1. 注解使用

? ? ? ? mybatis-plus提供了 ·@TableName·, @TableId, @TableField,?@TableLogic 四種注解，其含義分別為：

?@TableName

? ? ? ? ?@TableName("SPF_Require_Vehicle")? ? 用于聲明當(dāng)前class所對應(yīng)數(shù)據(jù)庫中的表，如果class的名字和表的名字完全相同，則不需要添加該注解，如果不一樣，則需要用該注解進(jìn)行聲明。

?@TableId

????????@TableId(value = "SPF_UID", type = IdType.AUTO)? ? ?用于聲明主鍵， value指定數(shù)據(jù)庫中主鍵的名稱，type為主鍵的生成類型，支持 Assign（雪花算法，java字段需要是Long）、Auto（數(shù)據(jù)庫字段需要聲明為auto_increment）， uuid

? @TableField

? ? ? ??@TableField("SPF_Name")? 用于聲明當(dāng)前字段對應(yīng)的表中的字段

? @TableLogic

? ? ? ? @TableLogic(value = "0", delval = "1")? ?用于軟刪除，value是默認(rèn)值，delval表示軟刪除后的值。

@TableName("SPF_Require_Vehicle")
@Data
public class Employee {
    /**
     * 指定主鍵名稱為SPF_uid, 類型為自增，即數(shù)據(jù)庫的字段必須是auto_increment
     */
    @TableId(value = "SPF_UID", type = IdType.AUTO)
    private Long id;

    /**
     * 指定數(shù)據(jù)庫中對應(yīng)的字段是 Part_PartSap
     */
    @TableField("Part_PartSap")
    private String partSap;

    @TableField("Part_PlateSap")
    private String plateSap;

    @TableField("SPF_Name")
    private String name;

    /**
     * 邏輯刪除
     */
    @TableLogic(value = "0", delval = "1")
    @TableField("IsActvie")
    private Boolean active;
}

@EnumValue

? ? ? ? 代碼簡潔性考慮：許多時候需要用到Enum，例如0表示男1表示女、0表示關(guān)閉1表示打開，and so on

1. ? ? ? ? ?在數(shù)據(jù)庫表中增加字段gender： 0表示男，1表示女
2. ? ? ? ? ? 定義枚舉類， @EnumValue注解表示該字段是向數(shù)據(jù)庫中插入的值，@JsonValue表示讀取的時候?qū)ν庹故镜闹????????

@Getter
public enum SexEnum {
    SEX_MALE(0, "男"),
    SEX_FEMALE(1, "女");

    /**
     * 表示當(dāng)前字段是執(zhí)行insert時向數(shù)據(jù)庫中插入的字段
     */
    @EnumValue
    private int sexVal;

    /**
     * 表示從數(shù)據(jù)庫讀取的時候?qū)ν怙@示的值
     */
    @JsonValue
    private String sexName;

    SexEnum(int sexVal, String sexName) {
        this.sexVal = sexVal;
        this.sexName = sexName;
    }

    /**
     * 配合 @JsonValue使用
     * @return 返回展示的值
     */
    @Override
    public String toString() {
        return this.sexName;
    }
}

? ? ? ? 3.? 使用處

?????????????????

????????????????

? ? ? ? ?插入的值為枚舉注釋的值

? ? ? ? 讀取的是 @JsonValue注釋的值

?????????

2. IService使用

2.1 批量插入

boolean saveBatch(Collection<T> entityList, int batchSize);

@Test
    public void baseBatchInsertTest() {
        List<Employee> list = new ArrayList<>();
        for (int i = 20; i < 30; i++) {
            Employee employee = new Employee();
            employee.setName("zhagnsan" + i);
            employee.setPartSap("123425-" + i);
            employee.setPlateSap("312342-" + i);
            list.add(employee);
        }
        // 批量插入，service提供了兩個函數(shù)，可以帶第二個參數(shù)，也可以不帶，不帶的情況下默認(rèn)是1000
        // 批量插入實際也是一條一條的插入，不同的是底層啟動了同一個session，插入完成后關(guān)閉，不需要每次都開啟關(guān)閉
        this.service.saveBatch(list, 10);
    }

2.2 批量插入修改

? ? ? ? 如果主鍵Id已經(jīng)在表中存在則修改，如果不存在則插入一條新數(shù)據(jù)

?// 第二個參數(shù)選填，默認(rèn)是1000

boolean saveOrUpdateBatch(Collection<T> entityList, int batchSize);

