spring mongodb中去掉_class列

调用mongoTemplate的save方法时, spring-data-mongodb的TypeConverter会自动给document添加一个_class属性, 值是你保存的类名. 这种设计并没有什么坏处. spring-data-mongodb是为了在把document转换成Java对象时能够转换到具体的子类. 但有时候我们并不希望出现这个字段, 主要是看上去会比较"烦". 可以通过设置MappingMongoConverter的MongoTypeMapper来解决这个问题.

DefaultMongoTypeMapper类的构造函数的第一个参数是Type在MongoDB中名字. 设置为null的话就不会在保存时自动添加_class属性.所以需要覆写 

spring的配置文件方式:

<mongo:mongo host="localhost" port="27017" />    
<mongo:db-factory dbname="database" />    
     
 <bean id="mappingContext"    
    class="org.springframework.data.mongodb.core.mapping.MongoMappingContext" />    
     
 <bean id="defaultMongoTypeMapper"    
    class="org.springframework.data.mongodb.core.convert.DefaultMongoTypeMapper">    
    <constructor-arg name="typeKey"><null/></constructor-arg>    
 </bean>    
     
 <bean id="mappingMongoConverter"    
    class="org.springframework.data.mongodb.core.convert.MappingMongoConverter">    
    <constructor-arg name="mongoDbFactory" ref="mongoDbFactory" />    
    <constructor-arg name="mappingContext" ref="mappingContext" />    
    <property name="typeMapper" ref="defaultMongoTypeMapper" />    
 </bean>    
     
 <bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate">    
    <constructor-arg name="mongoDbFactory" ref="mongoDbFactory" />    
    <constructor-arg name="mongoConverter" ref="mappingMongoConverter" />    
 </bean> 

   

注解方式：

@EnableMongoRepositories(  
        basePackages = {"com.dhp"},  
        repositoryFactoryBeanClass = DHBMongoRepositoryFactoryBean.class  
)  
@PropertySource("classpath:mongo.properties")  
@EnableMongoAuditing  
public class MongoConfig extends AbstractMongoConfiguration {  
  
    @Value("${mongo.connectionString}")  
    private String connectionString;  
    @Value("${mongo.dbName}")  
    private String dbName;  
  
    @Autowired  
    private ApplicationContext appContext;  
  
    @Override  
    protected String getDatabaseName() {  
        return dbName;  
    }  
  
    @Override  
    @Bean  
    public Mongo mongo() throws Exception {  
        MongoClientURI mongoClientURI = new MongoClientURI(connectionString);  
        return new MongoClient(mongoClientURI);  
    }  
  
    @Override  
    @Bean  
    public MongoTemplate mongoTemplate() throws Exception {  
        MongoDbFactory factory = mongoDbFactory();  
  
        MongoMappingContext mongoMappingContext = new MongoMappingContext();  
        mongoMappingContext.setApplicationContext(appContext);  
  
        MappingMongoConverter converter = new MappingMongoConverter(new DefaultDbRefResolver(factory), mongoMappingContext);  
        converter.setTypeMapper(new DefaultMongoTypeMapper(null));  
  
        return new MongoTemplate(factory, converter);  
    }  
  
  
    @Bean  
    public static PropertySourcesPlaceholderConfigurer propertyConfigInDev() {  
        return new PropertySourcesPlaceholderConfigurer();  
    }  
}  

　　

当使用Servlet 3初始化确保添加应用程序上下文到mongo中，如果不加上这两句，会报异常：org.springframework.expression.spel.SpelEvaluationException
@Autowired
private ApplicationContext appContext;
mongoMappingContext.setApplicationContext(appContext);