【团队】 冲刺一（7/10）

昨天所做：保存新建账单的数据到SQLite

代码是冲刺完才粘的，可能会和所说的有所不同

package com.example.accountbook;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteStatement;
import android.util.Log;
import android.widget.Toast;

import java.util.List;

public class DB extends SQLiteOpenHelper {

    private static final String DB_NAME="accountbook";
    private static final int DB_VERSION=1;
    private static DB mHelper=null;
    private SQLiteDatabase mDB=null;
    private static String TABLE_NAME="默认账本";
    private static final String TABLE_NAME_BOOK = "book";

    public DB(Context context)
    {
        super(context,DB_NAME,null,DB_VERSION);
    }
    public DB(Context context ,int version)
    {
        super(context,DB_NAME,null,version);
    }

    public SQLiteDatabase getMDB()
    {
        return mDB;
    }

    public void setTableName(String TABLE_NAME)
    {
        this.TABLE_NAME = TABLE_NAME;
    }

    //利用单例模式获取数据库帮助器的唯一实例
    public static DB getInstance(Context context,int version)
    {
        if (version>0&&mHelper==null)
        {
            mHelper=new DB(context, version);
        }else if (mHelper==null)
        {
            mHelper=new DB(context);
        }
        return mHelper;
    }

    //获取账本名
    public String getTableName()
    {
        return TABLE_NAME;
    }

    //打开数据库的读连接
    public SQLiteDatabase openReadLink()
    {
        if (mDB==null||!mDB.isOpen())
        {
            mDB=mHelper.getReadableDatabase();
        }
        return mDB;
    }
    //打开数据库的写连接
    public SQLiteDatabase openWriteLink()
    {
        if (mDB==null||!mDB.isOpen())
        {
            mDB=mHelper.getWritableDatabase();
        }
        return mDB;
    }
    //关闭数据库连接
    public void closeLink()
    {
        if (mDB!=null&&mDB.isOpen())
        {
            mDB.close();
            mDB=null;
        }
    }
    //创建数据库，执行建表语句
    public void onCreate(SQLiteDatabase db)
    {
        String drop_sql="DROP TABLE IF EXISTS "+TABLE_NAME+";";
        db.execSQL(drop_sql);
        String create_sql="CREATE TABLE IF NOT EXISTS "+TABLE_NAME+" ("
                +"id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,"
                +"money double NOT NULL,"
                +"choose VARCHAR NOT NULL,"
                +"sort varchar NOT NULL,"
                +"time varchar NOT NULL,"
                +"remark varchar"
                +")";
        db.execSQL(create_sql);
        Log.d("create","建表成功"+TABLE_NAME_BOOK);

    }


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

    }

    //添加账单
    public long insert(BillBean billbean)
    {
        long result = -1;
        ContentValues cv = new ContentValues();
        cv.put("money",billbean.getMoney());
        cv.put("choose",billbean.getChoose());
        cv.put("sort",billbean.getSort());
        cv.put("time",billbean.getTime());
        cv.put("remark",billbean.getRemark());
        result = mDB.insert(TABLE_NAME,"",cv);
        if(result >= 0)
        {
            Log.i("add", "添加账单成功");
        }
        return result;
    }//检测某个表是否存在，存在返回false，不存在返回true
    public boolean tableIsExist(String bookname){
        Log.d("exit","开始检测表 "+bookname+" 是否存在");
        if(bookname == null){
            Log.d("exit","表 "+bookname+" 名字为空");
            return false;
        }
        Cursor cursor = null;
        try {
            String sql = "select count(*) from "+TABLE_NAME_BOOK+" where bookname ='"+bookname+"' ";
            cursor = mDB.rawQuery(sql, null);
            if (cursor.getInt(0)==0) {
                Log.d("exit","表 "+bookname+" 检测返回值 false");
                return false;
            }

        } catch (Exception e) {
            // TODO: handle exception
        }
        Log.d("exit","表 "+bookname+" 检测返回值 true");
        return true;
    }
//获取表中数据的数量
    public long getCount(String tablename)
    {
        String select_sql = "select count(*) from "+tablename;
        SQLiteStatement statement = mDB.compileStatement(select_sql);
        long count = statement.simpleQueryForLong();
        return count;
    }

}

今天将做：将SQLite中的数据显示到主页面

遇到问题：

忘了截图

报错db是空指针

重写onResume()和onPause()