(Android review)SQLite

于 2014-07-11 19:09:40 发布
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本文链接：https://blog.youkuaiyun.com/hjd_love_zzt/article/details/37699803
本文详细介绍了一个简单的Android应用程序如何通过自定义的DBOpenHelper和PersonDao类来进行SQLite数据库的操作，包括数据库和表的创建、数据的增删改查等功能，并提供了具体的代码实现。

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其实，这一部分，总的来说，主要写DBOpenHelper类和PersonDao类即可。。。。

其中DBOpenHelper主要封装了数据库的创建、表的创建与修改。。而PersonDao主要封装对表的DAO操作。。。。



1、DBOpenHelper

package com.example.sqlitetest;

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

public class DBOpenHelper extends SQLiteOpenHelper {

	
	
	public DBOpenHelper(Context context){//父类没有无参构造函数,必须显示调用有参构造函数.
		/*
		 * 由于父类没有无参构造函数, 必须显式调用有参的构造函数
		 * 参数1: 上下文环境, 用来确定数据库文件存储的目录..创建的数据库存在于/data/data/应用的报名/databases/xxx.db
		 * 参数2: 数据库文件的名字
		 * 参数3: 生成游标的工厂, 填null就是使用默认的
		 * 参数4: 数据库的版本, 从1开始
		 */
		super(context,"njupt.db",null,2);
	}
	
	
	/**
	 * 一般来说,创建表的代码放在onCreate()中
	 */
	@Override
	public void onCreate(SQLiteDatabase db) {
		System.out.println("----------->onCreate");
		db.execSQL("CREATE TABLE person(id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR(20))");		// 执行SQL语句, 创建表
	}

	/**
	 * 修改表的代码放在onUpdate()中...
	 */
	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		System.out.println("---------->onUpdate");
		
		db.execSQL("ALTER TABLE person ADD balance INTEGER");
	}

}


2、PersonDao

package com.example.sqlitetest;

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

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

public class PersonDao {

	private Context context;
	private DBOpenHelper helper;
	
	public PersonDao(Context context) {
		this.context = context;
		helper = new DBOpenHelper(context);
	}
	
	public void insert(Person p){
		SQLiteDatabase db = helper.getWritableDatabase();
		db.execSQL("INSERT INTO person(name, balance) VALUES(?, ?)", new Object[] { p.getName(), p.getBalance() });		// 执行SQL语句, 插入
		db.close();
	}
	
	public void delete(int id){
		SQLiteDatabase db = helper.getWritableDatabase();
		db.execSQL("DELETE FROM person WHERE id=?", new Object[]{id});
		db.close();
	}
	
	public void update(Person p){
		SQLiteDatabase db = helper.getWritableDatabase();
		db.execSQL("UPDATE person SET name=?, balance=? WHERE id=?", new Object[]{p.getName(),p.getBalance(),p.getId()});
		db.close();		
	}
	
	public Person query(int id){
		SQLiteDatabase db = helper.getReadableDatabase();//获取数据库连接,可读的
		Cursor c = db.rawQuery("SELECT name, balance FROM person WHERE id=?", new String[]{id + ""});
		
		Person p = null;
		if(c.moveToNext()){//判断游标是否包含下一条记录,如果包含,将游标向后移一位
			
			String name = c.getString(0);//获取0号索引上的数据,转换为String类型
//			String name = c.getString(c.getColumnIndex("name"));//这种方法也是极好的
			int balance = c.getInt(1);
			
			p = new Person(id, name, balance);
		}
		c.close();
		db.close();
		return p;
	}
	
	public List<Person> queryAll(){
		SQLiteDatabase db = helper.getReadableDatabase();
		Cursor c = db.rawQuery("SELECT id, name, balance FROM person", null);
		List<Person> persons = new ArrayList<Person>();
		while(c.moveToNext()){
			Person p = new Person(c.getInt(0), c.getString(1), c.getInt(2));
			persons.add(p);
		}
		c.close();
		db.close();
		
		return persons;
	}
	
	public int queryCount(){
		SQLiteDatabase db = helper.getReadableDatabase();
		Cursor c = db.rawQuery("SELECT COUNT(*) FROM person", null);
		
		c.moveToNext();
		int count = c.getInt(0);
		
		c.close();
		db.close();
		
		return count;
	}
	
	public List<Person> queryPage(int pageNum,int capacity){
		String offset = (pageNum - 1)*capacity + "";
		String len = capacity + "";
		SQLiteDatabase db = helper.getReadableDatabase();
		Cursor c = db.rawQuery("SELECT id, name, balance FROM person LIMIT ?,?", new String[]{offset,len});
		List<Person> persons = new ArrayList<Person>();
		
		while(c.moveToNext()){
			Person p = new Person(c.getInt(0), c.getString(1), c.getInt(2));
			persons.add(p);
		}
		
		c.close();
		db.close();
		
		return persons;
	}
	
	/**
	 * 数据库的事务
	 * 
	 * 从from这个账户汇款到to这个账户,汇amount这个多钱
	 * @param from 
	 * @param to
	 * @param amount
	 */
	public void remit(int from,int to,int amount){
		SQLiteDatabase db = helper.getWritableDatabase();
		try{
			db.beginTransaction();//开始事务
			db.execSQL("UPDATE person SET balance=balance-? WHERE id=?", new Object[] { amount, from });
			db.execSQL("UPDATE person SET balance=balance+? WHERE id=?", new Object[] { amount, to });
			db.setTransactionSuccessful();//设置事务成功点...结束事务的时候执行成功点之前的sql语句
		}finally{
			db.endTransaction();//结束事务
			db.close();
		}
	}
}


3、Person

package com.example.sqlitetest;

public class Person {

	private Integer id;
	private String name;
	private Integer balance;
	
	public Person() {
		super();
	}

	public Person(Integer id, String name, Integer balance) {
		super();
		this.id = id;
		this.name = name;
		this.balance = balance;
	}

	@Override
	public String toString() {
		return "Person [id=" + id + ", name=" + name + ", balance=" + balance
				+ "]";
	}

	public Integer getId() {
		return id;
	}

	public void setId(Integer 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;
	}
	
	
	
}


4、DBTest

package com.example.sqlitetest;

import java.util.List;

import android.test.AndroidTestCase;

public class DBTest extends AndroidTestCase {

	public void testCreateDB(){
		DBOpenHelper helper = new DBOpenHelper(getContext());
		helper.getWritableDatabase();
	}
	
	
	public void testInsert(){
		PersonDao dao = new PersonDao(getContext());
		
		for(int i = 1 ;  i < 100 ; ++i){
			dao.insert(new Person(i,"hjd" + i , 45000+i));
		}
//		dao.insert(new Person(2, "hjd", 40000));
	}
	
	public void testDelete(){
		PersonDao dao = new PersonDao(getContext());
		dao.delete(1);
	}
	
	public void testUpdate(){
		PersonDao dao = new PersonDao(getContext());
		
		Person p = new Person(2, "zzt", 10000);
		dao.update(p);
	}
	
	public void testQuery(){
		PersonDao dao = new PersonDao(getContext());
		System.out.println(dao.query(2));
	}
	
	public void testQueryAll(){
		PersonDao dao = new PersonDao(getContext());
		List<Person> persons = dao.queryAll();

		for(Person p : persons){
			System.out.println(p);
		}
	}
	
	public void testQueryCount(){
		PersonDao dao = new PersonDao(getContext());
		
		System.out.println("--------->" + dao.queryCount());
		
	}
	
	public void testQueryPage(){
		PersonDao dao = new PersonDao(getContext());
		
		List<Person> persons = dao.queryPage(5, 10);
		
		for(Person p : persons){
			System.out.println(p);
		}
	}
	
}


5、MainActivity

package com.example.sqlitetest;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {

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

	@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;
	}

}


以上的PersonDao中所使用到的增删改查的实现方法都是需要直接写sql，其实还有一种方式来实现增删改查。

其实其底层实现也是将穿的哪些参数拼成sql语句的。。

以下将完整的PersonDao和DBTest贴出来

PersonDao

package com.example.sqlitetest;

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

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

public class PersonDao {

	private Context context;
	private DBOpenHelper helper;

	public PersonDao(Context context) {
		this.context = context;
		helper = new DBOpenHelper(context);
	}

	public void insert(Person p) {
		SQLiteDatabase db = helper.getWritableDatabase();
		db.execSQL("INSERT INTO person(name, balance) VALUES(?, ?)",
				new Object[] { p.getName(), p.getBalance() }); // 执行SQL语句, 插入
		db.close();
	}

	/**
	 * 某些情况之下程序会接受一个ContentValues,这时候采用这种存储方式比较方便...
	 * @param p
	 */
	public void insert1(Person p) {
		SQLiteDatabase db = helper.getWritableDatabase();

		/**
		 * ContentValues:类似于Map,键放列名,值放要插入的内容...
		 * 为什么说ContentValues类似于Map,其实看他的成员变量及put方法就知道了 Adds a value to the set.
		 * 
		 * @param key
		 *            the name of the value to put
		 * @param value
		 *            the data for the value to put
		 * 
		 *            public void put(String key, String value) {
		 *            mValues.put(key, value); }
		 */
		ContentValues values = new ContentValues();
		values.put("name", p.getName());
		values.put("balance", p.getName());

