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GraphQL杂谈（一）：starter及工程化模块化及理解

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项目地址

Github: dongfg/api

依赖

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<!-- 提供servlet入口 -->
<dependency>
    <groupId>com.graphql-java</groupId>
    <artifactId>graphql-spring-boot-starter</artifactId>
    <version>LATEST</version>
</dependency>
<!-- graphiql 提供查询界面-->
<dependency>
    <groupId>com.graphql-java</groupId>
    <artifactId>graphiql-spring-boot-starter</artifactId>
    <version>LATEST</version>
</dependency>
<!-- 解析schema文件，resolver等 -->
<dependency>
    <groupId>com.graphql-java</groupId>
    <artifactId>graphql-java-tools</artifactId>
    <version>LATEST</version>
</dependency>

配置过程简单分析

GraphQLWebAutoConfiguration

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@Autowired(required = false)
private List<GraphQLServletListener> listeners;

@Autowired(required = false)
private Instrumentation instrumentation;

@Autowired(required = false)
private GraphQLErrorHandler errorHandler;

@Autowired(required = false)
private Map<String, ExecutionStrategy> executionStrategies;

@Autowired(required = false)
private GraphQLContextBuilder contextBuilder;

@Autowired(required = false)
private GraphQLRootObjectBuilder graphQLRootObjectBuilder;

@Autowired(required = false)
private ObjectMapperConfigurer objectMapperConfigurer;

...

// GraphQLServlet 创建
@Bean
@ConditionalOnMissingBean
public GraphQLServlet graphQLServlet(GraphQLSchemaProvider schemaProvider, ExecutionStrategyProvider executionStrategyProvider) {
    return new SimpleGraphQLServlet(schemaProvider, executionStrategyProvider, objectMapperConfigurer, listeners, instrumentation, errorHandler, contextBuilder, graphQLRootObjectBuilder);
}

...

GraphiQLAutoConfiguration

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// graphiql 查询页面
@Bean
@ConditionalOnProperty(value = "graphiql.enabled", havingValue = "true", matchIfMissing = true)
GraphiQLController graphiQLController() {
    return new GraphiQLController();
}

GraphQLJavaToolsAutoConfiguration

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@Autowired(required = false)
private SchemaParserDictionary dictionary;

@Autowired(required = false)
private GraphQLScalarType[] scalars;

@Autowired(required = false)
private SchemaParserOptions options;

@Autowired
private ApplicationContext applicationContext;

@Bean
@ConditionalOnBean({GraphQLResolver.class})
@ConditionalOnMissingBean
public SchemaParser schemaParser(List<GraphQLResolver<?>> resolvers) throws IOException {

    SchemaParserBuilder builder = dictionary != null ? new SchemaParserBuilder(dictionary) : new SchemaParserBuilder();

    // 读取classpath下所有schema
    Resource[] resources = applicationContext.getResources("classpath*:**/*.graphqls");
    if(resources.length <= 0) {
        throw new IllegalStateException("No *.graphqls files found on classpath.  Please add a graphql schema to the classpath or add a SchemaParser bean to your application context.");
    }

    for(Resource resource : resources) {
        StringWriter writer = new StringWriter();
        IOUtils.copy(resource.getInputStream(), writer);
        builder.schemaString(writer.toString());
    }

    if(scalars != null) {
        builder.scalars(scalars);
    }

    if(options != null) {
        builder.options(options);
    }

    return builder.resolvers(resolvers)
        .build();
}


// 解析schema
@Bean
@ConditionalOnBean(SchemaParser.class)
@ConditionalOnMissingBean({GraphQLSchema.class, GraphQLSchemaProvider.class})
public GraphQLSchema graphQLSchema(SchemaParser schemaParser) {
    return schemaParser.makeExecutableSchema();
}

关于工程化

按照MVC的设计方法，resolver相当于controller层

关于模块化

schema 模块化

classpath 下所有 schema 文件都会加载，利用 extend type 的 feature 可以实现简单的模块化划分

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resources/graphqls
├── common.graphqls
├── mongo.graphqls
└── ssl.graphqls

common.graphqls

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type Query {
    version: String!
}

mongo.graphqls

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extend type Query {
    collectionNames: [String]
    collectionData(collectionName: String!): [String]
}

Resolver 模块化

FieldResolverScanner会在GraphQLQueryResolver所有实现类方法中查找schema的query

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query
├── CommonQueryResolver.java
├── MongoQueryResolver.java
└── SSLQueryResolver.java