《hibernate多对多的自关联》

电玩女神 2022-04-12 14:07 253阅读 0赞

**1.entity**

package com.zy.four.entity;
    
    import java.util.HashSet;
    import java.util.Set;
    
    public class Book {
    	
    //	book_id int primary key auto_increment,
    //	book_name varchar(50) not null,
    //	price float not null
    	
    	private Integer book_id;
    	private String book_name;
    	private Float price;
    	
    	private Set<Category> categorys = new HashSet<>();
    	
    	public Set<Category> getCategorys() {
    		return categorys;
    	}
    	public void setCategorys(Set<Category> categorys) {
    		this.categorys = categorys;
    	}
    	
    	public Integer getBook_id() {
    		return book_id;
    	}
    	public void setBook_id(Integer book_id) {
    		this.book_id = book_id;
    	}
    	public String getBook_name() {
    		return book_name;
    	}
    	public void setBook_name(String book_name) {
    		this.book_name = book_name;
    	}
    	public Float getPrice() {
    		return price;
    	}
    	public void setPrice(Float price) {
    		this.price = price;
    	}
    	
    	public Book() {
    		super();
    	}
    	public Book(Integer book_id, String book_name, Float price) {
    		super();
    		this.book_id = book_id;
    		this.book_name = book_name;
    		this.price = price;
    	}
    
    	@Override
    	public String toString() {
    		return "Book [book_id=" + book_id + ", book_name=" + book_name + ", price=" + price + "]";
    	}
    	
    
    }

package com.zy.four.entity;
    
    import java.util.HashSet;
    import java.util.Set;
    
    public class Category {
    	
    //	 category_id int primary key auto_increment,
    //	 category_name varchar(50) not null
    	
    	private Integer category_id;
    	private String category_name;
    	
    	private Set<Book> books = new HashSet<>();
    	
    	public Set<Book> getBooks() {
    		return books;
    	}
    	public void setBooks(Set<Book> books) {
    		this.books = books;
    	}
    	
    	public Integer getCategory_id() {
    		return category_id;
    	}
    	public void setCategory_id(Integer category_id) {
    		this.category_id = category_id;
    	}
    	public String getCategory_name() {
    		return category_name;
    	}
    	public void setCategory_name(String category_name) {
    		this.category_name = category_name;
    	}
    
    	public Category() {
    		super();
    	}
    	public Category(Integer category_id, String category_name) {
    		super();
    		this.category_id = category_id;
    		this.category_name = category_name;
    	}
    	
    	@Override
    	public String toString() {
    		return "Category [category_id=" + category_id + ", category_name=" + category_name + "]";
    	}
    	
    
    }

**2.entity.hbm.xml**

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE hibernate-mapping PUBLIC 
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    <hibernate-mapping>
        
    	<class name="com.zy.four.entity.Book" table="t_hibernate_book">
    	    
    		<id name="book_id" type="java.lang.Integer" column="book_id">
    		    
    			<generator class="increment"/> 
    		</id>
    		
    		
    		<property name="book_name" type="java.lang.String" column="book_name"></property>
    		<property name="price" type="java.lang.Float" column="price"></property>
    		
    		
    		
    		<set name="categorys" table="t_hibernate_book_category">
    		 
    		 <key column="bid"></key>
    		 
    		 <many-to-many class="com.zy.four.entity.Category" column="cid"></many-to-many>
    		</set>
    		
    	</class>
    </hibernate-mapping>

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE hibernate-mapping PUBLIC 
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
        
    
        
    <hibernate-mapping>
        
    	<class name="com.zy.four.entity.Category" table="t_hibernate_category">
    	    
    		<id name="category_id" type="java.lang.Integer" column="category_id">
    		    
    			<generator class="increment"/> 
    		</id>
    		
    		
    		<property name="category_name" type="java.lang.String" column="category_name"></property>
    		
