DAO设计模版

一、VO类

package cn.mldn.lxh.vo;

import java.util.Date;

public class Emp {
    private int empno;
    private String ename;
    private String job;
    private Date hiredate;
    private float sal;
    public int getEmpno() {
        return empno;
    }
    public void setEmpno(int empno) {
        this.empno = empno;
    }
    public String getEname() {
        return ename;
    }
    public void setEname(String ename) {
        this.ename = ename;
    }
    public String getJob() {
        return job;
    }
    public void setJob(String job) {
        this.job = job;
    }
    public Date getHiredate() {
        return hiredate;
    }
    public void setHiredate(Date hiredate) {
        this.hiredate = hiredate;
    }
    public float getSal() {
        return sal;
    }
    public void setSal(float sal) {
        this.sal = sal;
    }
    
    
}

二、数据库连接类

package cn.mldn.lxh.dbc;

import java.sql.Connection;
import java.sql.DriverManager;

public class DatabaseConnection {
    private static final String DBDRIVER = "com.mysql.jdbc.Driver";
    private static final String DBURL = "jdbc:mysql://localhost:3306/mldn";
    private static final String DBUSER = "root";
    private static final String DBPASS = "xyzk123";
    private Connection conn = null;
    public DatabaseConnection() throws Exception{ 
        try{
            Class.forName(DBDRIVER);
            this.conn = DriverManager.getConnection(DBURL, DBUSER, DBPASS);
        }catch(Exception e){
            throw e;
        }
    }
    public Connection getConnection(){
        return this.conn;
    }
    public void close()throws Exception{
        if(this.conn != null){
            try{
                this.conn.close();
            }catch(Exception e){
                throw e;
            }
        }
    }
}

三、DAO操作接口（标准）

package cn.mldn.lxh.dao;

import java.util.List;

import cn.mldn.lxh.vo.Emp;

public interface IEmpDAO {
    
    public boolean doCreate(Emp emp) throws Exception;    //数据增加操作
    
    public List<Emp> findAll(String keyWord) throws Exception;    //查询全部数据
    
    public Emp findById(int empno) throws Exception;    //根据雇员编号查询雇员信息
}

四、DAO接口的真实主题实现类

package cn.mldn.lxh.dao.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import cn.mldn.lxh.dao.IEmpDAO;
import cn.mldn.lxh.vo.Emp;

public class EmpDAOImpl implements IEmpDAO {
    private Connection conn = null;
    private PreparedStatement pstmt = null;
    public EmpDAOImpl(Connection conn){
        this.conn = conn;
    }
    
    public boolean doCreate(Emp emp) throws Exception {
        boolean flag = false;
        String sql = "INSERT INTO emp(empno,ename,job,hiredate,sal) VALUES(?,?,?,?,?)";
        this.pstmt = this.conn.prepareStatement(sql);
        this.pstmt.setInt(1, emp.getEmpno());
        this.pstmt.setString(2, emp.getEname());
        this.pstmt.setString(3, emp.getJob());
        this.pstmt.setDate(4, new java.sql.Date(emp.getHiredate().getTime()));
        this.pstmt.setFloat(5, emp.getSal());
        if(this.pstmt.executeUpdate()>0){
            flag = true;
        }
        this.pstmt.close();
        return flag;
    }
    
    public List<Emp> findAll(String keyWord) throws Exception {
        List<Emp> all = new ArrayList<Emp>();
        String sql = "SELECT empno,ename,job,hiredate,sal FROM emp WHERE ename LIKE ? OR job LIKE?";
        this.pstmt = this.conn.prepareStatement(sql);
        this.pstmt.setString(1, "%" + keyWord + "%");
        this.pstmt.setString(2, "%" + keyWord + "%");
        ResultSet rs = this.pstmt.executeQuery();
        Emp emp = null;
        while(rs.next()){
            emp = new Emp();
            emp.setEmpno(rs.getInt(1));
            emp.setEname(rs.getString(2));
            emp.setJob(rs.getString(3));
            emp.setHiredate(rs.getDate(4));
            emp.setSal(rs.getFloat(5));
            all.add(emp);
        }
        this.pstmt.close();
        return all;
    }
    
