MyBatis-Plus 主键生成策略的几种实现方式

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.ANNOTATION_TYPE})
public @interface TableId {
    String value() default "";

    IdType type() default IdType.NONE;
}

@TableName(value ="user")
@Data
public class User implements Serializable {
    /**
     * 主键ID
     */
    @TableId(value = "id",type = IdType.ASSIGN_ID)
    private Long userId;
    private String name;
    private Integer age;
    private String email;

public enum IdType {
    AUTO(0),
    NONE(1),
    INPUT(2),
    ASSIGN_ID(3),
    ASSIGN_UUID(4);

    private final int key;

    private IdType(int key) {
        this.key = key;
    }

    public int getKey() {
        return this.key;
    }
}

public DbConfig() {
    this.idType = IdType.ASSIGN_ID;
    this.tableUnderline = true;
    this.capitalMode = false;
    this.logicDeleteValue = "1";
    this.logicNotDeleteValue = "0";
    this.insertStrategy = FieldStrategy.NOT_NULL;
    this.updateStrategy = FieldStrategy.NOT_NULL;
    this.whereStrategy = FieldStrategy.NOT_NULL;
}

mybatis-plus.global-config.db-config.id-type=assign_id

public interface IdentifierGenerator {
    //根据id是否为null判断是否需要主动分配Id
    default boolean assignId(Object idValue) {
        return StringUtils.checkValNull(idValue);
    }

    //生成数值型Id
    Number nextId(Object entity);

    //生成字符型uuid
    default String nextUUID(Object entity) {
        return IdWorker.get32UUID();
    }
}

public class DefaultIdentifierGenerator implements IdentifierGenerator {
    private final Sequence sequence;

    public DefaultIdentifierGenerator() {
        this.sequence = new Sequence((InetAddress)null);
    }

    public DefaultIdentifierGenerator(InetAddress inetAddress) {
        this.sequence = new Sequence(inetAddress);
    }

    public DefaultIdentifierGenerator(long workerId, long dataCenterId) {
        this.sequence = new Sequence(workerId, dataCenterId);
    }

    public DefaultIdentifierGenerator(Sequence sequence) {
        this.sequence = sequence;
    }

    public Long nextId(Object entity) {
        return this.sequence.nextId();
    }
}

@TableName(value ="user")
@Data
public class User implements Serializable {
    /**
     * 主键ID
     */
    @TableId(value = "id",type = IdType.ASSIGN_ID)
    private Long userId;
    private String name;
    private Integer age;
    private String email;

@Configuration
public class IdAutoConfig {
    @Value("${mybatis-plus.zookeeper.serverLists}")
    private String zkServerLists;

    @Bean
    public IdentifierGenerator idGenerator() {
        return new ImadcnIdentifierGenerator(zkServerLists);
    }
}

public interface IKeyGenerator {
    //执行sql生成id
    String executeSql(String incrementerName);

    //获取数据库类型
    DbType dbType();
}

public class OracleKeyGenerator implements IKeyGenerator {
    public OracleKeyGenerator() {
    }

    public String executeSql(String incrementerName) {
        return "SELECT " + incrementerName + ".NEXTVAL FROM DUAL";
    }

    public DbType dbType() {
        return DbType.ORACLE;
    }
}

@KeySequence(value = "SEQ_ORACLE_STRING_KEY", clazz = String.class)
public class YourEntity {

    @TableId(value = "ID_STR", type = IdType.INPUT)
    private String idStr;

}

@Bean
public IKeyGenerator keyGenerator() {
    return new OracleKeyGenerator();
}

mybatis-plus.global-config.db-config.key-generators=com.baomidou.mybatisplus.extension.incrementer.OracleKeyGenerator

@Component
public class CustomIdGenerator implements IdentifierGenerator {
    @Override
    public Long nextId(Object entity) {
      	//可以将当前传入的class全类名来作为bizKey,或者提取参数来生成bizKey进行分布式Id调用生成.
      	String bizKey = entity.getClass().getName();
        //根据bizKey调用分布式ID生成
        long id = ....;
      	//返回生成的id值即可.
        return id;
    }
}

@Bean
public IdentifierGenerator idGenerator() {
    return new CustomIdGenerator();
}

@TableName(value ="user")
@Data
public class User implements Serializable {
    /**
     * 主键ID
     */
    @TableId(value = "id",type = IdType.ASSIGN_ID)
    private Long userId;
    private String name;
    private Integer age;
    private String email;