@Test
    public void testBatchInsertOrUpdate() {
        List<Employee> list = new ArrayList<>();
        Employee e1 = new Employee();
        // 1L已經(jīng)存在，會指定update
        e1.setId(1L);
        // 只添加了一個字段，也就是只修改一個字段
        e1.setName("車轱轆");
        Employee e2 = new Employee();
        // id在表中不存在，則新增
        e2.setId(50L);
        e2.setName("車頂");
        e2.setPartSap("123142314-00");
        e2.setPlateSap("423414-09");
        list.add(e1);
        list.add(e2);
        this.service.saveOrUpdateBatch(list,2);
    }

2.2 單個插入修改

? ? ? ?// 如果id存在則修改，否則插入

boolean saveOrUpdate(T entity);

2.3 單個刪除

default boolean removeById(Serializable id)

default boolean removeById(T entity)

@Test
    public void testRemoveSingle01() {
        /**
         * id如果存在則刪除，返回ture，否則返回false
         */
        boolean b = this.service.removeById(9);
        System.out.println("b:" + b);
    }


/*
* 有的時候，前端傳過來的是一個類，此時可以直接調(diào)用該函數(shù)刪除
*/
@Test
    public void testRemoveSignle02() {
        Employee employee = new Employee();
        employee.setId(8L);
        this.service.removeById(employee);
    }

2.4 有條件刪除?

? ? ? ? 實際中很多情況并不是根據(jù)Id進(jìn)行刪除而是根據(jù)實際需要進(jìn)行刪除， service也提供了該功能

removeByMap

default boolean removeByMap(Map<String, Object> columnMap)

????????

/*
* 下面代碼執(zhí)行的語句如下
* UPDATE SPF_Require_Vehicle SET IsActvie=1 WHERE Part_PlateSap = ? AND Part_PartSap = ? AND IsActvie=0
*/
@Test
    public void testRemoveByMap() {
        Map<String, Object> map = new HashMap<>();
        map.put("Part_PartSap", "123425-0");
        map.put("Part_PlateSap", "312342-0");
        this.service.removeByMap(map);
    }

remove（可根據(jù)條件批量刪除）

?也可以根據(jù)wrapper進(jìn)行刪除，刪除的時候使用的是QueryWrapper， Wrapper的用法有很多種，此處只展示in的用法，其他用法下文進(jìn)行介紹

default boolean remove(Wrapper<T> queryWrapper)

@Test
    public void testRemove03() {
        QueryWrapper<Employee> wrapper = new QueryWrapper<>();
        List<Long> list = new ArrayList<>();
        list.add(2L);
        list.add(3L);
        list.add(4L);
        wrapper.in(list != null && !list.isEmpty(), "SPF_UID", list);
        /**
         * UPDATE SPF_Require_Vehicle SET IsActvie=1 WHERE IsActvie=0 AND (SPF_UID IN (?,?,?))
         */
        this.service.remove(wrapper);
    }

2.5 批量刪除

根據(jù)主鍵批量刪除

removeByIds

default boolean removeByIds(Collection<?> list)

@Test
    public void testRemoveByIds() {
        List<Long> list = new ArrayList<>();
        list.add(2L);
        list.add(3L);
        list.add(5L);
        /**
         * 根據(jù)Ids批量刪除
         * UPDATE SPF_Require_Vehicle SET IsActvie=1 WHERE SPF_UID IN ( ? , ? , ? ) AND IsActvie=0
         */
        this.service.removeByIds(list);
    }

removeBatchByIds

采用jdbc批量刪除，底層使用for循環(huán)逐個刪除，這點是和上面函數(shù)的區(qū)別

default boolean removeBatchByIds(Collection<?> list, int batchSize)

@Test
    public void testremoveBatchByIds() {
        List<Long> list = new ArrayList<>();
        list.add(2L);
        list.add(3L);
        list.add(5L);
        /**
         * UPDATE SPF_Require_Vehicle SET IsActvie=1 WHERE SPF_UID=? AND IsActvie=0
         */
        this.service.removeBatchByIds(list, list.size());
    }

2.6 單個修改：根據(jù)Id修改

default boolean updateById(T entity)

@Test
    public void testupdateById() {
        Employee employee = new Employee();
        employee.setId(8L);
        employee.setName("doris");
        /**
         * UPDATE SPF_Require_Vehicle SET SPF_Name=? WHERE SPF_UID=? AND IsActvie=0
         */
        this.service.updateById(employee);
    }

2.7 有條件修改：根據(jù)wrapper修改

default boolean update(Wrapper<T> updateWrapper)

