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Monitoring Java Applications with Flight Recorder 1. Overview In this tutorial, we’ll examine Java Flight Recorder, its concepts, its basic commands, and how to use it. 2. Java Monitoring Utilities Java is not just a programming language but a very rich ecosystem with a lot of tools. The JDK contains… Continue Reading java-flight-recorder-monitoring
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Introduction to Leiningen for Clojure 1. Introduction Leiningen is a modern build system for our Clojure projects. It’s also written and configured entirely in Clojure. It works similarly to Maven, giving us a declarative configuration that describes our project, without needing to configure exact steps to be executed. Let’s jump… Continue Reading leiningen-clojure
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How to Fix java.lang.UnsupportedClassVersionError 1. Introduction In this short tutorial, we’re going to learn what causes the Java runtime error java.lang.UnsupportedClassVersionError: Unsupported major.minor version and how to fix it. 2. A Look at the Error Let’s start by looking at an example error: Exception in thread “main” java.lang.UnsupportedClassVersionError: com/baeldung/MajorMinorApp has been… Continue Reading java-lang-unsupportedclassversion
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Spring LDAP Overview 1. Overview LDAP directory servers are read-optimized hierarchical data stores. Typically, they’re used for storing user-related information required for user authentication and authorization. In this article, we’ll explore the Spring LDAP APIs to authenticate and search for users, as well as to create and modify users in… Continue Reading spring-ldap
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Test a REST API with Java 1. Overview This tutorial focuses on the basic principles and mechanics of testing a REST API with live Integration Tests (with a JSON payload). ##The main goal is to provide an introduction to testing the basic correctness of the API – and we’re going… Continue Reading integration-testing-a-rest-api
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Permissions-Based Access Control with Apache Shiro 1. Introduction In this tutorial, we’ll look at how to implement fine-grained Permissions-Based Access Control with the Apache Shiro Java security framework. 2. Setup We’ll use the same setup as our introduction to Shiro — that is, we’ll only add the shiro-core module to… Continue Reading apache-shiro-access-control
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Spring Security Expressions – hasRole Example 1. Overview Spring Security provides a large variety of Expressions, using the powerful Spring Expression Language (SpEL). Most of these security expressions are evaluated against a contextual object – the currently authenticated principal. The evaluation of these expressions is performed by the SecurityExpressionRoot –… Continue Reading spring-security-expressions-basic
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Common Java Exceptions 1. Introduction This tutorial focuses on some common Java exceptions. We’ll start by discussing what an exception basically is. Later, we’ll discuss different types of checked and unchecked exceptions in detail. 2. Exceptions An exception is an abnormal condition that occurs in a code sequence during the… Continue Reading java-common-exceptions
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Comparing Strings in Java 1. Overview In this article, we’ll talk about the different ways of comparing Strings in Java. As String is one of the most used data types in Java, this is naturally a very commonly used operation. 2. String Comparison with String Class ==== 2.1. Using “==”… Continue Reading java-compare-strings
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Simple Single Sign-On with Spring Security OAuth2 1. Overview In this tutorial, we’ll discuss how to implement SSO – Single Sign On – using Spring Security OAuth and Spring Boot. We’ll use three separate applications: An Authorization Server – which is the central authentication mechanism Two Client Applications: the applications… Continue Reading sso-spring-security-oauth2
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