Spring Batch – Timing Configurations / Improved Cron Expressions

Posted on May 2, 2022May 2, 2022 by coder

Usage

You typically create cron triggers with the @Scheduled annotation, which uses CronExpression internally, as of Spring Framework 5.3. This means that you can already start using the New Features if you are on that version.

If you want to play around with CronExpression yourself, you can create one through the static parse method:

var expression = CronExpression.parse("10 * * * * *");
var result = expression.next(LocalDateTime.now());
System.out.println(result);

var expression = CronExpression.parse("10 * * * * *");

var result = expression.next(LocalDateTime.now());

System.out.println(result);

 ┌───────────── second (0-59)
 │ ┌───────────── minute (0 - 59)
 │ │ ┌───────────── hour (0 - 23)
 │ │ │ ┌───────────── day of the month (1 - 31)
 │ │ │ │ ┌───────────── month (1 - 12) (or JAN-DEC)
 │ │ │ │ │ ┌───────────── day of the week (0 - 7)
 │ │ │ │ │ │          (or MON-SUN -- 0 or 7 is Sunday)
 │ │ │ │ │ │
 * * * * * *

┌───────────── second (0-59)

│ ┌───────────── minute (0 - 59)

│ │ ┌───────────── hour (0 - 23)

│ │ │ ┌───────────── day of the month (1 - 31)

│ │ │ │ ┌───────────── month (1 - 12) (or JAN-DEC)

│ │ │ │ │ ┌───────────── day of the week (0 - 7)

│ │ │ │ │ │ (or MON-SUN -- 0 or 7 is Sunday)

│ │ │ │ │ │

* * * * * *

Every 5 Seconds Example

Use @Scheduled(fixedRate = 5000). You can also use a CRON expression @Scheduled(cron = "*/5 * * * * ?") but it seems like an overkill.

1	Use @Scheduled(fixedRate = 5000). You can also use a CRON expression @Scheduled(cron = "/5 * * * ?") but it seems like an overkill.

Some rules apply:

A field may be an asterisk (*), which always stands for “first-last”. For the day-of-the-month or day-of-the-week fields, a question mark (?) may be used instead of an asterisk.
Commas (,) are used to separate items of a list.
Two numbers separated with a hyphen (-) express a range of numbers. The specified range is inclusive.
Following a range (or *) with / specifies the interval of the number’s value through the range.
English names can also be used for the day-of-month and day-of-week fields. Use the first three letters of the particular day or month (case does not matter).

Here are some examples:

Cron Expression Meaning

Cron Expression	Meaning
`0 0 * * * *`	top of every hour of every day
`/10 * * * *`	every ten seconds
`0 0 8-10 * * *`	8, 9 and 10 o’clock of every day
`0 0 6,19 * * *`	6:00 AM and 7:00 PM every day
`0 0/30 8-10 * * *`	8:00, 8:30, 9:00, 9:30, 10:00 and 10:30 every day
`0 0 9-17 * * MON-FRI`	on the hour nine-to-five weekdays
`0 0 0 25 12 ?`	every Christmas Day at midnight

0 0 * * * *

top of every hour of every day

*/10 * * * * *

every ten seconds

0 0 8-10 * * *

8, 9 and 10 o’clock of every day

0 0 6,19 * * *

6:00 AM and 7:00 PM every day

0 0/30 8-10 * * *

8:00, 8:30, 9:00, 9:30, 10:00 and 10:30 every day

0 0 9-17 * * MON-FRI

on the hour nine-to-five weekdays

0 0 0 25 12 ?

every Christmas Day at midnight

The next method returns the next occurrence of the trigger or null if there is none. It takes a java.time.temporal.Temporal as a parameter, which means it accepts not only LocalDateTime but also ZonedDateTime if time-zones are relevant.

New Features

Using the java.time APIs let us introduce several new features that put Spring’s support for cron expressions on an equal footing with other schedulers. You can start using these features in @Scheduled as of Spring Framework 5.3.

Macros

Expressions such as 0 0 * * * * are hard for humans to parse and are, therefore, hard to fix in case of bugs. To improve readability, Spring now supports the following macros, which represent commonly used sequences. You can use these macros instead of the six-digit value, thus: @Scheduled(cron = "@hourly").

Macro Meaning

Macro	Meaning
`@yearly` (or `@annually`)	once a year (`0 0 0 1 1 *`)
`@monthly`	once a month (`0 0 0 1 * *`)
`@weekly`	once a week (`0 0 0 * * 0`)
`@daily` (or `@midnight`)	once a day (`0 0 0 * * *`), or
`@hourly`	once an hour, (`0 0 * * * *`)

@yearly (or @annually)

once a year (0 0 0 1 1 *)

@monthly

once a month (0 0 0 1 * *)

@weekly

once a week (0 0 0 * * 0)

@daily (or @midnight)

once a day (0 0 0 * * *), or

@hourly

once an hour, (0 0 * * * *)

–

Ref : https://spring.io/blog/2020/11/10/new-in-spring-5-3-improved-cron-expressions

Ref : https://www.baeldung.com/spring-batch-start-stop-job

–

Example – Entity Interface 1

Posted on April 28, 2022April 28, 2022 by coder

Spring Application Properties Document

Posted on November 25, 2021November 25, 2021 by coder

Lombok

Posted on November 2, 2021November 16, 2021 by coder

@Data
@ApiModel(description = "User Model")
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class User {

    @NotEmpty(message = "email can not be empty")
    private String email;

    @NotEmpty(message = "password can not be empty")
    private String password;
}

@Data

@ApiModel(description = "User Model")

@NoArgsConstructor

@AllArgsConstructor

@Builder

public class User {

@NotEmpty(message = "email can not be empty")

private String email;

@NotEmpty(message = "password can not be empty")

private String password;

}

Ref: javabydeveloper.com (All the content!)

 @Data generates all the boilerplate that is normally associated with simple POJOs (Plain Old Java Objects) and beans:

1	@Data generates all the boilerplate that is normally associated with simple POJOs (Plain Old Java Objects) and beans:

    getter methods for all fields,
    setter methods for all non-final fields,
     appropriate toString(),
    appropriate equals() and
    hashCode() implementations that involve the fields of the class,
    and a constructor that initializes all final fields,
    as well as all non-final fields with no initializer that have been marked with @NonNull, in order to ensure the field is never null.

In the above code, two approaches are equal. @Dataannotation minimizes the usage of more annotations when you need to generate all the above 7 requirements, they are most common for the Pojo classes.

getter methods for all fields,

setter methods for all non-final fields,

appropriate toString(),

appropriate equals() and

hashCode() implementations that involve the fields of the class,

and a constructor that initializes all final fields,

as well as all non-final fields with no initializer that have been marked with @NonNull, in order to ensure the field is never null.

In the above code, two approaches are equal. @Dataannotation minimizes the usage of more annotations when you need to generate all the above 7 requirements, they are most common for the Pojo classes.

-->
@Setter(AccessLevel.PROTECTED) private String name;
###
protected void setName(String name) {
   this.name = name;
}
<--

-->
@Getter @Setter private int age = 10;
###
public int getAge() {
    return age;
}
  
/**
 * Age of the person. Water is wet.
 *
 * @param age New value for this person's age. Sky is blue.
 */
public void setAge(int age) {
  this.age = age;
}
<--

###############

-->

@Setter(AccessLevel.PROTECTED) private String name;

###

protected void setName(String name) {

this.name = name;

}

<--

-->

@Getter @Setter private int age = 10;

###

public int getAge() {

return age;

}

/**

* Age of the person. Water is wet.

