23. Getting started with servlet - user registration case

Case - Registration

1. Demand

1571732869531

2. Three tier architecture

• Layering in software: it is divided into different layers according to different functions. It is usually divided into three layers: presentation layer (web layer), business layer and persistence (database) layer.

img

• Naming of package names at different levels

• Meaning of stratification:
  1. Decoupling: reduce the coupling between layers.
  2. Maintainability: improve the maintainability of the software, and the modification and update of existing functions will not affect the original functions.
  3. Scalability: improve the scalability of the software. Adding new functions will not affect the existing functions.
  4. Reusability: when calling functions between different layers, the same functions can be reused.
• Purpose of program design:
  • High cohesion and low coupling
  • Strong scalability
  • Strong maintainability
  • Strong reusability

3. Complete the registration case

3.1 registration case ideas

image-20191209154418825

3.2 preparation

3.2.1 creating database

create database userdemo;
use userdemo;

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(40) DEFAULT NULL,
  `password` varchar(40) DEFAULT NULL,
  `address` varchar(40) DEFAULT NULL,
  `nickname` varchar(40) DEFAULT NULL,
  `gender` varchar(10) DEFAULT NULL,
  `email` varchar(20) DEFAULT NULL,
  `status` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8

3.2.2 creating engineering structures

image-20210112083937875

3.2.3 creating JavaBean s

Under the pojo package, create the User class as follows:

image-20210112084156225

public class User implements Serializable{
    private Integer id;
    private String username;
    private String password;
    private String address;
    private String nickname;
    private String gender;
    private String email;
    private String status;//1 means activated, 0 means inactive
 //...
}

3.3 configuring Maven dependencies

3.3.1 configuration database related dependencies

• mysql driver
• druid
• dbutils
• beanutils

Set the dependency in pom.xml of the project as follows:

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.lijw</groupId>
    <artifactId>javaweb_userdemo_01</artifactId>
    <version>1.0-SNAPSHOT</version>
    <!--  Packaging method  -->
    <packaging>war</packaging>

    <!-- Project properties, setting jdk And coding -->
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <!--  Set dependency  -->
    <dependencies>
        <!-- dbutils rely on       -->
        <!-- https://mvnrepository.com/artifact/commons-dbutils/commons-dbutils -->
        <dependency>
            <groupId>commons-dbutils</groupId>
            <artifactId>commons-dbutils</artifactId>
            <version>1.7</version>
        </dependency>
        <!--  druid rely on      -->
        <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.4</version>
        </dependency>
        <!--  mysql Connection dependency      -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.49</version>
        </dependency>
        <!-- Import BeanUtils rely on       -->
        <dependency>
            <groupId>commons-beanutils</groupId>
            <artifactId>commons-beanutils</artifactId>
            <version>1.9.3</version>
        </dependency>
        <!-- Import commons-io       -->
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>
        <!--introduce junit Dependence of       -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <!--introduce servlet Dependence of-->
        <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

</project>

3.4 required tool classes and configuration files

• DruidUtil
• druid.properties

image-20210215171518750

3.4.2 druid.properties

Configure the parameters related to druid connection to the database.

url=jdbc:mysql://localhost:3306/userdemo?rewriteBatchedStatements=true&serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf8&useSSL=false
username=root
password=Lijw******password**********0
driverClassName=com.mysql.jdbc.Driver

initialSize=10
maxActive=10

3.4.1 DruidUtil: used to obtain database connection pool

package com.utils;

import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.InputStream;
import java.util.Properties;

public class DruidUtil {

    private static DataSource dataSource;

    static {
        try {
            //1. Create Properties object
            Properties properties = new Properties();
            //2. Convert the configuration file into byte input stream
            InputStream is = DruidUtil.class.getClassLoader().getResourceAsStream("druid.properties");
            //3. Use the properties object to load is
            properties.load(is);
            //The druid bottom layer uses the factory design pattern to load the configuration file and create the DruidDataSource object
            dataSource = DruidDataSourceFactory.createDataSource(properties);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static DataSource getDataSource(){
        return dataSource;
    }
}

3.4.3 DruidUtilTest: Test DruidUtil to obtain database connection

public class DruidUtilTest {

    @Test
    public void getDataSource() throws SQLException {
        // Get database connection pool for druid
        DataSource dataSource = DruidUtil.getDataSource();

        //Test insert data
        QueryRunner queryRunner = new QueryRunner(DruidUtil.getDataSource());
        String sql = "insert into user(`username`, `password`, `address`, `nickname`, `gender`, `email`) values (?,?,?,?,?,?)";

        //Insert the data stored by user into the database
        int i = queryRunner.update(sql, "testuser05", "483212", "Shenzhen", "DevOps Fisherman of the sea", "male", "123@qq.com");
        System.out.println("Number of data rows inserted: " + i);
    }
}

The implementation is as follows:

image-20210215181045692

Well, here we are ready for the database connection code. Let's gradually and simply implement the case of user registration.

