spring-data-mongo 去除 _class 字段“失败”

去除 _class 字段成功

@Configuration
public class MongoConfiguration {

    @Bean
    public MongoDbFactory mongoDbFactory() throws Exception {
        // TODO 初始化 factory 工作
        MongoDbFactory object = ...;
        return object;
    }

    @Bean
    public MongoTemplate mongoTemplate() throws Exception {
        MappingMongoConverter mongoConverter = new MappingMongoConverter(new DefaultDbRefResolver(mongoDbFactory()), new MongoMappingContext());
        mongoConverter.setTypeMapper(new DefaultMongoTypeMapper(null)); // typeKey 设置为 null。默认的无参构造为 _class
        return new MongoTemplate(mongoDbFactory(), mongoConverter);
    }

}

去除 _class 字段失败

@Configuration
public class MongoConfiguration {

    @Bean
    public MongoDbFactory mongoDbFactory() throws Exception {
        // TODO 初始化 factory 工作
        MongoDbFactory object = ...;
        return object;
    }

    @Bean
    public MongoOperations mongoTemplate() throws Exception {
        MappingMongoConverter mongoConverter = new MappingMongoConverter(new DefaultDbRefResolver(mongoDbFactory()), new MongoMappingContext());
        mongoConverter.setTypeMapper(new DefaultMongoTypeMapper(null)); // typeKey 设置为 null。默认的无参构造为 _class
        return new MongoTemplate(mongoDbFactory(), mongoConverter);
    }

}

代码的区别

唯一的不同之处为 mongoTemplate() 方法。返回的类型范围不同，
返回向上转型后的类型 MongoOperations，该方式去除失败
返回原始类型 MongoTemplate，该方式成功

目前未发现该 bug 产生的原因。