Fachlicher Codevergleich

Vollständige Gegenüberstellung des Legacy- und Modern-Verhaltens, der strukturellen Änderung und der relevanten Migrationsrisiken.

Nr.	Modul	Legacy	Modern	Risiko	Einstufung
01	Dependency Injection	manual registry/service lookup	constructor injection with explicit ports	hidden dependencies, global state	NIEDRIG
02	AOP	dynamic proxy around target	annotation-driven Spring aspect	proxy limitations and cross-cutting coupling	NIEDRIG
03	REST	JAX-RS resource with in-memory repository	Spring MVC controller + service + repository	HTTP contract drift and validation gaps	NIEDRIG
04	Persistenz	manual JDBC DAO	Spring Data JPA repository + service	schema drift, lazy loading and transaction boundaries	NIEDRIG
05	Transaktionen	manual JDBC commit/rollback	declarative @Transactional service	partial writes and incorrect rollback rules	NIEDRIG
06	Batch	custom CSV loop/importer	Spring Batch job/step configuration	restartability, duplicate processing and bad-record policy	MITTEL
07	Messaging	embedded ActiveMQ Classic/JMS gateway	Spring JMS/Artemis publisher + listener	duplicate delivery, poison messages and vulnerable legacy broker	MITTEL
08	XML und JAXB	javax JAXB model/mapper	Jakarta JAXB model/mapper	namespace and schema compatibility	NIEDRIG
09	Servlet und Web	embedded Jetty servlet	Spring MVC controller	container/API migration and endpoint compatibility	NIEDRIG
10	SOAP	javax JAX-WS endpoint	Jakarta JAX-WS endpoint	WSDL/namespace compatibility and fault mapping	MITTEL
11	Java-Grundlagen	mutable JavaBean	record/enum-oriented value model	serialization/equality behavior changes	NIEDRIG
12	Collections	mutable collection wrapper	defensive/snapshot-oriented collection API	mutation leaks and ordering semantics	NIEDRIG
13	Generics	raw container	typed generic container/repository	runtime ClassCastException versus compile-time safety	NIEDRIG
14	Annotations und Reflection	manual reflection registry	annotation-driven command discovery	illegal access, duplicate commands and startup failures	NIEDRIG
15	Lambda und Streams	imperative loops/accumulator	stream pipeline	ordering, short-circuit and null semantics	NIEDRIG
16	Concurrency	manual thread/executor coordination	structured executor/future usage	race conditions, leaks and nondeterministic tests	NIEDRIG
17	Java I/O und NIO	stream-based file copy	NIO Path/Files service	resource handling, overwrite and atomicity	NIEDRIG
18	Exception Handling und Logging	catch-and-swallow behavior	exception translation with logging	lost root cause and unstable error contracts	NIEDRIG
19	JUnit und Testdesign	JUnit 4 style	JUnit Jupiter/parameterized tests	test lifecycle and assertion migration	NIEDRIG
20	HTTP-Client und Webtest	basic URL connection/testing	Java HttpClient with local HTTP server	timeouts, redirects and encoding	NIEDRIG
21	Maven Properties und Konfiguration	manual properties loading	typed configuration/value object	missing keys, precedence and environment drift	NIEDRIG
22	Spring JDBC	manual JDBC DAO	JdbcTemplate repository	SQL mapping, transaction and resource handling	NIEDRIG
23	Hibernate und JPA	native Hibernate 5 session/unit of work	Spring Data JPA	entity lifecycle, schema and query differences	NIEDRIG
24	MongoDB	driver/BSON mapper repository	Spring Data Mongo repository	document shape and mapping compatibility	NIEDRIG
25	JNDI und Service-Auflösung	service locator/JNDI lookup	constructor injection	runtime lookup failure and hidden dependency	NIEDRIG
26	JMX und Monitoring	manual MBean registration	Spring Boot Actuator	metric/endpoint naming and exposure	NIEDRIG
27	EJB und Services	EJB-style service boundary	Spring service/controller boundary	transaction/security semantics and remote contract drift	NIEDRIG
28	JPMS / Jigsaw	classpath-only modules	explicit module descriptors	split packages, exports and readability	MITTEL
29	Service Registry und ServiceLoader	custom service registry	Java ServiceLoader	provider discovery, ordering and duplicates	NIEDRIG
30	XML Parser	basic parser configuration	secure parser facade	XXE, entity expansion and malformed XML	NIEDRIG
31	XSLT	new transformer per call/basic factory	secure cached Templates/flyweight	external access, thread safety and cache invalidation	NIEDRIG
32	Kryptografie	AES/ECB legacy example	AES/GCM service with authenticated payload	confidentiality/integrity failure and nonce misuse	NIEDRIG
33	SMTP und Mail	javax.mail message factory	Jakarta Mail gateway	header injection, transport errors and charset drift	NIEDRIG
34	Patterns und Refactoring	conditional pricing calculator	Strategy + Factory + Service	branch growth and unsupported customer types	NIEDRIG

Bewertungsgrenzen

Struktur- und API-Vergleiche beruhen auf dem vollständigen lokalen Quellbestand.
Testzuordnung ist statisch und ersetzt keine JaCoCo-Line-Coverage.
Der Maven-Build wurde versucht; Maven Central war in der isolierten Laufzeit per DNS nicht erreichbar. Java-21-Syntax und JDK-only-Teilkompilierung wurden separat geprüft.