Spring4 MVC+Hibernate4 Many-to-many连接表+MySQL+Maven实例

这篇文章显示 Hibernate 的多对多实例，在 Spring MVC CRUD Web应用程序中连接表。我们将同时讨论管理多对多关系在视图和后端。 我们将使用应用程序的Web界面创建，更新，删除和查询。

本教程是利用 Spring 的 org.springframework.core.convert.converter.Converter 接口，它帮助我们在项目的数据库中实现实体的映射标识。

完整的示例的说明介绍如下。

使用以下技术：

• Spring 4.1.7.RELEASE
• Hibernate Core 4.3.10.Final
• validation-api 1.1.0.Final
• hibernate-validator 5.1.3.Final
• MySQL Server 5.6
• Maven 3
• JDK 1.7
• Tomcat 8.0.21
• Eclipse JUNO Service Release 2

现在，让我们开始！

步骤1.创建模式用于连接多对多表关联

APP_USER :包含用户。一个用户可以有多个配置[USER，ADMIN，DBA]。

USER_PROFILE : 包含用户配置文件。配置文件可以链接到多个用户。

APP_USER_USER_PROFILE : 这是一个连接表连接APP_USER＆USER_PROFILE中的多对多关系。

出于演示的目的，我们在这里只讨论许多对多的单向[用户到用户信息]设置。

create table APP_USER (
   id BIGINT NOT NULL AUTO_INCREMENT,
   sso_id VARCHAR(30) NOT NULL,
   password VARCHAR(100) NOT NULL,
   first_name VARCHAR(30) NOT NULL,
   last_name  VARCHAR(30) NOT NULL,
   email VARCHAR(30) NOT NULL,
   PRIMARY KEY (id),
   UNIQUE (sso_id)
);

create table USER_PROFILE(
   id BIGINT NOT NULL AUTO_INCREMENT,
   type VARCHAR(30) NOT NULL,
   PRIMARY KEY (id),
   UNIQUE (type)
);

CREATE TABLE APP_USER_USER_PROFILE (
    user_id BIGINT NOT NULL,
    user_profile_id BIGINT NOT NULL,
    PRIMARY KEY (user_id, user_profile_id),
    CONSTRAINT FK_APP_USER FOREIGN KEY (user_id) REFERENCES APP_USER (id),
    CONSTRAINT FK_USER_PROFILE FOREIGN KEY (user_profile_id) REFERENCES USER_PROFILE (id)
);

/* Populate USER_PROFILE Table */
INSERT INTO USER_PROFILE(type)
VALUES ('USER');

INSERT INTO USER_PROFILE(type)
VALUES ('ADMIN');

INSERT INTO USER_PROFILE(type)
VALUES ('DBA');

commit;

第2步：创建目录结构

以下是最终的项目结构：

第3步：更新pom.xml，包括所需的依赖关系

<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
	xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.yiibai.springmvc</groupId>
	<artifactId>SpringMVCMany2ManyCRUD</artifactId>
	<packaging>war</packaging>
	<version>1.0.0</version>
	<name>SpringMVCHibernateManyToManyCRUDExample</name>

  	<properties>
		<springframework.version>4.1.7.RELEASE</springframework.version>
		<hibernate.version>4.3.10.Final</hibernate.version>
		<mysql.connector.version>5.1.31</mysql.connector.version>
	</properties>

	<dependencies>
		<!-- Spring -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-core</artifactId>
			<version>${springframework.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-web</artifactId>
			<version>${springframework.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>${springframework.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-tx</artifactId>
			<version>${springframework.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-orm</artifactId>
			<version>${springframework.version}</version>
		</dependency>

		<!-- Hibernate -->
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-core</artifactId>
			<version>${hibernate.version}</version>
		</dependency>

		<!-- jsr303 validation -->
		<dependency>
			<groupId>javax.validation</groupId>
			<artifactId>validation-api</artifactId>
			<version>1.1.0.Final</version>
		</dependency>
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-validator</artifactId>
			<version>5.1.3.Final</version>
		</dependency>

		<!-- MySQL -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>${mysql.connector.version}</version>
		</dependency>

