车已清空",Toast.LENGTH_SHORT).show();

        } else {//settle结算
            AlertDialog.Builder builder=new AlertDialog.Builder(this);
            builder.setTitle("结算");
            builder.setMessage("下次见");
            builder.setPositiveButton("know",null);
            builder.create().show();
        }

    }
}