    		
    		<set name="books" table="t_hibernate_book_category" cascade="save-update" inverse="true">
    		 
    		 <key column="cid"></key>
    		 
    		 <many-to-many class="com.zy.four.entity.Book" column="bid"></many-to-many>
    		</set>
    		
    	</class>
    </hibernate-mapping>

**3.hibernate.cfg.xml**

<mapping resource="com/zy/four/entity/Book.hbm.xml"/>
    		<mapping resource="com/zy/four/entity/Category.hbm.xml"/>

**4.dao**

package com.zy.four.dao;
    
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    import org.hibernate.Hibernate;
    import org.hibernate.Session;
    import org.hibernate.Transaction;
    import org.hibernate.query.Query;
    
    import com.zy.four.entity.Book;
    import com.zy.six.dao.BaseDao;
    import com.zy.two.util.PageBean;
    import com.zy.two.util.SessionFactoryUtil;
    import com.zy.two.util.StringUtils;
    
    public class BookDao extends BaseDao{
    	
    	/**
    	 * 查询书本
    	 * @param book
    	 * @return
    	 */
    	public Book get(Book book) {
    		Session session = SessionFactoryUtil.getSession(); //获取session会话
    		Transaction transaction = session.beginTransaction(); //开启事物
    		
    		Book books = session.get(Book.class, book.getBook_id()); //操作数据库
    		Hibernate.initialize(books.getCategorys()); //强制加载代理对象
    		
    		transaction.commit(); //提交事物
    		session.close(); //关闭会话
    		return books;
    	}
    	
    	/**
    	 * 添加书本
    	 * @param book
    	 * @return
    	 */
    	public Integer save(Book book) {
    		Session session = SessionFactoryUtil.getSession(); //获取session会话
    		Transaction transaction = session.beginTransaction(); //开启事物
    		
    		Integer bid = (Integer) session.save(book); //操作数据库
    		
    		transaction.commit(); //提交事物
    		session.close(); //关闭会话
    		return bid;
    	}
    	
    	/**
    	 * 主控方删除
    	 * 删除书本
    	 * @param book
    	 * @return
    	 */
    	public void delete(Book book) {
    		Session session = SessionFactoryUtil.getSession(); //获取session会话
    		Transaction transaction = session.beginTransaction(); //开启事物
    		
    		session.delete(book); //操作数据库
    		
    		transaction.commit(); //提交事物
    		session.close(); //关闭会话
    	}
    	
    	
    	
    	/**
    	 * 分页
    	 * @return
    	 */
    	public List<Book> pageBookList(Book book, PageBean pageBean){
    		Session session = SessionFactoryUtil.getSession(); //获取session会话
    		Transaction transaction = session.beginTransaction(); //开启事物
    		
    		//操作数据库
    		String bookName = book.getBook_name();
    		
    		String hql = " from Book where 1=1 ";
    		if(StringUtils.isNotBlank(bookName)) {
    			hql+=" and book_name like :book_name ";
    		}
    		
    		Query query = session.createQuery(hql);
    		if(StringUtils.isNotBlank(bookName)) {
    			query.setParameter("book_name", "%"+bookName+"%");
    		}
    		
    		if(pageBean != null && pageBean.isPagination()) {
    			query.setFirstResult(pageBean.getStartIndex());
    			query.setMaxResults(pageBean.getRows());
    		}
    		
    		List list = query.list();
    		
    		transaction.commit(); //提交事物
    		session.close(); //关闭会话
    		return list;
    	}
    	
    	
    	/**
    	 * 通用分页
    	 * @return
    	 */
    	public List<Book> pageBookAll(Book book, PageBean pageBean){
    		Session session = SessionFactoryUtil.getSession(); //获取session会话
    		Transaction transaction = session.beginTransaction(); //开启事物
    		
    		//操作数据库
    		String bookName = book.getBook_name();
    		Map<String, Object> map = new HashMap<>();
    		