* @param age New value for this person's age. Sky is blue.

public void setAge(int age) {

this.age = age;

}

<--

###############

Lombok @Data ignore/exclude fields

@Data annotation alone not provide support for ignoring fields from generating getters/setters or toString or equals and hashCode methods. Following example demonstrates how to exclude fields when you are using @Data annotation.
@Data
public class User4 {
  @Setter(value = AccessLevel.NONE)
  private Long id;
  @Getter(value = AccessLevel.NONE)
  private String username;
  
  @ToString.Exclude          // !!!
  private boolean active;
  
  @EqualsAndHashCode.Exclude  /// !! 
  @ToString.Exclude   /// !! 
  private int role;
}

Lombok @Data ignore/exclude fields

@Data annotation alone not provide support for ignoring fields from generating getters/setters or toString or equals and hashCode methods. Following example demonstrates how to exclude fields when you are using @Data annotation.

@Data

public class User4 {

@Setter(value = AccessLevel.NONE)

private Long id;

@Getter(value = AccessLevel.NONE)

private String username;

@ToString.Exclude // !!!

private boolean active;

@EqualsAndHashCode.Exclude /// !!

@ToString.Exclude /// !!

private int role;

}

6. Lombok @Data and @Builder together

If you use @Data annotation alone, public required-args constructor is generated. If you are using @Data and @Builder annotations together, all-args constructor (Package access level) is generated. In case initializing objects is responsible for third party libraries like Spring Framework, most of the cases they look for no-args constructor.

Following example demonstrates how you can generate all-args and no-args constructor when you are using @Data and @Builder together.
@AllArgsConstructor(access = AccessLevel.PACKAGE)
@NoArgsConstructor
@Data @Builder
public class User5 {
  private Long id;
  private String username;
}

6. Lombok @Data and @Builder together

If you use @Data annotation alone, public required-args constructor is generated. If you are using @Data and @Builder annotations together, all-args constructor (Package access level) is generated. In case initializing objects is responsible for third party libraries like Spring Framework, most of the cases they look for no-args constructor.

Following example demonstrates how you can generate all-args and no-args constructor when you are using @Data and @Builder together.

@AllArgsConstructor(access = AccessLevel.PACKAGE)

@NoArgsConstructor

@Data @Builder

public class User5 {

private Long id;

private String username;

}

Delombok

# Usage

# Note that Lombok requires Java 6, but the plugin requires Java 7, or later, to execute at build time.
# Delombok

# Add the following to the pom.xml to activate the delombok goal:


<build>
  <plugins>
    <plugin>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok-maven-plugin</artifactId>
      <version>1.18.20.0</version>
      <executions>
        <execution>
          <phase>generate-sources</phase>
          <goals>
            <goal>delombok</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

# Place the java source code with lombok annotations 
  -- in src/main/lombok (instead of src/main/java). 
  -- During the build process, the src/main/lombok 
  -- code will be delomboked and the generated java code ends up 
  -- in target/generated-sources/delombok. 
  -- The delomboked code is compiled and analysed together with 
  -- the src/main/java code.

# Usage

# Note that Lombok requires Java 6, but the plugin requires Java 7, or later, to execute at build time.

# Delombok

# Add the following to the pom.xml to activate the delombok goal:

<build>

<groupId>org.projectlombok</groupId>

<artifactId>lombok-maven-plugin</artifactId>

<phase>generate-sources</phase>

<goals>

<goal>delombok</goal>

</goals>

</execution>

</executions>

</plugin>

</plugins>

</build>

# Place the java source code with lombok annotations

-- in src/main/lombok (instead of src/main/java).

-- During the build process, the src/main/lombok

-- code will be delomboked and the generated java code ends up

-- in target/generated-sources/delombok.

-- The delomboked code is compiled and analysed together with

-- the src/main/java code.

–

JWT – Security – Intro – Know How

Posted on November 1, 2021November 1, 2021 by coder

jwt-handbook-v0_14_1 – kutayzorlu.com

Spring Keycloak Server Proctected Service – 4

Posted on November 1, 2021November 1, 2021 by coder

Keycloak – 3 Spring Embedded Keycloak Server

Posted on October 29, 2021November 1, 2021 by coder

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