Android Studio 制作商品销售记录APP
制作这个APP之前首先要考虑的不是去怎么做，而是去想需求、从需求出发去建数据库、建表。话不多说开始动工吧！！！
预览项目逻辑结构：
本次项目逻辑层有三个包：bean、DBHelper、utils。前端界面部分：3个xml文件。
第一步：建立javabean。还是那句老话，从需求分析：我们这次的对象是商品，商品的属性有：商品id、商品名字、商品数量、商品价格（此处是单价）。既然是商品销售记录，那一定有总价了,数了数一共有5个属性，javabean里对应的也就有五个属性。
这五个属性都给他加上get和set方法，结果下：
package com.example.liaof.goodssale.bean;
/**
* Created by liaof on 2018/7/24.
*/
public class goods {
private Integer id;
private String goodsname;
private String goodscount;
private String goodsprice;
private String price;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getGoodsname() {
return goodsname;
}
public void setGoodsname(String goodsname) {
this.goodsname = goodsname;
}
public String getGoodscount() {
return goodscount;
}
public void setGoodscount(String goodscount) {
this.goodscount = goodscount;
}
public String getGoodsprice() {
return goodsprice;
}
public void setGoodsprice(String goodsprice) {
this.goodsprice = goodsprice;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
public goods(String goodsname, String goodscount, String goodsprice,String price) {
this.goodsname = goodsname;
this.goodscount = goodscount;
this.goodsprice = goodsprice;
this.price = price;
}
}
第二步：创建数据库SQLite(一款轻量级数据库，非常好用，不了解的可以网上百度学习一下SQLite的使用)，然后创建数据表，表里的字段和我们的javabean里的五个属性相对应，具体代码如下：
package com.example.liaof.goodssale.DBHelper;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
/**
* Created by liaof on 2018/7/24.
*/
public class DBHelper extends SQLiteOpenHelper {
public DBHelper(Context context){
super(context,"Goods.db",null,2);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table tb_goods(id integer primary key autoincrement,goodsname varchar(50),goodscount varchar(10),goodsprice varchar(10),price varchar(20))");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
第三步：写前端页面，页面很简单，就只有一个标题、三个商品信息输入框（分别是：商品名字、商品数量、商品单价）、外加两个按钮（确认添加、销售情况）代码如下index.xml：
前端效果如下图：
第四步：获取输入框内容然后对SQLite数据库进行增加数据操作。此处逻辑层要考虑：该商品是否是新入库商品，如果不是，则要查询该商品添加前的总价，并获取过去的单价，此处则不用再输入单价了。代码如下：
package com.example.liaof.goodssale.utils;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import com.example.liaof.goodssale.DBHelper.DBHelper;
import com.example.liaof.goodssale.R;
public class index extends AppCompatActivity {
private EditText edt_goodsname;
private EditText edt_goodscount;
private EditText edt_goodsprice;
private Button btn_add;
private Button To_goods;
private String price;
private DBHelper dbHelper;
private String goodsname;
private String goodscount;
private String goodsprice;
SQLiteDatabase db;
SQLiteDatabase redDb;
String oldcount;
ContentValues contentValues=new ContentValues();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.index);
init();
dbHelper=new DBHelper(this);
db=dbHelper.getWritableDatabase();
btn_add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
goodsname = edt_goodsname.getText().toString();
goodscount = edt_goodscount.getText().toString();
goodsprice = edt_goodsprice.getText().toString();
if (wasgoods(goodsname)) {
if(goodscount.equals("")||goodsname.equals("")||goodsprice.equals("")){
try{
Toast.makeText(index.this,"输入不能为空",Toast.LENGTH_SHORT).show();
price = String.valueOf((Float.parseFloat(goodsprice)) * (Integer.parseInt(goodscount)));
}
catch (Exception e){
e.printStackTrace();
}
return;
}
price = String.valueOf((Float.parseFloat(goodsprice)) * (Integer.parseInt(goodscount)));
System.out.println("总价1：" + price);
Toast.makeText(index.this, "添加成功！", Toast.LENGTH_SHORT).show();
contentValues.put("goodsname", goodsname);
contentValues.put("goodscount", goodscount);
contentValues.put("goodsprice", goodsprice);
contentValues.put("price", price);
db.insert("tb_goods", null, contentValues);
}else{
if(goodscount.equals("")||goodsname.equals("")){
try{
Toast.makeText(index.this,"输入不能为空",Toast.LENGTH_SHORT).show();
}
catch (Exception e){
e.printStackTrace();
}
return;
}
String sql="select * from tb_goods where goodsname=?";
Cursor cursor = db.rawQuery(sql, new String[] {goodsname});
while(cursor.moveToNext()){
oldcount=cursor.getString(cursor.getColumnIndex("goodscount"));
goodsprice=cursor.getString(cursor.getColumnIndex("goodsprice"));
