MongoDB新增Long型主键：抽象基类

假如不想创建自定义注解，也可以直接通过一个继承类，最关键这个类里可以定义一些自己想要的字段和方法，比如加一个更新的时间戳，或者一些DAO层方法等

package com.lihuia.demo.entity;

import org.springframework.data.annotation.Id;

public abstract class MongoBaseDO<T extends Number> {

    @Id
    private T id;

    public T getId() {
        return this.id;
    }

    public void setId(T id) {
        this.id = id;
    }
}

这个类id字段添加主键注解

这样，实体类就不需要定义主键id字段了，直接继承基类即可

package com.lihuia.demo.entity;

import lombok.Data;
import org.springframework.data.mongodb.core.mapping.Document;
import org.springframework.data.mongodb.core.mapping.Field;


@Document(collection = "user_center")
@Data
public class User extends MongoBaseDO<Long> {

    @Field
    private String name;

    @Field
    private Integer age;

    @Field
    private String phone;
}

注册子类，覆盖onBeforeConvert方法，拦截对象转换，同样获取自定义主键后再写入

package com.lihuia.demo.util;

import com.lihuia.demo.entity.MongoBaseDO;
import com.lihuia.demo.entity.SeqInfo;
import org.springframework.data.mongodb.core.FindAndModifyOptions;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.mapping.event.AbstractMongoEventListener;
import org.springframework.data.mongodb.core.mapping.event.BeforeConvertEvent;
import org.springframework.data.mongodb.core.query.Criteria;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.data.mongodb.core.query.Update;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;

@Component
public class InsertEventListener extends AbstractMongoEventListener<MongoBaseDO> {

    @Resource
    private MongoTemplate mongoTemplate;

    @Override
    public void onBeforeConvert(BeforeConvertEvent<MongoBaseDO> event) {
        MongoBaseDO source = event.getSource();
        Long id = getNextId(source.getClass().getSimpleName());
        source.setId(id);
    }


    private Long getNextId(String collectionName) {
        Query query = new Query(Criteria.where("collectionName").is(collectionName));
        Update update = new Update();
        /** 主键递增1，设置为Long型 */
        update.inc("seqId", 1L);
        FindAndModifyOptions options = new FindAndModifyOptions();
        options.upsert(true);
        options.returnNew(true);
        /** 原子操作，修改并返回 */
        SeqInfo seqInfo = mongoTemplate.findAndModify(query, update, options, SeqInfo.class);
        return seqInfo.getSeqId();
    }
}

实体对象写入mongodb之前，会注册发布BeforeConvertEvent事件，这里创建了InsertEventListener监听器监听这个事件，拦截后，生成自增主键，配置到实体对象当中