Mybatis 代理模式创建

• mybatis代理模式与非代理模式的区别：

  1. mapper类只需要定义接口，mapper映射文件的namespace的值必须为mapper接口的全类名

  2. 书写的SQL的ID 必须与mapper接口中的相对应的方法名相同

  配置文件mybatisConfig.xml

<configuration>
    <properties resource="jdbc.properties"/>
    <typeAliases>
        <package name="mybatis.domian"/>
        <package name="mybatis.vo"/>
    typeAliases>
    <environments default="mybatis_1">
        <environment id="mybatis_1">
            <transactionManager type="JDBC"/>
            <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="mybatis.mapper">package>
    mappers>
configuration>

实体类User

package mybatis.domian;

import java.io.Serializable;
import java.util.Date;
import java.util.Objects;

public class User implements Serializable{
    private Integer id;
    private String name;
    private  String password;
    private Float salary;
    private Date birthday;
    private Department department;

    public Department getDepartment() {
        return department;
    }

    public void setDepartment(Department department) {
        this.department = department;
    }

    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    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 Float getSalary() {
        return salary;
    }
    public void setSalary(Float salary) {
        this.salary = salary;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        User user = (User) o;
        return Objects.equals(id, user.id) &&
                Objects.equals(name, user.name) &&
                Objects.equals(salary, user.salary) &&
                Objects.equals(birthday, user.birthday);
    }

    @Override
    public int hashCode() {

        return Objects.hash(id, name, salary, birthday);
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", password='" + password + '\'' +
                ", salary=" + salary +
                ", birthday=" + birthday +
                '}';
    }
}

实体类Department

package mybatis.domian;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;

public class Department implements Serializable {
    private Integer id;
    private String name;
    private  String location;
   private Set set = new HashSet<>();

    public Set getSet() {
        return set;
    }

    public void setSet(Set set) {
        this.set = set;
    }

    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 String getLocation() {
        return location;
    }

    public void setLocation(String location) {
        this.location = location;
    }

    @Override
    public String toString() {
        return "Department{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", location='" + location + '\'' +
                '}';
    }
}

mapper接口 UserMapper

package mybatis.mapper;

import mybatis.domian.Department;
import mybatis.domian.User;
import mybatis.vo.UserQueryVo;

import java.util.List;
import java.util.Map;

public interface UserMapper {
    void save(User user);
    void delete(User user);
    void update(User user);
    User findById(Integer id);
    List<User> findAll();
    List<User> findByMap(Map<String,Object> map);
    List<User> findQueryVo(UserQueryVo userQueryVo);
    Department findDepaetmentByUserName(String name);
    Department findDepaetmentByUserName1(String name);
    User findUserByName(String name);

}

Service接口

package mybatis.service;

import mybatis.domian.Department;
import mybatis.domian.User;

import java.util.List;

public interface UserService {
    void addUser(User user);
    List findAllUserList();
    User checkLogin(String name,String password);

    /**
     * 查询某人所在部门
     * @param name
     * @return
     */
    Department findDepaetmentByUserName(String name);
    Department findDepaetmentByUserName1(String name);
    Department findDepaetmentByUserName2(String name);
}

package mybatis.service;

import mybatis.domian.User;

import java.util.List;

public interface DepartmentService {
    List<User> findUserListByDepartmenyName(String name);
    List<User> findUserListByDepartmenyName1(String name);
}

Service接口实现类

package mybatis.service.impl;

import mybatis.domian.Department;
import mybatis.domian.User;
import mybatis.mapper.UserMapper;
import mybatis.service.UserService;
import mybatis.util.MybatisUtils;
import mybatis.vo.UserQueryVo;
import org.apache.commons.collections.CollectionUtils;
import org.apache.ibatis.session.SqlSession;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

public class UerServiceImpl implements UserService{
    @Override
    public void addUser(User user) {
        SqlSession sqlSession = null;
        if (user == null) {
            throw new IllegalArgumentException("");
        }
        try{
            sqlSession = MybatisUtils.getSqlSession();
        /*
           如何mapper文件使用不是代理模式 则此处需要写成
           namespace+方法名
           使用的为代理模式时，则可以直接使用方法名
         */
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            mapper.save(user);
            sqlSession.commit();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            MybatisUtils.clolseSqlSession();
        }

