SQLite数据库使用

创建数据库

package com.example.yuekaoone.dao; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; public class MHelp extends SQLiteOpenHelper { public MHelp(Context context) { super(context, "user.db",null,1); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL("create table users(id Integer,name text , img1 text, img2 text, img3 text)"); } @Override public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) { } }

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创建dao包

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package com.example.yuekaoone.dao; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import com.example.yuekaoone.bean.Shu; import java.util.ArrayList; import java.util.List; public class Dao { //List<Shu> list = new ArrayList<>(); SQLiteDatabase database; public Dao(Context context) { MHelp mHelp = new MHelp(context); database = mHelp.getReadableDatabase(); } /* public void addAll(List<Shu> datas) { for (int i=0;i<datas.size();i++){ add(datas.get(i)); } } */ /* public void add(Shu data) { database.execSQL("insert into users(name,img1,img2,img3) values(?,?,?,?)",new String[]{data.getName(),data.getImg1(),data.getImg2(),data.getImg3()}); }*/ public void add(String name, String img1, String img2, String img3) { database.execSQL("insert into users(name,img1,img2,img3) values(?,?,?,?)",new String[]{name,img1,img2,img3}); } public int getDataCount() { int count = -1; Cursor cursor = database.query("users", new String[]{}, null, null, null, null, null); if(cursor.moveToNext()) { count = cursor.getCount(); } return count; } public List<Shu> cha() { // List<Shu> list = new ArrayList<>(); Cursor cursor = database.rawQuery("select * from users", null); while(cursor.moveToNext()){ String name = cursor.getString(cursor.getColumnIndex("name")); String img1 = cursor.getString(cursor.getColumnIndex("img1")); String img2 = cursor.getString(cursor.getColumnIndex("img2")); String img3 = cursor.getString(cursor.getColumnIndex("img3")); Shu shu =new Shu(name,img1,img2,img3); list.add(shu); } cursor.close(); return list; } public void delete() { database.execSQL("delete from users"); } }

在mainactivity创建dao 引用

//添加到数据库 for (int i=0;i<dataBeans.size();i++){ dao.add(dataBeans.get(i).getAuthor_name(),dataBeans.get(i).getThumbnail_pic_s(),dataBeans.get(i).getThumbnail_pic_s02(),dataBeans.get(i).getThumbnail_pic_s03()); } `` //查询 List<Shu> list11 = dao.cha(); adapter.setdata(Convers.db2response(list11));` //两个集合转换 package com.example.yuekaoone.bean; import java.util.ArrayList; import java.util.List; public class Convers { //db 的数据 -> 网络请求的 public static List<Bean.DataBean> db2response(List<Shu> datas) { List<Bean.DataBean> result = new ArrayList<>(); for (Shu shu:datas) { result.add(new Bean.DataBean(shu.name, shu.img1, shu.img2, shu.img3)); } return result; } //网络请求数据 -> db数据 public static List<Shu> response2db(List<Bean.DataBean> datas) { List<Shu> result = new ArrayList<>(); for (Bean.DataBean dataBean:datas) { result.add(new Shu(dataBean.getAuthor_name(), dataBean.getThumbnail_pic_s(), dataBean.getThumbnail_pic_s02(), dataBean.getThumbnail_pic_s03())); } return result; } }