Android之SQlite

Heller

2011-07-03

Android中数据库事务处理

使用SQLiteDatabase的beginTransaction()方法可以开启一个事务，程序执行到endTransaction() 方法时会检查事务的标志是否为成功，如果程序执行到endTransaction()之前调用了setTransactionSuccessful() 方法设置事务的标志为成功则提交事务，如果没有调用setTransactionSuccessful() 方法则回滚事务。使用例子如下：

SQLiteDatabase db = ....;
db.beginTransaction();//开始事务
try {
    db.execSQL("insert into person(name, age) values(?,?)", new Object[]{"传智播客", 4});
    db.execSQL("update person set name=? where personid=?", new Object[]{"传智", 1});
    db.setTransactionSuccessful();//调用此方法会在执行到endTransaction() 时提交当前事务，如果不调用此方法会回滚事务
} finally {
    db.endTransaction();//由事务的标志决定是提交事务，还是回滚事务
} 
db.close();

上面两条SQL语句在同一个事务中执行。

1:Person 类

package cn.itcast.domain;

public class Person {
	private Integer id;
	private String name;
	private Integer amount;
	
	public Integer getAmount() {
		return amount;
	}

	public void setAmount(Integer amount) {
		this.amount = amount;
	}

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

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


}

2：DBOpenHelper类

package cn.itcast.service;

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

public class DBOpenHelper extends SQLiteOpenHelper {
	private static final String DATABASENAME = "itcast.db"; //数据库名称
	private static final int DATABASEVERSION = 2;//数据库版本

	public DBOpenHelper(Context context) {
		super(context, DATABASENAME, null, DATABASEVERSION);
	}

	@Override
	public void onCreate(SQLiteDatabase db) {
		db.execSQL("CREATE TABLE person (personid integer primary key autoincrement, name varchar(20), amount integer)");//执行有更改的sql语句
	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		db.execSQL("DROP TABLE IF EXISTS person");
		onCreate(db);
	}

}

3（1）：通过SQlite访问方法一：PersonService类

package cn.itcast.service;

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

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

import cn.itcast.domain.Person;

public class PersonService {
	private DBOpenHelper dbOpenHelper;
	
	public PersonService(Context context) {
		this.dbOpenHelper = new DBOpenHelper(context);
	}

	public void payment(){
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		db.beginTransaction();//事启事务
		try{
			db.execSQL("update person set amount=amount-10 where personid=?", new Object[]{1});
			db.execSQL("update person set amount=amount+10 where personid=?", new Object[]{2});
			db.setTransactionSuccessful();//设置事务标志为成功，当结束事务时就会提交事务
		}finally{
			db.endTransaction();
		}
	}
	
	public void save(Person person){
		//如果要对数据进行更改，就调用此方法得到用于操作数据库的实例,该方法以读和写方式打开数据库
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		db.execSQL("insert into person (name,amount) values(?,?)",
				new Object[]{person.getName(),person.getAmount()});
	}
	
	public void update(Person person){
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		db.execSQL("update person set name=? where personid=?", 
				new Object[]{person.getName(),person.getId()});
	}
	
	public void delete(Integer id){
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		db.execSQL("delete from person where personid=?", new Object[]{id.toString()});
	}
	
	public Person find(Integer id){
		//如果只对数据进行读取，建议使用此方法
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		Cursor cursor = db.rawQuery("select * from person where personid=?", new String[]{id.toString()});
		if(cursor.moveToFirst()){
			int personid = cursor.getInt(cursor.getColumnIndex("personid"));
			String name = cursor.getString(cursor.getColumnIndex("name"));
			int amount = cursor.getInt(cursor.getColumnIndex("amount"));
			Person person = new Person(personid, name);
			person.setAmount(amount);
			return person;
		}
		return null;
	}
	
	public List<Person> getScrollData(Integer offset, Integer maxResult){
		List<Person> persons = new ArrayList<Person>();
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		Cursor cursor = db.rawQuery("select * from person limit ?,?",
				new String[]{offset.toString(), maxResult.toString()});
		while(cursor.moveToNext()){
			int personid = cursor.getInt(cursor.getColumnIndex("personid"));
			String name = cursor.getString(cursor.getColumnIndex("name"));
			int amount = cursor.getInt(cursor.getColumnIndex("amount"));
			Person person = new Person(personid, name);
			person.setAmount(amount);
			persons.add(person);
		}
		cursor.close();
		return persons;
	}
	
	public Cursor getCursorScrollData(Integer offset, Integer maxResult){
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		return db.rawQuery("select personid as _id, name, amount from person limit ?,?",
				new String[]{offset.toString(), maxResult.toString()});
	}
	
	public long getCount() {
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		Cursor cursor = db.rawQuery("select count(*) from person", null);
		cursor.moveToFirst();
		return cursor.getLong(0);
	}
}

