Spring学习笔记： Repository实现（一）

在使用Spring的过程中， 可以定义自己的Repository接口，并不需要完成具体的实现，Spring会帮助创建具体的实例.
如下面这样的对Mongo进行Query的Repository：

@Repositorypublic interface UserRepository extends MongoRepository<User, String> {    Optional<User> findOneByActivationKey(String activationKey);    List<User> findAllByActivatedIsFalseAndCreatedDateBefore(Instant dateTime);    Optional<User> findOneByResetKey(String resetKey);    Optional<User> findOneByEmail(String email);    Optional<User> findOneByLogin(String login);    Page<User> findAllByLoginNot(Pageable pageable, String login);}

问题来了，方法名应该遵循什么样的规则，Spring才能帮助实现呢。通过对Spring源码的分析，找到了对应的规则。
下面的例子是基于对Mongo的分析，Sql的基本类似，而且规则也是一样的。
源码库：spring-data-mongodb, spring-data-commons;

从MongoRepositoryFactory.java开始，这个Factory会去创建Repository的实例：

public class MongoRepositoryFactory extends RepositoryFactorySupport {}public abstract class RepositoryFactorySupport implements BeanClassLoaderAware, BeanFactoryAware {    public <T> T getRepository(Class<T> repositoryInterface) {        return getRepository(repositoryInterface, null);    }    public <T> T getRepository(Class<T> repositoryInterface, Object customImplementation) {        ...        // Create proxy        ProxyFactory result = new ProxyFactory();        result.setTarget(target);        result.setInterfaces(new Class[] { repositoryInterface, Repository.class });        ...        result.addAdvice(new QueryExecutorMethodInterceptor(information, customImplementation, target));        ...    }}

这里用ProxyFacotry实例，且添加了一个QueryExecutorMethodInterceptor. Proxy和MethodInterceptor,熟悉Javassist的都知道对应的用途， SpringAOP也有类似的实现，这里不赘述。
下面看QueryExecutorMethodInterceptor实现：

public class QueryExecutorMethodInterceptor implements MethodInterceptor {    public QueryExecutorMethodInterceptor(RepositoryInformation repositoryInformation, Object customImplementation,                Object target) {        ...        QueryLookupStrategy lookupStrategy = getQueryLookupStrategy(queryLookupStrategyKey,                 RepositoryFactorySupport.this.evaluationContextProvider);        ...        SpelAwareProxyProjectionFactory factory = new SpelAwareProxyProjectionFactory();        ...    }}

SpelAwareProxyProjectionFactory 以后再研究。 现在主要看一下QueryLookupStrategy的实现MongoQueryLookupStrategy。

private static class MongoQueryLookupStrategy implements QueryLookupStrategy {        @Override        public RepositoryQuery resolveQuery(Method method, RepositoryMetadata metadata, ProjectionFactory factory,                NamedQueries namedQueries) {            MongoQueryMethod queryMethod = new MongoQueryMethod(method, metadata, factory, mappingContext);            String namedQueryName = queryMethod.getNamedQueryName();            if (namedQueries.hasQuery(namedQueryName)) {                String namedQuery = namedQueries.getQuery(namedQueryName);                return new StringBasedMongoQuery(namedQuery, queryMethod, operations, EXPRESSION_PARSER,                        evaluationContextProvider);            } else if (queryMethod.hasAnnotatedQuery()) {                return new StringBasedMongoQuery(queryMethod, operations, EXPRESSION_PARSER, evaluationContextProvider);            } else {                return new PartTreeMongoQuery(queryMethod, operations);            }        }    }

如果没有用注解或xml定义query. 则会创建一个PartTreeMongoQuery实例。

public PartTreeMongoQuery(MongoQueryMethod method, MongoOperations mongoOperations) {        super(method, mongoOperations);        this.processor = method.getResultProcessor();        this.tree = new PartTree(method.getName(), processor.getReturnedType().getDomainType());        this.isGeoNearQuery = method.isGeoNearQuery();        this.context = mongoOperations.getConverter().getMappingContext();    }

解析创建的Repository里的方法主要是由PartTree来处理的。
PartTree里将方法分割成Subject和Predicate。以“By”为分割。
Subject源码列出来支持的操作，如”find|read|get|query|stream”, “count”,”exists”,”delete|remove”等。
而Predicate里则将字符用“Or”分割成OrPart， 而OrPart则用”And”分割成Part，Part源代码里列出了可用的关键词：

public static enum Type {        BETWEEN(2, "IsBetween", "Between"), IS_NOT_NULL(0, "IsNotNull", "NotNull"), IS_NULL(0, "IsNull", "Null"), LESS_THAN(                "IsLessThan", "LessThan"), LESS_THAN_EQUAL("IsLessThanEqual", "LessThanEqual"), GREATER_THAN("IsGreaterThan",                "GreaterThan"), GREATER_THAN_EQUAL("IsGreaterThanEqual", "GreaterThanEqual"), BEFORE("IsBefore", "Before"), AFTER(                "IsAfter", "After"), NOT_LIKE("IsNotLike", "NotLike"), LIKE("IsLike", "Like"), STARTING_WITH("IsStartingWith",                "StartingWith", "StartsWith"), ENDING_WITH("IsEndingWith", "EndingWith", "EndsWith"), NOT_CONTAINING(                "IsNotContaining", "NotContaining", "NotContains"), CONTAINING("IsContaining", "Containing", "Contains"), NOT_IN(                "IsNotIn", "NotIn"), IN("IsIn", "In"), NEAR("IsNear", "Near"), WITHIN("IsWithin", "Within"), REGEX(                "MatchesRegex", "Matches", "Regex"), EXISTS(0, "Exists"), TRUE(0, "IsTrue", "True"), FALSE(0, "IsFalse",                "False"), NEGATING_SIMPLE_PROPERTY("IsNot", "Not"), SIMPLE_PROPERTY("Is", "Equals");...}