Android學習（6）——案列（SQLite數據庫）

案例樣圖：

商品展示界面：

添加商品信息後的界面：

創建項目的文件目錄：

商品展示的佈局文件代碼（activity_main.xml）：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:layout_margin="8dp"
    tools:context="cn.edu.bzu.case_sql.MainActivity">

    <LinearLayout
        android:id="@+id/addLL"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <EditText
            android:id="@+id/nameET"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:hint="商品名稱"
            android:inputType="textPersonName"
            />
        <EditText
            android:id="@+id/balanceET"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:hint="金額"
            android:inputType="number"
            />
        |<ImageView
        android:onClick="add"
        android:id="@+id/addIV"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:src="@android:drawable/ic_input_add"
        />
    </LinearLayout>

    <ListView
        android:id="@+id/accountLV"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/addLL"
        >
    </ListView>
</LinearLayout>

ListView的item.xml

<?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:padding="10dp"
    android:orientation="horizontal">
    <TextView
        android:id="@+id/idTV"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="13"
        android:textColor="#000000"
        android:textSize="20sp"
        />
    <TextView
        android:id="@+id/nameTV"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="2"
        android:singleLine="true"
        android:text="PQ"
        android:textColor="#000000"
        android:textSize="20sp"
        />
    <TextView
        android:id="@+id/balanceTV"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="2"
        android:singleLine="true"
        android:text="123456"
        android:textColor="#000000"
        android:textSize="20sp"
        />
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        >
        <ImageView
        android:id="@+id/upIV"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="2dp"
        android:src="@android:drawable/arrow_up_float"
        />
        <ImageView
            android:id="@+id/downIV"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@android:drawable/arrow_down_float"
            />
    </LinearLayout>
    <ImageView
        android:id="@+id/deleteIV"
        android:layout_width="25dp"
        android:layout_height="25dp"
        android:src="@android:drawable/ic_menu_delete"/>
</LinearLayout>

MyHelper類（創建數據庫）：

package cn.edu.bzu.case_sql.dao;

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

/**
 * Created by HZY on 2017/4/22.
 */

public class MyHelper extends SQLiteOpenHelper {
    public MyHelper(Context context) {
        super(context, "itcast.db", null, 2);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        System.out.println("onCreate");
        db.execSQL("CREATE TABLE account(_id INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR(20),balance INTEGER)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        System.out.println("onUpgrade");

    }
}

Account類的代碼：

package cn.edu.bzu.case_sql.bean;

/**
 * Created by HZY on 2017/4/21.
 */

public class Account {
    private Long id;
    private String name;
    private Integer balance;

    public Account(Long id, String name, Integer balance) {
        this.id = id;
        this.name = name;
        this.balance = balance;
    }

    public Account(String name, Integer balance) {
        this.name = name;
        this.balance = balance;
    }

    public Account() {
        super();
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getBalance() {
        return balance;
    }

    public void setBalance(Integer balance) {
        this.balance = balance;
    }

    @Override
    public String toString() {
        return "[序號："+id+",商品名稱："+name+",餘額："+balance+"]";
    }
}

AccountDao類的代碼（數據庫操作）：

package cn.edu.bzu.case_sql.dao;

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

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

import cn.edu.bzu.case_sql.bean.Account;

/**
 * Created by HZY on 2017/4/22.
 */

public class AccountDao {
    private  MyHelper helper;
    public AccountDao(Context context) {
        //創建Dao，創建Helper
        helper =new MyHelper(context);
    }
    public void insert(Account account){
        //獲取數據對象
        SQLiteDatabase db=helper.getWritableDatabase();
        //用來裝載要插入的數據的Map<列名，列的值>
        ContentValues values=new ContentValues();
        values.put("name",account.getName());
        values.put("balance",account.getBalance());
        //向表插入數據values
        long id=db.insert("account",null,values);
        account.setId(id);
        db.close();
    }
    //根據id刪除數據
    public int delete(long id){
        SQLiteDatabase db=helper.getWritableDatabase();
        //按條件刪除指定表中的數據返回受影響的數據
        int count=db.delete("account","_id=?",new String[]{id+""});
        db.close();
        return count;
    }
    //更新數據
    public int update(Account account){
        SQLiteDatabase db=helper.getWritableDatabase();
        ContentValues values=new ContentValues();
        values.put("name",account.getName());
        values.put("balance",account.getBalance());
        int count=db.update("account",values,"_id=?",new String[]{account.getId()+""});
        db.close();
        return count;
    }
    //查詢所有數據倒序排列
    public List<Account> queryAll(){
        SQLiteDatabase db=helper.getWritableDatabase();
        Cursor c=db.query("account",null,null,null,null,null,"balance DESC");
        List<Account> list=new ArrayList<Account>();
        while(c.moveToNext()){
            //根據列名獲取索引
            long id=c.getLong(c.getColumnIndex("_id"));
            String name=c.getString(1);
            int balance=c.getInt(2);
            list.add(new Account(id,name,balance));
        }
        c.close();
        db.close();
        return list;
    }
}

