工厂模式之模板模式
文章目录
1.概念
1.模板模式通常又称之为模板方法模式,是指定一个一个算法的骨架流程,并允许子类对一个或者多个步骤[方法]提供实现;
2.属于行为性设计模式;
2.适用场景
1.一次性实现一个算法框架流程不变的部分,并将可变的行为留给子类来实现;
2.各个子类中公共的行为被提取出来并集中到一个公共的父类中,从而避免代码的重复
3.案例
3.1.面试流程案例
3.1.1.面试流程RecruitProcess
package com.gaoxinfu.demo.parttern.template.recruit;
/**
* Created by gaoxinfu on 2019/3/17.
*/
public abstract class RecruitProcess {
/**
* 招聘流程
*/
protected final void recruit(){
//1.分析需求人员
this.analyzeRequirements();
//2.发布招聘信息
this.publish();
//3.笔试
if (this.isNeedWrittenExamination()){
this.writtenExamination();;
}
//4.面试
this.interview();
//5.入职
this.entry();
}
/**
* 将方法定义为final修饰 主要是指定该方法不能被重写
*/
final void analyzeRequirements(){
System.out.println("分析人员需求");
}
final void publish(){
System.out.println("发布招聘信息");
}
/**
* 钩子方法：实现流程的微调 需要实现或者重写的方法,实现流程的微调
* @return
*/
protected Boolean isNeedWrittenExamination(){
//默认不需要笔试
return false;
}
/**
* 笔试具体根据不同的岗位要求,笔试的内容不一致,因此需要实现
*/
abstract void writtenExamination();
final void interview(){
System.out.println("面试");
}
final void entry(){
System.out.println("开始入职");
}
}
3.1.2.面试流程CivilianStaffRecruitProcess[文职人员面试流程]
package com.gaoxinfu.demo.parttern.template.recruit;
/**
* Created by gaoxinfu on 2019/3/17.
*/
public class CivilianStaffRecruitProcess extends RecruitProcess{
@Override
void writtenExamination() {
System.out.println("文职人员不需要笔试");
}
}
3.1.2.面试流程ItRecruitProcess[IT人员面试流程]
package com.gaoxinfu.demo.parttern.template.recruit;
/**
* Created by gaoxinfu on 2019/3/17.
*/
public class ItRecruitProcess extends RecruitProcess{
@Override
void writtenExamination() {
System.out.println("IT人员笔试流程");
}
protected Boolean isNeedWrittenExamination(){
//需要笔试
return true;
}
}
3.1.3.面试流程测试
3.1.3.1.IT人员测试
package com.gaoxinfu.demo.parttern.template.recruit;
/**
* Created by gaoxinfu on 2019/3/17.
*/
public class ItRecruitProcessTest {
public static void main(String[] args) {
RecruitProcess recruitProcess=new ItRecruitProcess();
recruitProcess.recruit();
}
}
3.1.3.2.文职人员测试[不需要笔试]
package com.gaoxinfu.demo.parttern.template.recruit;
/**
* Created by gaoxinfu on 2019/3/17.
*/
public class CivilianStaffRecruitProcessTest {
public static void main(String[] args) {
RecruitProcess recruitProcess=new CivilianStaffRecruitProcess();
recruitProcess.recruit();
}
}
3.1.JDBC流程案例
3.1.1.首先创建 ORM映射定制化的接口
package com.gaoxinfu.demo.parttern.template.jdbc;
import java.sql.ResultSet;
/**
* Created by gaoxinfu on 2019/3/17.
* ORM映射定制化的接口 主要是后面映射返回的数据对象
*
*/
public interface RowMapper<T> {
/**
* @param resultSet
* @param rowNum
* @return 这里的返回类型T,由入参类型T决定
* @throws Exception
*/
T mapRow(ResultSet resultSet,int rowNum) throws Exception;
}
3.1.2.创建JDBC模板
package com.gaoxinfu.demo.parttern.template.jdbc;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
/**
* Created by gaoxinfu on 2019/3/17.