    }

    @Override
    public List findAllUserList() {
        SqlSession sqlSession = null;
        List userList = Collections.emptyList(); // 避免空指针异常

        try{
            sqlSession = MybatisUtils.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            userList = mapper.findAll();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            MybatisUtils.clolseSqlSession();
        }
            return  userList;
    }

    /**
     * 登陆方法
     * @param name
     * @param password
     * @return
     */
    @Override
    public User checkLogin(String name ,String password) {
        SqlSession sqlSession = null;
        UserQueryVo userQueryVo = null;
        User user = null;
        try {
            sqlSession = MybatisUtils.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            userQueryVo = new UserQueryVo();
            userQueryVo.setName(name);
            userQueryVo.setPassword(password);
           List users = mapper.findQueryVo(userQueryVo);
           if (CollectionUtils.isNotEmpty(users)){
               user = users.get(0);
           }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            MybatisUtils.clolseSqlSession();
        }
        return user;
    }

    @Override
    public Department findDepaetmentByUserName(String name) {
        SqlSession sqlSession = null;
        UserQueryVo userQueryVo = null;
        Department department = null;
        try {
            sqlSession = MybatisUtils.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            department = new Department();
            department = mapper.findDepaetmentByUserName(name);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            MybatisUtils.clolseSqlSession();
        }
        return department;
    }

    @Override
    public Department findDepaetmentByUserName1(String name) {
        SqlSession sqlSession = null;
        UserQueryVo userQueryVo = null;
        Department department = null;
        try {
            sqlSession = MybatisUtils.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            department = new Department();
            department = mapper.findDepaetmentByUserName1(name);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            MybatisUtils.clolseSqlSession();
        }
        return department;
    }
    @Override
    public Department findDepaetmentByUserName2(String name){
        SqlSession sqlSession = null;
        UserQueryVo userQueryVo = null;
        User user = null;
        try {
            sqlSession = MybatisUtils.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            user = new User();
            user = mapper.findUserByName(name);
            System.out.println(user);
            if (user != null){
                return user.getDepartment();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            MybatisUtils.clolseSqlSession();
        }
        return null;
    }
}

package mybatis.service.impl;

import mybatis.domian.Department;
import mybatis.domian.User;
import mybatis.mapper.DepartmentMapper;
import mybatis.service.DepartmentService;
import mybatis.util.MybatisUtils;
import org.apache.commons.collections.CollectionUtils;
import org.apache.ibatis.session.SqlSession;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;

public class DepartmentServiceImpl implements DepartmentService {
    @Override
    public List findUserListByDepartmenyName(String name) {
        List userList = Collections.emptyList();
        SqlSession sqlSession = null;
        try{
            sqlSession = MybatisUtils.getSqlSession();
            DepartmentMapper mapper = sqlSession.getMapper(DepartmentMapper.class);
            userList = mapper.findUserListByDepartmenyName(name);
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            MybatisUtils.clolseSqlSession();
        }
        return userList;
    }
    @Override
    public List findUserListByDepartmenyName1(String name) {
        List userList = new ArrayList<>();
        Department department = null;
        SqlSession sqlSession = null;
        try{
            sqlSession = MybatisUtils.getSqlSession();
            DepartmentMapper mapper = sqlSession.getMapper(DepartmentMapper.class);
            department = mapper.findByName(name);
            if (department != null){
                Set userSet = department.getSet();
                // 将 userSet中的数据 全部加入到userList
                CollectionUtils.addAll(userList, userSet.iterator());
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            MybatisUtils.clolseSqlSession();
        }
        return userList;
    }
}

UserQueryVo

public class UserQueryVo extends User {
}

userMapper.xml

<mapper namespace="mybatis.mapper.UserMapper">

    <insert id="save" parameterType="User">
        INSERT  INTO
             mybatis_user(user_name,user_password,user_salary,user_birthday)
         VALUE
               (#{name},#{password},#{salary},#{birthday})

    insert>
    <select id="findAll" resultType="User">
        SELECT
            user_id id ,
            user_name name,
            user_password password ,
            user_salary salary ,
            user_birthday birthday
        FROM
            mybatis_user
    select>
    
    <select id="findQueryVo" resultType="User" parameterType="UserQueryVo">
        SELECT
                user_id id ,
                user_name name,
                user_password password ,
                user_salary salary ,
                user_birthday birthday
        FROM
                mybatis_user
        WHERE
            1=1
        <if test="name != null and name != '' ">
            AND user_name LIKE  "%" #{name} "%"
        if>
        <if test="password != null and password != ''">
             AND user_password LIKE "%" #{password}"%"
        if>
        <if test="salary != null and salary != '' ">
            AND user_salary LIKE  "%" #{salary} "%"
        if>
        <if test="birthday != null and birthday != ''">
            AND user_birthday LIKE "%" #{birthday} "%"
        if>
    select>
    <select id="findDepaetmentByUserName" parameterType="java.lang.String" resultType="Department">
          SELECT
                d.department_id id,
                d.department_name name,
                d.department_location location
          FROM
                mybatis_user u
          LEFT JOIN
                mybatis_department d
          ON
                u.department_id = d.department_id
          WHERE
                u.user_name = #{name}
    select>
    <resultMap id="DepartmentRM" type="Department">
          <id property="id" column="department_id"/>
          <result property="name" column="department_name"/>
          <result property="location" column="department_location"/>
    resultMap>
    <select id="findDepaetmentByUserName1" parameterType="java.lang.String" resultMap="DepartmentRM">
          SELECT
                d.department_id ,
                d.department_name ,
                d.department_location
          FROM
                mybatis_user u
          LEFT JOIN
                mybatis_department d
          ON
                u.department_id = d.department_id
          WHERE
                u.user_name = #{name}
    select>

    
    <resultMap id="UserRM" type="User">
        <id property="id" column="user_id"/>
        <result property="name" column="user_name"/>
        <result property="password" column="user_password"/>
        <result property="salary" column="user_salary"/>
        <result property="birthday" column="birthday"/>
        <association property="department" column="depaetment_id" javaType="Department">
            <id property="id" column="department_id"/>
            <result property="name" column="department_name"/>
            <result property="location" column="department_location"/>
        association>
    resultMap>
    <select id="findUserByName" parameterType="java.lang.String" resultMap="UserRM">
            SELECT
                u.user_id,
                u.user_name,
                u.user_salary,
                u.user_password,
                u.user_birthday,
                d.department_id ,
                d.department_name ,
                d.department_location
          FROM
                mybatis_user u
          INNER JOIN
                mybatis_department d
          ON
                u.department_id = d.department_id
          WHERE
                u.user_name = #{name}
    select>
mapper>

Department.xml

<mapper namespace="mybatis.mapper.DepartmentMapper">

    <select id="findUserListByDepartmenyName" parameterType="java.lang.String" resultType="User">
        SELECT
                u.user_id id ,
                u.user_name name,
                u.user_salary salary ,
                u.user_password password ,
                u.user_birthday birthday
          FROM
                mybatis_user u
                INNER JOIN
                    mybatis_department d
                     ON
                         u.department_id = d.department_id
          WHERE
                d.department_name = #{name}
    select>
    <resultMap id="DepartmentRM" type="Department">
        <id property="id" column="department_id"/>
        <result property="name" column="department_name"/>
        <result property="location" column="department_location"/>
        <collection property="set" column="depaetment_id" ofType="User">
            <id property="id" column="user_id"/>
            <result property="name" column="user_name"/>
            <result property="password" column="user_password"/>
            <result property="salary" column="user_salary"/>
            <result property="birthday" column="user_birthday"/>
        collection>
    resultMap>
    <select id="findByName" resultMap="DepartmentRM">
        SELECT
                u.user_id,
                u.user_name,
                u.user_salary,
                u.user_password,
                u.user_birthday,
                d.department_id ,
                d.department_name ,
                d.department_location
          FROM
                mybatis_user u
          INNER JOIN
                mybatis_department d
          ON
                u.department_id = d.department_id
          WHERE
                d.department_name = #{name}
    select>
mapper>

重点内容

---

collection: 集合 表示多的一方，比如一个部门中有多 个员工，其中property表示所映射的属性名，column该属性在数据库中的列名，ofType该属性的类型名称

association: 有一个 比如：一个员工对应一个部门property、column与collection中属性相同，javaType属性的类型名称

resultType： 表示结果类型，当数据库字段名与实体字段名相同时可直接使用实体类名

resultMap: 当数据库字段与实体字段不同，且SQL 对查询字段并未起表明时, 需要对结果进行映射

---

方法思想，在做条件查询时，创建了UserQueryVo实体类 ，通过集成实体类，得到实体的属性，实现对查询条件的封装

PS: 仅日常笔记整理，有错误请指出，喷子绕路