GitHub: github.com/hsowan/soms

SOMS

Supermarket Orders Management System

Day 01

Use MyBatis

MyBatis official document

Refer: www.mybatis.org/mybatis-3/z…

Type the alias

Type aliases are your go-to. Using them, you don’t have to type the fully qualified name of the class. Such as:

<! --> <typeAlias type="com.someapp.model.User" alias="User"/> <! <select id="selectUsers" resultType="User"> select id, username, hashedPassword from some_table where id = #{id} </select>Copy the code

log4j2

Refer: logging.apache.org/log4j/2.x/m…

Eclipse for Mac shortcut

To delete a line

Command + D

Refer: www.cnblogs.com/TankXiao/p/…

Formatting code

Shift + Command + F

Day 02

MyBatis core configuration

Mybatis – config. The XML configuration

Configuration
- Properties
- Settings
- typeAliases
- typeHandlers
- objectFactory
- Plugins
- Environments
  - Environment (environment variable)
    - transactionManager
    - A dataSource
- DatabaseIdProvider (Database vendor Identity)
- Mappers (mapper)

Refer: www.mybatis.org/mybatis-3/z…

Mapper. The XML configuration

Insert – Mapping insert statements
Update – Mapping update statement
Delete – Mapping delete statement
Select – Mapping query statement
ResultMap – The most complex and powerful element describing how to load objects from a database result set.
SQL – reusable block of statements that can be referenced by other statements.
Cache – The cache configuration for a given namespace.
Cache-ref – A reference to another namespace cache configuration.

Refer: www.mybatis.org/mybatis-3/z…

Create the SqlSessionFactory using the singleton pattern

/** * Main configuration file path */
private static String config = "mybatis-config.xml";
private static SqlSessionFactory sqlSessionFactory;

/** * Use singleton mode to get SqlSessionFactory *@return* /
private static synchronized SqlSessionFactory getSqlSessionFactory(a) {
	
	if (sqlSessionFactory == null) {
		try {
			// Create an input stream to read the configuration file
			InputStream is = Resources.getResourceAsStream(config);
			// Create a SQLSession factory
			sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
			
		} catch (IOException e) {
			// TODO Auto-generated catch blocke.printStackTrace(); }}return sqlSessionFactory;
}
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Maven

Using JUnit

Add the following plug-in to pom.xml:

<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> < version > 3.0.0 - M3 < / version > < / plugin >Copy the code

Perform unit tests: MVN test

Refer: maven.apache.org/surefire/ma…

Skipping Tests

mvn install -DskipTests

Refer: maven.apache.org/surefire/ma…

JSP nine built-in objects + four domain objects

Refer: my.oschina.net/u/3805464/b…

Java’s eight basic types

byte/8
char/16
short/16
int/32
float/32
long/64
double/64
boolean/~
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Day 03

Dynamic SQL

The official documentation

if
choose (when, otherwise)
trim (where, set)
foreach
bind

www.mybatis.org/mybatis-3/z…

if

Rewrite UserMapper. XML:

<select id="listByUsername" resultMap="userResultMap">
	select id, username, password
	from user
	where username like #{username}
	<! - page - >
	<if test="start ! = null and count ! = null">
		limit #{start}, #{count}
	</if>
</select>
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Rewrite unit test testListByUsername(use map to pass parameters):

Map<String, Object> params = new HashMap<String, Object>();
params.put("username"."%user%");

List<User> users = session.selectList("com.ncucoder.mapper.UserMapper.listByUsername", params);
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Execution Result:

==>  Preparing: select id, username, password from user where username like ? 
==> Parameters: %user%(String)
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Add unit tests testListByUsernameUsingLimit:

Map<String, Object> params = new HashMap<String, Object>();
params.put("username"."%user%");
params.put("start".0);
params.put("count".2);

List<User> users = session.selectList("com.ncucoder.mapper.UserMapper.listByUsername", params);
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Execution Result:

==>  Preparing: select id, username, password from user where username like ? limit ?, ? 
==> Parameters: %user%(String), 0(Integer), 2(Integer)
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Bind fuzzy query

Modify UserMapper. XML:

<! Select * from user where username = 'username';
<select id="listByUsername" resultMap="userResultMap">
	<bind name="username" value="'%' + _parameter.get('username') + '%'"/>
	select id, username, password
	from user
	where username like #{username}
	<if test="start ! = null and count ! = null">
		limit #{start}, #{count}
	</if>
</select>
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Modify unit test testListByUsername():

Map<String, Object> params = new HashMap<String, Object>();
// params.put("username", "%user%");
params.put("username"."user");

List<User> users = session.selectList("com.ncucoder.mapper.UserMapper.listByUsername", params);
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Execution Result:

==>  Preparing: select id, username, password from user where username like ? 
==> Parameters: %user%(String)
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SQL optimization in

Query the records whose IDS are less than 5 in the user table

Query execution plan (QEP) using IN:

mysql> explain select id, username, password from user where id in (1.2.3.4.5);
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
| id | select_type | table | partitions | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra       |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
|  1 | SIMPLE      | user  | NULL       | ALL  | PRIMARY       | NULL | NULL    | NULL |   10 |    50.00 | Using where |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
1 row in set.1 warning (0.00 sec)
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Use < QEP:

mysql> explain select id, username, password from user where id < 6;
+----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+----------- --+
| id | select_type | table | partitions | type  | possible_keys | key     | key_len | ref  | rows | filtered | Extra       |
+----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+----------- --+
|  1 | SIMPLE      | user  | NULL       | range | PRIMARY       | PRIMARY | 4       | NULL |    5 |   100.00 | Using where |
+----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+----------- --+
1 row in set.1 warning (0.00 sec)
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QEP with between:

mysql> explain select id, username, password from user where id between 1 and 5;
+----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+----------- --+
| id | select_type | table | partitions | type  | possible_keys | key     | key_len | ref  | rows | filtered | Extra       |
+----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+----------- --+
|  1 | SIMPLE      | user  | NULL       | range | PRIMARY       | PRIMARY | 4       | NULL |    5 |   100.00 | Using where |
+----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+----------- --+
1 row in set.1 warning (0.00 sec)
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typeRepresents the method of accessing the table (best to worst: NULL > system > const > eq_ref > ref > range > index > All)
keysaidMySQL Query Optimizerfrompossible_keysThe index selected for use in
rowssaidMySQL Query OptimizerThe number of records in the result set estimated based on the statistics collected by the system is simply the number of records to be scanned

Analysis: When in is used as the query condition, full table scan (ALL) is performed without index; when < and between are used as the query condition, primary key index and index range scan are used. Therefore, the execution efficiency of IN is the lowest

MySQL batch insert test data

Gets a random string of specified length
drop function if exists `rand_string`;
create function `rand_string`(n int) returns varchar(255) charset 'utf8'
begin
    DECLARE chars_str varchar(100) DEFAULT 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
    DECLARE return_str varchar(255) DEFAULT ' ';
    DECLARE i INT DEFAULT 0;
    WHILE i < n DO
    SET return_str = concat(return_str, substring(chars_str, FLOOR(1 + RAND() * 62), 1));
    SET i = i + 1;
    END WHILE;
    RETURN return_str;
end;

Insert a specified number of users
drop procedure if exists `create_users`;
create procedure `create_users`(n int)
begin
    declare i int default 0;
    while (i < n) do
        insert into user(username, password)
        values (rand_string(10), rand_string(32));
        set i = i + 1;
    end while;
end;

Call the stored procedure
call create_users(1000);

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Day 04

MyBatis Generator

The official documentation

www.mybatis.org/generator/c…

Question:

Mysql > alter DATABASE MySQL8 alter database MySQL8 alter database MySQL8

Add dependencies and plug-ins

mybatis-generator-core:

<dependency>
   <groupId>org.mybatis.generator</groupId>
   <artifactId>mybatis-generator-core</artifactId>
   <version>${mybatis-generator.version}</version>
</dependency>

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mybatis-generator-maven-plugin:

<plugin>
   <groupId>org.mybatis.generator</groupId>
   <artifactId>mybatis-generator-maven-plugin</artifactId>
   <version>${mybatis-generator.version}</version>
   <configuration>
      <overwrite>true</overwrite>
      <verbose>true</verbose>
   </configuration>
</plugin>

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Adding a Configuration File

generatorConfig.xml

Generate the corresponding mapping file, entity class, and interface class

cd ${your_project}
mvn mybatis-generator:generator

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Refer:

www.cnblogs.com/hhhshct/p/9…
Blog.csdn.net/liyonghong3…

Integration for SpringMVC

Add the dependent

<! -- Spring dependencies -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-beans</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-test</artifactId>
    <version>${spring.version}</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-tx</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis-spring</artifactId>
    <version>${mybatis-spring.version}</version>
</dependency>

<! -- Druid connection pool -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>${druid.version}</version>
</dependency>

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Modify the`web.xml`The configuration file

<! Create dispatcher -->
<servlet>
    <servlet-name>soms-dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:spring/spring-*.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
    <! -- Support asynchrony -->
    <async-supported>true</async-supported>
</servlet>
<servlet-mapping>
    <servlet-name>soms-dispatcher</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>
<! -- Chinese gibberish -->
<filter>
    <filter-name>encodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
        <param-name>forceEncoding</param-name>
        <param-value>true</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>encodingFilter</filter-name>
    <url-pattern>/ *</url-pattern>
</filter-mapping>
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Add the Spring configuration file

spring-web.xml
spring-dao.xml
spring-service.xml

Using MySQL8

Modify the dependent version (POM.xml):

<mysql-connector-java.version>8.0.16</mysql-connector-java.version>
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Modify driver path (db.properties):

driver=com.mysql.cj.jdbc.Driver
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Day 05

JWT + SpringSecurity

Github.com/hsowan/jwt-…

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Supermarket order management system

SOMS

Day 01

MyBatis official document

Type the alias

log4j2

Eclipse for Mac shortcut

To delete a line

Formatting code

Day 02

Mybatis – config. The XML configuration

Mapper. The XML configuration

Create the SqlSessionFactory using the singleton pattern

Maven

Using JUnit

Skipping Tests

JSP nine built-in objects + four domain objects

Java’s eight basic types

Day 03

The official documentation

if

Bind fuzzy query

SQL optimization in

MySQL batch insert test data

Day 04

MyBatis Generator

The official documentation

Add dependencies and plug-ins

Adding a Configuration File

Generate the corresponding mapping file, entity class, and interface class

Integration for SpringMVC

Add the dependent

Modify the`web.xml`The configuration file

Add the Spring configuration file

Using MySQL8

Day 05

JWT + SpringSecurity

Supermarket order management system

SOMS

Day 01

MyBatis official document

Type the alias

log4j2

Eclipse for Mac shortcut

To delete a line

Formatting code

Day 02

Mybatis – config. The XML configuration

Mapper. The XML configuration

Create the SqlSessionFactory using the singleton pattern

Maven

Using JUnit

Skipping Tests

JSP nine built-in objects + four domain objects

Java’s eight basic types

Day 03

The official documentation

if

Bind fuzzy query

SQL optimization in

MySQL batch insert test data

Day 04

MyBatis Generator

The official documentation

Add dependencies and plug-ins

Adding a Configuration File

Generate the corresponding mapping file, entity class, and interface class

Integration for SpringMVC

Add the dependent

Modify theweb.xmlThe configuration file

Add the Spring configuration file

Using MySQL8

Day 05

JWT + SpringSecurity

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Modify the`web.xml`The configuration file