3（2）数据增删改查之测试：PersonServiceTest

package cn.itcast.db;

import java.util.List;

import cn.itcast.domain.Person;
import cn.itcast.service.DBOpenHelper;
import cn.itcast.service.PersonService;
import android.test.AndroidTestCase;
import android.util.Log;

public class PersonServiceTest extends AndroidTestCase {
	private static final String TAG = "PersonServiceTest";

	public void testCreateDB() throws Throwable{
		DBOpenHelper dbOpenHelper = new DBOpenHelper(this.getContext());
		dbOpenHelper.getWritableDatabase();//第一次调用该方法就会创建数据库
	}
	
	public void testSave() throws Throwable{
		PersonService personService = new PersonService(this.getContext());
		Person person = new Person();
		person.setName("xiaoxiao");
		person.setAmount(100);
		personService.save(person);
		
		person = new Person();
		person.setAmount(50);
		person.setName("zhangliming");
		personService.save(person);
		
		person = new Person();
		person.setAmount(45);
		person.setName("libaobao");
		personService.save(person);
		
		person = new Person();
		person.setAmount(190);
		person.setName("taobao");
		personService.save(person);
	}
	
	public void testUpate() throws Throwable{
		PersonService personService = new PersonService(this.getContext());
		Person person = personService.find(1);	
		person.setName("lili");
		personService.update(person);
	}
	
	public void testDelete() throws Throwable{
		PersonService personService = new PersonService(this.getContext());
		personService.delete(1);
	}
	
	public void testFind() throws Throwable{
		PersonService personService = new PersonService(this.getContext());
		Person person = personService.find(1);
		Log.i(TAG, person.toString());
	}
	
	public void testGetScrollData() throws Throwable{
		PersonService personService = new PersonService(this.getContext());
		List<Person> persons = personService.getScrollData(0, 30);
		for(Person person : persons){
			Log.i(TAG, person.toString());
		}
	}
	
	public void testGetCount() throws Throwable{
		PersonService personService = new PersonService(this.getContext());
		Log.i(TAG, personService.getCount()+"");
	}
	
	public void testPayment() throws Throwable{
		PersonService personService = new PersonService(this.getContext());
		personService.payment();
	}
}

4(1):通过SQlite访问方法二：PersonService类

package cn.itcast.service;

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;

import cn.itcast.domain.Person;

public class OtherPersonService {
	private DBOpenHelper dbOpenHelper;
	
	public OtherPersonService(Context context) {
		this.dbOpenHelper = new DBOpenHelper(context);
	}

	public void save(Person person){
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		ContentValues values = new ContentValues();
		values.put("name", person.getName());
		db.insert("person", null, values);
	}
	
	public void update(Person person){
		// update person set name =? where personid =?
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		ContentValues values = new ContentValues();
		values.put("name", person.getName());
		db.update("person", values, "personid=?", new String[]{person.getId().toString()});
	}
	
	public void delete(Integer id){
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		db.delete("person", "personid=?", new String[]{id.toString()});
	}
	
	public Person find(Integer id){
		//如果只对数据进行读取，建议使用此方法
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		Cursor cursor = db.query("person", new String[]{"personid", "name"},
				"personid=?", new String[]{id.toString()}, null, null, null);
		//select personid,name from person where personid=? order by ... limit 3,5
		if(cursor.moveToFirst()){
			int personid = cursor.getInt(cursor.getColumnIndex("personid"));
			String name = cursor.getString(cursor.getColumnIndex("name"));
			return new Person(personid, name);
		}
		return null;
	}

	public List<Person> getScrollData(Integer offset, Integer maxResult){
		List<Person> persons = new ArrayList<Person>();
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		Cursor cursor = db.query("person", null, null, null, null, null, null, offset+","+ maxResult);
		while(cursor.moveToNext()){
			int personid = cursor.getInt(cursor.getColumnIndex("personid"));
			String name = cursor.getString(cursor.getColumnIndex("name"));
			Person person = new Person(personid, name);
			persons.add(person);
		}
		cursor.close();
		return persons;
	}

	public long getCount() {// select count(*) from person
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		Cursor cursor = db.query("person", new String[]{"count(*)"}, null, null, null, null, null);
		cursor.moveToFirst();
		return cursor.getLong(0);
	}
}

