Android SQLite数据库操作

Android定义了一个很方便的Sqlite操作类SQLiteOpenHelper...我们不再需要加载驱动而且要手写关闭一大堆PrepareStatement,Connection等等...

package com.example.db;
import android.content.Context;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class PersonSQLiteOpenHelper extends SQLiteOpenHelper {

/**
* 构造方法
* @param context 上下文
* @param name 数据库名称
* @param factory 使用什么游标，传null是使用默认游标
* @param version 版本，最小是1
*/
public PersonSQLiteOpenHelper(Context context, String name,
CursorFactory factory, int version) {
super(context, name, factory, version);
// TODO Auto-generated constructor stub
}
/**
* 数据库第一次被创建的时候调用的方法
*/
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("create table person (id integer primary key autoincrement, name varchar(20),number varchar(20),account varchar(20))");
}
/**
* 只有在数据库版本发生变化的时候调用
* @param db
* @param oldVersion
* @param newVersion
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}

}

定义personDataAccessObject..这是第一种写DAO的方法。---手写SQL语句

package com.example.dao;

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

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

import com.example.db.PersonSQLiteOpenHelper;
import com.example.domain.Person;

public class PersonDAO {
private PersonSQLiteOpenHelper helper;

// 在构造方法完成helper的初始化
public PersonDAO(Context context) {
super();
this.helper = new PersonSQLiteOpenHelper(context, "person.db", null, 1);
}

/**
* 添加一条记录到数据库
*
* @param name
*            姓名
* @param number
*            电话
*/
public void add(String name, String number) {
SQLiteDatabase db = helper.getWritableDatabase();
db.execSQL("insert into  person (name,number) values (?,?);",
new Object[] { name, number });
db.close();
}

/**
* 查询记录
*
* @param name
* @return true 查询结果存在 , false 查询结果不存在
*/
public boolean findPersonByName(String name) {
SQLiteDatabase db = helper.getWritableDatabase();
Cursor cursor = db.rawQuery("select * from person where name = ?",
new String[] { name });
boolean result = cursor.moveToNext();
cursor.close();
db.close();
return result;
}

/**
* 修改一条记录
*
* @param name
*            修改人的姓名
* @param newnumber
*            修改后密码
*/
public void updatePersonByName(String name, String newnumber) {
SQLiteDatabase db = helper.getWritableDatabase();
db.execSQL("update person set number=? where name = ?", new Object[] {
newnumber, name });
db.close();

}

public void deletePersonByName(String name) {
SQLiteDatabase db = helper.getWritableDatabase();
db.execSQL("delete from person where name = ?", new Object[] { name });
db.close();
}

public List<Person> getAll() {
SQLiteDatabase db = helper.getWritableDatabase();
List<Person> persons = new ArrayList<Person>();
Cursor cursor = db.rawQuery("select * from person", null);
while (cursor.moveToNext()) {
int id = cursor.getInt(0);
String name = cursor.getString(1);
String number = cursor.getString(2);
Person person = new Person(id, name, number);
persons.add(person);
}
cursor.close();
db.close();
return persons;
}
}

这是第二种写DAO的方法，Android已经为我们写好了SQL的操作，如果不记得SQL语句或者害怕出错，建议用这种方法

package com.example.dao;

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 com.example.db.PersonSQLiteOpenHelper;
import com.example.domain.Person;

public class PersonDAO2 {
private PersonSQLiteOpenHelper helper;

// 在构造方法完成helper的初始化
public PersonDAO2(Context context) {
super();
this.helper = new PersonSQLiteOpenHelper(context, "person.db", null, 1);
}

/**
* 添加一条记录到数据库
*
* @param name
*            姓名
* @param number
*            电话
*/
public long add(String name, String number) {
SQLiteDatabase db = helper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("name", name);
long id = db.insert("person", null, values);
db.close();
return id;
}

/**
* 查询记录
*
* @param name
* @return true 查询结果存在 , false 查询结果不存在
*/
public boolean findPersonByName(String name) {
SQLiteDatabase db = helper.getWritableDatabase();
Cursor cursor = db.query("person", null, "name=?",
new String[] { name }, null, null, null);
boolean result = cursor.moveToNext();
cursor.close();
db.close();
return result;
}

/**
* 修改一条记录
*
* @param name
*            修改人的姓名
* @param newnumber
*            修改后密码
*/
public int updatePersonByName(String name, String newnumber) {
SQLiteDatabase db = helper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("number", newnumber);
int number = db.update("person", values, "name=?", new String[] {});
db.close();
return number;
}

public int deletePersonByName(String name) {
SQLiteDatabase db = helper.getWritableDatabase();
int number = db.delete("person", "name=?", new String[] { name });
db.close();
return number;
}

public List<Person> getAll() {
SQLiteDatabase db = helper.getWritableDatabase();
Cursor cursor = db.query("person", null, null, null, null, null, null);
List<Person> persons = new ArrayList<Person>();
while (cursor.moveToNext()) {
int id = cursor.getInt(0);
String name = cursor.getString(1);
String number = cursor.getString(2);
Person person = new Person(id, name, number);
persons.add(person);
}
return persons;
}
}

其中的Person数据模型(Bean):

package com.example.domain;

public class Person {
private int id;
private String name;
private String number;
public Person(int id, String name, String number) {
super();
this.id = id;
this.name = name;
this.number = number;
}

public int getId() {
return id;
}

public String getName() {
return name;
}

public String getNumber() {
return number;
}

public void setId(int id) {
this.id = id;
}

public void setName(String name) {
this.name = name;
}

public void setNumber(String number) {
this.number = number;
}

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

Android单元测试:

package com.example.test;
/**
* 如果不想每次都getAll()
* sqlite3の使用
*/
import java.util.List;

import android.test.AndroidTestCase;

import com.example.dao.PersonDAO;
import com.example.dao.PersonDAO2;
import com.example.db.PersonSQLiteOpenHelper;
import com.example.domain.Person;

public class TestPersonDB extends AndroidTestCase {
public void testCreateDB() throws Exception
{
PersonSQLiteOpenHelper helper = new PersonSQLiteOpenHelper(getContext(),"person.db",null,1);
helper.getWritableDatabase();
}
public void testAdd() throws Exception{
PersonDAO dao = new PersonDAO(getContext());
for(int i = 123131121;i<123131121+20;i++)
dao.add("w5", i+"");
}
public void testFindPersonByName() throws Exception{
PersonDAO dao = new PersonDAO(getContext());
boolean result = dao.findPersonByName("w5");
AndroidTestCase.assertEquals(result, true);
}
public void testGetAll() throws Exception{
PersonDAO dao = new PersonDAO(getContext());
List<Person> all = dao.getAll();
System.out.println(all);
}
public void testUpdateByName() throws Exception{
PersonDAO dao = new PersonDAO(getContext());
dao.add("w5", "110" +
"");
}
public void testDeleteByName() throws Exception{
PersonDAO dao = new PersonDAO(getContext());
dao.deletePersonByName("w5");
}
}

为了方便的查看DataBase的值， ADB提供了sqlite3工具

使用方法adb shell



sqlite3 xxx.db