dao层代码示例

最新推荐文章于 2023-10-14 22:37:35 发布

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原文链接：https://kaiwu.lagou.com/

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#sql #数据库 #java

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本文介绍了Account Dao接口的定义，包括查询和更新操作，并展示了如何通过JdbcAccountDaoImpl实现类来操作数据库。重点在于Spring框架下数据库操作的步骤和示例代码。

AccountDao接口代码示例

package com.lagou.edu.dao;

import com.lagou.edu.pojo.Account;

/**
 * @author 应癫
 */
public interface AccountDao {

    Account queryAccountByCardNo(String cardNo) throws Exception;

    int updateAccountByCardNo(Account account) throws Exception;
}

JdbcAccountDaoImpl接口实现类代码示例

package com.lagou.edu.dao.impl;

import com.lagou.edu.pojo.Account;
import com.lagou.edu.dao.AccountDao;
import com.lagou.edu.utils.ConnectionUtils;
import com.lagou.edu.utils.DruidUtils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

/**
 * @author 应癫
 */
public class JdbcAccountDaoImpl implements AccountDao {

    private ConnectionUtils connectionUtils;

    public void setConnectionUtils(ConnectionUtils connectionUtils) {
        this.connectionUtils = connectionUtils;
    }


    public void init() {
        System.out.println("初始化方法.....");
    }

    public void destory() {
        System.out.println("销毁方法......");
    }

    @Override
    public Account queryAccountByCardNo(String cardNo) throws Exception {
        //从连接池获取连接
        Connection con = connectionUtils.getCurrentThreadConn();
        String sql = "select * from account where cardNo=?";
        PreparedStatement preparedStatement = con.prepareStatement(sql);
        preparedStatement.setString(1,cardNo);
        ResultSet resultSet = preparedStatement.executeQuery();

        Account account = new Account();
        while(resultSet.next()) {
            account.setCardNo(resultSet.getString("cardNo"));
            account.setName(resultSet.getString("name"));
            account.setMoney(resultSet.getInt("money"));
        }

        resultSet.close();
        preparedStatement.close();
        //con.close();

        return account;
    }

    @Override
    public int updateAccountByCardNo(Account account) throws Exception {

        // 从连接池获取连接
        // 改造为：从当前线程当中获取绑定的connection连接
        Connection con = connectionUtils.getCurrentThreadConn();
        String sql = "update account set money=? where cardNo=?";
        PreparedStatement preparedStatement = con.prepareStatement(sql);
        preparedStatement.setInt(1,account.getMoney());
        preparedStatement.setString(2,account.getCardNo());
        int i = preparedStatement.executeUpdate();

        preparedStatement.close();
        //con.close();
        return i;
    }
}