使用resultMap实现高级结果映射
使用resultMap实现高级结果映射 resultMap的属性: 1.属性 id:resultMap的唯一标识。 id:一般对应数据库的主键 id,设置此项可以提升数据库性能。 <resultMap type="User" id="userRoleResult"> <id property="id" column="id"/> <result property="userName" column="userName"/> <association property="role" javaType="Role"> <id property="roleName" column="roleName"/> </association> </resultMap> javaType:完整Java类名或者别名。若映射到一个JavaBean,则MyBatis通常会自行检测到其类型;若映射到一个HashMap,则应该明确指定javaType,类确保所需行为。此处为Role。 collection(属性是一个集合列表) <resultMap type="User" id="userRoleResult"> <id property="id" column="id"/> <result property="userName" column="userName"/> <collection property="List" ofType="Address"> <id property="id" column="id"/> <result property="postCode" column="postCode"/> </collection> </resultMap> ofType:完整Java类名或者别名,即集合所包含的类型,此处为Address。 一对多 实体
package com.smbms.entity; import java.math.BigInteger; import java.util.Date; import java.util.List; /** * 角色 */ DAO层
DAO层XML <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <!--namespace需要指向接口全路径--> <mapper namespace="com.smbms.dao.ISmbmsRoleDao"> <resultMap id="roleAndUserMapper" type="SmbmsRole"> <id column="rid" property="rid"></id> <result column="roleName" property="roleName"/> <!--映射多的一方 property代表实体当中多的一方的属性名 ofType代表集合当中泛型类型--> <!-- select 代表执行查询的ID column所引用的条件列 --> <collection property="userList" ofType="SmbmsUser" select="getRoleAndUserMutilSQL" column="rid"> </collection> </resultMap> <!--写成一条sql--> <select id="getRoleAndUser" resultMap="roleAndUserMapper"> select u.id,u.userName,u.userRole,r.rid,r.roleName from smbms_user as u,smbms_role as r where u.userRole=r.rid and r.rid=#{id} </select> <!--写成两条sql--> <select id="getRoleAndUser" resultMap="roleAndUserMapper"> select * from smbms_role where rid=#{id} </select> <select id="getRoleAndUserMutilSQL" resultType="SmbmsUser"> select * from smbms_user where userRole=#{rid} </select> </mapper> 测试 package com.smbms.test; import com.smbms.dao.ISmbmsRoleDao; import com.smbms.entity.SmbmsRole; import com.smbms.entity.SmbmsUser; import com.smbms.util.MybatisUtil; import org.apache.ibatis.session.SqlSession; import org.junit.Test; public class CollectionTest { @Test public void getRoleAndUserTest(){ SqlSession sqlSession = MybatisUtil.getSqlSession(); ISmbmsRoleDao mapper = sqlSession.getMapper(ISmbmsRoleDao.class); SmbmsRole role = mapper.getRoleAndUser(3); System.out.println("角色:"+role.getRoleName()); for(SmbmsUser user : role.getUserList()){ System.out.print("t用户:"+user.getUserName()); } } } 多对一 实体
? package com.smbms.entity; import java.math.BigInteger; import java.util.Date; /** * */ public class SmbmsUser { private Integer id; private String userCode; private String userName; private String userPassword; private Integer gender; private Date birthday; private String phone; private String address; private Integer userRole; private BigInteger createdBy; private Date creationDate; private BigInteger modifyBy; private Date modifyDate; //关联一的一方 private SmbmsRole role; public SmbmsRole getRole() { return role; } public void setRole(SmbmsRole role) { this.role = role; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getUserCode() { return userCode; } public void setUserCode(String userCode) { this.userCode = userCode; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getUserPassword() { return userPassword; } public void setUserPassword(String userPassword) { this.userPassword = userPassword; } public Integer getGender() { return gender; } public void setGender(Integer gender) { this.gender = gender; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } 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 Integer getUserRole() { return userRole; } public void setUserRole(Integer userRole) { this.userRole = userRole; } public BigInteger getCreatedBy() { return createdBy; } public void setCreatedBy(BigInteger createdBy) { this.createdBy = createdBy; } public Date getCreationDate() { return creationDate; } public void setCreationDate(Date creationDate) { this.creationDate = creationDate; } public BigInteger getModifyBy() { return modifyBy; } public void setModifyBy(BigInteger modifyBy) { this.modifyBy = modifyBy; } public Date getModifyDate() { return modifyDate; } public void setModifyDate(Date modifyDate) { this.modifyDate = modifyDate; } } ?