		/**
		 * 第二个参数随便写一个列名,用于处理values值为空的情况..因为列名不能为null
		 */
		db.insert("person", "name", values);//其实它底层也是采用拼SQL语句的方式的.返回插入的id是多少
		db.close();
	}

	public void delete(int id) {
		SQLiteDatabase db = helper.getWritableDatabase();
		db.execSQL("DELETE FROM person WHERE id=?", new Object[] { id });
		db.close();
	}

	public void delete1(int id){
		SQLiteDatabase db = helper.getWritableDatabase();
		db.delete("person", "id=?", new String[]{id + ""});
		db.close();
	}
	
	public void update(Person p) {
		SQLiteDatabase db = helper.getWritableDatabase();
		db.execSQL("UPDATE person SET name=?, balance=? WHERE id=?",
				new Object[] { p.getName(), p.getBalance(), p.getId() });
		db.close();
	}

	public void update1(Person p){
		SQLiteDatabase db = helper.getWritableDatabase();
		
		ContentValues values = new ContentValues();
		values.put("name", p.getName());
		values.put("balance", p.getBalance());
		
		db.update("person", values, "id=?", new String[]{p.getId() + ""});
	    db.close();
	}
	public Person query(int id) {
		SQLiteDatabase db = helper.getReadableDatabase();// 获取数据库连接,可读的
		Cursor c = db.rawQuery("SELECT name, balance FROM person WHERE id=?",
				new String[] { id + "" });

		Person p = null;
		if (c.moveToNext()) {// 判断游标是否包含下一条记录,如果包含,将游标向后移一位

			String name = c.getString(0);// 获取0号索引上的数据,转换为String类型
			// String name = c.getString(c.getColumnIndex("name"));//这种方法也是极好的
			int balance = c.getInt(1);

			p = new Person(id, name, balance);
		}
		c.close();
		db.close();
		return p;
	}

	public Person query1(int id){
		SQLiteDatabase db = helper.getReadableDatabase();// 获取数据库连接,可读的
//		Cursor c = db.rawQuery("SELECT name, balance FROM person WHERE id=?",
//				new String[] { id + "" });
		
		/**
		 * db.query(表名,需要查询的列名,查询条件,查询条件的参数,group by,having,order by);
		 */
		Cursor c = db.query("person", new String[]{"name","balance"}, "id=?", new String[]{id + ""}, null, null, null);
		
		Person p = null;
		if (c.moveToNext()) {// 判断游标是否包含下一条记录,如果包含,将游标向后移一位

			String name = c.getString(0);// 获取0号索引上的数据,转换为String类型
			// String name = c.getString(c.getColumnIndex("name"));//这种方法也是极好的
			int balance = c.getInt(1);

			p = new Person(id, name, balance);
		}
		c.close();
		db.close();
		return p;
	}
	
	public List<Person> queryAll() {
		SQLiteDatabase db = helper.getReadableDatabase();
		Cursor c = db.rawQuery("SELECT id, name, balance FROM person", null);
		List<Person> persons = new ArrayList<Person>();
		while (c.moveToNext()) {
			Person p = new Person(c.getInt(0), c.getString(1), c.getInt(2));
			persons.add(p);
		}
		c.close();
		db.close();

		return persons;
	}

	public List<Person> queryAll1(){
		SQLiteDatabase db = helper.getReadableDatabase();
//		Cursor c = db.rawQuery("SELECT id, name, balance FROM person", null);
		
		Cursor c = db.query("person", null, null, null, null, null, "id DESC");
		
		List<Person> persons = new ArrayList<Person>();
		while (c.moveToNext()) {
			Person p = new Person(c.getInt(0), c.getString(1), c.getInt(2));
			persons.add(p);
		}
		c.close();
		db.close();

		return persons;
	}
	
	public int queryCount() {
		SQLiteDatabase db = helper.getReadableDatabase();
//		Cursor c = db.rawQuery("SELECT COUNT(*) FROM person", null);
		Cursor c = db.query("person", new String[]{"COUNT(*)"}, null, null, null, null, null);
		c.moveToNext();
		int count = c.getInt(0);

		c.close();
		db.close();

		return count;
	}

	public int queryCount1(){
		SQLiteDatabase db = helper.getReadableDatabase();
		Cursor c = db.rawQuery("SELECT COUNT(*) FROM person", null);

		c.moveToNext();
		int count = c.getInt(0);

		c.close();
		db.close();

		return count;
	}
	
	public List<Person> queryPage(int pageNum, int capacity) {
		String offset = (pageNum - 1) * capacity + "";
		String len = capacity + "";
		SQLiteDatabase db = helper.getReadableDatabase();
		Cursor c = db.rawQuery(
				"SELECT id, name, balance FROM person LIMIT ?,?", new String[] {
						offset, len });
		List<Person> persons = new ArrayList<Person>();

		while (c.moveToNext()) {
			Person p = new Person(c.getInt(0), c.getString(1), c.getInt(2));
			persons.add(p);
		}

		c.close();
		db.close();

		return persons;
	}

	
	public List<Person> queryPage1(int pageNum,int capacity){
		String offset = (pageNum - 1) * capacity + "";
		String len = capacity + "";
		SQLiteDatabase db = helper.getReadableDatabase();
//		Cursor c = db.rawQuery(
//				"SELECT id, name, balance FROM person LIMIT ?,?", new String[] {
//						offset, len });
		
