BAEL-1793 Spring with Thymeleaf Pagination for a List (#4290)

* BAEL-1793 Spring with Thymeleaf Pagination for a List

* Replace tabs with 4 spaces in HTML based on editor's feedback.

spring-thymeleaf/src/main/java/com/baeldung/thymeleaf/controller/BookController.java

@@ -0,0 +1,48 @@
+package com.baeldung.thymeleaf.controller;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RequestParam;
+
+import com.baeldung.thymeleaf.model.Book;
+import com.baeldung.thymeleaf.model.Page;
+import com.baeldung.thymeleaf.utils.BookUtils;
+
+@Controller
+public class BookController {
+
+    private static int currentPage = 1;
+    private static int pageSize = 5;
+
+    @RequestMapping(value = "/listBooks", method = RequestMethod.GET)
+    public String listBooks(Model model, @RequestParam("page") Optional<Integer> page, @RequestParam("size") Optional<Integer> size) {
+        page.ifPresent(p -> currentPage = p);
+        size.ifPresent(s -> pageSize = s);
+
+        List<Book> books = BookUtils.buildBooks();
+        Page<Book> bookPage = new Page<Book>(books, pageSize, currentPage);
+
+        model.addAttribute("books", bookPage.getList());
+        model.addAttribute("selectedPage", bookPage.getCurrentPage());
+        model.addAttribute("pageSize", pageSize);
+
+        int totalPages = bookPage.getTotalPages();
+        model.addAttribute("totalPages", totalPages);
+
+        if (totalPages > 1) {
+            List<Integer> pageNumbers = IntStream.rangeClosed(1, totalPages)
+                .boxed()
+                .collect(Collectors.toList());
+            model.addAttribute("pageNumbers", pageNumbers);
+        }
+
+        return "listBooks.html";
+    }
+}

spring-thymeleaf/src/main/java/com/baeldung/thymeleaf/model/Book.java

@@ -0,0 +1,29 @@
+package com.baeldung.thymeleaf.model;
+
+public class Book {
+    private int id;
+    private String name;
+
+    public Book(int id, String name) {
+        super();
+        this.id = id;
+        this.name = name;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+}

spring-thymeleaf/src/main/java/com/baeldung/thymeleaf/model/Page.java

@@ -0,0 +1,61 @@
+package com.baeldung.thymeleaf.model;
+
+import java.util.Collections;
+import java.util.List;
+
+public class Page<T> {
+
+    private List<T> list;
+
+    private int pageSize = 0;
+
+    private int currentPage = 0;
+
+    private int totalPages = 0;
+
+    public Page(List<T> list, int pageSize, int currentPage) {
+
+        if (list.isEmpty()) {
+            this.list = list;
+        }
+
+        if (pageSize <= 0 || pageSize > list.size() || currentPage <= 0) {
+            throw new IllegalArgumentException("invalid page size or current page!");
+        }
+
+        this.pageSize = pageSize;
+
+        this.currentPage = currentPage;
+
+        if (list.size() % pageSize == 0) {
+            this.totalPages = list.size() / pageSize;
+        } else {
+            this.totalPages = list.size() / pageSize + 1;
+        }
+
+        int startItem = (currentPage - 1) * pageSize;
+        if (list.size() < startItem) {
+            this.list = Collections.emptyList();
+        }
+
+        int toIndex = Math.min(startItem + pageSize, list.size());
+        this.list = list.subList(startItem, toIndex);
+    }
+
+    public List<T> getList() {
+        return list;
+    }
+
+    public int getPageSize() {
+        return pageSize;
+    }
+
+    public int getCurrentPage() {
+        return currentPage;
+    }
+
+    public int getTotalPages() {
+        return totalPages;
+    }
+
+}

spring-thymeleaf/src/main/java/com/baeldung/thymeleaf/utils/BookUtils.java

@@ -0,0 +1,28 @@
+package com.baeldung.thymeleaf.utils;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.IntStream;
+
+import com.baeldung.thymeleaf.model.Book;
+
+public class BookUtils {
+
+    private static List<Book> books = new ArrayList<Book>();
+
+    private static final int NUM_BOOKS = 30;
+        
+    private static final int MIN_BOOK_NUM = 1000;
+
+    public static List<Book> buildBooks() {
+        if (books.isEmpty()) {
+            IntStream.range(0, NUM_BOOKS).forEach(n -> {
+                books.add(new Book(MIN_BOOK_NUM + n + 1, "Spring in Action"));
+            });
+            
+        }
+
+        return books;
+    }
+    
+}

spring-thymeleaf/src/main/resources/messages_en.properties

@@ -1,12 +1,13 @@
-msg.id=ID
-msg.name=Name
-msg.gender=Gender
-msg.percent=Percentage
-welcome.message=Welcome Student !!!
-msg.AddStudent=Add Student
-msg.ListStudents=List Students
-msg.Home=Home
-msg.ListTeachers=List Teachers
-msg.courses=Courses
-msg.skills=Skills
+msg.id=ID
+msg.name=Name
+msg.gender=Gender
+msg.percent=Percentage
+welcome.message=Welcome Student !!!
+msg.AddStudent=Add Student
+msg.ListStudents=List Students
+msg.Home=Home
+msg.ListTeachers=List Teachers
+msg.ListBooks=List Books with paging
+msg.courses=Courses
+msg.skills=Skills
 msg.active=Active

spring-thymeleaf/src/main/webapp/WEB-INF/views/home.html

@@ -21,6 +21,9 @@
 		<tr>
 			<td><a th:href="@{/listTeachers}" th:text="#{msg.ListTeachers}" /></td>
 		</tr>
+		<tr>
+			<td><a th:href="@{/listBooks}" th:text="#{msg.ListBooks}" /></td>
+		</tr>
 	</table>
 </body>
 </html>

spring-thymeleaf/src/main/webapp/WEB-INF/views/listBooks.html

@@ -0,0 +1,58 @@
+<!DOCTYPE html>
+<html xmlns="http://www.w3.org/1999/xhtml"
+    xmlns:th="http://www.thymeleaf.org">
+<style>
+.pagination {
+	display: inline-block;
+}
+
+.pagination a {
+	color: black;
+	float: left;
+	padding: 5px 5px;
+	text-decoration: none;
+}
+
+.pagination a.active {
+	background-color: gray;
+	color: white;
+	border-radius: 2px;
+}
+</style>
+<head>
+<title>Book List</title>
+</head>
+<body>
+    <h1>Book List</h1>
+    <table border="1">
+        <thead>
+            <tr>
+                <th th:text="#{msg.id}" />
+                <th th:text="#{msg.name}" />
+            </tr>
+        </thead>
+        <tbody>
+            <tr th:each="book, iStat : ${books}"
+                th:style="${iStat.odd}? 'font-weight: bold;'"
+                th:alt-title="${iStat.even}? 'even' : 'odd'">
+                <td th:text="${book.id}" />
+                <td th:text="${book.name}" />
+            </tr>
+        </tbody>
+    </table>
+    <div th:if="${totalPages > 1}" class="pagination"
+        th:each="pageNumber : ${pageNumbers}">
+        <a th:href="@{/listBooks(size=${pageSize}, page=${pageNumber})}"
+            th:text=${pageNumber}
+            th:class="${pageNumber==selectedPage} ? active"></a>
+    </div>
+
+    <div>
+        <p>
+            <a th:href="@{/}" th:text="#{msg.Home}"></a>
+        </p>
+    </div>
+</body>
+</html>
+
+