? DAO层 package com.smbms.dao; import com.smbms.entity.SmbmsUser; import java.util.List; public interface ISmbmsUserDao { //查询所有用户信息 包含角色信息 public List<SmbmsUser> getUserList(); }
DAO层XML <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <!--namespace需要指向接口全路径--> <mapper namespace="com.smbms.dao.ISmbmsUserDao"> <resultMap id="userListAndRole" type="SmbmsUser"> <id column="id" property="id"></id> <result column="userName" property="userName"/> <association property="role" javaType="SmbmsRole" select="getRole" column="userRole"> <id column="rid" property="rid"></id> <result column="roleName" property="roleName"/> </association> </resultMap> <!--<select id="getUserList" resultMap="userListAndRole"> select u.id,smbms_role as r where u.userRole=r.rid </select>--> <select id="getUserList" resultMap="userListAndRole"> select * from smbms_user </select> <select id="getRole" resultType="SmbmsRole"> select * from smbms_role where rid=#{userRole} </select> </mapper>
测试 package com.smbms.test; import com.smbms.dao.ISmbmsUserDao; import com.smbms.entity.SmbmsUser; import com.smbms.util.MybatisUtil; import org.apache.ibatis.session.SqlSession; import org.junit.Test; import java.util.List; public class AssociationTest { @Test public void getUserListTest(){ SqlSession sqlSession = MybatisUtil.getSqlSession(); ISmbmsUserDao mapper = sqlSession.getMapper(ISmbmsUserDao.class); List<SmbmsUser> userList = mapper.getUserList(); for(SmbmsUser user:userList){ System.out.println("用户:"+user.getUserName()+"t角色:"+user.getRole().getRoleName()); } } }
多对多 实体
? package com.smbms.entity; import java.util.List; public class Teacher { private Integer tid; private String tname; //植入学员集合,代表一名教员可以教授多名学员 private List<Student> students; public Integer getTid() { return tid; } public void setTid(Integer tid) { this.tid = tid; } public String getTname() { return tname; } public void setTname(String tname) { this.tname = tname; } public List<Student> getStudents() { return students; } public void setStudents(List<Student> students) { this.students = students; } } package com.smbms.entity; import java.util.List; public class Student { private Integer stuid; private String stuname; private String stuaddress; //植入Teacher集合,代表一名学员可以被多名教员教授 private List<Teacher> teachers; public List<Teacher> getTeachers() { return teachers; } public void setTeachers(List<Teacher> teachers) { this.teachers = teachers; } public Integer getStuid() { return stuid; } public void setStuid(Integer stuid) { this.stuid = stuid; } public String getStuname() { return stuname; } public void setStuname(String stuname) { this.stuname = stuname; } public String getStuaddress() { return stuaddress; } public void setStuaddress(String stuaddress) { this.stuaddress = stuaddress; } } ?
? DAO层 package com.smbms.dao; import com.smbms.entity.Student; import java.util.List; public interface IStudentDao { //查询所有学生信息 以及授课教员 public List<Student> getStudentInfo(); }
DAO层XML <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <!--namespace需要指向接口全路径--> <mapper namespace="com.smbms.dao.IStudentDao"> <resultMap id="studentAndTeacherMapper" type="Student"> <id column="stuid" property="stuid"/> <result column="stuname" property="stuname"/> <collection property="teachers" ofType="Teacher"> <id column="tid" property="tid"></id> <result property="tname" column="tname"/> </collection> </resultMap> <select id="getStudentInfo" resultMap="studentAndTeacherMapper"> select * from student,teacher,stu_t where student.stuid=stu_t.stuid and teacher.tid=stu_t.tid </select> </mapper>
测试 package com.smbms.test; import com.smbms.dao.IStudentDao; import com.smbms.entity.Student; import com.smbms.entity.Teacher; import com.smbms.util.MybatisUtil; import org.apache.ibatis.session.SqlSession; import org.junit.Test; import java.util.List; public class ManeyTooManey { @Test public void getStudentInfo(){ SqlSession sqlSession = MybatisUtil.getSqlSession(); IStudentDao mapper = sqlSession.getMapper(IStudentDao.class); List<Student> studentInfo = mapper.getStudentInfo(); for(Student stu:studentInfo){ System.out.println("学生:"+stu.getStuname()); for (Teacher teacher:stu.getTeachers()){ System.out.print("t教员:"+teacher.getTname()); } System.out.println(); } } }
自联接 实体
? package com.smbms.entity; import java.util.List; public class City { private Integer cid; private String cname; private Integer pid; //自关联集合 代表的是当前City对象的子集集合 public List<City> childCitys; @Override public String toString() { return "City{" + "cid=" + cid + ",cname=‘" + cname + ‘‘‘ + ",pid=" + pid + ",childCitys=" + childCitys + ‘}‘; } public List<City> getChildCitys() { return childCitys; } public void setChildCitys(List<City> childCitys) { this.childCitys = childCitys; } public Integer getCid() { return cid; } public void setCid(Integer cid) { this.cid = cid; } public String getCname() { return cname; } public void setCname(String cname) { this.cname = cname; } public Integer getPid() { return pid; } public void setPid(Integer pid) { this.pid = pid; } } ?
? DAO层 package com.smbms.dao; import com.smbms.entity.City; import java.util.List; public interface ICityDao { //查询河南省 下的所有子集 public City getCityAndChildCitys(Integer cid); }
DAO层XML <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <!--namespace需要指向接口全路径--> <mapper namespace="com.smbms.dao.ICityDao"> <resultMap id="CityAndChildCitysMapper" type="City"> <id column="cid" property="cid"></id> <result column="cname" property="cname"/> <result column="pid" property="pid"/> <collection property="childCitys" ofType="City" select="getCityAndChildCitysMutilSQL" column="cid"> <id column="cid" property="cid"></id> <result column="cname" property="cname"/> <result column="pid" property="pid"/> </collection> </resultMap> <select id="getCityAndChildCitys" resultMap="CityAndChildCitysMapper"> select * from city where cid=#{cid} </select> <select id="getCityAndChildCitysMutilSQL" resultMap="CityAndChildCitysMapper"> select * from city where pid=#{cid} </select> </mapper>
测试 package com.smbms.test; import com.smbms.dao.ICityDao; import com.smbms.entity.City; import com.smbms.util.MybatisUtil; import org.apache.ibatis.session.SqlSession; import org.junit.Test; public class DGTest { @Test public void getCityAndChildCitysTest(){ SqlSession sqlSession = MybatisUtil.getSqlSession(); ICityDao mapper = sqlSession.getMapper(ICityDao.class); City city = mapper.getCityAndChildCitys(410000); System.out.println(city.toString()); } } (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |