Spring Session

基本概念

由於web page是stateless，所以，很多的資料(如:登入、購物車)就必須靠session來儲存，早期的session是依賴在browser端的cookie，不過，cookie是不安全的做法，所以，現在的session都是依賴伺服器端來儲存。Spring Session提供更彈性化的session管理。Spring Session提供不同方式進行session管理，如:Redis, Pivotal GemFire, JDBC, Mongo, Hazelcast。以下的範例都以JDBC+MySQL為例，將session資料儲存在資料庫的好處是不會因為重啟web server就遺失所有的session資料。

設定

pom.xml (因為使用jdbc，所以，也需要jdbc的相關packages)

        <dependency>

                <groupId>org.springframework.session</groupId>

                <artifactId>spring-session-jdbc</artifactId>

        </dependency>

        <dependency>

                <groupId>org.springframework.boot</groupId>

                <artifactId>spring-boot-starter-jdbc</artifactId>

        </dependency>

        <dependency>

                <groupId>mysql</groupId>

                <artifactId>mysql-connector-java</artifactId>

                <scope>runtime</scope>

        </dependency>

application.properties (因為使用jdbc，所以，也需要jdbc的設定)，其中spring.session.jdbc.initializer.enabled=true會幫我們在資料庫建立所需要的資料表及欄位，所以，在資料表及欄位建立後就不需要了。

spring.datasource.url=jdbc:mysql://localhost/practice?verifyServerCertificate=false&useSSL=false&requireSSL=false

spring.datasource.username=root

spring.datasource.password=1234

spring.datasource.driver-class-name=com.mysql.jdbc.Driver

spring.session.store-type=jdbc

spring.session.jdbc.table-name=SPRING_SESSION

spring.session.jdbc.initializer.enabled=true

如果不使用initializer，可以自行產生相關的資料表

CREATE TABLE `SPRING_SESSION` (

  `SESSION_ID` char(36) NOT NULL DEFAULT '',

  `CREATION_TIME` bigint(20) NOT NULL,

  `LAST_ACCESS_TIME` bigint(20) NOT NULL,

  `MAX_INACTIVE_INTERVAL` int(11) NOT NULL,

  `PRINCIPAL_NAME` varchar(100) DEFAULT NULL,

  PRIMARY KEY (`SESSION_ID`),

  KEY `SPRING_SESSION_IX1` (`LAST_ACCESS_TIME`)

) ENGINE=InnoDB

還有

CREATE TABLE `SPRING_SESSION_ATTRIBUTES` (

  `SESSION_ID` char(36) NOT NULL DEFAULT '',

  `ATTRIBUTE_NAME` varchar(200) NOT NULL DEFAULT '',

  `ATTRIBUTE_BYTES` blob,

  PRIMARY KEY (`SESSION_ID`,`ATTRIBUTE_NAME`),

  KEY `SPRING_SESSION_ATTRIBUTES_IX1` (`SESSION_ID`),

  CONSTRAINT `SPRING_SESSION_ATTRIBUTES_FK` FOREIGN KEY (`SESSION_ID`) REFERENCES `SPRING_SESSION` (`SESSION_ID`) ON DELETE CASCADE

) ENGINE=InnoDB

可以在Application裡加@EnableJdbcHttpSession，攔截原本的HttpSession，以Spring Session取代。

package com.example.demo;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.session.jdbc.config.annotation.web.http.EnableJdbcHttpSession;

@SpringBootApplication

@EnableJdbcHttpSession

public class DemoSessionApplication {

  public static void main(String[] args) {

  SpringApplication.run(DemoSessionApplication.class, args);

或者，產生一個HttpSessionConfig，攔截原本的HttpSession，以Spring Session取代。

package com.example.demo;

import org.springframework.session.jdbc.config.annotation.web.http.EnableJdbcHttpSession;

@EnableJdbcHttpSession

public class HttpSessionConfig {

在controller (如:BookController)裡，可以直接利用HttpSession來存取Session (要import javax.servlet.http.HttpSession;)。

