效果展示

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注册

Servlet接口

接口包括五个方法

• void init(ServletConfig config)
• ServletConfig getServletConfig()
• void service(ServletRequest request, ServletResponse response)
• String getServletInfo()
• void destroy()

GenericServlet抽象类

实现Servlet、ServletConfig、Serializable接口，需重写service方法。

HttpServlet类

继承GenericServlet基础上的扩展，子类必须重写一个方法。
一般只需重写doGet和doPost方法。

• doGet
• doPost
• doPut
• doDelete

Servlet创建方式

实现Servlet接口

直接继承原生的Servlet，较为麻烦

package com.yma16;
import javax.servlet.*;
import java.io.IOException;
public class MyServlet implements Servlet {@Overridepublic void init(ServletConfig servletConfig) throws ServletException {}@Overridepublic ServletConfig getServletConfig() {return null;}@Overridepublic void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {System.out.println("测试1");}@Overridepublic String getServletInfo() {return null;}@Overridepublic void destroy() {}
}

继承HttpServlet

大部分开发人员推荐的创建方式，一般重写

@WebServlet("/hello")//value urlpattern
public class HelloServlet extends HttpServlet {protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{response.getWriter().print("测试！");}protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{doGet( request,response);}
}

实现登录注册

功能逻辑

传统的分为三层

• Entity（写数据库实体类）
• Dao（数据库表的增删改查）
• Service（调用Dao实现登陆注册）

细化的话还可以多一层requestmaping
cookie传递参数给前端界面

配置mysql连接

package com.yma16.batabase;
import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import org.apache.commons.dbutils.DbUtils;import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;public class Dbutils {private static DruidDataSource ds;private static final ThreadLocal<Connection> THREAD_LOCAL=new ThreadLocal<>();static{Properties properties=new Properties();InputStream inputStream= DbUtils.class.getResourceAsStream("/mysqldatabase.properties");//mysql连接try{properties.load(inputStream);ds=(DruidDataSource) DruidDataSourceFactory.createDataSource(properties);}catch (IOException e){e.printStackTrace();}catch(Exception e){e.printStackTrace();}}public static Connection getConnection(){Connection connection=THREAD_LOCAL.get();try{if(connection==null){connection=ds.getConnection();THREAD_LOCAL.set(connection);}}catch (SQLException e){e.printStackTrace();}return connection;}public static void begin(){Connection connection=null;try{connection=getConnection();connection.setAutoCommit(true);}catch (SQLException e){e.printStackTrace();}}public static void commit(){Connection connection=null;try{connection=getConnection();connection.commit();}catch (SQLException e){e.printStackTrace();}finally {closeAll(connection,null,null);}}public static void rollback(){Connection connection=null;try{connection=getConnection();connection.rollback();//回滚}catch (SQLException e){e.printStackTrace();}finally {closeAll(connection,null,null);}}public static void closeAll(Connection connection, Statement statement, ResultSet resultset){try{if(resultset!=null){resultset.close();}if(statement!=null){statement.close();}if(connection!=null){connection.close();THREAD_LOCAL.remove();}}catch (SQLException e){e.printStackTrace();}}
}

Entity

实体对应数据库表user

package com.yma16.entity;public class User {private String username,password;//对应数据库userpublic 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;}@Overridepublic String toString() {return "User{" +"username='" + username + '\'' +"password='" + password + '\'' +'}';}
}

Dao

数据增删改查接口

package com.yma16.dao;import com.yma16.entity.User;import java.util.List;public interface UserDao {//功能接口public User insert(String username,String password);//添加数据public User select(String username);//查询public int delete(String username);//删除数据public int update(User user);//public List<User> selectAll();//查找}

接口实现类

package com.yma16.dao;import com.yma16.batabase.Dbutils;
import com.yma16.entity.User;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import java.sql.SQLException;
import java.util.List;public class UserDaoImpl implements UserDao{//接口实现类private QueryRunner queryRunner=new QueryRunner();@Overridepublic User insert(String username,String password) {try{String sql="insert into user values(?,?)";User user=queryRunner.query(Dbutils.getConnection(),sql,new BeanHandler<User>(User.class),username,password);return user;}catch (SQLException e){e.printStackTrace();}return null;}@Overridepublic User select(String username) {try{String sql="select * from where username=?";User user=queryRunner.query(Dbutils.getConnection(),sql,new BeanHandler<User>(User.class),username);return user;}catch (SQLException e){e.printStackTrace();}return null;}@Overridepublic int delete(String username) {return 0;}@Overridepublic int update(User user) {return 0;}@Overridepublic List<User> selectAll() {try{List<User> users=queryRunner.query(Dbutils.getConnection(),"select * from user",new BeanListHandler<User>(User.class));return users;}catch (SQLException e){e.printStackTrace();}return null;}
}

Service

登陆注册接口

package com.yma16.service;import com.yma16.entity.User;import java.util.List;public interface UserService {public User register(String name,String password);//注册public User login(String name, String password);//登陆public List<User> showAllAdmin();//查询
}

接口实现

package com.yma16.service;import com.yma16.batabase.Dbutils;
import com.yma16.dao.UserDao;
import com.yma16.dao.UserDaoImpl;
import com.yma16.entity.User;import java.util.List;public class UserServiceImpl implements UserService{//实现service接口private UserDao userdao=new UserDaoImpl();//user接口功能@Overridepublic User register(String username, String password) {User result=null;try{Dbutils.begin();User user=userdao.insert(username,password);//插入用户名和密码if(user!=null){if(user.getPassword().equals(password)){result=user;//查询存在则给result}}Dbutils.commit();}catch (Exception e){e.printStackTrace();}return result;}@Overridepublic User login(String username, String password) {User result=null;System.out.println("loading login");try{Dbutils.begin();User user=userdao.select(username);//名字查询System.out.println(user);//查询的结果if(user!=null){if(user.getPassword().equals(password)){result=user;//查询存在则给result(对比)}}Dbutils.commit();}catch (Exception e){e.printStackTrace();}return result;}@Overridepublic List<User> showAllAdmin() {List<User> users=null;try{Dbutils.begin();users=userdao.selectAll();//查询所用userDbutils.commit();}catch (Exception e){Dbutils.rollback();e.printStackTrace();}return users;}
}

servlet调用service

登陆调用service的login

User user=userService.login(username,password);//调用sql查询

注册调用service的register

User user=userService.register(username,password);//注册

end
代码：我的仓库