@Test
    public void testupdate() {
        Integer minId = 9;
        Integer maxId = 14;
        String name = "doris";
        String nName = "wangshun";
        LambdaUpdateWrapper<Employee> wrapper = new LambdaUpdateWrapper<>();
        wrapper.gt(minId != null, Employee::getId, minId)
                .lt(maxId != null, Employee::getId, maxId)
                .or()
                .like(name != null && !name.isEmpty(), Employee::getName, name);
        wrapper.set(nName != null && !nName.isEmpty(), Employee::getName, nName);
        /**
         * UPDATE SPF_Require_Vehicle SET SPF_Name=? WHERE IsActvie=0 AND (SPF_UID > ? AND SPF_UID < ? OR SPF_Name LIKE ?)
         */
        this.service.update(wrapper);
    }

2.8 批量修改：根據(jù)Id修改

這個方法很使用，實際工作中，都是根據(jù)前端傳過來的結(jié)構(gòu)體進(jìn)行修改

boolean updateBatchById(Collection<T> entityList, int batchSize)

@Test
    public void testupdateBatchById() {
        List<Employee> list = new ArrayList<>();
        Employee e1 = new Employee();
        e1.setId(1L);
        e1.setName("wangwu");
        Employee e2 = new Employee();
        e2.setId(2L);
        e2.setName("wangbaochuan");
        list.add(e1);
        list.add(e2);
        /**
         * UPDATE SPF_Require_Vehicle SET SPF_Name=? WHERE SPF_UID=? AND IsActvie=0
         */
        this.service.updateBatchById(list, list.size());

    }

2.9 單個查詢

? ? ? ? 根據(jù)Id單個查詢

????????getById

@Test
    public void testgetById() {
        /**
         * SELECT SPF_UID AS id,Part_PartSap AS partSap,Part_PlateSap AS plateSap,SPF_Name AS name,IsActvie AS active FROM SPF_Require_Vehicle WHERE SPF_UID=? AND IsActvie=0
         */
        Employee byId = this.service.getById(1);
        System.out.println(byId);
    }

????????getOne

? ? ? ? ? // 根據(jù)條件查找時：如果有多個則會拋出異常

????????default T getOne(Wrapper<T> queryWrapper)

????????

@Test
    public void testgetOne() {
        LambdaQueryWrapper<Employee> wrapper = new LambdaQueryWrapper<>();
        String plateSap = "312342-6";
        wrapper.eq(plateSap != null && !plateSap.isEmpty(), Employee::getPlateSap, plateSap);
        /**
         * SELECT SPF_UID AS id,Part_PartSap AS partSap,Part_PlateSap AS plateSap,SPF_Name AS name,IsActvie AS active
         *  FROM SPF_Require_Vehicle WHERE IsActvie=0 AND (Part_PlateSap = ?)
         */
        Employee one = this.service.getOne(wrapper);
        System.out.println(one);
    }

????????

2.10 批量查詢

????????listByIds

????????

@Test
    public void testlistByIds() {
        List<Long> list = new ArrayList<>();
        list.add(1L);
        list.add(2L);
        list.add(3L);
        List<Employee> employees = this.service.listByIds(list);
        /**
         * SELECT SPF_UID AS id,Part_PartSap AS partSap,Part_PlateSap AS plateSap,SPF_Name AS name,IsActvie AS active FROM SPF_Require_Vehicle WHERE SPF_UID IN ( ? , ? , ? ) AND IsActvie=0
         */
        employees.forEach(System.out::println);
    }

list

?????????

@Test
    public void testList() {
        List<Employee> list = this.service.list();
        /**
         * SELECT SPF_UID AS id,Part_PartSap AS partSap,Part_PlateSap AS plateSap,SPF_Name AS name,IsActvie AS active
         *  FROM SPF_Require_Vehicle WHERE IsActvie=0
         */
        list.forEach(System.out::println);
    }

2.11 有條件批量查詢

????????listByMap

????????default List<T> listByMap(Map<String, Object> columnMap)

@Test
    public void testlistByMap() {
        Map<String, Object> map = new HashMap<>();
        map.put("SPF_Name", "wangshun");
        map.put("Part_PlateSap", "312342-20");
        /**
         * SELECT SPF_UID AS id,Part_PartSap AS partSap,Part_PlateSap AS plateSap,SPF_Name AS name,IsActvie AS active 
         *  FROM SPF_Require_Vehicle WHERE Part_PlateSap = ? AND SPF_Name = ? AND IsActvie=0
         */
        List<Employee> employees = this.service.listByMap(map);
        employees.forEach(System.out::println);
    }

list

default List<T> list(Wrapper<T> queryWrapper)

@Test
    public void testList() {
        LambdaQueryWrapper<Employee> wrapper = new LambdaQueryWrapper<>();
        wrapper.like(Employee::getName, "wangshun");
        List<Employee> list = this.service.list(wrapper);
        /**
         *  SELECT SPF_UID AS id,Part_PartSap AS partSap,Part_PlateSap AS plateSap,SPF_Name AS name,IsActvie AS active 
         *      FROM SPF_Require_Vehicle WHERE IsActvie=0 AND (SPF_Name LIKE ?)
         */
        list.forEach(System.out::println);
    }

