22_7mybaits注解开发

这几年来注解开发越来越流行，Mybatis 也可以使用注解开发方式，这样我们就可以减少编写 Mapper 映射文件了。

1.常用注解说明

@Insert:实现新增

@Update:实现更新

@Delete:实现删除

@Select:实现查询

@Result:实现结果集封装

@Results:可以与@Result 一起使用，封装多个结果集

@ResultMap:实现引用@Results 定义的封装

@One:实现一对一结果集封装

@Many:实现一对多结果集封装

@SelectProvider: 实现动态 SQL 映射

@CacheNamespace:实现注解二级缓存的使用

2.使用Mybatis注解实现基本CRUD

2.1查询数据库

2.2创建maven工程导入jar包的坐标

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.itheima</groupId>

    <artifactId>day04_eesy_03annotation_mybaitis</artifactId>

    <version>1.0-SNAPSHOT</version>

    <packaging>jar</packaging>

    <dependencies>

        <dependency>

            <groupId>org.mybatis</groupId>

            <artifactId>mybatis</artifactId>

            <version>3.4.5</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>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>4.10</version>

        </dependency>

    </dependencies>

</project>

2.3配置数据库连接信息

jdbc.driver=com.mysql.jdbc.Driver

jdbc.url=jdbc:mysql://localhost:3306/eesy_mybatis

jdbc.username=root

jdbc.password=123456

<?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">

<configuration>

    <!-- 引入外部配置文件-->

    <properties resource="jdbcConfig.properties"></properties>

    <!--配置别名-->

    <typeAliases>

        <package name="com.itheima.domain"></package>

    </typeAliases>

    <!--配置环境-->

    <environments default="mysql">

        <environment id="mysql">

            <transactionManager type="JDBC"></transactionManager>

            <dataSource type="POOLED">

                <property name="driver" value="${jdbc.driver}"></property>

                <property name="url" value="${jdbc.url}"></property>

                <property name="username" value="${jdbc.username}"></property>

                <property name="password" value="${jdbc.password}"></property>

            </dataSource>

        </environment>

    </environments>

    <!-- 指定带有注解的dao接口所在位置 -->

    <mappers>

        <mapper class="com.itheima.dao.IUserDao"></mapper>

    </mappers>

</configuration>

2.4编写实体类

package com.itheima.domain;

import java.io.Serializable;

import java.util.Date;

public class User implements Serializable {

    private Integer id;

    private String username;

    private String address;

    private String sex;

    private Date birthday;

    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 getAddress() {

        return address;

    }

    public void setAddress(String address) {

        this.address = address;

    }

    public String getSex() {

        return sex;

    }

    public void setSex(String sex) {

        this.sex = sex;

    }

    public Date getBirthday() {

        return birthday;

    }

    public void setBirthday(Date birthday) {

        this.birthday = birthday;

    }

    @Override

    public String toString() {

        return "User{" +

                "id=" + id +

                ", username='" + username + '\'' +

                ", address='" + address + '\'' +

                ", sex='" + sex + '\'' +

                ", birthday=" + birthday +

                '}';

    }

}

2.5使用注解方式开发持久层接口

package com.itheima.dao;

import com.itheima.domain.User;

import org.apache.ibatis.annotations.Select;

import java.util.List;

/**

 * @Select @Insert @Update @Delete

 */

public interface IUserDao {

    /**

     * 查询所有用户

     * @return

     */

    @Select("select * from user")

    List<User> findAll();

}

2.6编写测试方法

package com.itheima.test;

import com.itheima.dao.IUserDao;

import com.itheima.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 java.io.InputStream;

import java.util.List;

public class MybatisAnnoTest {

    /**

     * 测试基于注解的mybatis使用

     * @param args

     */

    public static void main(String[] args) throws  Exception{

        //1.获取字节输入流

        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");

        //2.根据字节输入流构建SqlSessionFactory

        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);

        //3.根据SqlSessionFactory生产一个SqlSession

        SqlSession session = factory.openSession();

        //4.使用SqlSession获取Dao的代理对象

        IUserDao userDao = session.getMapper(IUserDao.class);

        //5.执行Dao的方法

        List<User> users = userDao.findAll();

        for(User user : users){

            System.out.println(user);

        }

        //6.释放资源

        session.close();

        in.close();

    }

}

2.7CURD

package com.itheima.dao;

import com.itheima.domain.User;

import org.apache.ibatis.annotations.Delete;

import org.apache.ibatis.annotations.Insert;

import org.apache.ibatis.annotations.Select;

import org.apache.ibatis.annotations.Update;

import java.util.List;

/**

 * @Select @Insert @Update @Delete

 */

public interface IUserDao {

    /**

     * 查询所有用户

     *

     * @return

     */

    @Select("select * from user")

    List<User> findAll();

    /**

     * 保存用户

     *

     * @param user

     */

    @Insert("insert into user(username,address,sex,birthday)values(#{username},#{address},#{sex},#{birthday})")

    void saveUser(User user);

    @Update("update user set username=#{username},sex=#{sex},birthday=#{birthday},address=#{address} where id=#{id}")

    void updateUser(User user);

    @Delete("delete from user where id=#{id} ")

    void deleteUser(Integer userId);

    @Select("select * from user  where id=#{id} ")

    User findById(Integer userId);

    @Select("select * from user where username like #{username} ")

    List<User> findUserByName(String username);

    @Select("select count(*) from user ")

    int findTotalUser();

}

package com.itheima.test;

import com.itheima.dao.IUserDao;

import com.itheima.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 AnnotationCRUDTest {

    private InputStream in;

    private SqlSessionFactory factory;

    private SqlSession session;

    private IUserDao userDao;

    @Before

    public void init() throws Exception {

        in = Resources.getResourceAsStream("SqlMapConfig.xml");

        factory = new SqlSessionFactoryBuilder().build(in);

        session = factory.openSession();

        userDao = session.getMapper(IUserDao.class);

    }

    @After

    public void destroy() throws Exception {

        session.commit();

        session.close();

        in.close();

    }

    @Test

    public void testSave() {

        User user = new User();

        user.setUsername("mybatis annotation");

        user.setAddress("nanchang");

        userDao.saveUser(user);

    }

    @Test

    public void testUpdate() {

        User user = new User();

        user.setId(60);

        user.setUsername("mybatis annotation");

        user.setAddress("nanchang");

        user.setSex("男");

        userDao.updateUser(user);

    }

    @Test

    public void testDelete() {

        userDao.deleteUser(60);

    }

    @Test

    public void testFindOne() {

        User user = userDao.findById(58);

        System.out.println(user);

    }

    @Test

    public void testFindByName() {

        List<User> users = userDao.findUserByName("%mybatis%");

        for (User user : users) {

            System.out.println(user);

        }

    }

    @Test

    public  void testFindTotal(){

        int total = userDao.findTotalUser();

        System.out.println(total);

    }

}

3.在注解配置中解决数据库字段名和实体类字段名不对应问题

package com.itheima.domain;

import java.io.Serializable;

import java.util.Date;

import java.util.List;

public class User implements Serializable {

    private Integer userId;

    private String userName;

    private String userAddress;

    private String userSex;

    private Date userBirthday;

    public Integer getUserId() {

        return userId;

    }

    public void setUserId(Integer userId) {

        this.userId = userId;

    }

    public String getUserName() {

        return userName;

    }

    public void setUserName(String userName) {

        this.userName = userName;

    }

    public String getUserAddress() {

        return userAddress;

    }

    public void setUserAddress(String userAddress) {

        this.userAddress = userAddress;

    }

    public String getUserSex() {

        return userSex;

    }

    public void setUserSex(String userSex) {

        this.userSex = userSex;

    }

    public Date getUserBirthday() {

        return userBirthday;

    }

    public void setUserBirthday(Date userBirthday) {

        this.userBirthday = userBirthday;

    }

    @Override

    public String toString() {

        return "User{" +

                "userId=" + userId +

                ", userName='" + userName + '\'' +

                ", userAddress='" + userAddress + '\'' +

                ", userSex='" + userSex + '\'' +

                ", userBirthday=" + userBirthday +

                '}';

    }

}

package com.itheima.dao;

import com.itheima.domain.User;

import org.apache.ibatis.annotations.*;

import java.util.List;

/**

 * @Select @Insert @Update @Delete

 */

public interface IUserDao {

    /**

     * 查询所有用户

     *

     * @return

     */

    @Select("select * from user")

    @Results(id="userMap",value= {

            @Result(id = true, column = "id", property = "userId"),

            @Result(column = "username", property = "userName"),

            @Result(column = "address", property = "userAddress"),

            @Result(column = "sex", property = "userSex"),

            @Result(column = "birthday", property = "userBirthday")

    })

    List<User> findAll();

    /**

     * 根据id查询用户

     *

     * @param userId

     * @return

     */

    @Select("select * from user  where id=#{id} ")

//    @ResultMap(value = {"userMap"})

    @ResultMap("userMap")

    User findById(Integer userId);

    /**

     * 根据用户名称模糊查询

     *

     * @param username

     * @return

     */

    @Select("select * from user where username like #{username} ")

    List<User> findUserByName(String username);

}

4.多表1对1查询

4.1实体类

package com.itheima.domain;

import java.io.Serializable;

import java.util.Date;

import java.util.List;

public class User implements Serializable {

    private Integer userId;

    private String userName;

    private String userAddress;

    private String userSex;

    private Date userBirthday;

    public Integer getUserId() {

        return userId;

