1.知識圖譜

數據庫的增刪查改的功能實現模板

連接數據庫，首先得在java下新建一個.db包，在新建的db包下新建一個.db文件

DbHelper.java的代碼如下：

package com.yindan.db;


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

/**
 * Created by Administrator on 2017/6/25 0025.
 */

public class DbHelper extends SQLiteOpenHelper {

    /**
     *
     * @param context   上下文
     * @param name       數據庫的名字，“文件名.db”
     * @param factory   數據庫工廠，null
     * @param version   數據庫版本
     */
    public DbHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
        Log.i("test","構造方法");
    }

    //使用該方法，創建表
    //只會調用一次
    @Override
    public void onCreate(SQLiteDatabase db) {
        Log.i("test","創建表");
        db.execSQL("create table login (uid integer primary key autoincrement,uname,upass)");
    }

    //數據庫版本，低-------》高
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.i("test","升級數據庫版本");

    }

    //數據庫版本   高----------》低
//    @Override
//    public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
//        super.onDowngrade(db, oldVersion, newVersion);
//    }
}

xml代碼

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.cookie.android0625sqlite.MainActivity">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="請輸入用戶名"
        android:id="@+id/et_main_uname"/>
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="請輸入密碼"
        android:id="@+id/et_main_upass"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="operation"
        android:text="操作"/>

</LinearLayout>

JAVA代碼

package com.example.cookie.android0625sqlite;

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.EditText;
import android.widget.Toast;

import com.yindan.db.DbHelper;

public class MainActivity extends AppCompatActivity {

    private EditText et_main_uname;
    private EditText et_main_upass;
    private SQLiteDatabase sqLiteDatabase;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        et_main_uname = (EditText) findViewById(R.id.et_main_uname);
        et_main_upass = (EditText) findViewById(R.id.et_main_upass);
        DbHelper dbHelper=new DbHelper(this,"CookieOne.db",null,1);
        sqLiteDatabase = dbHelper.getWritableDatabase();
    }

    public void operation(View view){
        String uname=et_main_uname.getText().toString();
        String upass=et_main_upass.getText().toString();
        //添加1
//        ContentValues contentValues=new ContentValues();
//        contentValues.put("uname",uname);
//        contentValues.put("upass",upass);
//        contentValues.putNull("uid");
//        sqLiteDatabase.insert("login","uname",contentValues);
        //添加2
//        for (int i = 0; i <100 ; i++) {
//            sqLiteDatabase.execSQL("insert into login (uname,upass) values ('小"+i+"','123')");
//        }

        //修改
//        ContentValues contentValues=new ContentValues();
//        contentValues.put("uname",uname);
//        contentValues.put("upass",upass);
//        sqLiteDatabase.update("login",contentValues,"uid=?",new String[]{1+""});

        //刪除
        // sqLiteDatabase.delete("login","uid=?",new String[]{102+""});

        //查詢
        //sqLiteDatabase.query();
        int pageNo=1;
        int pageSize=3;
       Cursor cursor= sqLiteDatabase.rawQuery("select * from login limit ?,?",new String[]{((pageNo-1)*pageSize)+"",pageSize+""});
        while (cursor.moveToNext()){
            int uid=cursor.getInt(cursor.getColumnIndex("uid"));
            String name=cursor.getString(cursor.getColumnIndex("uname"));
            String pass=cursor.getString(cursor.getColumnIndex("upass"));
            Log.i("test",uid+" "+name+" "+pass);
        }

        Toast.makeText(this, "操作", Toast.LENGTH_SHORT).show();
    }

}