Spring REST – JSON Response for Access Denied Request
Return 403 access denied response in jSON in REST API where principal should be pre-authenticated but is null in AbstractPreAuthenticatedProcessingFilter.
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Lokesh Gupta
Website: https://howtodoinjava.com
Github: https://github.com/lokeshgupta1981/
Twitter: @HowToDoInJAVA
My Articles:
Spring WebMVC HTTP OPTIONS Request Handler
Learn to handle the HTTP OPTIONS requests specific to REST resource in Spring WebMVC applications by adding handler methods.
Spring MVC Validation of Request Body and Parameters
Learn to validate the request body of a REST API built with Spring MVC. Also, validate @PathVariable and @RequestParam parameters in resource URIs using the hibernate validator framework. In this Spring MVC validation example, we will add validations in REST APIs created for the CRUD example. 1. Request Body Validation …
Spring Custom Token Authentication Example
Learn to add custom token based authentication to REST APIs using created with Spring REST and Spring security 5. In given example, a request with header name “AUTH_API_KEY” with a predefined value will pass through. All other requests will return HTTP 403 response.
Compare Two LocalDateTime Instances
Learn to compare two LocalDateTime instances to find out which date represents an older timestamp in comparison to other timestamp. LocalDateTime class is part of java.time package added in Java 8.
REST API Error Handling in Spring Boot
Learn to handle exceptions locally and globally in Spring Boot REST APIs using @ControllerAdvice, @ExceptionHandler, and other latest approaches.
Spring REST CRUD Example with JPA Configuration
Learn to create REST APIs for crud operations using Spring REST and JPA configuration (H2 database as backend) without Spring boot auto configuration feature.
Compare Two LocalDate Instances in Java
Learn to compare two LocalDate instances to find out which date represents an older date in comparison to second date. LocalDate class is part of java.time package added in Java 8.
Using cURL on Windows PowerShell
Learn to execute the cURL commands from Windows. Beginning in Insider Build 17063, Tar and curl are available from the command-line for all SKUs of Windows.
Spring Boot – OAuth2 Authorization and Resource Servers
In this Spring security oauth2 tutorial, learn to build an authorization server to authenticate your identity to provide access_token, which you can use to request data from resource server.
Guide to AtomicInteger in Java
The AtomicInteger class protects an underlying int value by providing methods that perform atomic operations on the value. It shall not be used as a replacement for an Integer class.
Format Timestamp in 12 Hours Pattern (AM-PM) in Java
Learn to format date and time in either 12 hours pattern. The formatted date string will have the AM/PM information as applicable to the timestamp.
How to Format LocalDate in Java
Java examples to format LocalDate to String using inbuilt and custom patterns using FormatType and format(formatter) API.
Java Check Leap Year Examples
Java programs to find if a given year is a leap year using new Java 8 APIs (LocalDate and Year), legacy Java 7 GregorianCalendar, and custom code.
Compare Two ZonedDateTime Instances
Learn to compare two instances of ZonedDateTime either in the same timezone or in different timezones in Java 8. 2. Comparing at Same Instant As we know an instance of ZonedDateTime is a point in the universal timeline with an offset. So to compare two such instances, logically, both instances …
Format ZonedDateTime to String in Java
Learn to format a ZonedDateTime to string using ZonedDateTime.format (DateTimeFormatter) method in Java 8. Convert ZonedDateTime to String example.
Convert between LocalDate and ZonedDateTime
Learn to convert from LocalDate to ZonedDateTime and from ZonedDateTime to LocalDate in Java 8. As we know, LocalDate represents a calendar date without the time and the zone information. ZonedDateTime instance contains all three information i.e. date, time and zone. ZonedDateTime = LocalDate + time + timezone 1. LocalDate …
Convert between LocalDate and LocalDateTime
Learn to convert from LocalDate to LocalDateTime and from LocalDateTime to LocalDate in Java 8.
Parse String to ZonedDateTime in Java
Java 8 ZonedDateTime class represents an instant in the universal timeline with the timezone information. In this tutorial, we will learn to parse a string to ZonedDateTime object using its parse() method. 1. Parsing a Date Time with ZonedDateTime.parse() Java program to convert a given string into ZonedDateTime instance. After …
Convert String to LocalDateTime in Java
Java LocalDateTime class represents an instant in local timeline i.e. without any timezone id. Learn to convert string to LocalDateTime.
Convert String to LocalDate in Java
Java LocalDate class represents a calendar date without time (hour/minute/seconds) and timezone information. Learn to convert a string to LocalDate object in Java.
Java ZonedDateTime
Learn about the ZonedDateTime class in Java, how to create its instances and other use cases such as parsing, formatting and adding duration and periods.
