android小功能实现之SQLite数据库的基本操作

浏览数：37 / 时间：2015年06月11日

创建一个Android工程

一新建数据库

1 新建一个类DBOpenHelper

内容如下：

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

public class DBOpenHelper extends SQLiteOpenHelper {
    public DBOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        // 数据库保持位置<包>/databases
        super(context, name, factory, version);
    }

    @Override
    // 数据库第一次被创建时调用
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE person(id integer primary key autoincrement, name varchar(20))");
    }

    @Override
    // 数据库文件的版本号发生变更时调用
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("ALTER TABLE person ADD phone VARCHAR(12) NULL");
    }
}

onCreate函数在数据库创建时调用；
onUpgrade在数据库版本号version发生变化时调用。

2 测试
修改MainActivity.java代码如下：

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        int version = 1;
        DBOpenHelper dbOpenHelper = new DBOpenHelper(getApplicationContext(), "test.db", null, version);
        dbOpenHelper.getWritableDatabase();
    }

此时在data文件夹中可以看到test.db文件如图：

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打开可以看到：

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打开person:

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修改version的值：
int version = 2;

再次查看test.db的内容：

二数据库的基本操作

1 新建一个类Person类

用于保存对象数据，内容如下：

public class Person {
    private Integer id;
    private String name;
    private String phone;

    public Person(){

    }

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

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

    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 String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", phone='" + phone + '\'' +
                '}';
    }
}

2 新建一个类PersonService类

用于对数据进行操作，内容如下：

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

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

public class PersonService {
    private DBOpenHelper dbOpenHelper;


    public PersonService(Context context) {
        int version = 2;
        this.dbOpenHelper = new DBOpenHelper(context, "test.db", null, version);
    }

    // 增
    public void save(Person person){
        SQLiteDatabase db = this.dbOpenHelper.getWritableDatabase();
        db.execSQL("insert into person(name, phone) values(?, ?)", new Object[]{person.getName(), person.getPhone()});
    }

    // 删
    public void delete(Integer id){
        SQLiteDatabase db = this.dbOpenHelper.getWritableDatabase();
        db.execSQL("delete from person where id=?", new Object[]{id});
    }

    // 改
    public void update(Person person){
        SQLiteDatabase db = this.dbOpenHelper.getWritableDatabase();
        db.execSQL("update person set name=?,phone=? where id=?", new Object[]{person.getName(), person.getPhone(), person.getId()});
    }

    // 查
    public  Person find(Integer id){
        SQLiteDatabase db = this.dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from person where id=?", new String[]{id.toString()});
        if (cursor.moveToFirst()){
            int personId = cursor.getInt(cursor.getColumnIndex("id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));
            String phone = cursor.getString(cursor.getColumnIndex("phone"));
            return new Person(personId, name, phone);
        }
        cursor.close();
        return null;
    }

    // 分页获取记录，跳过前offset条记录，查找maxResult条记录
    public List<Person> getScrollData(int offset, int maxResult){
        SQLiteDatabase db = this.dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from person order by id asc limit ?,?",
                new String[]{String.valueOf(offset), String.valueOf(maxResult)});
        List<Person> persons = new ArrayList<Person>();
        while (cursor.moveToNext()){
            int personId = cursor.getInt(cursor.getColumnIndex("id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));
            String phone = cursor.getString(cursor.getColumnIndex("phone"));
            persons.add(new Person(personId, name, phone));
        }
        cursor.close();
        return  persons;
    }

    // 获取记录条数
    public long getCount(){
        SQLiteDatabase db = this.dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select count(*) from person",null);
        cursor.moveToFirst();
        long res = cursor.getLong(0);
        cursor.close();
        return res;
    }
}

3 测试添加数据

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 创建数据库
        int version = 2;
        DBOpenHelper dbOpenHelper = new DBOpenHelper(getApplicationContext(), "test.db", null, version);
        dbOpenHelper.getWritableDatabase();
        // 数据库基本操作
        PersonService service = new PersonService(getApplicationContext());
        Person person = new Person("寒风", "1596262XXXX");
        service.save(person);
    }

再次查看test.db的内容：

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4 测试查找数据

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 创建数据库
        int version = 2;
        DBOpenHelper dbOpenHelper = new DBOpenHelper(getApplicationContext(), "test.db", null, version);
        dbOpenHelper.getWritableDatabase();
        // 数据库基本操作
        PersonService service = new PersonService(getApplicationContext());
        /*
        Person person = new Person("寒风", "1596262XXXX");
        service.save(person);
        */
        Person p = service.find(1);
        Log.i("PersonService", p.toString());
    }

注释掉之前添加数据的代码，讲查询出的数据打印到logcat，结果如下：

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5 测试更新数据

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 创建数据库
        int version = 2;
        DBOpenHelper dbOpenHelper = new DBOpenHelper(getApplicationContext(), "test.db", null, version);
        dbOpenHelper.getWritableDatabase();
        // 数据库基本操作
        PersonService service = new PersonService(getApplicationContext());
        /*
        Person person = new Person("寒风", "1596262XXXX");
        service.save(person);
        */

        Person p = service.find(1);
        p.setName("丿寒灬风丨");
        service.update(p);
        Person p1 = service.find(1);
        Log.i("PersonService", p1.toString());
    }

修改了名称，并更新到数据库，再次执行查询结果如图：

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注意，前一条是上一次输出的结果。

5 测试获取记录条数

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 创建数据库
        int version = 2;
        DBOpenHelper dbOpenHelper = new DBOpenHelper(getApplicationContext(), "test.db", null, version);
        dbOpenHelper.getWritableDatabase();
        // 数据库基本操作
        PersonService service = new PersonService(getApplicationContext());
        /*
        Person person = new Person("寒风", "1596262XXXX");
        service.save(person);
        */
        /*
        Person p = service.find(1);
        p.setName("丿寒灬风丨");
        service.update(p);
        Log.i("PersonService", p.toString());
        */
        Log.i("PersonService","count:"+ String.valueOf(service.getCount()));
    }

结果如图：

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5 测试分页方法

5.1 添加多条测试数据

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 创建数据库
        int version = 2;
        DBOpenHelper dbOpenHelper = new DBOpenHelper(getApplicationContext(), "test.db", null, version);
        dbOpenHelper.getWritableDatabase();
        // 数据库基本操作
        PersonService service = new PersonService(getApplicationContext());
        for (int i=0; i<20;++i) {
            Person person = new Person("寒风", "1596262XXX"+i);
            service.save(person);
        }
        /*
        Person p = service.find(1);
        p.setName("丿寒灬风丨");
        service.update(p);
        Log.i("PersonService", p.toString());
        */

        // Log.i("PersonService","count:"+ String.valueOf(service.getCount()));
    }

查看test.db的内容：

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5.2 测试删除方法

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 创建数据库
        int version = 2;
        DBOpenHelper dbOpenHelper = new DBOpenHelper(getApplicationContext(), "test.db", null, version);
        dbOpenHelper.getWritableDatabase();
        // 数据库基本操作
        PersonService service = new PersonService(getApplicationContext());
        /*
        for (int i=0; i<20;++i) {
            Person person = new Person("寒风", "1596262XXX"+i);
            service.save(person);
        }
        */
        /*
        Person p = service.find(1);
        p.setName("丿寒灬风丨");
        service.update(p);
        Log.i("PersonService", p.toString());
        */

        // Log.i("PersonService","count:"+ String.valueOf(service.getCount()));

        List<Person> persons = service.getScrollData(0, 5);
        for(Person person:persons){
            Log.i("PersonService", person.toString());
        }
        Log.i("PersonService","-------------------------");
        List<Person> persons1 = service.getScrollData(5, 5);
        for(Person person:persons1){
            Log.i("PersonService", person.toString());
        }
    }

结果如图：

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6 测试删除方法

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 创建数据库
        int version = 2;
        DBOpenHelper dbOpenHelper = new DBOpenHelper(getApplicationContext(), "test.db", null, version);
        dbOpenHelper.getWritableDatabase();
        // 数据库基本操作
        PersonService service = new PersonService(getApplicationContext());
        /*
        for (int i=0; i<20;++i) {
            Person person = new Person("寒风", "1596262XXX"+i);
            service.save(person);
        }
        */
        /*
        Person p = service.find(1);
        p.setName("丿寒灬风丨");
        service.update(p);
        Log.i("PersonService", p.toString());
        */

        // Log.i("PersonService","count:"+ String.valueOf(service.getCount()));

        /*
        List<Person> persons = service.getScrollData(0, 5);
        for(Person person:persons){
            Log.i("PersonService", person.toString());
        }
        Log.i("PersonService","-------------------------");
        List<Person> persons1 = service.getScrollData(5, 5);
        for(Person person:persons1){
            Log.i("PersonService", person.toString());
        }
        */
        service.delete(1);
    }