    public Emp findById(int empno) throws Exception {
        Emp emp = null;
        String sql = "SELECT empno,ename,job,hiredate,sal FROM emp WHERE empno = ?";
        this.pstmt = this.conn.prepareStatement(sql);
        this.pstmt.setInt(1, empno);
        ResultSet rs = this.pstmt.executeQuery();
        if(rs.next()){
            emp  = new Emp();
            emp.setEmpno(rs.getInt(1));
            emp.setEname(rs.getString(2));
            emp.setJob(rs.getString(3));
            emp.setHiredate(rs.getDate(4));
            emp.setSal(rs.getFloat(5));
        }
        this.pstmt.close();
        return emp;
    }
}

五、代理实现类

package cn.mldn.lxh.dao.proxy;

import java.util.List;

import cn.mldn.lxh.dao.IEmpDAO;
import cn.mldn.lxh.dao.impl.EmpDAOImpl;
import cn.mldn.lxh.dbc.DatabaseConnection;
import cn.mldn.lxh.vo.Emp;

public class EmpDAOProxy implements IEmpDAO{
    private DatabaseConnection dbc = null;
    private IEmpDAO dao = null;
    public EmpDAOProxy() throws Exception{
        this.dbc = new DatabaseConnection();
        this.dao = new EmpDAOImpl(this.dbc.getConnection());
    }
    public boolean doCreate(Emp emp) throws Exception{
        boolean flag = false;
        try{
            if(this.dao.findById(emp.getEmpno()) == null){
                flag = this.dao.doCreate(emp);
            }
        }catch(Exception e){
            throw e;
        }finally{
            this.dbc.close();
        }
        return flag;
    }
    public List<Emp> findAll(String keyWord) throws Exception {
        List<Emp> all = null;
        try{
            all = this.dao.findAll(keyWord);
            }catch(Exception e){
                throw e;
            }finally{
                this.dbc.close();
            }
        return all;
    }
    public Emp findById(int empno) throws Exception {
        Emp emp = null;
        try{
            emp = this.dao.findById(empno);
        }catch(Exception e){
            throw e;
        }finally{
            this.dbc.close();
        }
        return emp;
    }
}

六、DAO工厂类

package cn.mldn.lxh.factory;

import cn.mldn.lxh.dao.IEmpDAO;
import cn.mldn.lxh.dao.proxy.EmpDAOProxy;

public class DAOFactory {
    public static IEmpDAO getIEmpDAOInstance()throws Exception{
        return new EmpDAOProxy();
    }
}

七、简单测试

（1）

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Dao</title>
</head>

<body>
    <form action="emp_insert_do.jsp" method="post">
        编号：<input type="text" name="empno" /><br />
        姓名：<input type="text" name="ename" /><br />
        职位：<input type="text" name="job" /><br />
        日期：<input type="text" name="hiredate" /><br />
        工资：<input type="text" name="sal" /><br />
        <input type="submit" value="注册" />
        <input type="reset" value="重置" />
    </form>
</body>
</html>

（2）

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>peixun</title>
</head>

<body>
    <%
        Emp emp = new Emp();
        emp.setEmpno(Integer.parseInt(request.getParameter("empno")));
        emp.setEname(request.getParameter("ename"));
        emp.setJob(request.getParameter("job"));
        
        emp.setHiredate(new SimpleDateFormat("yyyy-MM-dd").parse(request
            .getParameter("hiredate")));
        
        emp.setSal(Float.parseFloat(request.getParameter("sal")));
        try{
            if(DAOFactory.getIEmpDAOInstance().doCreate(emp)){
    %>
                <h3>信息添加成功</h3>
    <%
            }else{
    %>
                <h3>信息添加失败</h3>
    <%
            }
    
        }catch(Exception e){
            e.printStackTrace();
        }
    %>
</body>
</html>