MyBatis框架基於Annotation註解的多對多關聯對映
阿新 • • 發佈：2018-12-31
程式碼：
mybatis-config.xml
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <!-- XML 配置檔案包含對 MyBatis 系統的核心設定 --> <configuration> <properties resource="db.properties"/> <!-- 指定 MyBatis 所用日誌的具體實現 --> <settings> <setting name="logImpl" value="LOG4J"/> <!-- 要使延遲載入生效必須配置下面兩個屬性 --> <setting name="lazyLoadingEnabled" value="true"/> <setting name="aggressiveLazyLoading" value="false"/> </settings> <environments default="mysql"> <!-- 環境配置，即連線的資料庫。 --> <environment id="mysql"> <!-- 指定事務管理型別，type="JDBC"指直接簡單使用了JDBC的提交和回滾設定 --> <transactionManager type="JDBC"/> <!-- dataSource指資料來源配置，POOLED是JDBC連線物件的資料來源連線池的實現。 --> <dataSource type="POOLED"> <property name="driver" value="${driver}"/> <property name="url" value="${url}"/> <property name="username" value="${username}"/> <property name="password" value="${password}"/> </dataSource> </environment> </environments> <!-- mappers告訴了MyBatis去哪裡找持久化類的對映檔案 --> <mappers> <mapper class="com.mapper.UserMapper"/> <mapper class="com.mapper.OrderMapper"/> <mapper class="com.mapper.ArticleMapper"/> </mappers> </configuration>
Article.java
package com.bean; import java.io.Serializable; import java.util.List; public class Article implements Serializable { private Integer id; // 商品id，主鍵 private String name; // 商品名稱 private Double price; // 商品價格 private String remark; // 商品描述 // 商品和訂單是多對多的關係，即一種商品可以包含在多個訂單中 private List<Order> orders; public Article() { super(); // TODO Auto-generated constructor stub } public Article(String name, Double price, String remark) { super(); this.name = name; this.price = price; this.remark = remark; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Double getPrice() { return price; } public void setPrice(Double price) { this.price = price; } public String getRemark() { return remark; } public void setRemark(String remark) { this.remark = remark; } public List<Order> getOrders() { return orders; } public void setOrders(List<Order> orders) { this.orders = orders; } @Override public String toString() { return "Article [id=" + id + ", name=" + name + ", price=" + price + ", remark=" + remark + "]"; } }
Order.java
package com.bean; import java.io.Serializable; import java.util.List; public class Order implements Serializable { private Integer id; // 訂單id，主鍵 private String code; // 訂單編號 private Double total; // 訂單總金額 // 訂單和使用者是多對一的關係，即多個訂單隻屬於一個使用者 private User user; // 訂單和商品是多對多的關係，即一個訂單可以包含多種商品 private List<Article> articles; public Order() { super(); // TODO Auto-generated constructor stub } public Order(String code, Double total) { super(); this.code = code; this.total = total; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getCode() { return code; } public void setCode(String code) { this.code = code; } public Double getTotal() { return total; } public void setTotal(Double total) { this.total = total; } public User getUser() { return user; } public void setUser(User user) { this.user = user; } public List<Article> getArticles() { return articles; } public void setArticles(List<Article> articles) { this.articles = articles; } @Override public String toString() { return "Order [id=" + id + ", code=" + code + ", total=" + total + "]"; } }
User.java
package com.bean;
import java.io.Serializable;
import java.util.List;
public class User implements Serializable{
private Integer id; // 使用者id，主鍵
private String username; // 使用者名稱
private String loginname; // 登入名
private String password; // 密碼
private String phone; // 聯絡電話
private String address; // 收貨地址
// 使用者和訂單是一對多的關係，即一個使用者可以有多個訂單
private List<Order> orders;
public User() {
super();
// TODO Auto-generated constructor stub
}
public User(String username, String loginname, String password, String phone, String address) {
super();
this.username = username;
this.loginname = loginname;
this.password = password;
this.phone = phone;
this.address = address;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getLoginname() {
return loginname;
}
public void setLoginname(String loginname) {
this.loginname = loginname;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public List<Order> getOrders() {
return orders;
}
public void setOrders(List<Order> orders) {
this.orders = orders;
}
@Override
public String toString() {
return "User [id=" + id + ", username=" + username + ", loginname=" + loginname + ", password=" + password + ", phone=" + phone
+ ", address=" + address + "]";
}
}
FKSqlSessionFactory.java
package com.factory;
import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class FKSqlSessionFactory {
private static SqlSessionFactory sqlSessionFactory = null;
// 初始化建立SqlSessionFactory物件
static{
try {
// 讀取mybatis-config.xml檔案
InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder()
.build(inputStream);
} catch (Exception e) {
e.printStackTrace();
}
}
// 獲取SqlSession物件的靜態方法
public static SqlSession getSqlSession(){
return sqlSessionFactory.openSession();
}
// 獲取SqlSessionFactory的靜態方法
public static SqlSessionFactory getSqlSessionFactory() {
return sqlSessionFactory;
}
}
ArticleMapper.xml
package com.mapper;
import java.util.List;
import org.apache.ibatis.annotations.Select;
import com.bean.Article;
import com.bean.User;
public interface ArticleMapper {
@Select("select * from tb_article where id in (select article_id from tb_item where order_id = #{id})")
List<Article> selectByOrderId(Integer order_id);
}
OrderMapper.xml
package com.mapper;
import org.apache.ibatis.annotations.Many;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.mapping.FetchType;
import com.bean.Order;
public interface OrderMapper {
@Select("select * from tb_order where id = #{id}")
@Results({
@Result(id=true,column="id",property="id"),
@Result(column="code",property="code"),
@Result(column="total",property="total"),
@Result(column="user_id",property="user",
[email protected](select="com.mapper.UserMapper.selectById",fetchType=FetchType.EAGER)),
@Result(column="id",property="articles",[email protected](select="com.mapper.ArticleMapper.selectByOrderId",fetchType=FetchType.LAZY))
})
Order selectById(Integer id);
}
UserMapper.xml
package com.mapper;
import org.apache.ibatis.annotations.Select;
import com.bean.User;
public interface UserMapper {
@Select("select * from tb_user where id = #{id}")
User selectById(Integer id);
}
ManyToManyTest.java
package com.test;
import org.apache.ibatis.session.SqlSession;
import com.bean.Order;
import com.factory.FKSqlSessionFactory;
import com.mapper.OrderMapper;
public class ManyToManyTest {
public static void main(String[] args) {
// TODO Auto-generated method stub
SqlSession session = FKSqlSessionFactory.getSqlSession();
OrderMapper om = session.getMapper(OrderMapper.class);
Order order =om.selectById(1);
// 檢視查詢到的Order物件
System.out.println(order.getId() + " " + order.getCode() + " " + order.getTotal());
// 檢視Order關聯的User物件
System.out.println(order.getUser());
// 檢視關聯的Article集合，因為配置使用的是LAZY懶載入，所以當使用時才執行SQL語句
order.getArticles().forEach(article -> System.out.println(article));
session.commit();
session.close();
}
}
截圖：