    		String hql = " from Book where 1=1 ";
    		if(StringUtils.isNotBlank(bookName)) {
    			hql+=" and book_name like :book_name ";
    			map.put("book_name", "%"+bookName+"%");
    		}
    		
    		List list = super.executeQuery(session, hql, map, pageBean);
    		
    		transaction.commit(); //提交事物
    		session.close(); //关闭会话
    		return list;
    	}
    	
    	
    	/**
    	 * 原生SQL分页
    	 * @return
    	 */
    	public List pageBook(Book book, PageBean pageBean){
    		Session session = SessionFactoryUtil.getSession(); //获取session会话
    		Transaction transaction = session.beginTransaction(); //开启事物
    		
    		//操作数据库
    		String sql = "select * from t_hibernate_book";
    		List list = session.createSQLQuery(sql).list();
    		
    		transaction.commit(); //提交事物
    		session.close(); //关闭会话
    		return list;
    	}
    	
    
    }

package com.zy.four.dao;
    
    import org.hibernate.Hibernate;
    import org.hibernate.Session;
    import org.hibernate.Transaction;
    
    import com.zy.four.entity.Book;
    import com.zy.four.entity.Category;
    import com.zy.two.util.SessionFactoryUtil;
    
    public class CategoryDao {
    	
    	/**
    	 * 查询类别
    	 * @param category
    	 * @return
    	 */
    	public Category get(Category category) {
    		Session session = SessionFactoryUtil.getSession(); //获取session会话
    		Transaction transaction = session.beginTransaction(); //开启事物
    		
    		Category categorys = session.get(Category.class, category.getCategory_id()); //操作数据库
    		Hibernate.initialize(categorys.getBooks());
    		
    		transaction.commit(); //提交事物
    		session.close(); //关闭会话
    		return categorys;
    	}
    	
    	/**
    	 * 添加类别
    	 * @param category
    	 * @return
    	 */
    	public Integer save(Category category) {
    		Session session = SessionFactoryUtil.getSession(); //获取session会话
    		Transaction transaction = session.beginTransaction(); //开启事物
    		
    		Integer cid = (Integer) session.save(category); //操作数据库
    		
    		transaction.commit(); //提交事物
    		session.close(); //关闭会话
    		return cid;
    	}
    	
    	/**
    	 * 被控方删除
    	 * 1.先要获取到被控方的数据
    	 * 2.利用被控方获取到主控方来解除关联关系
    	 * 3.最后将被控方给删除
    	 * 
    	 * 删除类别
    	 * @param book
    	 * @return
    	 */
    	public void delete(Category category) {
    		Session session = SessionFactoryUtil.getSession(); //获取session会话
    		Transaction transaction = session.beginTransaction(); //开启事物
    		
    		//操作数据库
    		Category c = session.get(Category.class, category.getCategory_id()); //1.获取到被控方的数据
    		for (Book b : c.getBooks()) {
    			b.getCategorys().remove(c); //2.解除关联关系
    		}
    		session.delete(c); //3.将被控方给删除
    		
    		transaction.commit(); //提交事物
    		session.close(); //关闭会话
    	}
    
    }

**5.daoTest**

package com.zy.four.dao;
    
    import static org.junit.Assert.*;
    
    import java.lang.reflect.Array;
    import java.util.Arrays;
    import java.util.List;
    
    import org.junit.Test;
    
    import com.zy.four.entity.Book;
    import com.zy.four.entity.Category;
    import com.zy.two.util.PageBean;
    
    public class BookDaoTest {
    	
    	private BookDao bDao = new BookDao();
    
    	/**
    	 * 查询
    	 */
    	@Test
    	public void testGet() {
    		Book book = new Book();
    		book.setBook_id(4);
    		Book b = bDao.get(book);
    		System.out.println(b.getBook_name());
    		System.out.println(b);
    		System.out.println(b.getCategorys());
    		for (Category c : b.getCategorys()) {
    			System.out.println(c.getCategory_name());
    		}
    	}
    	