    @RequestMapping(value = "/", method = RequestMethod.GET)

    public ModelAndView openFormLogin() {

       ModelAndView model = new ModelAndView("hi");

       return model;

    @RequestMapping(value = "/HelloWithId", method = RequestMethod.POST)

    public ModelAndView processForm(@ModelAttribute("id") String id, HttpSession session) {

       ModelAndView model = new ModelAndView("redirect:/bookRetrieveAll");

       session.setAttribute("loginId", id);

       return model;

在view (如:bookList.html)就可以利用${session.loginId}來取得資料。

<!DOCTYPE html>

<html lang="en" xmlns:th="http://www.thymeleaf.org">

<head>

    <meta charset="UTF-8"/>

    <title>List ALl Books</title>

</head>

<body>

Hello <span th:text="${session.loginId}">login id</span>!

<form action="bookRetrieveByCategory" method ="post">

  類別:<select name = "bookCategory" th:field="${bookCategory.id}">

  <option th:each="bookCategory : ${allBookCategories}"

          th:value="${bookCategory.id}"

          th:text="${bookCategory.name}">商業</option>

</select>

 <input type="submit" value="Submit"/>

 <a href="bookRetrieveAll"><input type="button" value="Show All Books"/></a>

</form>

 <a href="shoppingCartList"><input type="button" value="Show Shopping Cart"/></a>

<table>

  <tr>

  <th>編號</th>

  <th>類別</th>

  <th>名稱</th>

  <th>價格</th>

  <th></th>

 </tr>

    <tr th:each="book : ${allBooks} " th:object="${book}">

        <td th:text="*{id}">1</td>

        <td th:text="*{bookCategory.name}">business</td>

        <td th:text="*{name}">Ben</td>

        <td th:text="*{price}">300</td>

        <td><a th:href="@{shoppingCartAdd(id=*{id})}">加入購物車</a></td>

    </tr>

</table>

</body>

</html>

Session Bean

如果儲存在session裡的是個類別，我們就稱這個類別為session bean。在Spring 4.3之後，可以使用@SessionScope來設定這個類別是個session bean。如果我們採用JdbcHttpSession，那就要將這個類別設為Serializable，並且定義serialVersionUID。(詳參:https://www.mkyong.com/java-best-practices/understand-the-serialversionuid/)

package com.example.demo.entity;

import java.io.Serializable;

import java.util.ArrayList;

import java.util.List;

import org.springframework.stereotype.Component;

import org.springframework.web.context.annotation.SessionScope;

@SessionScope

@Component

public class ShoppingCart implements Serializable{

/**

*/

 private static final long serialVersionUID = -5494311567944263493L;

 private List<Book> cart = new ArrayList<Book>();

 public Iterable<Book> getCart(){

   return cart;

 public void add(Book book){

  cart.add(book);

 public void cleanup(){

  cart = new ArrayList<Book>();

如果我們採用JdbcHttpSession，那就要將Book.java設為Serializable，並且定義serialVersionUID。

package com.example.demo.entity;

import java.io.Serializable;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.JoinColumn;

import javax.persistence.ManyToOne;

@Entity

public class Book implements Serializable{

/**

*/

 private static final long serialVersionUID = 3316076651716569539L;

@Id

 @GeneratedValue(strategy = GenerationType.AUTO)

 private Long id;

 private String name;

 private int price;

 // JoinColumn refers to the column name in the table

 @ManyToOne

 @JoinColumn(name = "category")

 private BookCategory bookCategory;

 public Long getId() {

  return id;

 public void setId(Long id) {

  this.id = id;

 public String getName() {

  return name;

 public void setName(String name) {

  this.name = name;

 public int getPrice() {

  return price;

 public void setPrice(int price) {

  this.price = price;

 public BookCategory getBookCategory() {

  return bookCategory;

 public void setBookCategory(BookCategory bookCategory) {

  this.bookCategory = bookCategory;

如果我們採用JdbcHttpSession，那就要將BookCategory.java設為Serializable，並且定義serialVersionUID。

package com.example.demo.entity;

import java.io.Serializable;

import java.util.List;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.OneToMany;

import javax.persistence.Table;

@Entity

@Table(name = "book_category")

public class BookCategory implements Serializable{

/**

*/

 private static final long serialVersionUID = -2957645392914180170L;

@Id

 @GeneratedValue(strategy = GenerationType.AUTO)

 private Long id;

 private String name;

 // mappedBy refers to the variable in Book

 @OneToMany(mappedBy = "bookCategory")

 private List<Book> books;

 public Long getId() {

  return id;

 public void setId(Long id) {

  this.id = id;

 public String getName() {

  return name;

 public void setName(String name) {

  this.name = name;

 public Iterable<Book> getBooks() {

  return books;

在Controller裡(如:BookController)，利用@Autowired就可以使用這個session bean了!

package com.example.demo.controller;

import javax.servlet.http.HttpSession;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.ModelAttribute;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RequestParam;

import org.springframework.web.servlet.ModelAndView;

import com.example.demo.dao.BookCategoryDAO;

import com.example.demo.dao.BookDAO;

import com.example.demo.entity.Book;

import com.example.demo.entity.BookCategory;

import com.example.demo.entity.ShoppingCart;

@Controller

public class BookController {

  @Autowired

 BookDAO dao;

 @Autowired

 BookCategoryDAO categoryDao;

 @Autowired

 ShoppingCart cart;

    @RequestMapping(value = "/", method = RequestMethod.GET)

    public ModelAndView openFormLogin() {

       ModelAndView model = new ModelAndView("hi");

       return model;

    @RequestMapping(value = "/HelloWithId", method = RequestMethod.POST)

    public ModelAndView processForm(@ModelAttribute("id") String id, HttpSession session) {

       ModelAndView model = new ModelAndView("redirect:/bookRetrieveAll");

  session.setAttribute("loginId", id);

  System.out.println("loginId:"+id);

       return model;

 @RequestMapping(value = "/bookCreate", method = RequestMethod.GET)

 public ModelAndView openFormCreate() {

  ModelAndView model = new ModelAndView("bookCreate");

  Iterable<BookCategory> categories = categoryDao.findAll();

  model.addObject("allBookCategories", categories);

  return model;

 @RequestMapping(value = "/bookCreate", method = RequestMethod.POST)

 public ModelAndView processFormCreate(@ModelAttribute Book book) {

  // ModelAndView model = new ModelAndView("bookDone");

  ModelAndView model = new ModelAndView("redirect:/bookRetrieveAll");

  dao.save(book);

  model.addObject(book);

  return model;

 @RequestMapping(value = { "/bookRetrieveAll"}, method = RequestMethod.GET)

 public ModelAndView retrieveBooks() {

  ModelAndView model = new ModelAndView("bookList");

  Iterable<BookCategory> categories = categoryDao.findAll();

  model.addObject("allBookCategories", categories);

  BookCategory category = categories.iterator().next();//get first category

  model.addObject("bookCategory", category);

  Iterable<Book> books = dao.findAll();

  model.addObject("allBooks", books);

  return model;

 @RequestMapping(value = { "/bookRetrieveByCategory" }, method = RequestMethod.POST)

 public ModelAndView retrieveBooksByCategory(

   @RequestParam(value = "id", required = false, defaultValue = "1") Long id) {

  ModelAndView model = new ModelAndView("bookList");

  Iterable<BookCategory> categories = categoryDao.findAll();

  model.addObject("allBookCategories", categories);

  BookCategory category = categoryDao.findOne(id);

  model.addObject("bookCategory", category);

  model.addObject("allBooks", category.getBooks());

  return model;

 @RequestMapping(value = "/bookUpdate", method = RequestMethod.GET)

 public ModelAndView openFormUpdate(

   @RequestParam(value = "id", required = false, defaultValue = "1") Long id) {

  ModelAndView model = new ModelAndView("bookUpdate");

  Book book = dao.findOne(id);

  model.addObject(book);

  Iterable<BookCategory> categories = categoryDao.findAll();

  model.addObject("allBookCategories", categories);

  return model;

 @RequestMapping(value = "/bookUpdate", method = RequestMethod.POST)

 public ModelAndView processFormUpdate(@ModelAttribute Book book) {

  ModelAndView model = new ModelAndView("redirect:/bookRetrieveAll");

  dao.save(book);

  return model;

 @RequestMapping(value = "/bookDelete", method = RequestMethod.GET)

 public ModelAndView deleteBook(

   @RequestParam(value = "id", required = false, defaultValue = "1") Long id) {

  ModelAndView model = new ModelAndView("redirect:/bookRetrieveAll");

  dao.delete(id);

  return model;

 @RequestMapping(value = "/shoppingCartAdd", method = RequestMethod.GET)

 public ModelAndView addShoppingCart(

   @RequestParam(value = "id", required = false, defaultValue = "1") Long id) {

  ModelAndView model = new ModelAndView("redirect:/bookRetrieveAll");

  Book book = dao.findOne(id);

  cart.add(book);

  return model;

 @RequestMapping(value = "/shoppingCartList", method = RequestMethod.GET)

 public ModelAndView showShoppingCart() {

  ModelAndView model = new ModelAndView("shoppingCart");

  return model;

 @RequestMapping(value = "/cleanShoppingCart", method = RequestMethod.GET)

 public ModelAndView cleanShoppingCart() {

  ModelAndView model = new ModelAndView("shoppingCart");

  cart.cleanup();

  return model;

bookList.html稍微修改一下，可以將所想購買的物品置入購物車(呼叫/shoppingCartAdd)。

<!DOCTYPE html>

<html lang="en" xmlns:th="http://www.thymeleaf.org">

<head>

    <meta charset="UTF-8"/>

    <title>List ALl Books</title>

</head>

<body>

Hello <span th:text="${session.loginId}">login id</span>!

<form action="bookRetrieveByCategory" method ="post">

  類別:<select name = "bookCategory" th:field="${bookCategory.id}">

  <option th:each="bookCategory : ${allBookCategories}"

          th:value="${bookCategory.id}"

          th:text="${bookCategory.name}">商業</option>

</select>

 <input type="submit" value="Submit"/>

 <a href="bookRetrieveAll"><input type="button" value="Show All Books"/></a>

</form>

 <a href="shoppingCartList"><input type="button" value="Show Shopping Cart"/></a>

<table>

  <tr>

  <th>編號</th>

  <th>類別</th>

  <th>名稱</th>

  <th>價格</th>

  <th></th>

 </tr>

    <tr th:each="book : ${allBooks} " th:object="${book}">

        <td th:text="*{id}">1</td>

        <td th:text="*{bookCategory.name}">business</td>

        <td th:text="*{name}">Ben</td>

        <td th:text="*{price}">300</td>

        <td><a th:href="@{shoppingCartAdd(id=*{id})}">加入購物車</a></td>

    </tr>

</table>

</body>

</html>

另外，新增一個shoppingCart.html稍微修改一下，可以看到session bean裡的內容，在Thymeleaf裡使用"@"來取得bean的內容(如:${@shoppingCart.cart})。

<!DOCTYPE html>

<html lang="en" xmlns:th="http://www.thymeleaf.org">

<head>

    <meta charset="UTF-8"/>

    <title>Shopping Cart</title>

</head>

<body>

Shopping Cart for <span th:text="${session.loginId}">login id</span>

<a href="bookRetrieveAll"><input type="button" value="Keep Shopping"/></a>

<a href="cleanShoppingCart"><input type="button" value="Clean up Shopping Cart"/></a>

<table>

  <tr>

  <th>編號</th>

  <th>類別</th>

  <th>名稱</th>

  <th>價格</th>

  <th></th>

 </tr>

     <tr th:each="book : ${@shoppingCart.cart} " th:object="${book}">

        <td th:text="*{id}">1</td>

        <td th:text="*{bookCategory.name}">business</td>

        <td th:text="*{name}">Ben</td>

        <td th:text="*{price}">300</td>

    </tr>

</table>

</body>

</html>

參考資料

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