		<!-- Servlet+JSP+JSTL -->
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>javax.servlet-api</artifactId>
			<version>3.1.0</version>
		</dependency>
		<dependency>
			<groupId>javax.servlet.jsp</groupId>
			<artifactId>javax.servlet.jsp-api</artifactId>
			<version>2.3.1</version>
		</dependency>
		<dependency>
		    <groupId>javax.servlet</groupId>
		    <artifactId>jstl</artifactId>
		    <version>1.2</version>
		</dependency>

	</dependencies>

	<build>
		<pluginManagement>
			<plugins>
				<plugin>
					<groupId>org.apache.maven.plugins</groupId>
					<artifactId>maven-war-plugin</artifactId>
					<version>2.4</version>
					<configuration>
						<warSourceDirectory>src/main/webapp</warSourceDirectory>
						<warName>SpringMVCMany2ManyCRUD</warName> <failOnMissingWebXml>false</failOnMissingWebXml>
					</configuration>
				</plugin>
			</plugins>
		</pluginManagement>
		<finalName>SpringMVCMany2ManyCRUD</finalName>
	</build>
</project>

第4步：准备Model类

package com.yiibai.springmvc.model;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;

import org.hibernate.validator.constraints.NotEmpty;

@Entity
@Table(name="APP_USER")
public class User {

	@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
	private Integer id;

	@NotEmpty
	@Column(name="SSO_ID", unique=true, nullable=false)
	private String ssoId;

	@NotEmpty
	@Column(name="PASSWORD", nullable=false)
	private String password;

	@NotEmpty
	@Column(name="FIRST_NAME", nullable=false)
	private String firstName;

	@NotEmpty
	@Column(name="LAST_NAME", nullable=false)
	private String lastName;

	@NotEmpty
	@Column(name="EMAIL", nullable=false)
	private String email;

	@NotEmpty
	@ManyToMany(fetch = FetchType.LAZY)
	@JoinTable(name = "APP_USER_USER_PROFILE",
             joinColumns = { @JoinColumn(name = "USER_ID") },
             inverseJoinColumns = { @JoinColumn(name = "USER_PROFILE_ID") })
	private Set<UserProfile> userProfiles = new HashSet<UserProfile>();

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getSsoId() {
		return ssoId;
	}

	public void setSsoId(String ssoId) {
		this.ssoId = ssoId;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	public String getFirstName() {
		return firstName;
	}

	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}

	public String getLastName() {
		return lastName;
	}

	public void setLastName(String lastName) {
		this.lastName = lastName;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	public Set<UserProfile> getUserProfiles() {
		return userProfiles;
	}

	public void setUserProfiles(Set<UserProfile> userProfiles) {
		this.userProfiles = userProfiles;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ((id == null) ? 0 : id.hashCode());
		result = prime * result + ((ssoId == null) ? 0 : ssoId.hashCode());
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (!(obj instanceof User))
			return false;
		User other = (User) obj;
		if (id == null) {
			if (other.id != null)
				return false;
		} else if (!id.equals(other.id))
			return false;
		if (ssoId == null) {
			if (other.ssoId != null)
				return false;
		} else if (!ssoId.equals(other.ssoId))
			return false;
		return true;
	}

	@Override
	public String toString() {
		return "User [id=" + id + ", ssoId=" + ssoId + ", password=" + password
				+ ", firstName=" + firstName + ", lastName=" + lastName
				+ ", email=" + email + "]";
	}

}

再看看 UserProfiles 属性是如何标注了多对多。

@ManyToMany表示用户和用户配置之间有多到多关系。一个用户可以有多个资料[USER，ADMIN，DBA]用户资料信息可以属于多个用户。@JoinTable表示它使用两个表的表外键链接来约束自己的主键。这个注解，主要用于关系的拥有方。joinColumns是指拥有方(用户ID)的列名，inverseJoinColumns是指关系的反向端(USER_PROFILE的ID)的列。这个连接表的主键是USER_ID & USER_PROFILE_ID 组合。

延迟加载：

要特别注意fetch = FetchType.LAZY。在这里，我们通知 Hibernate 懒加载用户资料集合。 这也是默认的行为。在此设置中，首先访问仅当查询加载集合将被触发。这是一个很好的方式，以避免加载-这是一个昂贵的操作所有连接的对象。 当在事务/活动会话，并会尝试访问集合，Hibernate会触发不同的选择来获取它们。

但是，如果您不在活动的会话(会话关闭/无事务：如在JSP)，并试图访问集合，你会遇到报应:org.hibernate.LazyInitializationException – could not initialize proxy – no Session. 为了避免它，需要通过调用 Hibernate.initialize(user.getUserProfiles()); 来初始化对需要的集合; 在有效会话中[在DAO方法，在显示视图之前，可以调用这个初始化方法]。

还要注意的是，我们没有使用任何级联。这是因为用户个人资料不依赖用户，并能独立生存。

重要：如果是*Many* 关联它总是覆盖 hashCode 和 equals 方法，它是通过 Hibernate 持有合并形成集合。

package com.yiibai.springmvc.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="USER_PROFILE")
public class UserProfile {

	@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
	private Integer id;	

	@Column(name="TYPE", length=15, unique=true, nullable=false)
	private String type = UserProfileType.USER.getUserProfileType();

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getType() {
		return type;
	}

	public void setType(String type) {
		this.type = type;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ((id == null) ? 0 : id.hashCode());
		result = prime * result + ((type == null) ? 0 : type.hashCode());
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (!(obj instanceof UserProfile))
			return false;
		UserProfile other = (UserProfile) obj;
		if (id == null) {
			if (other.id != null)
				return false;
		} else if (!id.equals(other.id))
			return false;
		if (type == null) {
			if (other.type != null)
				return false;
		} else if (!type.equals(other.type))
			return false;
		return true;
	}

	@Override
	public String toString() {
		return "UserProfile [id=" + id + ", type=" + type + "]";
	}

}

既然我们都显示单向关系(User到UserProfile)，无须参考用户UserProfile。

package com.yiibai.springmvc.model;

public enum UserProfileType {
	USER("USER"),
	DBA("DBA"),
	ADMIN("ADMIN");

	String userProfileType;

	private UserProfileType(String userProfileType){
		this.userProfileType = userProfileType;
	}

	public String getUserProfileType(){
		return userProfileType;
	}

}

第5步：创建DAO层

package com.yiibai.springmvc.dao;

import java.util.List;

import com.yiibai.springmvc.model.User;

public interface UserDao {

	User findById(int id);

	User findBySSO(String sso);

	void save(User user);

	void deleteBySSO(String sso);

	List<User> findAllUsers();

}

package com.yiibai.springmvc.dao;

import java.util.List;

import com.yiibai.springmvc.model.UserProfile;

public interface UserProfileDao {

	List<UserProfile> findAll();

	UserProfile findByType(String type);

	UserProfile findById(int id);
}

package com.yiibai.springmvc.dao;

import java.io.Serializable;

import java.lang.reflect.ParameterizedType;

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;

public abstract class AbstractDao<PK extends Serializable, T> {

	private final Class<T> persistentClass;

	@SuppressWarnings("unchecked")
	public AbstractDao(){
		this.persistentClass =(Class<T>) ((ParameterizedType) this.getClass().getGenericSuperclass

()).getActualTypeArguments()[1];
	}

	@Autowired
	private SessionFactory sessionFactory;

	protected Session getSession(){
		return sessionFactory.getCurrentSession();
	}

	@SuppressWarnings("unchecked")
	public T getByKey(PK key) {
		return (T) getSession().get(persistentClass, key);
	}

	public void persist(T entity) {
		getSession().persist(entity);
	}

	public void delete(T entity) {
		getSession().delete(entity);
	}

	protected Criteria createEntityCriteria(){
		return getSession().createCriteria(persistentClass);
	}

}

package com.yiibai.springmvc.dao;

import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.Hibernate;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Restrictions;
import org.springframework.stereotype.Repository;

import com.yiibai.springmvc.model.User;

@Repository("userDao")
public class UserDaoImpl extends AbstractDao<Integer, User> implements UserDao {

	public User findById(int id) {
		User user = getByKey(id);
		if(user!=null){
			Hibernate.initialize(user.getUserProfiles());
		}
		return user;
	}

	public User findBySSO(String sso) {
		System.out.println("SSO : "+sso);
		Criteria crit = createEntityCriteria();
		crit.add(Restrictions.eq("ssoId", sso));
		User user = (User)crit.uniqueResult();
		if(user!=null){
			Hibernate.initialize(user.getUserProfiles());
		}
		return user;
	}

	@SuppressWarnings("unchecked")
	public List<User> findAllUsers() {
		Criteria criteria = createEntityCriteria().addOrder(Order.asc("firstName"));
		criteria.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);//To avoid duplicates.
		List<User> users = (List<User>) criteria.list();

