android中的内容提供者把自己数据库暴露出来

郑州app开发通过内容提供者把自己数据库暴露出来。布局代码主要是两个按钮，一个是查询按钮，一个是插入按钮，就不再这里展示了。

MainActivity.java

package cn.xhhkj.cyd;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ComponentName;

import android.content.Intent;

import android.content.ServiceConnection;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.os.Bundle;

import android.os.IBinder;

import android.util.Log;

import android.view.View;

public class MainActivity extends AppCompatActivity {

    private SQLiteDatabase database;

    private static final String TAG = "结果是";

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        MyOpenHelper helper = new MyOpenHelper(this);

        database = helper.getReadableDatabase();

    }

    public void insert(View view) {

        database.execSQL("insert into info(name,phone) values('王小明','13777777')");

        database.execSQL("insert into info(name,phone) values('赵小明','13888888')");

        database.execSQL("insert into info(name,phone) values('李大明','13666666')");

    }

    public void query(View view) {

        Cursor cursor = database.rawQuery("select * from info", null);

        while(cursor.moveToNext()){

            String name = cursor.getString(cursor.getColumnIndex("name"));

            String phone = cursor.getString(cursor.getColumnIndex("phone"));

            System.out.println("name="+name+"phone="+phone);

            Log.d(TAG,"name="+name+"phone="+phone);

        }

        cursor.close();

    }

    @Override

    protected void onDestroy() {

        super.onDestroy();

        database.close();

    }

}

MyOpenHelper.java

package cn.xhhkj.cyd;

import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

public class MyOpenHelper extends SQLiteOpenHelper {

    public MyOpenHelper(Context context) {

        super(context, "xhhkj.db", null, 1);

    }

    @Override

    public void onCreate(SQLiteDatabase db) {

        db.execSQL("create table info(_id integer primary key autoincrement,name varchar(20),phone varchar(20))");

        db.execSQL("alter table info add age integer");

    }

    @Override

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

    }

}