lJ2EE三层架构简介
表示层 、业务逻辑层、数据访问层，三层之间用接口隔离。
定义表结构对象userInfo，定义存取用户的接口
用JDBC实现接口
用配置文件(properties)和反射实现与具体类的耦合
数据库：
构造设计：
代码实现：
userInfo.java
package com.us.domain;
import java.util.Date;
public class userInfo {
int id;
String username;
String passwd;
String type;
Date birthday;
float money;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPasswd() {
return passwd;
}
public void setPasswd(String passwd) {
this.passwd = passwd;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public float getMoney() {
return money;
}
public void setMoney(float money) {
this.money = money;
}
}
userInfodao.java
package com.us.dao;
import com.us.domain.userInfo;
public interface userInfodao {
public void addUser(userInfo user);
public userInfo getUser(int userid);
public userInfo findUser(String loginName,String passwd);
public void updateUser(userInfo user);
public void deleteUser(userInfo user);
}
useInfoimpl.java
package com.us.daoimpl;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import com.us.dao.userInfodao;
import com.us.domain.userInfo;
import day820.jdbcUtils;
public class useInfoimpl implements userInfodao {
public void addUser(userInfo user) {
// TODO Auto-generated method stub
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = jdbcUtils.getConnection();
//3.创建语句
String sql = "insert into userInfo(username,passwd,type,birthday,money) values (?,?,?,?,?)";
ps = conn.prepareStatement(sql);
ps.setString(1, user.getUsername());
ps.setString(2, user.getPasswd());
ps.setString(3, user.getType());
ps.setDate(4, new java.sql.Date(user.getBirthday().getTime()));
ps.setFloat(5, user.getMoney());
ps.executeUpdate();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally {
//6.释放资源
//jdbcUtils.free(rs,st,conn);
jdbcUtils.free(rs, ps, conn);
}
}
public userInfo getUser(int userid) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
userInfo user =null;
try {
conn = jdbcUtils.getConnection();
//String sql = "insert into userInfo(username,passwd,type,birthday,money) values (?,?,?,?,?)";
String sql = "select username,passwd,type,birthday,money from userInfo where id=?";
ps = conn.prepareStatement(sql);
ps.setInt(1,userid);
rs = ps.executeQuery();
while (rs.next()){
user = new userInfo();
user.setUsername(rs.getString("username"));
user.setPasswd(rs.getString("passwd"));
user.setType(rs.getString("type"));
user.setBirthday(rs.getDate("birthday"));
user.setMoney(rs.getFloat("money"));
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally {
//6.释放资源
//jdbcUtils.free(rs,st,conn);
jdbcUtils.free(rs, ps, conn);
}
return user;
}
public userInfo findUser(String loginName, String passwd) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
userInfo user =null;
try {
conn = jdbcUtils.getConnection();
String sql = "select username,passwd,type,birthday,money from userInfo where username=?";
ps = conn.prepareStatement(sql);
ps.setString(1,loginName);
rs = ps.executeQuery();
while (rs.next()){
user = new userInfo();
user.setUsername(rs.getString("username"));
user.setPasswd(rs.getString("passwd"));
user.setType(rs.getString("type"));
user.setBirthday(rs.getDate("birthday"));
user.setMoney(rs.getFloat("money"));
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally {
//6.释放资源
//jdbcUtils.free(rs,st,conn);
jdbcUtils.free(rs, ps, conn);
}
return user;
}
public void updateUser(userInfo user) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = jdbcUtils.getConnection();
//3.创建语句
//String sql = "insert into userInfo(username,passwd,type,birthday,money) values (?,?,?,?,?)";
String sql ="update userInfo set username=?,passwd=?,type=?,birthday=?,money=? where id =?";
ps = conn.prepareStatement(sql);
ps.setString(1, user.getUsername());
ps.setString(2, user.getPasswd());
ps.setString(3, user.getType());
ps.setDate(4, new java.sql.Date(user.getBirthday().getTime()));
ps.setFloat(5, user.getMoney());
ps.setInt(6, user.getId());
ps.executeUpdate();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally {
//6.释放资源
//jdbcUtils.free(rs,st,conn);
jdbcUtils.free(rs, ps, conn);
}
}
public void deleteUser(userInfo user) {
// TODO Auto-generated method stub
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = jdbcUtils.getConnection();
//3.创建语句
//String sql = "insert into userInfo(username,passwd,type,birthday,money) values (?,?,?,?,?)";
String sql ="delete from useInfo where name=?";
ps = conn.prepareStatement(sql);
ps.setString(1, user.getUsername());
ps.executeUpdate();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally {
//6.释放资源
//jdbcUtils.free(rs,st,conn);
jdbcUtils.free(rs, ps, conn);
}
}
}
模拟程序测试：
package com.us.test;
import java.util.Date;
import com.us.dao.userInfodao;
import com.us.daoimpl.useInfoimpl;
import com.us.domain.userInfo;
public class userInfotest {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
userInfodao userdao = new useInfoimpl();
userInfo user = new userInfo();
user.setUsername("woli");
user.setPasswd("hello");
user.setBirthday(new Date());
user.setType("1");
user.setMoney(5000.0f);
userdao.addUser(user);
userInfo user1 = new userInfo();
//
user = userdao.getUser(2);
System.out.println(user.getMoney());
}
}
实现了数据库的增删改查。
但是如果底层数据层useInfoimpl.java有改变，业务逻辑层就需要做相关的调整，要解决这个依赖，实现方法：
DAO工厂模式：
接口通过配置文件切换数据访问层的实现
减少依赖 import
在配置文件中注明 接口的实现类
config.properties
userInfodaoclass=com.us.daoimpl.userInfodaoimpldao工厂：
使用反射形式，从配合文件读取字符串，返回实现接口的对象：
package com.us.dao;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
public class DaoFactory {
private static userInfodao userdao = null;
private static DaoFactory instance = new DaoFactory();
//private static userInfodao userdao = null;
//通过私有的构造方法实例化（运用反射的方式）获取userdao
private DaoFactory() {
try {
//通过Properties获取config.properties 键值对
Properties prop = new Properties();
//方式一
//InputStream inStream = new FileInputStream(new File("src/config.properties"));
//方式二好处是不需要定义文件的位置 ，推荐使用
InputStream inStream = DaoFactory.class.getClassLoader().getResourceAsStream("config.properties");
//加载
prop.load(inStream);
String userdaoclass = prop.getProperty("userInfodaoclass");
//通过反射构造实例
userdao = (userInfodao) Class.forName(userdaoclass).newInstance();
} catch (Throwable e) {
// TODO Auto-generated catch block
e.printStackTrace();
throw new ExceptionInInitializerError(e);
}
}
public static DaoFactory getinstance() {
return instance;
}
public userInfodao getuserInfodao() {
return userdao;
}
}
业务逻辑层获取dao工厂返回的对象，就能操作数据库了。不需要再逻辑层创建对象，减少了对数据层的依赖，利于数据层的切换。
package com.us.test;
import java.util.Date;
import com.us.dao.DaoFactory;
import com.us.dao.userInfodao;
import com.us.daoimpl.userInfodaoimpl;
import com.us.sqltable.userInfo;
public class userInfotest {
public static void main(String[] args) {
// TODO Auto-generated method stub
//实例化接口可使用接口里面的方法
//userInfodao userdao = new userInfodaoimpl();
userInfodao userdao = DaoFactory.getinstance().getuserInfodao();
userInfo user = new userInfo();
user.setUsername("user1");
user.setPasswd("ps1");
user.setType("type1");
user.setBirthday(new Date());
user.setMoney(3000.10f);
userdao.addUser(user);
user = userdao.findUser("user1", null);
System.out.println(user.getUsername()+" " +user.getBirthday());
}
}