[EDIT]二次実装である支出分析の年月表示を実装しました

src/main/java/com/example/demo/app/domain/service/AnalysisService.java

@@ -4,6 +4,9 @@ import com.example.demo.app.domain.model.AnalysisModel;
 
 public interface AnalysisService {
 
-    AnalysisModel getAnalysis(Long userId);
+    AnalysisModel getAnalysis(
+    		Long userId,
+    		Integer year,
+    		Integer month);
 
 }

src/main/java/com/example/demo/app/domain/service/impl/AnalysisServiceImpl.java

@@ -30,7 +30,7 @@ public class AnalysisServiceImpl implements AnalysisService {
 	private final CategoryRepository categoryRepository;
 	
 	@Override
-	public AnalysisModel getAnalysis(Long userId) {
+	public AnalysisModel getAnalysis(Long userId, Integer year, Integer month) {
 		
 		// ユーザー情報取得、月別使用可能資金取得
 		UserEntity userEntity = userRepository.findById(userId).orElseThrow(() ->
@@ -44,12 +44,15 @@ public class AnalysisServiceImpl implements AnalysisService {
 		Integer monthlyBudget =userEntity.getMonthlyBudget();
 		
 		// 今月の期間取得
-		LocalDate currentMonthStartDate = LocalDate.now().withDayOfMonth(1);
-		LocalDate currentMonthEndDate = LocalDate.now().withDayOfMonth(LocalDate.now().lengthOfMonth());
+		LocalDate targetDate = LocalDate.of(year, month, 1);
+		LocalDate currentMonthStartDate = targetDate.withDayOfMonth(1);
+		LocalDate currentMonthEndDate = targetDate.withDayOfMonth(targetDate.lengthOfMonth());
 		
 		// 前月の期間取得
-		LocalDate previousMonthStartDate = LocalDate.now().minusMonths(1).withDayOfMonth(1);
-		LocalDate previousMonthEndDate = LocalDate.now().minusMonths(1).withDayOfMonth(LocalDate.now().minusMonths(1).lengthOfMonth());
+		LocalDate previousDate = targetDate.minusMonths(1);
+		
+		LocalDate previousMonthStartDate = previousDate.withDayOfMonth(1);
+		LocalDate previousMonthEndDate = previousDate.withDayOfMonth(previousDate.lengthOfMonth());
 		
 		// 今月の支出取得
 		Integer currentMonthTotalAmount = transactionRepository.findTotalExpense(currentMonthStartDate, currentMonthEndDate, userId);

src/main/java/com/example/demo/app/presentation/controller/AnalysisController.java

@@ -1,10 +1,13 @@
 package com.example.demo.app.presentation.controller;
 
+import java.time.LocalDate;
+
 import jakarta.servlet.http.HttpSession;
 
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestParam;
 
 import com.example.demo.app.domain.model.AnalysisModel;
 import com.example.demo.app.domain.model.LoginModel;
@@ -21,18 +24,45 @@ public class AnalysisController {
 	private final AnalysisService analysisService;
 	
 	@GetMapping("/analysis")
-	public String showAnalysis(Model model, HttpSession session) {
+	public String showAnalysis(
+			@RequestParam(required = false) Integer year,
+			@RequestParam(required = false) Integer month,
+			Model model,
+			HttpSession session) {
 		
 		//ログインユーザーの取得（セッション）
         LoginModel loginUser = (LoginModel) session.getAttribute("loginUser");
         
+        //初期年月表示
+        LocalDate nowDate = LocalDate.now();
+
+        if (year == null) {
+            year = nowDate.getYear();
+        }
+
+        if (month == null) {
+            month = nowDate.getMonthValue();
+        }
+        
+        //前月・翌月作成
+        LocalDate targetDate = LocalDate.of(year, month, 1);
+
+        LocalDate previousDate = targetDate.minusMonths(1);
+        LocalDate nextDate = targetDate.plusMonths(1);
+        
 		//分析結果の取得(Service)
-        AnalysisModel analysisModel = analysisService.getAnalysis(loginUser.getUserId());
+        AnalysisModel analysisModel = analysisService.getAnalysis(loginUser.getUserId(), year, month);
         
         AnalysisForm analysisForm = AnalysisForm.convertFrom(analysisModel);
         
 		//model格納
         model.addAttribute("analysisForm", analysisForm);
+        model.addAttribute("year", year);
+        model.addAttribute("month", month);
+        model.addAttribute("previousYear", previousDate.getYear());
+        model.addAttribute("previousMonth", previousDate.getMonthValue());
+        model.addAttribute("nextYear", nextDate.getYear());
+        model.addAttribute("nextMonth", nextDate.getMonthValue());
 		
 		return "analysis";
 	}

src/main/resources/templates/analysis.html

@@ -5,6 +5,7 @@
 <title>分析画面</title>
 <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
 </head>
+
 <body class="pb-5 pt-5">
 	
 	<div th:replace="~{header :: header}">
@@ -13,6 +14,23 @@
 	<div class="container mt-4">
 	<h2 class="text-center">支出分析</h2>
 	
+	<div class="text-center">
+
+		<a class="month-button" th:href="@{/analysis(year=${previousYear}, month=${previousMonth})}">
+			←
+		</a>
+
+		<div class="calendar-date">
+			<span class="year" th:text="|${year}年|"></span>
+			<span class="month" th:text="|${month}月|"></span>
+		</div>
+
+		<a class="month-button" th:href="@{/analysis(year=${nextYear}, month=${nextMonth})}">
+			→
+		</a>
+
+	</div>
+	
 	<table class="table text-center">
         <thead>
 	        <tr>