Android---SQLite数据库存储

推荐使用：LitePal 这个开源库

1、新建一个继承于SQLiteOpenHelper

package com.mycompany.databasesqlite;

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

/**
 * Created by sstek_mars on 2017/9/1.
 */

public class MyDatabaseHelper extends SQLiteOpenHelper {

    // 建表
    public static final String CREAT_BOOK = "create table book ("
            + "id integer primary key autoincrement, "
            + "author text, "
            + "price real, "
            + "pages integer, "
            + "name text)";

    // 建新表
    public static final String CREATE_CATEGORY = "create table Category ("
            + "id integer primary key autoincrement, "
            + "category_name text, "
            + "category_code text)";

    private Context mContext;

    /**
     *
     * @param context 必须有它才可以对数据库进行操作
     * @param name 数据库名
     * @param factory 参数运行我们在查询数据的时候返回一个自定义的Cursor，一般为 null
     * @param version 数据库的版本号
     */
    public MyDatabaseHelper(Context context, String name,
                            SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
        mContext = context;
    }

    // 创建数据库，如果已经存在了，是不会再去创建数据库
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREAT_BOOK);
        db.execSQL(CREATE_CATEGORY);
        Toast.makeText(mContext, "创建数据库成功", Toast.LENGTH_SHORT).show();
    }

    // 升级数据库
    // 解决在已有数据库的情况下，再新建一个新的数据库失败问题
    // 必须传一个大于之前版本的数，才会执行
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("drop table if exists Book");
        db.execSQL("drop table if exists Category");
        onCreate(db);
    }
}

2、使用

package com.mycompany.databasesqlite;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    private MyDatabaseHelper dbHelper;

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

        // 第一次新建
        // dbHelper = new MyDatabaseHelper(this, "BookStore.db", null, 1);

        // 升级 版本号必须大于前一次版本号
        dbHelper = new MyDatabaseHelper(this, "BookStore.db", null, 2);

        // 新建按钮
        Button createDatabase = (Button) findViewById(R.id.create_database);
        createDatabase.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dbHelper.getWritableDatabase();
            }
        });

        // 增
        Button addDatabase = (Button) findViewById(R.id.add_data);
        addDatabase.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                ContentValues values = new ContentValues();

                // 开始组装第一条数据
                values.put("name", "The da vinvi code");
                values.put("author", "dan brown");
                values.put("pages", 222);
                values.put("price", 111);
                // 插入第一条数据
                db.insert("Book", null, values);
                values.clear();

                // 开始第二条数据
                values.put("name", "11 da vinvi code");
                values.put("author", "11 brown");
                values.put("pages", 222);
                values.put("price", 111);
                db.insert("Book", null, values);
            }
        });

        // 改
        Button updateData = (Button) findViewById(R.id.update_data);
        updateData.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                ContentValues values = new ContentValues();
                values.put("name", "hahaha");
                db.update("Book", values, "name = ?", new String[]{"The da vinvi code"});
            }
        });

        // 删
        Button deleteData = (Button) findViewById(R.id.delete_data);
        deleteData.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                db.delete("Book", "pages > ?", new String[]{"500"});
            }
        });

        // 查
        Button queryData = (Button) findViewById(R.id.query_data);
        queryData.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                Cursor cursor = db.query("Book", null , null, null, null, null, null);
                if (cursor.moveToFirst()){
                    do {
                        // 遍历Cursor 取出数据并打印
                        String name = cursor.getString(cursor.getColumnIndex("name"));
                        Log.d("MainActivity", "书名是：" + name);
                    } while (cursor.moveToNext());
                }
                cursor.close();
            }
        });

    }
}