Java LocalDateTime
Learn about the LocalDateTime class in Java, how to create its instances and other use cases such as parsing, formatting and adding duration and periods. 1. Overview java.time.LocalDateTime class, introduced in Java 8 Date Time API, represents a date and time object without a timezone often viewed as ‘year-month-day-hour-minute-second‘. It …
Java LocalTime
Learn to create and use the LocalTime class in Java. Learn how to create LocalTime, parse and format the LocalTime instances, including common operations such as adding or subtracting hours from a given time.
Java LocalDate
Learn about the LocalDate class in Java, how to create its instances and other use cases such as parsing, formatting and adding duration and periods.
Java Stream Filter on Multiple Conditions using Predicates
Learn to filter a stream of items for multiple if-else style conditions using complex predicates and process filtered items as required.
Join or Append Stream Elements in Java
Learn to join a stream of strings with a delimiter, prefix, and suffix using Collectors.joining(), String.join(), and append elements using StringBuilder.
Java 8 Stream.concat(): How to Combine Streams?
The Java 8 Stream.concat() method merges two streams into one stream. The combined stream consists of all the elements of both streams.
Sorting a Stream by Multiple Fields in Java
Java 8 example to sort stream of objects by multiple fields using comparators and Comparator.thenComparing() method. This method returns a lexicographic-order comparator with another comparator. It gives the same effect as SQL group by clause.
How to Sort a Stream in Java
Learn to sort stream of numbers and strings in ascending (natural order) and descending orders (reverse order) using Stream.sorted() method.
Generic Functional Interfaces in Java
Learn to create generic functional interfaces with and without type restrictions in Java. Learn to create specialized functional interfaces.
Java Collect Stream to List (with Examples)
Learn to convert stream to list using Collectors.toList() and Collectors.toCollection() APIs. This post contains multiple examples for collecting stream elements to list under different usecases.
Java Stream toArray() Example
Learn to convert stream to array using Stream.toArray() API. This post contains multiple examples for collecting stream elements to array under different usecases.
Java Collectors.toMap(): Collecting Stream Items into Map
Learn to collect Stream items into Map using Collectors.toMap() and Collectors.groupingBy() when Map keys are distinct or duplicates.
Java Stream Reuse – Consume Stream Multiple Times?
Java streams cannot be reused. Once a terminal operation is performed on a stream, it is considered consumed and cannot be reused.
Java Stream findFirst() vs findAny(): What’s Difference?
Java Stream has two methods findFirst() and findAny() for retrieving elements. Learn the difference between both methods in parallel streams with examples.
Java Stream noneMatch()
Java Stream noneMatch(predicate) is a short-circuiting terminal operation to check if no element in the stream matches the given predicate.
Java Stream allMatch()
Java Stream allMatch() is a short-circuiting terminal operation that is used to check if all the elements in the stream satisfy the provided predicate. 1. Stream allMatch() Method 1.1. Syntax Here predicate a non-interfering, stateless predicate to apply to all the elements of the stream. The allMatch() method returns always …
Java Stream anyMatch()
Java Stream anyMatch (Predicate predicate) is terminal-short-circuiting operation which is used to check if the stream contains any matching element with provided predicate.
How to Create Infinite Streams in Java
Java 8 examples to create an infinite stream of elements. We will use Stream’s generate() and iterate() methods to get the infinite streams.
Java Stream skip()
Java Stream skip(n) method returns a new stream consisting of the remaining elements of this stream, after the n elements have been skipped.
Java Stream limit()
We can use Stream.limit(long) to retrieve elements while they must not be greater than a certain maximum count. Java 8 Stream limit() example
Java Stream peek()
Java 8 Stream interface has peek(Consumer action) method which returns a new stream consists of all the elements of original stream after applying the method argument Consumer action.
Java Stream map() vs. flatMap() with Examples
The difference between map() vs flatMap() with example. map() is used for transformation only, but flatMap() is used for both transformation and flattening.
Java Stream flatMap()
Learn to use Java Stream flatMap() method which is used to flatten a stream of collections to a stream of elements combined from all collections.
Java Stream map()
Learn to use Java Stream map() method which produces one output value of a different type ‘X’ for each input value of type ‘Y’.
Java Stream min()
Learn to use Stream min() method to select the smallest element in the stream according to the comparator provided in its argument.
Java Stream max()
Learn to use Java Stream max() method to select the largest element in the stream according to the comparator provided in its argument.
Java Stream sorted() Example with/without Comparator
Learn to use Stream sorted() method to sort a stream of elements in their natural order and also according to the provided Comparator.
Chaining Multiple Predicates in Java
Java examples of chained predicates and to perform ‘logical AND‘ and ‘logical OR‘ operations and collect the elements into a list.