struts-jsp-patterns

name	struts-jsp-patterns
description	Struts 1.x/2.x and JSP anti-patterns, code archeology patterns, and legacy code understanding. For software archeology consulting.
user-invocable	false
allowed-tools	Read, Grep, Glob
catalog_description	Struts/JSP anti-patterns, legacy code archeology, and modernization assessment.

Struts + JSP — Patterns & Anti-Patterns

Software archeology reference for understanding and assessing legacy Java web applications.

Stack Detection

Indicator	Version	Location
struts-config.xml	Struts 1.x	WEB-INF/
struts.xml	Struts 2.x	src/main/resources/ or classpath
tiles-defs.xml	Tiles 1.x/2.x	WEB-INF/
<% ... %> scriptlets	JSP (any)	*.jsp files
ActionForm extends	Struts 1.x	Java source
ActionSupport extends	Struts 2.x	Java source
web.xml with ActionServlet	Struts 1.x	WEB-INF/web.xml
web.xml with StrutsPrepareAndExecuteFilter	Struts 2.x	WEB-INF/web.xml
<%@ taglib uri="/WEB-INF/struts-*.tld"	Struts 1.x	*.jsp
<%@ taglib prefix="s" uri="/struts-tags"	Struts 2.x	*.jsp

Struts 1.x Architecture

Browser Request
    |
    v
web.xml (ActionServlet mapping: *.do)
    |
    v
struts-config.xml (action-mappings)
    |
    v
ActionForm.validate() → validation errors → input JSP
    |
    v
Action.execute(mapping, form, request, response)
    |
    v
ActionForward (name → path in struts-config.xml)
    |
    v
JSP (with Struts tag libs: html, bean, logic, tiles)

Key Classes (Struts 1.x)

• org.apache.struts.action.Action — controller base class
• org.apache.struts.action.ActionForm — form data binding
• org.apache.struts.action.ActionForward — navigation result
• org.apache.struts.action.ActionMapping — URL-to-action mapping
• org.apache.struts.action.ActionServlet — front controller servlet
• org.apache.struts.tiles.TilesPlugin — layout templating
• org.apache.struts.validator.ValidatorPlugIn — XML-based validation

Anti-Patterns (Struts 1.x)

Anti-Pattern	What to look for	Risk	Spring Boot equivalent
God Action	Action class >500 lines, handles multiple paths via if/else on form fields	High	Split into @Controller methods
ActionForm bloat	ActionForm with 30+ fields, nested objects	Medium	@RequestBody DTO + validation groups
Business logic in Action	Database calls, calculations in execute()	High	Service layer (@Service)
Request/Session abuse	request.setAttribute() / session.setAttribute() for everything	Medium	Model attributes, @SessionAttributes
Struts MessageResources as i18n	MessageResources.getMessage() scattered everywhere	Low	MessageSource + @MessageSource
DynaActionForm	Dynamic forms via XML — hard to refactor	Medium	Typed DTOs
DispatchAction abuse	Single action handles CRUD via method param	Medium	REST endpoints

Struts 2.x Architecture

Browser Request
    |
    v
web.xml (StrutsPrepareAndExecuteFilter: /*)
    |
    v
struts.xml (package → action mapping)
    |
    v
Interceptor Stack (params, validation, fileUpload, exception, etc.)
    |
    v
Action class (POJO with execute() or method name)
    |
    v
Result (JSP, Freemarker, JSON, redirect)

Anti-Patterns (Struts 2.x)

Anti-Pattern	What to look for	Risk	Spring Boot equivalent
OGNL in views	<s:property value="%{user.name}"/> with complex expressions	Critical (security)	${user.name} in Thymeleaf
ServletRequestAware/SessionAware	Action implements *Aware interfaces	Medium	@RequestParam, @SessionAttribute
ValueStack manipulation	ActionContext.getContext().getValueStack()	High	Model/ModelAndView
Wildcard mappings	<action name="*" method="{1}">	High (security)	Explicit @RequestMapping
Interceptor soup	20+ custom interceptors in stack	Medium	Spring filters/aspects

JSP Anti-Patterns

Anti-Pattern	Example	Fix
Scriptlet logic	<% if(user != null) { %>	<c:if test="${not empty user}">
Scriptlet DB access	<% Connection con = ... %>	Move to DAO/Service layer
Scriptlet import	<%@ page import="java.sql.*" %>	Remove — indicates wrong layer
No JSTL	HTML mixed with <%= request.getAttribute("x") %>	${x} with EL
Inline CSS/JS	<style> and <script> in every JSP	External files, asset pipeline
Include vs Tiles	<%@ include file="header.jsp" %> everywhere	Tiles template inheritance
Form action hardcoding	<form action="/app/saveUser.do">	<html:form action="/saveUser">

Code Archeology Checklist

When first encountering a Struts/JSP codebase:

1. Read web.xml — understand servlet mappings, filters, listeners, context params
2. Read struts-config.xml or struts.xml — map all actions to Action classes
3. Count JSP files — find . -name "*.jsp" | wc -l
4. Count Action classes — grep -rl "extends Action" src/ or grep -rl "extends ActionSupport" src/
5. Identify DAO pattern — JDBC? Hibernate? iBatis? JPA?
6. Check dependency versions — pom.xml or lib/*.jar versions
7. Measure scriptlet density — grep -rc '<%[^@=-]' webapp/ --include="*.jsp"
8. Check test coverage — find . -name "*Test.java" | wc -l
9. Identify security model — Container auth? Custom filter? Struts interceptor?
10. Map URL patterns — Extract all *.do or action mappings

Technical Debt Scoring

Category	Low Debt	Medium Debt	High Debt
Scriptlets	<10 across all JSPs	10-100	>100
God Actions	None >200 lines	1-3 large actions	>3 or >500 lines
Test coverage	>50%	20-50%	<20%
SQL injection risk	Parameterized queries	Mixed	String concatenation
Dependency age	<5 years old	5-10 years	>10 years
Build system	Maven 3+	Maven 2	Ant only