Android-SQLite数据库操作详解

 主要就是创建数据库，添加、查询、更新、删除这几项。

首先是创建数据库，这里要用到SQLiteOpenHelper这个类，这是个抽象类，我们需要去继承他，它里面有两个抽象方法需要实现：onCreate()和onUpgrade(),分别是创建和升级数据库用的。

package com.wr.sqlite;

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 MyDatebaseHelper extends SQLiteOpenHelper {

	public static final String CREATE_BOOK = "create table Book ("
			+ "id integer primary key autoincrement, " + "author text, "
			+ "price real, " + "pages integer, " + "name text) ";

	public static final String CREATE_CATEGORY = "create table Category ("
			+ "id integer primary key autoincrement, " + "category_name text, "
			+ "category_code integer) ";

	private Context mContext;

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

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

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		// TODO Auto-generated method stub
		switch (oldVersion) {
		case 1:
			db.execSQL(CREATE_CATEGORY);
		case 2:
			db.execSQL("alter table Book add column category_id integer");
		}
	}

}

这里将见表语句定义成了字符串，在哦你Create（）方法中建表。

然后就是对数据库的一系列的操作，首先布局文件activity_main.xml。

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <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:text="Add date" />

    <Button
        android:id="@+id/update_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Update date" />

    <Button
        android:id="@+id/delete_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Delete date" />

    <Button
        android:id="@+id/query_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Query date" />

    <Button
        android:id="@+id/replace_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Replace date" />

</LinearLayout>

最后在MainActiity中，实现一系列的操作。MainActivity.java

package com.wr.sqlite;

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.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {

	private MyDatebaseHelper dbHelper;

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

		dbHelper = new MyDatebaseHelper(this, "BookStore.db", null, 2);
		Button createDatabase = (Button) findViewById(R.id.create_database);
		createDatabase.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				dbHelper.getWritableDatabase();
			}
		});

		Button addData = (Button) findViewById(R.id.add_data);
		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 Vinci Code");
				values.put("author", "Dan Brown");
				values.put("pages", 454);
				values.put("price", 16.96);
				db.insert("Book", null, values);
				values.clear();

				values.put("name", "The Lost Sysbol");
				values.put("author", "Dan Brown");
				values.put("pages", 510);
				values.put("price", 19.95);
				db.insert("Book", null, values);
			}
		});

		Button updateData = (Button) findViewById(R.id.update_data);
		updateData.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				SQLiteDatabase db = dbHelper.getWritableDatabase();
				ContentValues values = new ContentValues();
				values.put("price", 10.99);
				db.update("Book", values, "name = ?",
						new String[] { "The Da Vinci Code" });
			}
		});

		Button deleteData = (Button) findViewById(R.id.delete_data);
		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" });
			}
		});

		Button queryData = (Button) findViewById(R.id.query_data);
		queryData.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				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();
			}
		});

		Button replaceData = (Button) findViewById(R.id.replace_data);
		replaceData.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				SQLiteDatabase db = dbHelper.getWritableDatabase();
				db.beginTransaction();
				try {
					db.delete("Book", null, null);
					
					ContentValues values = new ContentValues();
					values.put("name", "Game of Thrones");
					values.put("author", "George Martin");
					values.put("pages", "720");
					values.put("price", 20.85);
					db.insert("Book", null, values);
					db.setTransactionSuccessful();
				} catch (Exception e) {
					e.printStackTrace();
				} finally {
					db.endTransaction();
				}
			}
		});
	}

	@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;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// Handle action bar item clicks here. The action bar will
		// automatically handle clicks on the Home/Up button, so long
		// as you specify a parent activity in AndroidManifest.xml.
		int id = item.getItemId();
		if (id == R.id.action_settings) {
			return true;
		}
		return super.onOptionsItemSelected(item);
	}
}

这其中也包含了事物的使用。比较具体。

Demo下载：http://download.csdn.net/detail/xdwyyan/8077323

标签： 数据库

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