MainActivity（頁面交互代碼）：

package cn.edu.bzu.case_sql;

import android.content.ContentProviderOperation;
import android.content.DialogInterface;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.app.NotificationCompat;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;
import java.util.Objects;
//import java.util.stream.DoubleStream;

import cn.edu.bzu.case_sql.bean.Account;
import cn.edu.bzu.case_sql.dao.AccountDao;

public class MainActivity extends AppCompatActivity {
    //需要適配的數據集合
    private List<Account> list;
    //數據庫增刪改查操作類
    private AccountDao dao;
    //輸入姓名的EditText
    private EditText nameET;
    //輸入金額的EditText
    private EditText balanceET;
    //適配器
    private  MyAdapter adapter;
    //ListView
    private ListView accountLV;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //初始化控件
        initView();
        dao=new AccountDao(this);
        //從數據庫中查詢出所有數據
        list=dao.queryAll();
        adapter=new  MyAdapter();
        accountLV.setAdapter(adapter);//給ListView添加適配器（自動把數據生成條目）
    }
    //初始化控件
    private void initView(){
        accountLV=(ListView)findViewById(R.id.accountLV);
        nameET=(EditText)findViewById(R.id.nameET);
        balanceET=(EditText)findViewById(R.id.balanceET);
        //添加監聽器，監聽條目點擊事件
        accountLV.setOnItemClickListener(new  MyOnItemClickListener());

    }
    //activity_mian.xml對應ImageView的點擊事件觸發的方法
    public void add(View v){
        String name=nameET.getText().toString().trim();
        String balance=balanceET.getText().toString().trim();
        //三目運算符balance.equals("")則等於0
        //如果balance不是空字符串 則進行類型轉換
        Account a=new Account(name,balance.equals("")?0:Integer.parseInt(balance));
        dao.insert(a);
        list.add(a);
        adapter.notifyDataSetChanged();
        //選中最後一個
        accountLV.setSelection(accountLV.getCount()-1);
        nameET.setText("");
        balanceET.setText("");
    }
    //自定義一個適配器（把數據裝到ListView的工具）
    private class MyAdapter extends BaseAdapter{
        public int getCount(){            //獲取條目總數
            return list.size();
        }
        public Object getItem(int position){      //根據位置獲取對象
            return list.get(position);
        }

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


        //獲取一個條目視圖
        public  View getView(int position , View convertView, ViewGroup parent){
            //重用convertView
            View item=convertView!=null?convertView:View.inflate(
                    getApplicationContext(),R.layout.item,null);
            //獲取該視圖中的TextView
            TextView idTV=(TextView)item.findViewById(R.id.idTV);
            TextView nameTV=(TextView)item.findViewById(R.id.nameTV);
            TextView balanceTV=(TextView)item.findViewById(R.id.balanceTV);
            //根據當前位置獲取Account對象
            final Account a=list.get(position);
            //把Account對象中的數據放到TextView中
            idTV.setText(a.getId()+"");
            nameTV.setText(a.getName());
            balanceTV.setText(a.getBalance()+"");
            ImageView upIV=(ImageView)item.findViewById(R.id.upIV);
            ImageView downIV=(ImageView) item.findViewById(R.id.downIV);
            ImageView deleteIV=(ImageView) item.findViewById(R.id.deleteIV);
            //向上箭頭的點擊事件觸發的方法
            upIV.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    a.setBalance(a.getBalance()+1);
                    notifyDataSetChanged();
                    dao.update(a);
                }
            });
            //向下箭頭的點擊事件觸發的方法
           downIV.setOnClickListener(new View.OnClickListener(){

               @Override
               public void onClick(View view) {
                   a.setBalance(a.getBalance()-1);
                   notifyDataSetChanged();
                   dao.update(a);
               }
           });
            //刪除圖片的點擊事件觸發的方法
            deleteIV.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    //刪除之前先彈出一個對話框
                    android.content.DialogInterface.OnClickListener listener=
                            new android.content.DialogInterface.OnClickListener(){

                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    list.remove(a);
                                    dao.delete(a.getId());
                                    notifyDataSetChanged();
                                }
                            };
                    //創建對話框
                    AlertDialog.Builder builder=new AlertDialog.Builder(MainActivity.this);
                    builder.setTitle("確定要刪除嗎？");//設置標題
                    //設置確定按鈕的文本以及監聽器
                    builder.setPositiveButton("確定",listener);
                    builder.setNegativeButton("取消",null);
                    builder.show();//顯示對話框
                }
            });
            return item;
        }
    }
    //ListView 的Item點擊事件
    private class MyOnItemClickListener implements AdapterView.OnItemClickListener{
        public void onItemClick(AdapterView<?>parent,View view,int position,long id){
            //獲取點擊位置上的數據
            Account a=(Account) parent.getItemAtPosition(position);
            Toast.makeText(getApplicationContext(),a.toString(),Toast.LENGTH_SHORT).show();
        }
    }
}

完成後的效果

Android學習（6）——案列（SQLite數據庫）

Android學習之路——網絡編程學習——新聞客戶端（AsyncHttpClient）

Java——淺談反射

數據結構（C語言）學習之路（1）——緒論

Android學習之路——廣播接受者

Android學習之路（5）——數據存儲方式

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

linux以太網驅動總結