    }

    public void setUserId(Integer userId) {

        this.userId = userId;

    }

    public String getUserName() {

        return userName;

    }

    public void setUserName(String userName) {

        this.userName = userName;

    }

    public String getUserAddress() {

        return userAddress;

    }

    public void setUserAddress(String userAddress) {

        this.userAddress = userAddress;

    }

    public String getUserSex() {

        return userSex;

    }

    public void setUserSex(String userSex) {

        this.userSex = userSex;

    }

    public Date getUserBirthday() {

        return userBirthday;

    }

    public void setUserBirthday(Date userBirthday) {

        this.userBirthday = userBirthday;

    }

    @Override

    public String toString() {

        return "User{" +

                "userId=" + userId +

                ", userName='" + userName + '\'' +

                ", userAddress='" + userAddress + '\'' +

                ", userSex='" + userSex + '\'' +

                ", userBirthday=" + userBirthday +

                '}';

    }

}

package com.itheima.domain;

import java.io.Serializable;

public class Account implements Serializable {

    private Integer id;

    private Integer uid;

    private Double money;

    //多对一（mybatis中称之为一对一）的映射：一个账户只能属于一个用户

    private User user;

    public User getUser() {

        return user;

    }

    public void setUser(User user) {

        this.user = user;

    }

    public Integer getId() {

        return id;

    }

    public void setId(Integer id) {

        this.id = id;

    }

    public Integer getUid() {

        return uid;

    }

    public void setUid(Integer uid) {

        this.uid = uid;

    }

    public Double getMoney() {

        return money;

    }

    public void setMoney(Double money) {

        this.money = money;

    }

    @Override

    public String toString() {

        return "Account{" +

                "id=" + id +

                ", uid=" + uid +

                ", money=" + money +

                '}';

    }

}

4.2添加账户的持久层接口并使用注解配置

package com.itheima.dao;

import com.itheima.domain.Account;

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 java.util.List;

public interface IAccountDao {

    /**

     * 查询所有账户，并且获取每个账户所属的用户信息

     * @return

     */

    @Select("select * from account")

    @Results(id="accountMap",value = {

            @Result(id=true,column = "id",property = "id"),

            @Result(column = "uid",property = "uid"),

            @Result(column = "money",property = "money"),

            @Result(property = "user",column = "uid",one=@One(select="com.itheima.dao.IUserDao.findById",fetchType= FetchType.EAGER))

    })

    List<Account> findAll();

    /**

     * 根据用户id查询账户信息

     * @param userId

     * @return

     */

    @Select("select * from account where uid = #{userId}")

    List<Account> findAccountByUid(Integer userId);

}

package com.itheima.dao;

import com.itheima.domain.User;

import org.apache.ibatis.annotations.*;

import java.util.List;

/**

 * @Select @Insert @Update @Delete

 */

public interface IUserDao {

    /**

     * 查询所有用户

     *

     * @return

     */

    @Select("select * from user")

    @Results(id="userMap",value= {

            @Result(id = true, column = "id", property = "userId"),

            @Result(column = "username", property = "userName"),

            @Result(column = "address", property = "userAddress"),

            @Result(column = "sex", property = "userSex"),

            @Result(column = "birthday", property = "userBirthday")

    })

    List<User> findAll();

    /**

     * 根据id查询用户

     *

     * @param userId

     * @return

     */

    @Select("select * from user  where id=#{id} ")

//    @ResultMap(value = {"userMap"})

    @ResultMap("userMap")

    User findById(Integer userId);

    /**

     * 根据用户名称模糊查询

     *

     * @param username

     * @return

     */

    @Select("select * from user where username like #{username} ")

    List<User> findUserByName(String username);

}

4.3测试类

package com.itheima.test;

import com.itheima.dao.IAccountDao;

import com.itheima.domain.Account;

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.InputStream;

import java.util.List;

public class AccountTest {

    private InputStream in;

    private SqlSessionFactory factory;

    private SqlSession session;

    private IAccountDao accountDao;

    @Before

    public  void init()throws Exception{

        in = Resources.getResourceAsStream("SqlMapConfig.xml");

        factory = new SqlSessionFactoryBuilder().build(in);

        session = factory.openSession();

        accountDao = session.getMapper(IAccountDao.class);

    }

    @After

    public  void destroy()throws  Exception{

        session.commit();

        session.close();

        in.close();

    }

    @Test

    public  void  testFindAll(){

        List<Account> accounts = accountDao.findAll();

        for(Account account : accounts){

            System.out.println("----每个账户的信息-----");

            System.out.println(account);

            System.out.println(account.getUser());

        }

    }

}

5.使用注解实现一对多复杂关系映射

需求：
　　查询用户信息时，也要查询他的账户列表。使用注解方式实现。
分析：
　　一个用户具有多个账户信息，所以形成了用户(User)与账户(Account)之间的一对多关系。

5.1User实体类加入List<Account>

package com.itheima.domain;

import java.io.Serializable;

import java.util.Date;

import java.util.List;

public class User implements Serializable {

    private Integer userId;

    private String userName;

    private String userAddress;

    private String userSex;

    private Date userBirthday;

    //一对多关系映射：一个用户对应多个账户

    private List<Account> accounts;

    public List<Account> getAccounts() {

        return accounts;

    }

    public void setAccounts(List<Account> accounts) {

        this.accounts = accounts;

    }

    public Integer getUserId() {

        return userId;

    }

    public void setUserId(Integer userId) {

        this.userId = userId;

    }

    public String getUserName() {

        return userName;

    }

    public void setUserName(String userName) {

        this.userName = userName;

    }

    public String getUserAddress() {

        return userAddress;

    }

    public void setUserAddress(String userAddress) {

        this.userAddress = userAddress;

    }

    public String getUserSex() {

        return userSex;

    }

    public void setUserSex(String userSex) {

        this.userSex = userSex;

    }

    public Date getUserBirthday() {

        return userBirthday;

    }

    public void setUserBirthday(Date userBirthday) {

        this.userBirthday = userBirthday;

    }

    @Override

    public String toString() {

        return "User{" +

                "userId=" + userId +

                ", userName='" + userName + '\'' +

                ", userAddress='" + userAddress + '\'' +

                ", userSex='" + userSex + '\'' +

                ", userBirthday=" + userBirthday +

                '}';

    }

}

5.2编写用户的持久层接口并使用注解配置

package com.itheima.dao;

import com.itheima.domain.User;

import org.apache.ibatis.annotations.*;

import org.apache.ibatis.mapping.FetchType;

import java.util.List;

/**

 * @Select @Insert @Update @Delete

 */

public interface IUserDao {

    /**

     * 查询所有用户

     *

     * @return

     */

    @Select("select * from user")

    @Results(id="userMap",value= {

            @Result(id = true, column = "id", property = "userId"),

            @Result(column = "username", property = "userName"),

            @Result(column = "address", property = "userAddress"),

            @Result(column = "sex", property = "userSex"),

            @Result(column = "birthday", property = "userBirthday"),

            @Result(property = "accounts",column = "id",

                    many = @Many(select = "com.itheima.dao.IAccountDao.findAccountByUid",

                            fetchType = FetchType.LAZY))

    })

    List<User> findAll();

    /**

     * 根据id查询用户

     *

     * @param userId

     * @return

     */

    @Select("select * from user  where id=#{id} ")

//    @ResultMap(value = {"userMap"})

    @ResultMap("userMap")

    User findById(Integer userId);

    /**

     * 根据用户名称模糊查询

     *

     * @param username

     * @return

     */

    @Select("select * from user where username like #{username} ")

    List<User> findUserByName(String username);

}

5.3编写账户的持久层接口并使用注解配置

package com.itheima.dao;

import com.itheima.domain.Account;

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 java.util.List;

public interface IAccountDao {

    /**

     * 根据用户id查询账户信息

     * @param userId

     * @return

     */

    @Select("select * from account where uid = #{userId}")

    List<Account> findAccountByUid(Integer userId);

}

5.4测试类

 @Test

    public  void findAll() {

        List<User> users = userDao.findAll();

        for (User u :users ) {

            System.out.println("每个用户的信息。。。");

            System.out.println(u);

            System.out.println(u.getAccounts());

        }

    }

6.mybatis基于注解的二级缓存

6.1在SqlMapConfig

<!-- 配置二级缓存 -->

<settings>

    <!-- 开启二级缓存的支持 -->

    <setting name="cacheEnabled" value="true"/>

</settings>

6.2在持久层接口中使用注解配置二级缓存

@CacheNamespace(blocking=true)//mybatis 基于注解方式实现配置二级缓存

public interface IUserDao {}

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22_7mybaits注解开发

1.常用注解说明

2.使用Mybatis注解实现基本CRUD

2.1查询数据库

2.2创建maven工程导入jar包的坐标

2.3配置数据库连接信息

2.4编写实体类

2.5使用注解方式开发持久层接口

2.6编写测试方法

2.7CURD

3.在注解配置中解决数据库字段名和实体类字段名不对应问题

4.多表1对1查询

4.1实体类

4.2添加账户的持久层接口并使用注解配置

4.3测试类

5.使用注解实现一对多复杂关系映射

5.1User实体类加入List<Account>

5.2编写用户的持久层接口并使用注解配置

5.3编写账户的持久层接口并使用注解配置

5.4测试类

6.mybatis基于注解的二级缓存

6.1在SqlMapConfig

6.2在持久层接口中使用注解配置二级缓存

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