实验 Android数据存储和访问-SQLite（一）

一  实验现象



创建表



添加数据



更新数据



删除数据



查询



二   实验部分代码

Mainactivity

package com.example.sqllite;

import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity
{
private mydatabasehelper dbhelper;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbhelper = new mydatabasehelper(this,"BOOKStore.db",null,2);
Button createdatabase = (Button) findViewById(R.id.create_database);
Button adddata =(Button) findViewById(R.id.add_data);
Button updateData = (Button) findViewById(R.id.update_data);
Button deleteData = (Button) findViewById(R.id.delete_data);
Button queryData = (Button) findViewById(R.id.query_data);
createdatabase.setOnClickListener(new OnClickListener()
{

@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
dbhelper.getWritableDatabase();
}
});
adddata.setOnClickListener(new OnClickListener()
{

@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
SQLiteDatabase db = dbhelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("name","The Da Vinvi Code");
values.put("author", "Dan Brown");
values.put("pages", 454);
values.put("price", 16.96);
db.insert("Book", null, values); // 插入第一条数据
values.clear();
// 开始组装第二条数据
values.put("name", "The Lost Symbol");
values.put("author", "Dan Brown");
values.put("pages", 510);
values.put("price", 19.95);

db.insert("Book", null, values); // 插入第二条数据
}

});
updateData.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = dbhelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("price", 10.99);
db.update("Book", values, "name = ?", new String[] { "The Da Vinci Code" });
}
});
deleteData.setOnClickListener(new OnClickListener()
{

@Override
public void onClick(View arg0)
{
// TODO Auto-generated method stub
SQLiteDatabase db = dbhelper.getWritableDatabase();
db.delete("Book", "pages > ?", new String[] { "500" });

}
});
queryData.setOnClickListener(new OnClickListener()
{

@Override
public void onClick(View arg0)
{
SQLiteDatabase db = dbhelper.getWritableDatabase();
Cursor cursor = db.query("Book", null, null, null, null, null, null);
if (cursor.moveToFirst()) {
do {
String name = cursor.getString(cursor. getColumnIndex("name"));
String author = cursor.getString(cursor. getColumnIndex("author"));
int pages = cursor.getInt(cursor.getColumnIndex ("pages"));
double price = cursor.getDouble(cursor. getColumnIndex("price"));
Log.d("MainActivity", "book name is " + name);
Log.d("MainActivity", "book author is " + author);
Log.d("MainActivity", "book pages is " + pages);
Log.d("MainActivity", "book price is " + price);
} while (cursor.moveToNext());
}
cursor.close();
}
});

}

@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

}
mydatabasehelper代码
package com.example.sqllite;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;

public class mydatabasehelper extends SQLiteOpenHelper
{
private Context mContext;
public static final String CREATE_BOOK = "create table book("
+ "id integer primary key autoincrement,"
+ "author text,"
+ "price real,"
+ "pages interger,"
+ "name text)";
public static final String CREATE_CATEGORY = "create table Category ("
+ "id integer primary key autoincrement, "
+ "category_name text, "
+ "category_code integer)";

public mydatabasehelper(Context context, String name,
CursorFactory factory, int version)
{
super(context, name, factory, version);
// TODO Auto-generated constructor stub
mContext =context;
}

@Override
public void onCreate(SQLiteDatabase db)
{
// TODO Auto-generated method stub
db.execSQL(CREATE_BOOK);
db.execSQL(CREATE_CATEGORY);
Toast.makeText(mContext, "Creat succeeded", Toast.LENGTH_SHORT).show();
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
// TODO Auto-generated method stub
db.execSQL("drop table if exists Book");
db.execSQL("drop table if exists Category");
onCreate(db);

}

}
程序界面
<Button
android:id="@+id/create_database"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Create database"

/>
<Button
android:id="@+id/add_data"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/create_database"
android:text="Add data"
/>
<Button
android:id="@+id/update_data"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/add_data"
android:text="update data"
/>
<Button
android:id="@+id/delete_data"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/update_data"
android:text="delete data"
/>
<Button
android:id="@+id/query_data"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/delete_data"
android:text="query data"
/>


三 实验后的体会

         此次实验需要一定的SQL的知识，对数据表的简历，添加数据，更新数据和删除。本实验的添加数据代码过长，可以简化。对表的创造，开始已经创造一个Book表,再创造Categeory表没有成功，刚开始是将程序卸载重写启动，但很麻烦，在onUpgrade()方法中执行两条drop即可。本次实验中还是有部分错误未能达到预期效果，还需改正。