2.12?查詢指定列

getmap

? ? ? ? // 如果查詢出過個，則只取第一個

Map<String, Object> getMap(Wrapper<T> queryWrapper);

@Test
    public void testSelectMap() {
        String name = "wangshun";
        LambdaQueryWrapper<Employee> wrapper = new LambdaQueryWrapper<>();
        wrapper.like(!name.isEmpty(), Employee::getName, name);
        /**
         * 只查詢這兩列，如果同時查詢出多行，則只取第一行
         * SELECT Part_PlateSap AS plateSap,Part_PartSap AS partSap FROM SPF_Require_Vehicle WHERE IsActvie=0 AND (SPF_Name LIKE ?)
         */
        wrapper.select(Employee::getPlateSap, Employee::getPartSap);
        Map<String, Object> map = this.service.getMap(wrapper);
        System.out.println(map);
    }

listMap

? ? ? ? 可查詢多行

@Test
    public void testlistMaps() {
        LambdaQueryWrapper<Employee> wrapper = new LambdaQueryWrapper<>();
        wrapper.like(Employee::getName, "wangshun");
        /**
         * 只顯示這三列
         */
        wrapper.select(Employee::getPartSap, Employee::getPlateSap, Employee::getName);
        List<Map<String, Object>> maps = this.service.listMaps(wrapper);
        for (Map<String, Object> map : maps) {
            System.out.println(map);
        }
    }

????????

default List<Map<String, Object>> listMaps()  如果不見條件則查詢所有的行

2.13 個數(shù)查詢? ? ??

// 查詢表中國有效的總行數(shù)
default long count()

// 根據(jù)條件查詢行數(shù)
default long count(Wrapper<T> queryWrapper)

2.14 分頁查詢

? ? ? ? 分頁查詢需要首先注冊mybatis-plus的攔截器，配置如下

@Configuration
public class MpConfig {
    @Bean
    public MybatisPlusInterceptor getIntercepter() {
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return mybatisPlusInterceptor;
    }
}

@Test
    public void testPage01() {
        Page<Employee> page = new Page<>(2, 4);
        LambdaQueryWrapper<Employee> wrapper = new LambdaQueryWrapper<>();
        wrapper.like(Employee::getName, "wangshun");
        this.service.page(page, wrapper);
        System.out.println(page);
        // 查詢到的內(nèi)容
        System.out.println("records: " + page.getRecords());
        // 總頁數(shù)
        System.out.println("pages: " + page.getPages());
        // 當(dāng)前頁數(shù)
        System.out.println("current: " + page.getCurrent());
        // 總條目數(shù)
        System.out.println("total: " + page.getTotal());
    }

2.15 SQL分頁查詢

? ? ? ? 許多時候需要手寫語句實現(xiàn)分頁查詢，例如同時從多張表中查詢數(shù)據(jù)，這個時候需要自己寫條件。

01. 在 application.yml中指定mybatis-plus的相關(guān)配置，尤其要指定xml的路徑，默認(rèn)在mapper下，本人仍習(xí)慣指明位置

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  # 指定mapper.xml所在的位置
  mapper-locations: classpath:/mapper/*.xml

02. 在Mapper中增加聲明

 /**
     * 手寫語句實現(xiàn)分頁查詢
     * @param page 攔截器使用，當(dāng)前sql中不需要
     * @param employee 查詢對象
     * @return 查詢結(jié)果
     */
    Page<Employee> getEmployeeInfoByPage(@Param("page") Page<Employee> page, @Param("employee") Employee employee);

03. 添加Mapper對應(yīng)的xml文件并增加對應(yīng)的函數(shù)

<?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">
<mapper namespace="com.ssm01.mapper.EmployeeMapper">
    <resultMap id="baseResultMap" type="com.ssm01.pojo.Employee">
        <result column="SPF_UID" property="id"/>
        <result column="Part_PartSap" property="partSap"/>
        <result column="Part_PlateSap" property="plateSap"/>
        <result column="SPF_Name" property="name"/>
    </resultMap>
    <select id="getEmployeeInfoByPage" resultMap="baseResultMap">
        select * from SPF_Require_Vehicle where SPF_Name = #{employee.name} and IsActvie = 0
    </select>
</mapper>

04. 在自己的service中增加相應(yīng)的方法，調(diào)用mapper中的函數(shù)文章來源地址http://www.zghlxwxcb.cn/news/detail-728319.html

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