		Cursor c = db.query("person",null, null, null, null, null, null,offset + "," + len);
		List<Person> persons = new ArrayList<Person>();

		while (c.moveToNext()) {
			Person p = new Person(c.getInt(0), c.getString(1), c.getInt(2));
			persons.add(p);
		}

		c.close();
		db.close();

		return persons;
	}
	/**
	 * 数据库的事务
	 * 
	 * 从from这个账户汇款到to这个账户,汇amount这个多钱
	 * 
	 * @param from
	 * @param to
	 * @param amount
	 */
	public void remit(int from, int to, int amount) {
		SQLiteDatabase db = helper.getWritableDatabase();
		try {
			db.beginTransaction();// 开始事务
			db.execSQL("UPDATE person SET balance=balance-? WHERE id=?",
					new Object[] { amount, from });
			db.execSQL("UPDATE person SET balance=balance+? WHERE id=?",
					new Object[] { amount, to });
			db.setTransactionSuccessful();// 设置事务成功点...结束事务的时候执行成功点之前的sql语句
		} finally {
			db.endTransaction();// 结束事务
			db.close();
		}
	}
}


DBTest

package com.example.sqlitetest;

import java.util.List;

import android.test.AndroidTestCase;

public class DBTest extends AndroidTestCase {

	public void testCreateDB(){
		DBOpenHelper helper = new DBOpenHelper(getContext());
		helper.getWritableDatabase();
	}
	
	/**
	 * 需要注意的是，在这个例子中,person表中的id是自增的....不收Person中的id这个成员变量影响...
	 */
	
	public void testInsert(){
		PersonDao dao = new PersonDao(getContext());
		
		for(int i = 1 ;  i < 100 ; ++i){
			dao.insert(new Person(i,"hjd" + i , 45000+i));
		}
//		dao.insert(new Person(2, "hjd", 40000));
	}
	
	public void testInsert1(){
		PersonDao dao = new PersonDao(getContext());
		
		for(int i = 0 ; i < 100 ; ++i){
			dao.insert1(new Person(i, "hjd" + i, 30000));
		}
//		dao.insert1(new Person(3, "dzdp", 10000));
	}
	
	public void testDelete(){
		PersonDao dao = new PersonDao(getContext());
		dao.delete(1);
	}
	
	public void testDelete1(){
		PersonDao dao = new PersonDao(getContext());
		dao.delete1(1);
	}
	
	public void testUpdate(){
		PersonDao dao = new PersonDao(getContext());
		
		Person p = new Person(2, "zzt", 10000);
		dao.update(p);
	}
	
	public void testUPdate1(){
		PersonDao dao = new PersonDao(getContext());
		
		Person p = new Person(2, "hjd", 40000);
		dao.update1(p);
	}
	public void testQuery(){
		PersonDao dao = new PersonDao(getContext());
		System.out.println(dao.query(2));
	}
	
	public void testQuery1(){
		PersonDao dao = new PersonDao(getContext());
		System.out.println("------------>" + dao.query1(2));
	}
	
	public void testQueryAll(){
		PersonDao dao = new PersonDao(getContext());
		List<Person> persons = dao.queryAll();

		for(Person p : persons){
			System.out.println(p);
		}
	}
	
	public void testQueryAll1(){
		PersonDao dao = new PersonDao(getContext());
		List<Person> persons = dao.queryAll1();

		for(Person p : persons){
			System.out.println( "----------->" + p);
		}
	}
	
	public void testQueryCount(){
		PersonDao dao = new PersonDao(getContext());
		
		System.out.println("--------->" + dao.queryCount());
		
	}
	
	public void testQueryCount1(){
		PersonDao dao = new PersonDao(getContext());
		
		System.out.println("------->queryCount1:" + dao.queryCount1());
	}
	
	public void testQueryPage(){
		PersonDao dao = new PersonDao(getContext());
		
		List<Person> persons = dao.queryPage(5, 10);
		
		for(Person p : persons){
			System.out.println(p);
		}
	}
	
	public void testQueryPage1(){
		PersonDao dao = new PersonDao(getContext());
		List<Person> persons = dao.queryPage1(2, 10);
		
		for(Person p : persons){
			System.out.println("--------->" + p);
		}
		
	}
	
}



源码下载：http://download.youkuaiyun.com/detail/caihongshijie6/7623211






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