		// No need to fetch userProfiles since we are not showing them on list page. Let them lazy load.
		// Uncomment below lines for eagerly fetching of userProfiles if you want.
		/*
		for(User user : users){
			Hibernate.initialize(user.getUserProfiles());
		}*/
		return users;
	}

	public void save(User user) {
		persist(user);
	}

	public void deleteBySSO(String sso) {
		Criteria crit = createEntityCriteria();
		crit.add(Restrictions.eq("ssoId", sso));
		User user = (User)crit.uniqueResult();
		delete(user);
	}

}

package com.yiibai.springmvc.dao;

import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Restrictions;
import org.springframework.stereotype.Repository;

import com.yiibai.springmvc.model.UserProfile;

@Repository("userProfileDao")
public class UserProfileDaoImpl extends AbstractDao<Integer, UserProfile>implements UserProfileDao{

	public UserProfile findById(int id) {
		return getByKey(id);
	}

	public UserProfile findByType(String type) {
		Criteria crit = createEntityCriteria();
		crit.add(Restrictions.eq("type", type));
		return (UserProfile) crit.uniqueResult();
	}

	@SuppressWarnings("unchecked")
	public List<UserProfile> findAll(){
		Criteria crit = createEntityCriteria();
		crit.addOrder(Order.asc("type"));
		return (List<UserProfile>)crit.list();
	}

}

第6步：创建服务层

package com.yiibai.springmvc.service;

import java.util.List;
import com.yiibai.springmvc.model.UserProfile;

public interface UserProfileService {

	UserProfile findById(int id);

	UserProfile findByType(String type);

	List<UserProfile> findAll();

}

package com.yiibai.springmvc.service;

import java.util.List;
import com.yiibai.springmvc.model.User;

public interface UserService {

	User findById(int id);

	User findBySSO(String sso);

	void saveUser(User user);

	void updateUser(User user);

	void deleteUserBySSO(String sso);

	List<User> findAllUsers(); 

	boolean isUserSSOUnique(Integer id, String sso);

}

package com.yiibai.springmvc.service;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.yiibai.springmvc.dao.UserProfileDao;
import com.yiibai.springmvc.model.UserProfile;

@Service("userProfileService")
@Transactional
public class UserProfileServiceImpl implements UserProfileService{

	@Autowired
	UserProfileDao dao;

	public UserProfile findById(int id) {
		return dao.findById(id);
	}

	public UserProfile findByType(String type){
		return dao.findByType(type);
	}

	public List<UserProfile> findAll() {
		return dao.findAll();
	}
}

package com.yiibai.springmvc.service;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.yiibai.springmvc.dao.UserDao;
import com.yiibai.springmvc.model.User;

@Service("userService")
@Transactional
public class UserServiceImpl implements UserService{

	@Autowired
	private UserDao dao;

	public User findById(int id) {
		return dao.findById(id);
	}

	public User findBySSO(String sso) {
		User user = dao.findBySSO(sso);
		return user;
	}

	public void saveUser(User user) {
		dao.save(user);
	}

	/*
	 * Since the method is running with Transaction, No need to call hibernate update explicitly.
	 * Just fetch the entity from db and update it with proper values within transaction.
	 * It will be updated in db once transaction ends.
	 */
	public void updateUser(User user) {
		User entity = dao.findById(user.getId());
		if(entity!=null){
			entity.setSsoId(user.getSsoId());
			entity.setPassword(user.getPassword());
			entity.setFirstName(user.getFirstName());
			entity.setLastName(user.getLastName());
			entity.setEmail(user.getEmail());
			entity.setUserProfiles(user.getUserProfiles());
		}
	}

	public void deleteUserBySSO(String sso) {
		dao.deleteBySSO(sso);
	}

	public List<User> findAllUsers() {
		return dao.findAllUsers();
	}

	public boolean isUserSSOUnique(Integer id, String sso) {
		User user = findBySSO(sso);
		return ( user == null || ((id != null) && (user.getId() == id)));
	}

}

第7步：创建Hibernate配置

package com.yiibai.springmvc.configuration;

import java.util.Properties;
import javax.sql.DataSource;

import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate4.HibernateTransactionManager;
import org.springframework.orm.hibernate4.LocalSessionFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@EnableTransactionManagement
@ComponentScan({ "com.yiibai.springmvc.configuration" })
@PropertySource(value = { "classpath:application.properties" })
public class HibernateConfiguration {

