I. JPA

1. Creating projects

2. Importing Thymeleaf dependencies in pom.xml files

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.8.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.xjj</groupId>
    <artifactId>springboot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <!-- Thymeleaf Dependent version number of -->
        <thymeleaf.version>3.0.11.RELEASE</thymeleaf.version>
        <thymeleaf-layout-dialect.version>2.2.2</thymeleaf-layout-dialect.version>
    </properties>

    <dependencies>
        <!-- JPA rely on -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <!-- JDBC rely on -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <!-- mybatis rely on -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.0</version>
        </dependency>
        <!-- Mysql Partial dependency -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!-- Thymeleaf Dependence -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <!-- Dependencies used in testing -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- web Component dependency -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

3. Configure connection database information and JPA, using yaml file writing here

spring:
  datasource:
    username: root
    password: 1234
    url: jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC
    driver-class-name: com.mysql.cj.jdbc.Driver
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true

4. Creating Entity Classes for Mapping Data Tables

package com.xjj.springboot.entity;

import javax.persistence.*;

/**
 * @Entity Description is entity class
 * @Table Specify which table to map, default to lowercase at the beginning
 * @Id Note is the primary key
 * @GenerationValue(strategy = GenerationType.IDENTIFY)Primary key policy is specified
 * @Column Note the corresponding column attributes, the default name is the hump rule, length is the length of varchar
 * @Author xjj
 */
@Entity
@Table
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer bookId;
    @Column(length = 50)
    private String bookName;
    @Column
    private Double bookPrice;

    public Integer getBookId() {
        return bookId;
    }

    public void setBookId(Integer bookId) {
        this.bookId = bookId;
    }

    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    public Double getBookPrice() {
        return bookPrice;
    }

    public void setBookPrice(Double bookPrice) {
        this.bookPrice = bookPrice;
    }

    @Override
    public String toString() {
        return "Book{" +
                "bookId=" + bookId +
                ", bookName='" + bookName + '\'' +
                ", bookPrice=" + bookPrice +
                '}';
    }
}

5. Creating interfaces to inherit JpaRepository

package com.xjj.springboot.dao;

import com.xjj.springboot.entity.Book;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * After inheriting JpaRepository, the interface class can inherit the basic functions of addition, deletion, modification and paging.
 * The first generic of JpaRepository corresponds to which entity class, and the second is the type of primary key.
 * @author xjj
 */
public interface BookRepository extends JpaRepository<Book,Integer> {
    
}

6. Create service layer and controller, and query all information in book table

package com.xjj.springboot.service;

import com.xjj.springboot.entity.Book;

import java.util.List;

/**
 * @author xjj
 */
public interface BookService {
    /**
     * Used to query book tables
     * @return 
     */
    List<Book> findAll();
}

package com.xjj.springboot.service.impl;

import com.xjj.springboot.dao.BookRepository;
import com.xjj.springboot.entity.Book;
import com.xjj.springboot.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

/**
 * @author xjj
 * Among them, bookRepository itself comes with basic addition, deletion, modification and paging methods.
 */
@Service
public class BookServiceImpl implements BookService {
    @Autowired
    private BookRepository bookRepository;

    @Override
    public List<Book> findAll(){
        return bookRepository.findAll();
    }
}

package com.xjj.springboot.controller;

import com.xjj.springboot.entity.Book;
import com.xjj.springboot.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.List;

/**
 * @author xjj
 */
@Controller
public class BookController {
    @Autowired
    private BookService bookService;

    @RequestMapping("/findAll")
    @ResponseBody
    public List<Book> findAll(){
        return bookService.findAll();
    }
}

7. Start-up project

Mybatis - Next, the Jpa above operates to create a method that can query the book table by id

1. Create Mapper's interface file

package com.xjj.springboot.dao;

import com.xjj.springboot.entity.Book;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Component;

/**
 * @Author xjj
 */
@Mapper
@Component
public interface BookMapper {
    /**
     * Query the data according to the id of the book
     * @param bookId
     * @return
     */
    Book queryBookByBookId(@Param("bookId") Integer bookId);
}

2. Create Mybatis Core Profile

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!-- Since all the classes created automatically are named after humps, there will be other humps in the future. mybatis Configuration can also be added here -->
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
</configuration>

