Android数据库SQLite的简单使用

Android数据库SQLite的简单使用：

根据扣丁课堂的教程学习

源码地址：http://download.csdn.net/detail/ash_zheng/9117207


首先可以创建一个类 用来表示数据库：
package com.ashzheng.sqlitetest.sqlite;

import android.provider.BaseColumns;

/**
 * Created by Administrator on 2015/9/17.
 *
 * 元数据的定义
 */

//不被继承
public final class PetMetData {

    //不允许被实例化，私有构造方法
    private PetMetData(){}

    //表
    public static abstract class DogTable implements BaseColumns{
        public static final String TABLE_NAME = "dog";
        public static final String NAME = "name";
        public static final String AGE = "age";
    }
}


然后可以新建类 用来表示一个实体，方便后续的操作：
package com.ashzheng.sqlitetest.sqlite;

/**
 * Created by Administrator on 2015/9/17.
 */
public class Dog {

    private int id;
    private String name;
    private int age;

    public Dog() {

    }

    public Dog(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public Dog(int id, String name, int age) {

        this.id = id;
        this.name = name;
        this.age = age;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

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




然后新建一个 继承自SQLiteOpenHelper的助手类：
package com.ashzheng.sqlitetest.sqlite;

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

/**
 * Created by Administrator on 2015/9/17.
 */
public class DataBaseHelper extends SQLiteOpenHelper{

    private static final String DB_NAME = "pet.db";
    private static final int VERSION = 1;

    private static final String CREAT_TABLE = "CREATE TABLE dog(_id INTEGER PRIMARY KEY AUTOINCREMENT," +
            "name TEXT, age INTEGER)";
    private static final String DROP_TABLE = "DROP TABLE IF EXISTS dog";

    public DataBaseHelper(Context context) {
        super(context, DB_NAME, null, VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

        db.execSQL(CREAT_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        db.execSQL(DROP_TABLE);
        db.execSQL(CREAT_TABLE);
    }
}




然后新建一个DataBaseAdapter的类用来操作（增删改查等）数据库：
package com.ashzheng.sqlitetest.sqlite;

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

import java.util.ArrayList;

/**
 * Created by Administrator on 2015/9/17.
 */
public class DataBaseAdapter {

    private DataBaseHelper dbHelper;

    public DataBaseAdapter(Context context) {
        dbHelper = new DataBaseHelper(context);
    }

    public void add(Dog dog) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(PetMetData.DogTable.NAME, dog.getName());
        values.put(PetMetData.DogTable.AGE, dog.getAge());

        //null表示可以为空的列 的列
        db.insert(PetMetData.DogTable.TABLE_NAME, null, values);
        db.close();
    }

    public void delete(int id) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();

        String whereClause = PetMetData.DogTable._ID + "=?";
        String[] whereArgs = {String.valueOf(id)};

        //表名，条件，条件值
        db.delete(PetMetData.DogTable.TABLE_NAME, whereClause, whereArgs);
        db.close();
    }

    public void update(Dog dog) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(PetMetData.DogTable.NAME, dog.getName());
        values.put(PetMetData.DogTable.AGE, dog.getAge());

        String whereClause = PetMetData.DogTable._ID + "=?";
        String[] whereArgs = {String.valueOf(dog.getId())};

        db.update(PetMetData.DogTable.TABLE_NAME, values, whereClause, whereArgs);
        db.close();
    }

    public Dog findById(int id) {

        SQLiteDatabase db = dbHelper.getReadableDatabase();
        String[] colums = {PetMetData.DogTable._ID, PetMetData.DogTable.NAME, PetMetData.DogTable.AGE};

        //是否去除重复记录，表名，要查询的列，查询条件，查询条件的值，分组条件，分组条件的值，排序，分页条件
        Cursor cursor = db.query(true, PetMetData.DogTable.TABLE_NAME, colums, PetMetData.DogTable._ID + "=?",
                new String[]{String.valueOf(id)}, null, null, null, null);

        Dog dog = null;
        if (cursor.moveToNext()) {
            dog = new Dog();
            dog.setId(cursor.getInt(cursor.getColumnIndexOrThrow(PetMetData.DogTable._ID)));
            dog.setName(cursor.getString(cursor.getColumnIndexOrThrow(PetMetData.DogTable.NAME)));
            dog.setAge(cursor.getInt(cursor.getColumnIndexOrThrow(PetMetData.DogTable.AGE)));
        }

        return dog;

    }

    public ArrayList<Dog> findAll() {
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        String[] colums = {PetMetData.DogTable._ID, PetMetData.DogTable.NAME, PetMetData.DogTable.AGE};

        //是否去除重复记录，表名，要查询的列，查询条件，查询条件的值，分组条件，分组条件的值，排序，分页条件
        Cursor cursor = db.query(true, PetMetData.DogTable.TABLE_NAME, colums, null, null, null, null, null, 

null);

        ArrayList<Dog> dogs = new ArrayList<>();
        Dog dog = null;
        while (cursor.moveToNext()) {
            dog = new Dog();
            dog.setId(cursor.getInt(cursor.getColumnIndexOrThrow(PetMetData.DogTable._ID)));
            dog.setName(cursor.getString(cursor.getColumnIndexOrThrow(PetMetData.DogTable.NAME)));
            dog.setAge(cursor.getInt(cursor.getColumnIndexOrThrow(PetMetData.DogTable.AGE)));
            dogs.add(dog);
        }

        return dogs;
    }
}


这样就完成了，下面可以进行测试了
我在布局中加了几个按钮
<Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:onClick="addClick"
        android:text="增" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/button"
        android:onClick="deleteClick"
        android:text="删" />

    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/button2"
        android:onClick="updateClick"
        android:text="改" />

    <Button
        android:id="@+id/button4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/button3"
        android:onClick="findByIdClick"
        android:text="查一条" />

    <Button
        android:id="@+id/button5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/button4"
        android:onClick="findAllClick"
        android:text="查所有" />


对应的：
package com.ashzheng.sqlitetest;

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

import com.ashzheng.sqlitetest.sqlite.DataBaseAdapter;
import com.ashzheng.sqlitetest.sqlite.Dog;

import java.util.ArrayList;

public class MainActivity extends Activity {

    DataBaseAdapter dataBaseAdapter;

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

        dataBaseAdapter = new DataBaseAdapter(this);
    }

    public void addClick(View v) {

        Dog dog = new Dog("one", 5);
        dataBaseAdapter.add(dog);
        System.out.println("666666   " + "已添加！！！");
    }

    public void deleteClick(View v) {
        dataBaseAdapter.delete(1);
        System.out.println("666666   " + "已删除id为1的！！！");
    }

    public void updateClick(View v) {

        Dog dog = new Dog(1, "two", 10);
        dataBaseAdapter.update(dog);
        System.out.println("666666   " + "已更新！！！");
    }

    public void findByIdClick(View v) {

        Dog dog;
        dog = dataBaseAdapter.findById(1);
        System.out.println("666666   " + dog.toString());
    }

    public void findAllClick(View v) {

        ArrayList<Dog> dogs;
        dogs = dataBaseAdapter.findAll();

        int count = dogs.size();
        for (int i = 0; i < count; i++) {
            System.out.println("666666  " + dogs.get(i).toString());
        }
    }
}

如上
详情可看视频http://www.codingke.com/course/167/learn#lesson/509