    @Autowired
    private Environment environment;

    @Bean
    public LocalSessionFactoryBean sessionFactory() {
        LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
        sessionFactory.setDataSource(dataSource());
        sessionFactory.setPackagesToScan(new String[] { "com.yiibai.springmvc.model" });
        sessionFactory.setHibernateProperties(hibernateProperties());
        return sessionFactory;
     }

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(environment.getRequiredProperty("jdbc.driverClassName"));
        dataSource.setUrl(environment.getRequiredProperty("jdbc.url"));
        dataSource.setUsername(environment.getRequiredProperty("jdbc.username"));
        dataSource.setPassword(environment.getRequiredProperty("jdbc.password"));
        return dataSource;
    }

    private Properties hibernateProperties() {
        Properties properties = new Properties();
        properties.put("hibernate.dialect", environment.getRequiredProperty("hibernate.dialect"));
        properties.put("hibernate.show_sql", environment.getRequiredProperty("hibernate.show_sql"));
        properties.put("hibernate.format_sql", environment.getRequiredProperty("hibernate.format_sql"));
        return properties;
    }

	@Bean
    @Autowired
    public HibernateTransactionManager transactionManager(SessionFactory s) {
       HibernateTransactionManager txManager = new HibernateTransactionManager();
       txManager.setSessionFactory(s);
       return txManager;
    }
}

以上 Hibernate 的配置使用下面提到 application.properties

jdbc.driverClassName = com.mysql.jdbc.Driver
jdbc.url = jdbc:mysql://localhost:3306/yiibai
jdbc.username = myuser
jdbc.password = passwd123
hibernate.dialect = org.hibernate.dialect.MySQLDialect
hibernate.show_sql = true
hibernate.format_sql = true

第8步：创建控制器

package com.yiibai.springmvc.controller;

import java.util.List;
import java.util.Locale;

import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.SessionAttributes;

import com.yiibai.springmvc.model.User;
import com.yiibai.springmvc.model.UserProfile;
import com.yiibai.springmvc.service.UserProfileService;
import com.yiibai.springmvc.service.UserService;

@Controller
@RequestMapping("/")
@SessionAttributes("roles")
public class AppController {

	@Autowired
	UserService userService;

	@Autowired
	UserProfileService userProfileService;

	@Autowired
	MessageSource messageSource;

	/**
	 * This method will list all existing users.
	 */
	@RequestMapping(value = { "/", "/list" }, method = RequestMethod.GET)
	public String listUsers(ModelMap model) {

		List<User> users = userService.findAllUsers();
		model.addAttribute("users", users);
		return "userslist";
	}

	/**
	 * This method will provide the medium to add a new user.
	 */
	@RequestMapping(value = { "/newuser" }, method = RequestMethod.GET)
	public String newUser(ModelMap model) {
		User user = new User();
		model.addAttribute("user", user);
		model.addAttribute("edit", false);
		return "registration";
	}

	/**
	 * This method will be called on form submission, handling POST request for
	 * saving user in database. It also validates the user input
	 */
	@RequestMapping(value = { "/newuser" }, method = RequestMethod.POST)
	public String saveUser(@Valid User user, BindingResult result,
			ModelMap model) {

		if (result.hasErrors()) {
			return "registration";
		}

		/*
		 * Preferred way to achieve uniqueness of field [sso] should be implementing custom @Unique annotation
		 * and applying it on field [sso] of Model class [User].
		 *
		 * Below mentioned peace of code [if block] is to demonstrate that you can fill custom errors outside the 

validation
		 * framework as well while still using internationalized messages.
		 *
		 */
		if(!userService.isUserSSOUnique(user.getId(), user.getSsoId())){
			FieldError ssoError =new FieldError("user","ssoId",messageSource.getMessage("non.unique.ssoId", new 

String[]{user.getSsoId()}, Locale.getDefault()));
		    result.addError(ssoError);
			return "registration";
		}

		userService.saveUser(user);

		model.addAttribute("success", "User " + user.getFirstName() + " "+ user.getLastName() + " registered 

successfully");
		//return "success";
		return "registrationsuccess";
	}

	/**
	 * This method will provide the medium to update an existing user.
	 */
	@RequestMapping(value = { "/edit-user-{ssoId}" }, method = RequestMethod.GET)
	public String editUser(@PathVariable String ssoId, ModelMap model) {
		User user = userService.findBySSO(ssoId);
		model.addAttribute("user", user);
		model.addAttribute("edit", true);
		return "registration";
	}