3. Create Mapper's mapping file

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.xjj.springboot.dao.BookMapper">
    <select id="queryBookByBookId" resultType="com.xjj.springboot.entity.Book">
        select * from book
    </select>
</mapper>

4. service layer and conotroler layer

package com.xjj.springboot.service;

import com.xjj.springboot.entity.Book;

import java.util.List;

/**
 * @author xjj
 */
public interface BookService {
    /**
     * Used to query book tables
     * @return
     */
    List<Book> findAll();

    /**
     * Use serial numbers to query book tables
     * @param bookId
     * @return
     */
    Book queryBookByBookId(Integer bookId);
}

package com.xjj.springboot.service.impl;

import com.xjj.springboot.dao.BookMapper;
import com.xjj.springboot.dao.BookRepository;
import com.xjj.springboot.entity.Book;
import com.xjj.springboot.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

/**
 * @author xjj
 * Among them, bookRepository itself comes with basic addition, deletion, modification and paging methods.
 */
@Service
public class BookServiceImpl implements BookService {
    @Autowired
    private BookRepository bookRepository;
    @Autowired
    private BookMapper bookMapper;

    @Override
    public List<Book> findAll(){
        return bookRepository.findAll();
    }

    @Override
    public Book queryBookByBookId(Integer bookId) {
        return bookMapper.queryBookByBookId(bookId);
    }

}

package com.xjj.springboot.controller;

import com.xjj.springboot.dao.BookMapper;
import com.xjj.springboot.entity.Book;
import com.xjj.springboot.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.List;

/**
 * @author xjj
 */
@Controller
public class BookController {
    @Autowired
    private BookService bookService;

    @RequestMapping("/findAll")
    @ResponseBody
    public List<Book> findAll(){
        return bookService.findAll();
    }
    @RequestMapping("/queryBookByBookId/{bookId}")
    @ResponseBody
    public Book queryBookByBookId(@PathVariable Integer bookId){
        return bookService.queryBookByBookId(bookId);
    }
}

5. Modify yaml file configuration

spring:
  datasource:
    username: root
    password: 1234
    url: jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC
    driver-class-name: com.mysql.cj.jdbc.Driver
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
mybatis:
  config-location: classpath:mybatis/config/mybatis-config.xml
  mapper-locations: classpath:mybatis/mapper/BookMapper.xml

6. Start-up project

3. Druid - Next to the above file

1. Introducing Druid and log4j dependencies

<!-- Druid Dependence -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.16</version>
</dependency>
<!-- log4j Dependence -->
<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

2. Injecting attributes into Druid and modifying yaml files

spring:
  datasource:
    username: root
    password: 1234
    url: jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC
    driver-class-name: com.mysql.cj.jdbc.Driver
    # Introducing Druid's Data Source and Configuration
    type: com.alibaba.druid.pool.DruidDataSource
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdel: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    connectionProperties: druid:stat.mergeSql=true;druid.stat.slowSqlMills=500
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
mybatis:
  config-location: classpath:mybatis/config/mybatis-config.xml
  mapper-locations: classpath:mybatis/mapper/BookMapper.xml

3. Creating Druid Configuration Files

package com.xjj.springboot.config;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

/**
 * @Author xjj
 */
@Configuration
public class DruidConfig {
    /**
     * Inject attributes under spring. data source in yaml file
     * @return
     */
    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean
    public DataSource druid(){
        return new DruidDataSource();
    }

    /**
     * Configuring Druid Monitoring
     * The loginUsername and loginPassword are the user and password at the time of login.
     * @return
     */
    @Bean
    public ServletRegistrationBean statViewServlet(){
        ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");
        Map<String,String> initParams=new HashMap<>();
        initParams.put("loginUsername","admin");
        initParams.put("loginPassword","admin");
        initParams.put("allow","localhost");
        bean.setInitParameters(initParams);
        return bean;
    }
    @Bean
    public FilterRegistrationBean webStatFilter(){
        FilterRegistrationBean bean=new FilterRegistrationBean();
        bean.setFilter(new WebStatFilter());
        Map<String,String> map=new HashMap<>();
        map.put("exclusions","*.js,*.css,/druid/*");
        bean.setInitParameters(map);
        bean.setUrlPatterns(Arrays.asList("/*"));
        return bean;
    }
}

4. Start-up project