4. Registration case realization

4.1 registration page

image-20210215174146646

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>register</title>
</head>
<body>
    <!-- Form for submitting registration information: for each field name The value needs to be consistent with the field name of the database for subsequent use BeanUtils.populate Encapsulate data   -->
    <form action="/userDemo/register" method="post">
        user name<input type="text" name="username"><br>
        password<input type="text" name="password"><br>
        nickname<input type="text" name="nickname"><br>
        address<input type="text" name="address"><br>
        mailbox<input type="text" name="email"><br>
        Gender<input type="radio" name="gender" value="male">male
        <input type="radio" name="gender" value="female">female
        <br>
        <input type="submit" value="register">
    </form>
</body>
</html>

Start tomcat to view this page, as follows:

image-20210215174350090

OK, the registration page has been written. Let's continue to write the Servlet of registration business

4.2 code of registerservlet

image-20210215181311490

package com.servlet;

import com.pojo.User;
import com.utils.DruidUtil;
import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.dbutils.QueryRunner;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;

/**
 * @author Aron.li
 * @date 2021/2/15 17:44
 */
@WebServlet("/register")
public class RegisterServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. Solve the garbled code problem at the front: the Chinese garbled code of the request parameter and the Chinese garbled code of the response
        //Solve the Chinese garbled code of request parameters
        request.setCharacterEncoding("UTF-8");
        //Solve Chinese garbled code in response
        response.setContentType("text/html;charset=utf-8");

        //2. Get all request parameters
        Map<String, String[]> parameterMap = request.getParameterMap();
        System.out.println("Received parameters: ");
        for (Map.Entry<String, String[]> entry : parameterMap.entrySet()) {
            for (String value : entry.getValue()) {
                System.out.println(entry.getKey() + ": " + value);
            }
        }

        //3. Use BeanUtils to store the data in the parameterMap into the User object
        User user = new User();

        //Set the default status to "0"
        user.setStatus("0");

        try {
            // Use BeanUtils.populate to save the received parameters to the user object
            BeanUtils.populate(user,parameterMap);

            //4. Use DBUtils to store user information in the database
            //The jar packages of mysql driver, druid and dbutils are required here
            QueryRunner queryRunner = new QueryRunner(DruidUtil.getDataSource());
            String sql = "insert into user values (null,?,?,?,?,?,?,?)";

            //Insert the data stored by user into the database
            queryRunner.update(sql,user.getUsername(),user.getPassword(),user.getAddress(),
                    user.getNickname(),user.getGender(),user.getEmail(),user.getStatus());

            //If the registration is successful, respond to the browser with the sentence "registration is successful"
            response.getWriter().write("login was successful");

        } catch (Exception e) {
            e.printStackTrace();

            //If the registration fails, respond to the browser with "registration failed"
            response.getWriter().write("login has failed");
        }
    }
}

Perform registration on the registration page as follows:

image-20210215181420271

4.3 viewing the inserted registration data in the database

mysql> select * from user \G
*************************** 1. row ***************************
      id: 1
username: testuser05
password: 483212
 address: Shenzhen
nickname: DevOps Fisherman of the sea
  gender: male
   email: 123@qq.com
  status: 0
1 row in set (0.00 sec)

mysql> 

4.4 create a successful login homepage index.html

After the above RegisterServlet is registered successfully, only the information of successful registration is returned in the page. Let's write a successful login page to provide page redirection.

image-20210215181705163

4.5 modify the RegisterServlet. After successful registration, jump to index.html

image-20210215182016293

package com.servlet;

import com.pojo.User;
import com.utils.DruidUtil;
import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.dbutils.QueryRunner;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;

/**
 * @author Aron.li
 * @date 2021/2/15 17:44
 */
@WebServlet("/register")
public class RegisterServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. Solve the garbled code problem at the front: the Chinese garbled code of the request parameter and the Chinese garbled code of the response
        //Solve the Chinese garbled code of request parameters
        request.setCharacterEncoding("UTF-8");
        //Solve Chinese garbled code in response
        response.setContentType("text/html;charset=utf-8");

        //2. Get all request parameters
        Map<String, String[]> parameterMap = request.getParameterMap();
        System.out.println("Received parameters: ");
        for (Map.Entry<String, String[]> entry : parameterMap.entrySet()) {
            for (String value : entry.getValue()) {
                System.out.println(entry.getKey() + ": " + value);
            }
        }

        //3. Use BeanUtils to store the data in the parameterMap into the User object
        User user = new User();

        //Set the default status to "0"
        user.setStatus("0");

        try {
            // Use BeanUtils.populate to save the received parameters to the user object
            BeanUtils.populate(user,parameterMap);

            //4. Use DBUtils to store user information in the database
            //The jar packages of mysql driver, druid and dbutils are required here
            QueryRunner queryRunner = new QueryRunner(DruidUtil.getDataSource());
            String sql = "insert into user values (null,?,?,?,?,?,?,?)";

            //Insert the data stored by user into the database
            queryRunner.update(sql,user.getUsername(),user.getPassword(),user.getAddress(),
                    user.getNickname(),user.getGender(),user.getEmail(),user.getStatus());

            //If the registration is successful, respond to the browser with the sentence "registration is successful"
//            response.getWriter().write("registration succeeded");
            //If the registration is successful, go to index.html
            response.sendRedirect("/userDemo/index.html");

        } catch (Exception e) {
            e.printStackTrace();

            //If the registration fails, respond to the browser with "registration failed"
            response.getWriter().write("login has failed");
        }
    }
}

4.6 test registration page

image-20210215181915592

image-20210215181933542

5. Summary

1. Registration essence: insert a record into the database
2. Idea (in RegisterServlet)
   • Obtain the data submitted by the User and encapsulate it into a User object using BeanUtils
   • Complete User object (status)
   • Use DBUtils to insert a record into the database
   • response