	/**
	 * This method will be called on form submission, handling POST request for
	 * updating user in database. It also validates the user input
	 */
	@RequestMapping(value = { "/edit-user-{ssoId}" }, method = RequestMethod.POST)
	public String updateUser(@Valid User user, BindingResult result,
			ModelMap model, @PathVariable String ssoId) {

		if (result.hasErrors()) {
			return "registration";
		}

		/*//Uncomment below 'if block' if you WANT TO ALLOW UPDATING SSO_ID in UI which is a unique key to a User.
		if(!userService.isUserSSOUnique(user.getId(), user.getSsoId())){
			FieldError ssoError =new FieldError("user","ssoId",messageSource.getMessage("non.unique.ssoId", new 

String[]{user.getSsoId()}, Locale.getDefault()));
		    result.addError(ssoError);
			return "registration";
		}*/

		userService.updateUser(user);

		model.addAttribute("success", "User " + user.getFirstName() + " "+ user.getLastName() + " updated successfully");
		return "registrationsuccess";
	}

	/**
	 * This method will delete an user by it's SSOID value.
	 */
	@RequestMapping(value = { "/delete-user-{ssoId}" }, method = RequestMethod.GET)
	public String deleteUser(@PathVariable String ssoId) {
		userService.deleteUserBySSO(ssoId);
		return "redirect:/list";
	}

	/**
	 * This method will provide UserProfile list to views
	 */
	@ModelAttribute("roles")
	public List<UserProfile> initializeProfiles() {
		return userProfileService.findAll();
	}

}

在下面提到的 messages.properties 文件中定义消息

NotEmpty.user.firstName=First name can not be blank.
NotEmpty.user.lastName=Last name can not be blank.
NotEmpty.user.email=Email can not be blank.
NotEmpty.user.password=Password can not be blank.
NotEmpty.user.ssoId=SSO ID can not be blank.
NotEmpty.user.userProfiles=At least one profile must be selected.
non.unique.ssoId=SSO ID {0} already exist. Please fill in different value.

第9步：创建转换器

这是这篇文章的核心。是需要映射单个 userProfile 的ID在实际的 UserProfile 实体在数据库中。

package com.yiibai.springmvc.converter;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.convert.converter.Converter;
import org.springframework.stereotype.Component;

import com.yiibai.springmvc.model.UserProfile;
import com.yiibai.springmvc.service.UserProfileService;

/**
 * A converter class used in views to map id's to actual userProfile objects.
 */
@Component
public class RoleToUserProfileConverter implements Converter<Object, UserProfile>{

	@Autowired
	UserProfileService userProfileService;

	/**
	 * Gets UserProfile by Id
	 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
	 */
	public UserProfile convert(Object element) {
		Integer id = Integer.parseInt((String)element);
		UserProfile profile= userProfileService.findById(id);
		System.out.println("Profile : "+profile);
		return profile;
	}

}

第10步、创建Spring配置文件

package com.yiibai.springmvc.configuration;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.ResourceBundleMessageSource;
import org.springframework.format.FormatterRegistry;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.PathMatchConfigurer;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;

import com.yiibai.springmvc.converter.RoleToUserProfileConverter;

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "com.yiibai.springmvc")
public class AppConfig extends WebMvcConfigurerAdapter{

	@Autowired
	RoleToUserProfileConverter roleToUserProfileConverter;

	/**
     * Configure ViewResolvers to deliver preferred views.
     */
	@Override
	public void configureViewResolvers(ViewResolverRegistry registry) {

		InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
		viewResolver.setViewClass(JstlView.class);
		viewResolver.setPrefix("/WEB-INF/views/");
		viewResolver.setSuffix(".jsp");
		registry.viewResolver(viewResolver);
	}

	/**
     * Configure ResourceHandlers to serve static resources like CSS/ Javascript etc...
     */
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("/static/");
    }

    /**
     * Configure Converter to be used.
     * In our example, we need a converter to convert string values[Roles] to UserProfiles in newUser.jsp
     */
    @Override
    public void addFormatters(FormatterRegistry registry) {
        registry.addConverter(roleToUserProfileConverter);
    }