    	/**
    	 * 添加
    	 * Category.hbm.xml: cascade="save-update" inverse="true"
    	 * Book.hbm.xml:
    	 * 组合的含义是：
    	 * 将中间表t_hibernate_book_category中的数据新增以及修改的权利交给book类
    	 */
    	@Test
    	public void testSave() {
    		Book book = new Book();
    		book.setBook_name("海底两万里");
    		book.setPrice(88f);
    		Category category = new Category();
    		category.setCategory_id(3);
    		book.getCategorys().add(category);
    		Integer bid = bDao.save(book);
    		System.out.println(bid);
    	}
    	
    	/**
    	 * 主控方删除
    	 * 删除
    	 */
    	@Test
    	public void testDelete() {
    		Book book = new Book();
    		book.setBook_id(5);
    		bDao.delete(book);
    	}
    	
    	
    	
    	/**
    	 * 分页(测试)
    	 */
    	@Test
    	public void testpageBookList() {
    		Book book = new Book();
    		PageBean pageBean = new PageBean();
    		pageBean.setRows(2);
    		List<Book> bookList = bDao.pageBookList(book, pageBean);
    		for (Book b : bookList) {
    			System.out.println(b.getBook_name());
    		}
    	}
    	
    	/**
    	 * 通用分页(测试)
    	 */
    	@Test
    	public void testpageBookAll() {
    		Book book = new Book();
    		book.setBook_name("abc");
    		PageBean pageBean = new PageBean();
    		pageBean.setRows(2);
    		pageBean.setPage(1);
    		List<Book> bookList = bDao.pageBookAll(book, pageBean);
    		for (Book b : bookList) {
    			System.out.println(b.getBook_name());
    		}
    	}
    	
    	/**
    	 * 原生SQL分页(测试)
    	 */
    	@Test
    	public void testpageBook() {
    		List bookList = bDao.pageBook(null, null);
    		for (Object object : bookList) {
    			System.out.println(Arrays.toString((Object[])object));
    		}
    	}
    
    }

package com.zy.four.dao;
    
    import static org.junit.Assert.*;
    
    import org.junit.Test;
    
    import com.zy.four.entity.Book;
    import com.zy.four.entity.Category;
    
    public class CategoryDaoTest {
    	
    	private CategoryDao cDao = new CategoryDao();
    
    	/**
    	 * 查询
    	 */
    	@Test
    	public void testGet() {
    		Category category = new Category();
    		category.setCategory_id(3);
    		Category c = cDao.get(category);
    		System.out.println(c.getCategory_name());
    		System.out.println(c);
    		System.out.println(c.getBooks());
    		for (Book b : c.getBooks()) {
    			System.out.println(b.getBook_name());
    		}
    	}
    	
    	/**
    	 * 新增
    	 * Category.hbm.xml: cascade="save-update" inverse="true"
    	 * Book.hbm.xml:
    	 * 组合的含义是：
    	 * 将中间表t_hibernate_book_category中的数据新增以及修改的权利交给book类，category类没有新增以及修改权利
    	 * 所以此方法会报错：
    	 * ERROR: Column 'book_name' cannot be null
         * ERROR: HHH000346: Error during managed flush [org.hibernate.exception.ConstraintViolationException: could not execute statement]
    	 */
    	@Test
    	public void testSave() {
    		Category category = new Category();
    		category.setCategory_name("科幻");
    		Book book = new Book();
    		book.setBook_id(5);
    		category.getBooks().add(book);
    		Integer cid = cDao.save(category);
    		System.out.println(cid);
    	}
    	
    	/**
    	 * 被控方删除
    	 */
    	@Test
    	public void testDelete() {
    		Category category = new Category();
    		category.setCategory_id(3);
    		cDao.delete(category);
    	}
    
    }