Android SQLite实现数据持久化存储购买商品小案例
案例界面：
实现代码：
主界面activity_main实现代码：
通过效果图可以看到我们需要两个EditText一个ImageButton和一个ListView。总体布局可以采用相对布局的方式，上面的两个EditText和ImageButton可以包含在一个线性布局里。下面ListView的Item可以用线性布局来实现。
DbHelper实现代码：
package bzu.edu.cn.cartview;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.provider.Settings;
import android.widget.Toast;
/**
* Created by 海贼宝宝 on 2017/4/18.
*/
public class DbHelper extends SQLiteOpenHelper {
public DbHelper(Context context) {
super(context, "Ware.db", null, 2);
}
@Override
public void onCreate(SQLiteDatabase db) {
System.out.println("onCreate");
db.execSQL("CREATE TABLE ware(id INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR(20),money INTEGER)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists ware");
onCreate(db);
}
}类Ware实现代码：
package bzu.edu.cn.cartview;
/**
* Created by 海贼宝宝 on 2017/4/17.
*/
public class Ware {
private int id;
private String warename;
private int money;
public Ware(int id, String warename, int money) {
this.id = id;
this.warename = warename;
this.money = money;
}
public Ware(String warename, int money) {
this.warename = warename;
this.money = money;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getWarename() {
return warename;
}
public void setWarename(String warename) {
this.warename = warename;
}
public int getMoney() {
return money;
}
public void setMoney(int money) {
this.money = money;
}
public String toString(){
return "[序号："+id+",商品名称："+warename+",金额："+money+"]";
}
}类WareDao实现代码：
package bzu.edu.cn.cartview;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
/**
* Created by 海贼宝宝 on 2017/4/18.
*/
public class WareDao {
private DbHelper dbHelper;
private Ware ware;
public WareDao(Context context) {
dbHelper = new DbHelper(context);
}
public void insert(Ware ware)
{
SQLiteDatabase db=dbHelper.getWritableDatabase();
ContentValues contentValues=new ContentValues();
contentValues.put("name",ware.getWarename());
contentValues.put("money",ware.getMoney());
int id= (int) db.insert("ware",null,contentValues);
ware.setId(id);
db.close();
}
public int delete(int id)
{
SQLiteDatabase db=dbHelper.getWritableDatabase();
int count=db.delete("ware","id=?",new String[]{id+""});
db.close();
return count;
}
public int update(Ware ware)
{
SQLiteDatabase db=dbHelper.getWritableDatabase();
ContentValues contentValues=new ContentValues();
contentValues.put("name",ware.getWarename());
contentValues.put("money",ware.getMoney());
int count=db.update("ware",contentValues,"id=?",new String[]{ware.getId()+""});
db.close();
return count;
}
public List query()
{
SQLiteDatabase db=dbHelper.getReadableDatabase();
Cursor cursor=db.query("ware",null,null,null,null,null,null);
List list=new ArrayList();
while (cursor.moveToNext())
{
int id = cursor.getInt(cursor.getColumnIndex("id"));
String name=cursor.getString(1);
String money=cursor.getString(2);
list.add(new Ware(id,name,Integer.parseInt(money)));
}
cursor.close();
db.close();
return list;
}
} MainActivity代码：
package bzu.edu.cn.cartview;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private ListView ware1;
private WareAdapter wareAdapter;
private List wareList;
private EditText et_name,et_money;
private WareDao wareDao;
private TextView tv_id;
private TextView tv_name;
private TextView tv_money;
private int i = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/*获取控件*/
ware1=(ListView) findViewById(R.id.ware);
et_name=(EditText)findViewById(R.id.name);
et_money=(EditText)findViewById(R.id.sum);
wareDao=new WareDao(MainActivity.this);
wareList = wareDao.query();
wareAdapter = new WareAdapter();
ware1.setAdapter(wareAdapter);
}
public void add(View view){
String name = et_name.getText().toString();
String money = et_money.getText().toString();
Ware ware = new Ware(name, Integer.parseInt(money));
wareDao.insert(ware);
wareList.add(ware);
wareAdapter.notifyDataSetChanged();
ware1.setSelection(ware1.getCount() - 1);
et_money.setText("");
et_name.setText("");
}
private class WareAdapter extends BaseAdapter {
public int getCount() {
return wareList.size();
}
public Object getItem(int position) {
return wareList.get(position);
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
View item = convertView != null ? convertView : View.inflate(
getApplicationContext(), R.layout.ware, null
);
TextView t1 = (TextView) item.findViewById(R.id.id);
TextView t2 = (TextView) item.findViewById(R.id.warename);
TextView t3 = (TextView) item.findViewById(R.id.money);
final Ware w = wareList.get(position);
t1.setText(w.getId() + "");
t2.setText(w.getWarename());
t3.setText(w.getMoney() + "");
ImageButton up = (ImageButton) item.findViewById(R.id.up);
ImageButton down = (ImageButton) item.findViewById(R.id.down);
ImageButton delete = (ImageButton) item.findViewById(R.id.delete);
up.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
w.setMoney(w.getMoney() - 1);
notifyDataSetChanged();
wareDao.update(w);
}
});
down.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
w.setMoney(w.getMoney() - 1);
notifyDataSetChanged();
wareDao.update(w);
}
});
delete.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
final DialogInterface.OnClickListener listener = new android.content.DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
wareList.remove(w);
wareDao.delete(w.getId());
notifyDataSetChanged();
}
};
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setTitle("确定要删除吗？");
builder.setPositiveButton("确定", listener);
builder.setNegativeButton("取消", null);
builder.show();
}
});
return item;
}
private class MyOnItemClickListener implements AdapterView.OnItemClickListener {
public void onItemClick(AdapterView parent, View view, int position, long id){
Ware w = (Ware) parent.getItemAtPosition(position);
Toast.makeText(getApplicationContext(),w.toString(),Toast.LENGTH_SHORT).show();
}
}
}
} 功能分析：
通过布局中的按钮调用Onclick方法实现对 数据库 的增删该查。