*/
public class JdbcTemplate {
private DataSource dataSource;
public JdbcTemplate(DataSource dataSource) {
this.dataSource = dataSource;
}
public List<?> executeQuery(String sql,RowMapper<?> rowMapper,Object[] values) throws Exception {
/**
* 1.获取连接
*/
Connection connection=this.getConnection();
//2.创建语句集
PreparedStatement preparedStatement=this.createPrepareStatement(connection,sql);
//3.执行语句集
ResultSet resultSet=this.executeQuery(preparedStatement,values);
//4.处理结果集
List<?> result=this.parseResultSet(resultSet,rowMapper);
//5.关闭结果集
this.closeResultSet(resultSet);
//6.关闭语句集
this.closeStatement(preparedStatement);
//7.关闭连接
this.closeConnection(connection);
return result;
}
protected Connection getConnection() throws SQLException {
return this.dataSource.getConnection();
}
protected PreparedStatement createPrepareStatement(Connection conn,String sql) throws SQLException {
return conn.prepareStatement(sql);
}
protected ResultSet executeQuery(PreparedStatement preparedStatement,Object[] values) throws Exception {
for (int i = 0;i<values.length;i++){
preparedStatement.setObject(i,values[i]);
}
return preparedStatement.executeQuery();
}
protected List<?> parseResultSet(ResultSet resultSet,RowMapper<?> rowMapper) throws Exception {
List<Object> result=new ArrayList<>();
int rowNum=1;
while(resultSet.next()){
result.add(rowMapper.mapRow(resultSet,rowNum++));
}
return result;
}
protected void closeStatement(PreparedStatement preparedStatement) throws SQLException {
preparedStatement.close();
}
protected void closeResultSet(ResultSet resultSet) throws SQLException {
resultSet.close();;
}
protected void closeConnection(Connection conn) throws Exception {
//数据库连接池，我们不是关闭
conn.close();
}
}
3.1.3.模拟创建数据库实体返回的结果集对象
package com.gaoxinfu.demo.parttern.template.jdbc;
/**
* Created by gaoxinfu on 2019/3/17.
*/
public class Member {
private String username;
private String password;
private String nickname;
private int age;
private String addr;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getNickname() {
return nickname;
}
public void setNickname(String nickname) {
this.nickname = nickname;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getAddr() {
return addr;
}
public void setAddr(String addr) {
this.addr = addr;
}
}
3.1.4.创建指定实体对象的查询库的DAO对象
package com.gaoxinfu.demo.parttern.template.jdbc.dao;
import com.gaoxinfu.demo.parttern.template.jdbc.JdbcTemplate;
import com.gaoxinfu.demo.parttern.template.jdbc.Member;
import com.gaoxinfu.demo.parttern.template.jdbc.RowMapper;
import javax.sql.DataSource;
import java.sql.ResultSet;
import java.util.List;
/**
* Created by gaoxinfu on 2019/3/17.
*/
public class MemberDAO extends JdbcTemplate{
public MemberDAO(DataSource dataSource) {
super(dataSource);
}
public List<?> selectAll() throws Exception {
String sql="select * from t_member";
return super.executeQuery(sql, new RowMapper<Member>() {
public Member mapRow(ResultSet rs, int rowNum) throws Exception {
Member member = new Member();
//字段过多，原型模式
member.setUsername(rs.getString("username"));
member.setPassword(rs.getString("password"));
member.setAge(rs.getInt("age"));
member.setAddr(rs.getString("addr"));
return member;
}
},null);
}
}
3.1.5.测试
import com.gaoxinfu.demo.parttern.template.jdbc.dao.MemberDAO;
import java.util.List;
/**
* Created by gaoxinfu on 2019/3/17.
*/
public class MemberDaoTest {
public static void main(String[] args) throws Exception {
MemberDAO memberDAO=new MemberDAO(null);
List<?> result=memberDAO.selectAll();
System.out.println(result);
}
}
由于我们数据库都没有配置,因此,测试肯定不通的,大家理解原理即可
4.补充实际框架的应用举例
4.1.JDK中AbstractList
AbstractList中的get方法等等,由于其实现类不同,实现的方法不一致;
4.3.Mybatis中的 BaseExecutor
java中基础的sql执行类
多个实现类