Spring MVC+Hibernata Many-to-many连接表+MySQL+Maven例子

本教程是易百教程上摘下来的，要实事求是嘛。但跟着教程一步步做下来后，遇到了一些错误，虽然不多但也折腾了一下午，不过解决了所有错误后，终于也跑出了结果。以下是我完善并订正这个教程后的内容。如需看原文和代码可以点击 http://www.yiibai.com/spring_mvc/springmvc-hibernate-many-to-many-join-table.html# 。

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 1.8
Tomcat 8.0.21
Eclipse JUNO Service Release 2

可以不用管以上工具的版本，遇到版本不匹配错误可以在eclipse里配置，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（这里需要说明，改动了，配置特别重要）

	xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	4.0.0
	com.yiibai.springmvc
	SpringMVCMany2ManyCRUD
	war
	1.0.0
	SpringMVCHibernateManyToManyCRUDExample


  	
		4.1.7.RELEASE
		4.3.10.Final
		5.1.31
	


	
		
		
			org.springframework
			spring-core
			${springframework.version}
		
		
			org.springframework
			spring-web
			${springframework.version}
		
		
			org.springframework
			spring-webmvc
			${springframework.version}
		
		
			org.springframework
			spring-tx
			${springframework.version}
		
		
			org.springframework
			spring-orm
			${springframework.version}
		


		
		
			org.hibernate
			hibernate-core
			${hibernate.version}
		


		
		
			javax.validation
			validation-api
			1.1.0.Final
		
		
			org.hibernate
			hibernate-validator
			5.1.3.Final
		


		
		
			mysql
			mysql-connector-java
			${mysql.connector.version}
		


		
		
			javax.servlet
			javax.servlet-api
			3.1.0
		
		
			javax.servlet.jsp
			javax.servlet.jsp-api
			2.3.1
		
		
		    javax.servlet
		    jstl
		    1.2
		
		
	
	
		
			
				
				org.apache.maven.plugins
				maven-compiler-plugin
				2.4
				
				1.7  
                     1.7  
		src/main/webapp
		SpringMVCMany2ManyCRUD false
				
				
			
		
		SpringMVCMany2ManyCRUD

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 userProfiles = new HashSet();

	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 getUserProfiles() {
		return userProfiles;
	}

	public void setUserProfiles(Set 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 findAllUsers();

}

package com.yiibai.springmvc.dao;

import java.util.List;

import com.yiibai.springmvc.model.UserProfile;


public interface UserProfileDao {

	List 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 {
	
	private final Class persistentClass;
	
	@SuppressWarnings("unchecked")
	public AbstractDao(){
		this.persistentClass =(Class) ((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 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 findAllUsers() {
		Criteria criteria = createEntityCriteria().addOrder(Order.asc("firstName"));
		criteria.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);//To avoid duplicates.
		List users = (List) 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 AbstractDaoimplements 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 findAll(){
		Criteria crit = createEntityCriteria();
		crit.addOrder(Order.asc("type"));
		return (List)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 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 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 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 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。yiibai---换成自己数据库的名字，例如mydb。jdbc.username、jdbc.password换成自己MySQL数据库的名字和密码。

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 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 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{

	@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：

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" %>



	
	Users List
	
	



	
		
			  
		  	List of Users 
			
					
	    		
		      		
				        Firstname
				        Lastname
				        Email
				        SSO ID
				        
				        
					
		    	
	    		
				
						${user.firstName}
						${user.lastName}
						${user.email}
						${user.ssoId}
						edit
						delete
					
				
	    		
	    	
		
	 	
	 		Add New User

Firstname	Lastname	Email	SSO ID
${user.firstName}	${user.lastName}	${user.email}	${user.ssoId}	edit	delete

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" %>




	
	User Registration Form
	
	




 	
	User Registration Form
 	
		
		
		
			
				First Name
				
					
					
						
					
				
			
		

		
			
				Last Name
				
					
					
						
					
				
			
		

		
			
				SSO ID
				
					
						
							
						
						
							
							
								
							
						
					
				
			
		

		
			
				Password
				
					
					
						
					
				
			
		

		
			
				Email
				
					
					
						
					
				
			
		

		
			
				Roles
				
					
					
						
					
				
			
		

		
			
				
					
						 or Cancel
					
					
						 or Cancel

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" %>




	
	Registration Confirmation Page
	
	



	
    	${success}
	
	
	
		Go to Users List

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

通过Maven的命令行( mvn clean install). 部署 war 到Servlet3.0容器，然后右击项目—run as—run on a server启动Tomcat。打开浏览器，浏览URL => http://localhost:8080/SpringMVCMany2ManyCRUD/。注意：1.这里的Tomcate有两种配置方式，可以使用Tomcat插件，在Eclipse里启动（推荐使用这种方法）。或者链接Tomcat的安装路径，但是需要选中“Use Tomcat installation”，否则在浏览器上打开loca:8080会报404错误。2.Tomcat尽量不要放在C:\Program Files (x86)或者C:\Program Files 路径下，有的系统很奇葩设置访问权限，会一直报一个.txt日志文件无法访问的错误，可以直接放在C盘下。3.启动前，记得设置正确Hibernate的访问路径，数据库路径不对的话，也会报错哦~