    /**
     * Configure MessageSource to lookup any validation/error message in internationalized property files
     */
    @Bean
	public MessageSource messageSource() {
	    ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
	    messageSource.setBasename("messages");
	    return messageSource;
	}

    /**Optional. It's only required when handling '.' in @PathVariables which otherwise ignore everything after last '.' in 

@PathVaidables argument.
     * It's a known bug in Spring [https://jira.spring.io/browse/SPR-6164], still present in Spring 4.1.7.
     * This is a workaround for this issue.
     */
    @Override
    public void configurePathMatch(PathMatchConfigurer matcher) {
        matcher.setUseRegisteredSuffixPatternMatch(true);
    }
} 

第一个有趣的事情是注册转换器，我们在上一步中使用addFormatters创建了Spring配置。其次是方法configurePathMatch它提供了一个解决方法(虽然其他解决方法存在)在Spring中是一个已知的错误，这仍然在Spring4.1.7.RELEASE中有发现。

上述XML配置转换器设置为：

	<mvc:annotation-driven conversion-service="conversionService"/>

	<bean id="conversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">

		<property name="converters">
			<list>
				<bean id="roleToUserProfile" class="com.yiibai.springsecurity.configuration.RoleToUserProfileConverter" />
			</list>
		</property>
	</bean>

添加初始化类：

package com.yiibai.springmvc.configuration;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class AppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

	@Override
	protected Class<?>[] getRootConfigClasses() {
		return new Class[] { AppConfig.class };
	}

	@Override
	protected Class<?>[] getServletConfigClasses() {
		return null;
	}

	@Override
	protected String[] getServletMappings() {
		return new String[] { "/" };
	}

}

第11步：添加视图/ JSP

请注意，我们使用 Bootstrap 样式在JSP中。

userslist.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>

<head>
	<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
	<title>Users List</title>
	<link href="<c:url value='/static/css/bootstrap.css' />" rel="stylesheet"></link>
	<link href="<c:url value='/static/css/app.css' />" rel="stylesheet"></link>
</head>

<body>
	<div class="generic-container">
		<div class="panel panel-default">
			  <!-- Default panel contents -->
		  	<div class="panel-heading"><span class="lead">List of Users </span></div>
			<table class="table table-hover">
	    		<thead>
		      		<tr>
				        <th>Firstname</th>
				        <th>Lastname</th>
				        <th>Email</th>
				        <th>SSO ID</th>
				        <th width="100"></th>
				        <th width="100"></th>
					</tr>
		    	</thead>
	    		<tbody>
				<c:forEach items="${users}" var="user">
					<tr>
						<td>${user.firstName}</td>
						<td>${user.lastName}</td>
						<td>${user.email}</td>
						<td>${user.ssoId}</td>
						<td><a href="<c:url value='/edit-user-${user.ssoId}' />" class="btn btn-success custom-width">edit</a></td>
						<td><a href="<c:url value='/delete-user-${user.ssoId}' />" class="btn btn-danger custom-width">delete</a></td>
					</tr>
				</c:forEach>
	    		</tbody>
	    	</table>
		</div>
	 	<div class="well">
	 		<a href="<c:url value='/newuser' />">Add New User</a>
	 	</div>
   	</div>
</body>
</html>

registration.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<html>

<head>
	<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
	<title>User Registration Form</title>
	<link href="<c:url value='/static/css/bootstrap.css' />" rel="stylesheet"></link>
	<link href="<c:url value='/static/css/app.css' />" rel="stylesheet"></link>
</head>

<body>

 	<div class="generic-container">
	<div class="well lead">User Registration Form</div>
 	<form:form method="POST" modelAttribute="user" class="form-horizontal">
		<form:input type="hidden" path="id" id="id"/>

		<div class="row">
			<div class="form-group col-md-12">
				<label class="col-md-3 control-lable" for="firstName">First Name</label>
				<div class="col-md-7">
					<form:input type="text" path="firstName" id="firstName" class="form-control input-sm"/>
					<div class="has-error">
						<form:errors path="firstName" class="help-inline"/>
					</div>
				</div>
			</div>
		</div>

		<div class="row">
			<div class="form-group col-md-12">
				<label class="col-md-3 control-lable" for="lastName">Last Name</label>
				<div class="col-md-7">
					<form:input type="text" path="lastName" id="lastName" class="form-control input-sm" />
					<div class="has-error">
						<form:errors path="lastName" class="help-inline"/>
					</div>
				</div>
			</div>
		</div>