4（2）数据增删改查之测试：OtherPersonServiceTest

package cn.itcast.db;

import java.util.List;

import cn.itcast.domain.Person;
import cn.itcast.service.DBOpenHelper;
import cn.itcast.service.OtherPersonService;
import cn.itcast.service.PersonService;
import android.test.AndroidTestCase;
import android.util.Log;

public class OtherPersonServiceTest extends AndroidTestCase {
	private static final String TAG = "PersonServiceTest";
	
	public void testSave() throws Throwable{
		OtherPersonService personService = new OtherPersonService(this.getContext());
		Person person = new Person();
		person.setName("xiaoxiao");
		personService.save(person);
		
		person = new Person();
		person.setName("zhangliming");
		personService.save(person);
		
		person = new Person();
		person.setName("libaobao");
		personService.save(person);
		
		person = new Person();
		person.setName("taobao");
		personService.save(person);
	}
	
	public void testUpate() throws Throwable{
		OtherPersonService personService = new OtherPersonService(this.getContext());
		Person person = personService.find(1);	
		person.setName("lili");
		personService.update(person);
	}
	
	public void testDelete() throws Throwable{
		OtherPersonService personService = new OtherPersonService(this.getContext());
		personService.delete(1);
	}
	
	public void testFind() throws Throwable{
		OtherPersonService personService = new OtherPersonService(this.getContext());
		Person person = personService.find(1);
		Log.i(TAG, person.toString());
	}
	
	public void testGetScrollData() throws Throwable{
		OtherPersonService personService = new OtherPersonService(this.getContext());
		List<Person> persons = personService.getScrollData(0, 10);
		for(Person person : persons){
			Log.i(TAG, person.toString());
		}
	}
	
	public void testGetCount() throws Throwable{
		OtherPersonService personService = new OtherPersonService(this.getContext());
		Log.i(TAG, personService.getCount()+"");
	}
}

5：事务处理与数据显示

package cn.itcast.db;

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

import cn.itcast.domain.Person;
import cn.itcast.service.PersonService;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.SimpleCursorAdapter;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;

public class MainActivity extends Activity {
    private PersonService personService;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        this.personService = new PersonService(this);
       
        ListView listView = (ListView) this.findViewById(R.id.listView);
        Cursor cursor = personService.getCursorScrollData(0, 5);
        SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, R.layout.item, cursor,
        		new String[]{"_id", "name", "amount"}, new int[]{R.id.id, R.id.name, R.id.amount});
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new OnItemClickListener() {
			@Override
			public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
				ListView lView = (ListView)parent;
				Cursor data = (Cursor)lView.getItemAtPosition(position);
				int personid = data.getInt(data.getColumnIndex("_id"));
				Toast.makeText(MainActivity.this, personid+"", 1).show();
			}
		});
        /*
        List<Person> persons = personService.getScrollData(0, 5);
        List<HashMap<String, Object>> data = new ArrayList<HashMap<String, Object>>();
        for(Person person : persons){
        	HashMap<String, Object> item = new HashMap<String, Object>();
        	item.put("id", person.getId());
        	item.put("name", person.getName());
        	item.put("amount", person.getAmount());
        	data.add(item);
        }
        SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.item,
        		new String[]{"id", "name", "amount"}, new int[]{R.id.id, R.id.name, R.id.amount});
        listView.setAdapter(adapter);
        
        listView.setOnItemClickListener(new OnItemClickListener() {
			@Override
			public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
				ListView lView = (ListView)parent;
				HashMap<String, Object> item = (HashMap<String, Object>)lView.getItemAtPosition(position);
				Toast.makeText(MainActivity.this, item.get("id").toString(), 1).show();
			}
		});
		*/
        
        Button button = (Button) this.findViewById(R.id.insertbutton);
        button.setOnClickListener(new View.OnClickListener() {			
			@Override
			public void onClick(View v) {
				ContentResolver contentResolver = getContentResolver();
				Uri insertUri = Uri.parse("content://cn.itcast.providers.personprovider/person");
				ContentValues values = new ContentValues();
				values.put("name", "itcastliming");
				values.put("amount", 100);
				Uri uri = contentResolver.insert(insertUri, values);
				Toast.makeText(MainActivity.this, "添加完成", 1).show();
			}
		});
    }
}

sqlite