首先數(shù)據(jù)庫(kù)表展示

User表

Role角色表

關(guān)聯(lián)User表與Role表關(guān)系的user_role表

因?yàn)槭且?lián)關(guān)系所以需要設(shè)置外鍵，以下是外鍵展示

工程目錄展示

pom.xml依賴(lài)配置

<dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.10</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.4</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.6</version></dependency><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.12</version></dependency></dependencies>

順便附上Maven阿里云倉(cāng)庫(kù)

這樣比較快 我之前創(chuàng)建一個(gè)項(xiàng)目都要10來(lái)分鐘，現(xiàn)在只需要幾秒

<mirrors><mirror> <id>alimaven</id> <name>aliyun maven</name> <url>http://maven.aliyun.com/nexus/content/groups/public/</url> <mirrorOf>central</mirrorOf> </mirror> </mirrors>

SqlMapConfig.xml配置

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration><properties resource="jdbc.properties"></properties><!--typeAliases 得放在properties下面 不然會(huì)報(bào)錯(cuò)--><typeAliases><package name="com.domain" /></typeAliases><environments default="mysql"><environment id="mysql"><transactionManager type="JDBC"></transactionManager><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><package name="com.DAO"/></mappers> </configuration>

實(shí)體類(lèi)

user

package com.domain;import java.io.Serializable; import java.util.Date; import java.util.List;public class User implements Serializable {private int id;private String username;private Date birthday;private String sex;private String address;/*多對(duì)多關(guān)系映射*/private List<Role> roles;public List<Role> getRoles() {return roles;}public void setRoles(List<Role> roles) {this.roles = roles;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", birthday=" + birthday +", sex='" + sex + '\'' +", address='" + address + '\'' +'}';} }

Role

package com.domain;import com.sun.xml.internal.bind.v2.model.core.ID;import java.io.Serializable; import java.util.List;public class Role implements Serializable {private int ID;private String ROLE_NAME;private String ROLE_DESC;/*多對(duì)多關(guān)系映射*/private List<User> users;public List<User> getUsers() {return users;}public void setUsers(List<User> users) {this.users = users;}public int getID() {return ID;}public void setID(int ID) {this.ID = ID;}public String getROLE_NAME() {return ROLE_NAME;}public void setROLE_NAME(String ROLE_NAME) {this.ROLE_NAME = ROLE_NAME;}public String getROLE_DESC() {return ROLE_DESC;}public void setROLE_DESC(String ROLE_DESC) {this.ROLE_DESC = ROLE_DESC;}@Overridepublic String toString() {return "Role{" +"ID=" + ID +", ROLE_NAME='" + ROLE_NAME + '\'' +", ROLE_DESC='" + ROLE_DESC + '\'' +'}';} }

dao

package com.DAO;import com.domain.User;import java.util.List;public interface IUser {List<User> findAll();} package com.DAO;import com.domain.Role;import java.util.List;public interface IRole {List<Role> findAll(); }

對(duì)應(yīng)的Mapper映射配置文件及測(cè)試

IUser.xml

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.DAO.IUser"><resultMap id="UserRole" type="User"><id property="id" column="id"></id><result property="username" column="username"></result><result property="address" column="address"></result><result property="sex" column="sex"></result><result property="birthday" column="birthday"></result><collection property="roles" ofType="Role"><result property="ID" column="ID"></result><result property="ROLE_NAME" column="ROLE_NAME"></result><result property="ROLE_DESC" column="ROLE_DESC"></result></collection></resultMap><select id="findAll" resultMap="UserRole" >select u.*,r.* from user u left outer join user_role ur on u.id=ur.uid left outer join role r on r.id=ur.rid</select></mapper>

附上測(cè)試類(lèi)代碼

package com.test;import com.DAO.IUser;import com.domain.User; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import org.junit.After; import org.junit.Before; import org.junit.Test;import java.io.IOException; import java.io.InputStream; import java.util.List;public class UserTest {private InputStream in=null;private SqlSessionFactory factory=null;private SqlSession sqlSession=null;private IUser iUser=null;@Beforepublic void Init() throws IOException {in= Resources.getResourceAsStream("SqlMapConfig.xml");factory=new SqlSessionFactoryBuilder().build(in);sqlSession=factory.openSession();iUser=sqlSession.getMapper(IUser.class);}@Afterpublic void Close() throws IOException {sqlSession.commit();//提交事務(wù)if(sqlSession!=null){sqlSession.close();}if(in!=null){in.close();}}@Testpublic void TestfindAll(){List<User> user=iUser.findAll();for(User user1:user){System.out.println(user1);System.out.println( user1.getRoles());}} }

查詢(xún)所有用戶(hù)的信息及其身份的結(jié)果集展示

IRole.xml

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.DAO.IRole"><resultMap id="RoleUser" type="Role"><id property="ID" column="ID"></id><result property="ROLE_NAME" column="ROLE_NAME"></result><result property="ROLE_DESC" column="ROLE_DESC"></result><collection property="users" ofType="User"><id property="id" column="id"></id><result property="username" column="username"></result><result property="password" column="password"></result><result property="address" column="address"></result><result property="sex" column="sex"></result><result property="birthday" column="birthday"></result></collection></resultMap><select id="findAll" resultMap="RoleUser">select r.*,u.* from Role r left outer join user_role ur on r.id=ur.rid left outer join User u on u.id=ur.uid</select> </mapper>

附上測(cè)試類(lèi)代碼

package com.test;import com.DAO.IRole; import com.DAO.IUser; import com.domain.Role; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import org.junit.After; import org.junit.Before; import org.junit.Test;import java.io.IOException; import java.io.InputStream; import java.util.List;public class RoleTest {private InputStream in=null;private SqlSessionFactory factory=null;private SqlSession sqlSession=null;private IRole iRole=null;@Beforepublic void Init() throws IOException {in= Resources.getResourceAsStream("SqlMapConfig.xml");factory=new SqlSessionFactoryBuilder().build(in);sqlSession=factory.openSession();iRole=sqlSession.getMapper(IRole.class);}@Afterpublic void Close() throws IOException {sqlSession.commit();//提交事務(wù)if(sqlSession!=null){sqlSession.close();}if(in!=null){in.close();}}@Testpublic void TestfindAll(){List<Role> roles=iRole.findAll();for(Role role:roles){System.out.println(role);System.out.println(role.getUsers());}}}

查詢(xún)所有身份信息及對(duì)應(yīng)的用戶(hù)信息的結(jié)果集

其實(shí)在這多對(duì)多中也映射了一對(duì)多的關(guān)系
查詢(xún)這邊運(yùn)用了多表查詢(xún)中的左外連接
具體可以參考這篇大佬的博客 mysql多表查詢(xún)

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