edt_goodsprice.setText(goodsprice);
goodscount=String.valueOf((Integer.parseInt(goodscount))+(Integer.parseInt(oldcount)));
price = String.valueOf((Float.parseFloat(goodsprice)) * (Integer.parseInt(goodscount)));
System.out.println("总价：" + price);
Toast.makeText(index.this, "添加成功！", Toast.LENGTH_SHORT).show();
contentValues.put("goodscount",goodscount);
contentValues.put("price",price);
db.update("tb_goods",contentValues,"goodsname=?",new String[]{goodsname});
}
}
}
});
To_goods.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent=new Intent(index.this,showgoods.class);
startActivity(intent);
finish();
}
});
}
public void init(){
edt_goodsname=(EditText)findViewById(R.id.edt_goodsname);
edt_goodscount=(EditText)findViewById(R.id.edt_goodscount);
edt_goodsprice=(EditText)findViewById(R.id.edt_goodsprice);
btn_add=(Button)findViewById(R.id.add_btn);
To_goods=(Button)findViewById(R.id.To_goods);
}
public boolean wasgoods(String name){
SQLiteDatabase db = dbHelper.getWritableDatabase();
String sql="select * from tb_goods where goodsname=?";
Cursor cursor = db.rawQuery(sql, new String[] {name});
System.out.println(cursor.getCount());
if(cursor.getCount()!=0){
System.out.println("调用了1");
cursor.close();
return false;
}
System.out.print("调用了2");
return true;
}
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if (keyCode == android.view.KeyEvent.KEYCODE_BACK ){
finish();
}
return false;
}
}
第四步：点击销售情况时跳转到商品销售详情显示页面，采用了listview去渲染，因此在showgoods类里要写一个适配器方法。先看前端代码：
1、item 布局，每一条消息的样式：
2、showgoods页面：
逻辑层代码：
要用sql语句将所有的商品总价加起来作为总价显示出来，具体代码如下
package com.example.liaof.goodssale.utils;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
import com.example.liaof.goodssale.DBHelper.DBHelper;
import com.example.liaof.goodssale.R;
import com.example.liaof.goodssale.bean.goods;
import java.util.ArrayList;
public class showgoods extends AppCompatActivity {
private ListView listView;
private DBHelper dbHelper;
private ArrayList goodsList;
private TextView tv_all_price;
private double all_money;
SQLiteDatabase db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.showgoods);
listView=(ListView)findViewById(R.id.list_goods);
tv_all_price=(TextView)findViewById(R.id.tv_all_price);
dbHelper=new DBHelper(this);
db=dbHelper.getReadableDatabase();
goodsList=new ArrayList<>();
String sql="select * from tb_goods";
Cursor cursor=db.rawQuery(sql,null);
while (cursor.moveToNext()){
String goodsname=cursor.getString(cursor.getColumnIndex("goodsname"));
String goodscount=cursor.getString(cursor.getColumnIndex("goodscount"));
String goodsprice=cursor.getString(cursor.getColumnIndex("goodsprice"));
String price=cursor.getString(cursor.getColumnIndex("price"));
all_money=Double.parseDouble(price)+all_money;
goods good=new goods(goodsname,goodscount,goodsprice,price);
goodsList.add(good);
}
tv_all_price.setText(String.valueOf(all_money)+"元");
listView.setAdapter(new BaseAdapter() {
@Override
public int getCount() {
return goodsList.size();
}
@Override
public Object getItem(int position) {
return position;
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int i, View convertView, ViewGroup parent) {
View view;
if (convertView==null){
view = View.inflate(getBaseContext(),R.layout.list_goods_item,null);
}else{
view = convertView;
}
goods good=goodsList.get(i);
TextView goodsname=(TextView)view.findViewById(R.id.tv_goodsname);
TextView goodscount=(TextView)view.findViewById(R.id.tv_goodscount);
TextView goodsprice=(TextView)view.findViewById(R.id.tv_goodsprice);
TextView price=(TextView)view.findViewById(R.id.tv_price);
goodsname.setText(good.getGoodsname());
goodscount.setText(good.getGoodscount());
goodsprice.setText(good.getGoodsprice());
price.setText(good.getPrice());
return view;
}
});
}
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if (keyCode == android.view.KeyEvent.KEYCODE_BACK ){
Intent intent=new Intent(showgoods.this,index.class);
startActivity(intent);
finish();
}
return false;
}
}
看看效果吧：
1、添加商品：
2、查看商品：
看到上图的结果正是我们需要的结果，这就说明已满足需求
3、再添加vipSp不写单价
结果：
vipSp也变化了，这个程序也算是做好了！！！
源码地址在我的下载那里，找‘商品销售情况’