spring - org.springframework.core.convert.ConverterNotFoundException : No converter found capable of converting from type to type [java. lang.String] - Redis

Question

我在 Spring Boot 2.0 示例中使用 Spring Data Redis。在此示例中，我尝试将客户数据 + 学生数据保存在一起。我不太确定这里的数据建模是如何发生的，但假设它与 Mongo DB 相同(纯非关系型)。

有人可以帮忙解决以下错误吗？很明显，预计会有一些转化来看到这些数据。

错误:

org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [com.javasampleapproach.redis.model.Customer] to type [java.lang.String]
    at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:321)
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:194)
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:174)
    at org.springframework.data.redis.serializer.GenericToStringSerializer$Converter.convert(GenericToStringSerializer.java:120)
    at org.springframework.data.redis.serializer.GenericToStringSerializer.serialize(GenericToStringSerializer.java:88)
    at org.springframework.data.redis.core.AbstractOperations.rawHashValue(AbstractOperations.java:184)
    at org.springframework.data.redis.core.DefaultHashOperations.put(DefaultHashOperations.java:175)
    at com.javasampleapproach.redis.repository.CustomerRepositoryImpl.save(CustomerRepositoryImpl.java:33)
    at com.javasampleapproach.redis.repository.CustomerRepositoryImpl$$FastClassBySpringCGLIB$$88e26a2c.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
    at com.javasampleapproach.redis.repository.CustomerRepositoryImpl$$EnhancerBySpringCGLIB$$7d20fd4e.save(<generated>)
    at com.javasampleapproach.controller.WebController.save(WebController.java:31)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:158)
    at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:126)
    at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:111)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.boot.actuate.web.trace.servlet.HttpTraceFilter.doFilterInternal(HttpTraceFilter.java:90)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1468)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)

RedisConfig.java

@Configuration
@ComponentScan("com.javasampleapproach.*")
public class RedisConfig {
    @Bean
    public JedisConnectionFactory jedisConnectionFactory() {
        return new JedisConnectionFactory();
    }

    @Bean
    public RedisTemplate<String, Object> redisTemplate(){
        final RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(jedisConnectionFactory());
        template.setKeySerializer(new StringRedisSerializer());
        template.setHashValueSerializer(new GenericToStringSerializer<Object>(Object.class));
        template.setValueSerializer(new GenericToStringSerializer<Object>(Object.class));
        return template;
    }
}

Controller.java

@RequestMapping("/save")
public String save() {

    List<Student> students = new ArrayList<>();
    Student student = Student.builder().firstName("John").build();
    students.add(student);
    customerRepository.save(Customer.builder().id(1).firstName("Jack").lastName("Smith").students(students).build());

    return "Done";
}

CustomerRepositoryImpl.java

@Repository
public class CustomerRepositoryImpl implements CustomerRepository {
    private static final String KEY = "Customer";

    private RedisTemplate<String, Object> redisTemplate;
    private HashOperations<String, Long, Customer> hashOperations;

    @Autowired
    public CustomerRepositoryImpl(RedisTemplate<String, Object> redisTemplate) {
        this.redisTemplate = redisTemplate;
    }

    @PostConstruct
    private void init() {
        hashOperations = redisTemplate.opsForHash();
    }

    @Override
    public void save(Customer customer) {
        hashOperations.put(KEY, customer.getId(), customer);
    }

    @Override
    public Customer find(Long id) {
        return hashOperations.get(KEY, id);
    }

    @Override
    public Map<Long, Customer> findAll() {
        return hashOperations.entries(KEY);
    }

    @Override
    public void update(Customer customer) {
        hashOperations.put(KEY, customer.getId(), customer);
    }

    @Override
    public void delete(Long id) {
        hashOperations.delete(KEY, id);
    }
}

pom.xml

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.3.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>redis.clients</groupId>
            <artifactId>jedis</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

Answer 1

在持久化对象之前，您应该使用序列化器。请参阅Spring Data Redis docs的这一部分:

Data can be stored by using various data structures within Redis. Jackson2JsonRedisSerializer can convert objects in JSON format. Ideally, JSON can be stored as a value by using plain keys. You can achieve a more sophisticated mapping of structured objects by using Redis hashes. Spring Data Redis offers various strategies for mapping data to hashes (depending on the use case):

• Direct mapping, by using HashOperations and a serializer
• Using Redis Repositories
• Using HashMapper and HashOperations

编辑:

将 RedisTemplate bean 定义中的 GenericToStringSerializer 替换为 JdkSerializationRedisSerializer (默认序列化程序)或 Jackson2JsonRedisSerializer 或 GenericJackson2JsonRedisSerializer 以 JSON 格式序列化。