首页手记 Java通过反射机制简化Dao层的繁琐操作

Java通过反射机制简化Dao层的繁琐操作

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Java

配置文件 jdbc.properties

jdbc=jdbc:mysql://localhost:3306/wangyi
Driver=com.mysql.jdbc.Driver
name=root
password=123456

Config.java

package com.Wangyi.config;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

/**
 * Created by Administrator on 2017/1/1.
 */
public class Config {
    public static void main(String[] args) {
        System.out.println(getConfig("Driver"));
    }
    public static String getConfig(String nKey){
        try {
            Properties pro=new Properties();
            InputStream is=Config.class.getClassLoader().getResourceAsStream("jdbc.properties");
            pro.load(is);
            return pro.getProperty(nKey);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

BaseDao.java

package com.Dao;

import java.lang.reflect.Field;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

import com.Wangyi.config.Config;

/**
 * Created by Administrator on 2017/1/1.
 * Dao层 实现与数据库的交互工作
 */
public class BaseDao {
    private static Connection con = null;
    private static PreparedStatement ps = null;
    private static ResultSet rs = null;

    /**
     * 静态初始化块
     * 加载驱动
     * 获取连接
     */
    static {
        try {
            Class.forName(Config.getConfig("Driver"));
            con = DriverManager.getConnection(Config.getConfig("jdbc"), Config.getConfig("name"), Config.getConfig("password"));
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    /**
     * 执行从Dao层提交的sql语句
     * @param sql           sql语句
     * @param parameter     sql语句需要设置的属性
     * @param cla           将查询的属性赋予给一个对象（比如：查询user表 则新建一个user表的模型与之对应）
     * @return              返回结果
     */
    public static List<?> setsql(String sql, Object[] parameter, Class<?> cla) {
        List<Object> list = new ArrayList();
        try {
            con = getCon();
            ps = con.prepareStatement(sql);
            if (parameter != null && parameter.length > 0) {
                for (int i = 0; i < parameter.length; i++) {
                    ps.setObject((i + 1), parameter[i]);
                }
            }
            if (sql.toLowerCase().startsWith("select")) {
                rs = ps.executeQuery();
                while (rs.next()) {
                    ResultSetMetaData meta = rs.getMetaData();
                    int count = meta.getColumnCount();
                    Object nClass = cla.newInstance();
                    for (int i = 0; i < count; i++) {
                        String metaName = meta.getColumnName(i + 1);
                        Object metaValue = rs.getObject(metaName);
                        Field fieldName = cla.getDeclaredField(metaName);
                        fieldName.setAccessible(true);
                        fieldName.set(nClass, metaValue);
                    }
                    list.add(nClass);
                }
            } else {
                list.add(ps.executeUpdate());
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        }
        return list;
    }

    /**
     * 调用连接
     * @return
     */
    public static Connection getCon() {
        return con;
    }

    /**
     * 关闭连接释放资源
     * @param con   关闭Connection
     * @param ps    关闭PreparedStatement
     * @param rs    关闭ResultSet
     */
    public static void getClose(Connection con, PreparedStatement ps, ResultSet rs) {
        try {
            if (con != null) con.close();
            if (ps != null) ps.close();
            if (rs != null) rs.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Dao.java

package com.Dao;

import com.model.user;

import java.util.List;

/**
 * Created by Administrator on 2017/1/1.
 */
public class Dao extends BaseDao{
    public static void main(String[] args) {
        System.out.println(uNameIsFlag("ss"));
    }
    /**
     * 将注册的信息添加到数据库中
     * @param uName 用户名
     * @param uPassword 用户密码
     * @param Sex   性别
     * @param Name  真实姓名
     * @param nickName  昵称
     * @param Telephone 电话号码
     * @param Email 电子邮箱
     * @return
     */
    public static Boolean AddUser(String uName,String uPassword,int Sex,String Name,String nickName,String Telephone,String Email){
        String sql="Insert into user(uName,uPassword,Sex,Name,nickName,Telephone,Email) Values(?,?,?,?,?,?,?)";
        Object[] Parameter={uName,uPassword,Sex,Name,nickName,Telephone,Email};
        int num=(Integer)Dao.setsql(sql,Parameter,null).get(0);
        if(num>0) return true;
        return false;
    }

