SQLLite数据库的简单使用

首先创建sqllite辅助类，继承SQLiteOpenHelper 

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

public class Mysql extends SQLiteOpenHelper {
    public Mysql(Context context) {
        super(context, "数据库名（英文）", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {

    //创建表，添加数据
        sqLiteDatabase.execSQL("create table t_shop (a varchar(20), aa varchar(11), aaa varchar(20) , aaaa varchar(20))");
        sqLiteDatabase.execSQL("insert into t_shop values('羊毛衫男','新品','恒轩祥','高领')");
        sqLiteDatabase.execSQL("insert into t_shop values('衬衣','新品','男长袖','保暖')");
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
}

创建一个数据库工具类Dao类，用于操作数据库

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

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

public class Dao {
    //获取帮助类对象--->通过帮助类对象得到操作数据库对象(mh.getWritableDatabase())---->  SQLiteDatabase
    Mysql mh;

    public Dao(Context ctx) {
        super();
        mh=new Mysql(ctx);  //获取帮助类实例对象
    }

  /*  //执行添加操作
    public void add(){
        //获取SQLiteDatabase对象
        SQLiteDatabase database = mh.getWritableDatabase();
        //执行添加的操作
        database.execSQL("insert into t_users values (?,'zhao','151100335')"); //无返回值

        //关闭数据库对象的方法
        database.close();
    }*/

  /*  //执行删除操作
    public void delete(){
        //获取SQLiteDatabase对象
        SQLiteDatabase database = mh.getWritableDatabase();
        //执行添加的操作  执行sql语句
        database.execSQL("delete from t_users where _id=1");  //无返回值

        //关闭数据库对象的方法
        database.close();
    }

    public List<Users> select(){
        // 创建存放所有行对象集合
        List<Users>  us=new ArrayList<Users>();

        //获取SQLiteDatabase对象
        SQLiteDatabase database = mh.getWritableDatabase();

        //执行查询的sql语句--->获取到结果集对象  Cursor
        Cursor query = database.rawQuery("select * from t_users", null);   //null是为sequel语句中的占位符赋值

        //是否有下一行
        while(query.moveToNext()){
            //获取当前行中每个列的值
            int _id = query.getInt(0);
            String uname= query.getString(1);
            String tel= query.getString(2);
            Users u=new Users(_id, uname, tel);
            us.add(u);
        }

        //关闭数据库对象的方法
        database.close();

        return us;
    }*/
  public List<Users> select() {
      // 创建存放所有行对象集合
      List<Users> us = new ArrayList<Users>();

      //获取SQLiteDatabase对象
      SQLiteDatabase database = mh.getWritableDatabase();

      //执行查询的sql语句--->获取到结果集对象  Cursor
      Cursor query = database.rawQuery("select * from t_shop", null);   //null是为sequel语句中的占位符赋值

      //是否有下一行
      while (query.moveToNext()) {
          //获取当前行中每个列的值
          String a = query.getString(0);
          String aa = query.getString(1);
          String aaa = query.getString(2);
          String aaaa = query.getString(3);
          Users u = new Users(a, aa, aaa, aaaa);
          us.add(u);
      }
      database.close();
      return us;
  }
  public void insert(Users users){
      SQLiteDatabase database = mh.getWritableDatabase();
      database.execSQL("insert into t_shop values('"+users.getA()+"','"+users.getAa()+"','"+users.getAaa()+"','"+users.getAaaa()+"')");
      database.close();
  }
  public void clear(){
      SQLiteDatabase database = mh.getWritableDatabase();
      database.execSQL("delete from t_shop");
  }
}

在创建一个实体类

public class Users {
    private String a;
    private String aa;
    private String aaa;
    private String aaaa;

    public Users(String a) {
        this.a = a;
    }

    public Users(String a, String aa, String aaa, String aaaa) {
        this.a = a;
        this.aa = aa;
        this.aaa = aaa;
        this.aaaa = aaaa;
    }

    public String getA() {
        return a;
    }

    public void setA(String a) {
        this.a = a;
    }

    public String getAa() {
        return aa;
    }

    public void setAa(String aa) {
        this.aa = aa;
    }

    public String getAaa() {
        return aaa;
    }

    public void setAaa(String aaa) {
        this.aaa = aaa;
    }

    public String getAaaa() {
        return aaaa;
    }

    public void setAaaa(String aaaa) {
        this.aaaa = aaaa;
    }
}

最后记得不要忘记添加权限

 <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>