查看test.db的内容：

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三使用封装方法实现

SQLiteDatabase类中对SQL语句做了简单的封装，每个方法对于如下：

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

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

public class PersonService {
    private DBOpenHelper dbOpenHelper;


    public PersonService(Context context) {
        int version = 2;
        this.dbOpenHelper = new DBOpenHelper(context, "test.db", null, version);
    }

    // 增
    public void save(Person person){
        SQLiteDatabase db = this.dbOpenHelper.getWritableDatabase();
        db.execSQL("insert into person(name, phone) values(?, ?)", new Object[]{person.getName(), person.getPhone()});
    }

    public void save1(Person person){
        SQLiteDatabase db = this.dbOpenHelper.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("name", person.getName());
        values.put("phone", person.getPhone());
        db.insert("person",null, values);
    }

    // 删
    public void delete(Integer id){
        SQLiteDatabase db = this.dbOpenHelper.getWritableDatabase();
        db.execSQL("delete from person where id=?", new Object[]{id});
    }
    public void delete1(Integer id){
        SQLiteDatabase db = this.dbOpenHelper.getWritableDatabase();
        db.delete("person", "id=?",new String[]{id.toString()});
    }

    // 改
    public void update(Person person){
        SQLiteDatabase db = this.dbOpenHelper.getWritableDatabase();
        db.execSQL("update person set name=?,phone=? where id=?", new Object[]{person.getName(), person.getPhone(), person.getId()});
    }

    public void update1(Person person) {
        SQLiteDatabase db = this.dbOpenHelper.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("name", person.getName());
        values.put("phone", person.getPhone());
        db.update("person",values,"id=?", new String[]{person.getId().toString()});
    }

    // 查
    public  Person find(Integer id){
        SQLiteDatabase db = this.dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from person where id=?", new String[]{id.toString()});
        if (cursor.moveToFirst()){
            int personId = cursor.getInt(cursor.getColumnIndex("id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));
            String phone = cursor.getString(cursor.getColumnIndex("phone"));
            return new Person(personId, name, phone);
        }
        cursor.close();
        return null;
    }

    public  Person find1(Integer id) {
        SQLiteDatabase db = this.dbOpenHelper.getReadableDatabase();
        //db.query("person", null, "id=?", new String[]{id.toString()},null, null,null);
        Cursor cursor = db.query("person", new String[]{"id","name","phone"}, "id=?", new String[]{id.toString()},null, null,null);
        if (cursor.moveToFirst()){
            int personId = cursor.getInt(cursor.getColumnIndex("id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));
            String phone = cursor.getString(cursor.getColumnIndex("phone"));
            return new Person(personId, name, phone);
        }
        cursor.close();
        return null;
    }

    // 分页获取记录
    public List<Person> getScrollData(int offset, int maxResult){
        SQLiteDatabase db = this.dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from person order by id asc limit ?,?",
                new String[]{String.valueOf(offset), String.valueOf(maxResult)});
        List<Person> persons = new ArrayList<Person>();
        while (cursor.moveToNext()){
            int personId = cursor.getInt(cursor.getColumnIndex("id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));
            String phone = cursor.getString(cursor.getColumnIndex("phone"));
            persons.add(new Person(personId, name, phone));
        }
        cursor.close();
        return  persons;
    }

    public List<Person> getScrollData1(int offset, int maxResult){
        SQLiteDatabase db = this.dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.query("person", null, null,null,null,null,"id asc", offset+","+maxResult);
                new String[]{String.valueOf(offset), String.valueOf(maxResult)});
        List<Person> persons = new ArrayList<Person>();
        while (cursor.moveToNext()){
            int personId = cursor.getInt(cursor.getColumnIndex("id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));
            String phone = cursor.getString(cursor.getColumnIndex("phone"));
            persons.add(new Person(personId, name, phone));
        }
        cursor.close();
        return  persons;
    }

    // 获取记录条数
    public long getCount(){
        SQLiteDatabase db = this.dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select count(*) from person",null);
        cursor.moveToFirst();
        long res = cursor.getLong(0);
        cursor.close();
        return res;
    }
    public long getCount1(){
        SQLiteDatabase db = this.dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.query("person", new String[]{"count(*)"},null,null,null,null,null);
        cursor.moveToFirst();
        long res = cursor.getLong(0);
        cursor.close();
        return res;
    }
}

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android小功能实现之SQLite数据库的基本操作