Java BaseDao

最新推荐文章于 2025-09-12 18:08:49 发布

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最新推荐文章于 2025-09-12 18:08:49 发布

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CC 4.0 BY-SA版权

文章标签： java 数据库

原文链接：http://www.cnblogs.com/zhengcheng/p/4250759.html

本文介绍如何使用BaseDao类来实现数据库的增删改查操作，包括获取连接、执行查询和更新操作，并在最后展示了如何利用此类获取员工列表。

BaseDao类:

package dao;

import java.sql.*;

public class BaseDao {
    private static final String driver = "oracle.jdbc.driver.OracleDriver";
    private static final String url = "jdbc:oracle:thin:@localhost:1521:ACCP";
    private static final String uid = "scott";
    private static final String pwd = "scott";

    private static Connection con;
    private static PreparedStatement pstmt;

    /**
     * 建立连接对象
     * @return
     */
    public static Connection getConnection() {
        try {
            Class.forName(driver);
            con = DriverManager.getConnection(url, uid, pwd);
            return con;
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 关闭对象
     * @param rs 数据集对象
     */
    public static void Close(ResultSet rs) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if (pstmt != null) {
            try {
                pstmt.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if (con != null) {
            try {
                con.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    /**
     * 执行查询操作
     * @param sql  查询的sql语句
     * @param paras  查询的参数 Object[]数组
     * @return 结果集
     */
    public static ResultSet ExecuteQuery(String sql, Object[] paras) {
        getConnection();
        try {
            pstmt = con.prepareStatement(sql);
            if (paras != null && paras.length > 0) {
                for (int i = 0; i < paras.length; i++) {
                    pstmt.setObject(i + 1, paras[i]);
                }
            }
            ResultSet rs = pstmt.executeQuery();

            return rs;

        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 执行增加、修改、删除操作
     * @param sql  操作的sql语句
     * @param paras  操作的参数
     * @return 受影响的行数
     */
    public static int ExecuteUpdate(String sql, Object[] paras) {
        getConnection();
        try {
            pstmt = con.prepareStatement(sql);
            if (paras != null && paras.length > 0) {
                for (int i = 0; i < paras.length; i++) {
                    pstmt.setObject(i + 1, paras[i]);
                }
            }
            int rs = pstmt.executeUpdate();

            return rs;

        } catch (SQLException e) {
            e.printStackTrace();
            return -1;
        }
    }
}

调用：

package dao;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

import entities.Emp;

public class empDao {

    public List<Emp> GetEmpList() {
        ResultSet rs = BaseDao.ExecuteQuery("select * from emp", null);
        
        try {
            List<Emp> list = new ArrayList<Emp>();
            while (rs.next()) {
                Emp e = new Emp();
                e.setEmpno(rs.getInt("empno"));
                e.setEname(rs.getString("ename"));
                e.setJob(rs.getString("job"));
                e.setMgr(rs.getInt("mgr"));
                e.setHiredate(rs.getDate("hiredate"));
                e.setSal(rs.getDouble("sal"));
                e.setComm(rs.getDouble("comm"));
                e.setDeptno(rs.getInt("deptno"));
                list.add(e);
            }
            return list;
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        } finally {
            BaseDao.Close(rs);
        }
    }
}