		<div class="row">
			<div class="form-group col-md-12">
				<label class="col-md-3 control-lable" for="ssoId">SSO ID</label>
				<div class="col-md-7">
					<c:choose>
						<c:when test="${edit}">
							<form:input type="text" path="ssoId" id="ssoId" class="form-control input-sm" disabled="true"/>
						</c:when>
						<c:otherwise>
							<form:input type="text" path="ssoId" id="ssoId" class="form-control input-sm" />
							<div class="has-error">
								<form:errors path="ssoId" class="help-inline"/>
							</div>
						</c:otherwise>
					</c:choose>
				</div>
			</div>
		</div>

		<div class="row">
			<div class="form-group col-md-12">
				<label class="col-md-3 control-lable" for="password">Password</label>
				<div class="col-md-7">
					<form:input type="password" path="password" id="password" class="form-control input-sm" 

/>
					<div class="has-error">
						<form:errors path="password" class="help-inline"/>
					</div>
				</div>
			</div>
		</div>

		<div class="row">
			<div class="form-group col-md-12">
				<label class="col-md-3 control-lable" for="email">Email</label>
				<div class="col-md-7">
					<form:input type="text" path="email" id="email" class="form-control input-sm" />
					<div class="has-error">
						<form:errors path="email" class="help-inline"/>
					</div>
				</div>
			</div>
		</div>

		<div class="row">
			<div class="form-group col-md-12">
				<label class="col-md-3 control-lable" for="userProfiles">Roles</label>
				<div class="col-md-7">
					<form:select path="userProfiles" items="${roles}" multiple="true" itemValue="id" 

itemLabel="type" class="form-control input-sm" />
					<div class="has-error">
						<form:errors path="userProfiles" class="help-inline"/>
					</div>
				</div>
			</div>
		</div>

		<div class="row">
			<div class="form-actions floatRight">
				<c:choose>
					<c:when test="${edit}">
						<input type="submit" value="Update" class="btn btn-primary btn-sm"/> or <a 

href="<c:url value='/list' />">Cancel</a>
					</c:when>
					<c:otherwise>
						<input type="submit" value="Register" class="btn btn-primary btn-sm"/> or <a 

href="<c:url value='/list' />">Cancel</a>
					</c:otherwise>
				</c:choose>
			</div>
		</div>
	</form:form>
	</div>
</body>
</html>

registrationsuccess.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<html>
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
	<title>Registration Confirmation Page</title>
	<link href="<c:url value='/static/css/bootstrap.css' />" rel="stylesheet"></link>
	<link href="<c:url value='/static/css/app.css' />" rel="stylesheet"></link>
</head>
<body>
<div class="generic-container">
	<div class="alert alert-success lead">
    	${success}
	</div>

	<span class="well floatRight">
		Go to <a href="<c:url value='/list' />">Users List</a>
	</span>
</div>
</body>

</html>

这里是一个小自定义样式表文件：

app.css

body, #mainWrapper {
	height: 100%;
	background-color:rgb(245, 245, 245);
}

body, .form-control{
	font-size:14px!important;
}

.floatRight{
	float:right;
	margin-right: 18px;
}

.has-error{
	color:red;
}

.generic-container {
  position:fixed;
  width:80%;
  margin-left: 20px;
  margin-top: 20px;
  margin-bottom: 20px;
  padding: 20px;
  background-color: #EAE7E7;
  border: 1px solid #ddd;
  border-radius: 4px;
  box-shadow: 0 0 30px black;
}

.custom-width {
    width: 80px !important;
}

第12步：构建，部署和运行应用程序

现在构建War(前面提到的Eclipse教程)或通过Maven的命令行( mvn clean install). 部署 war 到Servlet3.0容器。

打开浏览器，浏览URL => http://localhost:8080/SpringMVCMany2ManyCRUD/

点击 ‘Add New User’

直接提交而不填写任何东西。

详细填写信息：

Submit.

点击 ‘Users List’ 链接：

查看数据库，三张表的数据结果如下。

添加更多的用户信息：

点击用户"Si"编辑按钮。修改他的角色为Admin。

提交，如下结果显示：

查看数据库，现在存储的数据如下：

现在回到列表，点击删除“Si”用户。

最后，查看数据库，这里结果如下所示：