    /**
     * 判断数据库中是否存在该用户
     * @param uName 用户名
     * @return  返回匹配结果
     */
    public static boolean uNameIsFlag(String uName){
        String sql="select uName from user";
        List<user> list= (List<user>) Dao.setsql(sql,null, user.class);
        for (user user:list) {
            if(user.getuName().equals(uName)){
                return true;
            }
        }
        return false;
    }

}

services.java

package com.Services;

import com.Dao.Dao;
import com.model.user;

/**
 * Created by Administrator on 2017/1/1.
 * 业务逻辑层 进行各种逻辑处理
 */
public class Services {
    public static boolean doRegister(user user) {
        if (!user.getuName().matches("^[a-zA-Z0-9][a-zA-Z0-9\\-\\._]{2,16}[a-zA-Z0-9]$")) return false;
        if (Dao.uNameIsFlag(user.getuName())) return false;
        if (!user.getuPassword().equals(user.getConfirmPassword())) return false;
        if (!user.getTelephone().matches("^(13|15|18|17)\\d{9}$")) return false;
        if (!user.getEmail().matches("^\\w+@\\w+(\\.[a-zA-Z]{2,3}){1,2}$")) return false;
        Boolean Flag = Dao.AddUser(user.getuName(), user.getuPassword(), user.getSex(), user.getName(), user.getNickName(), user.getTelephone(), user.getEmail());
        if (!Flag) return false;
        return true;
    }
}

ServletForRegister.jsp

package com.Wangyi.Action;

import com.Services.Services;
import com.model.user;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * Created by Administrator on 2017/1/1.
 * Action层 调用Services层的方法来处理页面的 请求
 */
public class ServletForRegister extends HttpServlet{
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        String uName=req.getParameter("uName");
        String uPassword=req.getParameter("uPassword");
        String confirmPassword=req.getParameter("confirmPassword");
        int Sex=Integer.parseInt(req.getParameter("Sex"));
        String Name=req.getParameter("Name");
        String nickName=req.getParameter("nickName");
        String Telephone=req.getParameter("Telephone");
        String Email=req.getParameter("Email");
        user user=new user(uName,uPassword,confirmPassword,Sex,Name,nickName,Telephone,Email);
        if(Services.doRegister(user)) {
            req.setAttribute("user", user);
            req.getRequestDispatcher("pages/Success.jsp").forward(req, resp);
        }else {
            req.getRequestDispatcher("pages/Fail.jsp").forward(req,resp);
        }
    }
}

user.java (模型对象)

package com.model;

/**
 * Created by Administrator on 2017/1/1.
 * 模型层
 */
public class user {
    private String uName;
    private String uPassword;
    private String confirmPassword;
    private int Sex;
    private String Name;
    private String nickName;
    private String Telephone;
    private String Email;

    public user() {
    }

    public user(String uName, String uPassword, String confirmPassword, int sex, String name, String nickName, String telephone, String email) {
        this.uName = uName;
        this.uPassword = uPassword;
        this.confirmPassword = confirmPassword;
        Sex = sex;
        Name = name;
        this.nickName = nickName;
        Telephone = telephone;
        Email = email;
    }

    @Override
    public String toString() {
        return "用户名："+uName+"\n密码："+uPassword+"\n性别："+Sex+"\n真实姓名："+Name+"\n昵称："+nickName+"\n电话号码："+Telephone+"\nEmail："+Email;
    }

    public String getuName() {
        return uName;
    }

    public void setuName(String uName) {
        this.uName = uName;
    }

    public String getuPassword() {
        return uPassword;
    }

    public void setuPassword(String uPassword) {
        this.uPassword = uPassword;
    }

    public String getConfirmPassword() {
        return confirmPassword;
    }

    public void setConfirmPassword(String confirmPassword) {
        this.confirmPassword = confirmPassword;
    }

    public int getSex() {
        return Sex;
    }

    public void setSex(int sex) {
        Sex = sex;
    }

    public String getName() {
        return Name;
    }

    public void setName(String name) {
        Name = name;
    }

    public String getNickName() {
        return nickName;
    }

    public void setNickName(String nickName) {
        this.nickName = nickName;
    }

    public String getTelephone() {
        return Telephone;
    }

    public void setTelephone(String telephone) {
        Telephone = telephone;
    }

    public String getEmail() {
        return Email;
    }

    public void setEmail(String email) {
        Email = email;
    }
}

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