Question

我遇到的问题与链接中提到的相同： Mongo spring-data issue with java.util.Currency 我尝试了接受的答案。但它没有工作，我在线上得到NullPointerException：

angular.module('admin', []) .provider('users', function () { this.users = 'default'; this.$get = function () { var that = this; return { getUsers: function () { return that.users; } } }; }) .run(function (users, $http) { users.users = $http('url'); // and others }) .controller('test', function ($scope, users) { $scope.users = users.getUsers(); });

所以我在新类中定义了转换器，如下所示：

new CustomConversions(Arrays.asList(currencyToString, stringToCurrency));

和

@Component
public class CurrencyToStringConverter implements Converter<Currency,String>{

    /* (non-Javadoc)
     * @see com.fasterxml.jackson.databind.util.Converter#convert(java.lang.Object)
     */
    @Override
    public String convert(Currency arg0) {
        System.out.println("***INSIDE CurrencyToStringConverter***"+arg0);
        return arg0.getCurrencyCode();
    }
  }

我在“customConversions（）”中使用它们，如下所示：

@Component
public class StringToCurrencyConverter implements Converter<String,Currency>{
/* (non-Javadoc)
 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
 */
    @Override
    public Currency convert(String arg0) {
        System.out.println("***INSIDE StringToCurrencyConverter***"+arg0);
        return Currency.getInstance(arg0);
    }
}

当spring-boot应用程序启动时，我可以看到以下打印的语句：

@Configuration
public class CustomMongoConfiguration extends AbstractMongoConfiguration {
    @Autowired
    private Environment env;

    @Bean
  @Override
  public CustomConversions customConversions() {
      System.out.println("***CUSTOM MONGO CONVERSIONS***");
    List<Converter<?,?>> converters=new ArrayList<>();
    converters.add(new CurrencyToStringConverter());
    converters.add(new StringToCurrencyConverter());

    return new CustomConversions(converters);
  }

    /* (non-Javadoc)
     * @see org.springframework.data.mongodb.config.AbstractMongoConfiguration#getDatabaseName()
     */
    @Override
    protected String getDatabaseName() {
        // TODO Auto-generated method stub
        String prop = env.getProperty("spring.data.mongodb.database");
        System.out.println("database naem:: "+prop);
        return prop;
    }

    /* (non-Javadoc)
     * @see org.springframework.data.mongodb.config.AbstractMongoConfiguration#mongo()
     */
    @Override
    @Bean
    public Mongo mongo() throws Exception {
        String prop = env.getProperty("spring.data.mongodb.host");
        System.out.println("host naem:: "+prop);
        return new MongoClient(prop);
    }
}

但是当我尝试从MongoDB获取对象时，它从不在Converter类中调用“转换”方法，而且，我总是得到这个例外：

System.out.println("***CUSTOM MONGO CONVERSIONS***");
System.out.println("database naem:: "+prop);
System.out.println("host naem:: "+prop);

我也跟着这个链接：

Spring not using mongo custom converters

我按照链接中的建议将@Configuration注释更改为类org.springframework.data.mapping.model.MappingException: No property null found on entity class java.util.Currency to bind constructor parameter to! at org.springframework.data.mapping.model.PersistentEntityParameterValueProvider.getParameterValue(PersistentEntityParameterValueProvider.java:74) at org.springframework.data.mapping.model.SpELExpressionParameterValueProvider.getParameterValue(SpELExpressionParameterValueProvider.java:63) at org.springframework.data.convert.ReflectionEntityInstantiator.createInstance(ReflectionEntityInstantiator.java:71) at org.springframework.data.convert.ClassGeneratingEntityInstantiator.createInstance(ClassGeneratingEntityInstantiator.java:83) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:251) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:231) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readValue(MappingMongoConverter.java:1186) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.access$200(MappingMongoConverter.java:78) at org.springframework.data.mongodb.core.convert.MappingMongoConverter$MongoDbPropertyValueProvider.getPropertyValue(MappingMongoConverter.java:1134) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.getValueInternal(MappingMongoConverter.java:870)中的@Component。但它也没有用。如果我使用@Component注释，下面的语句将被多次打印。我不知道原因。

CustomMongoConfiguration

我正在使用spring-boot版本1.3.2.RELEASE。

System.out.println("***CUSTOM MONGO CONVERSIONS***");
System.out.println("database naem:: "+prop);
System.out.println("host naem:: "+prop);

顺便说一下，我正在使用<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.3.2.RELEASE</version> <relativePath />  </parent>来配置mongodb属性，而不是任何基于java的配置：

application.properties

过去三天我一直在努力解决这个问题。任何人都可以帮助我。

Answer 1

<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>SVG</title> <style type="text/css" media="screen"> body { background: #eee; margin: 0; } svg { display: block; border: 1px solid #ccc; position: absolute; top: 0; left: 0; width: 100%; height: 100%; background: #fff; } .face { stroke: #000; stroke-width: 20px; stroke-linecap: round } </style> </head> <body> <svg xmlns="http://www.w3.org/2000/svg" viewBox="-350 -250 700 500"> <circle r="200" class="face" fill="red"/> <path fill="none" class="face" transform="translate(-396,-230)" d="M487.41,282.411c-15.07,36.137-50.735,61.537-92.333,61.537 c-41.421,0-76.961-25.185-92.142-61.076"/> <circle id="leftEye" cx="-60" cy="-50" r="20" fill="#00F"/> <circle id="rightEye" cx="60" cy="-50" r="20" fill="#00F"/> </svg> <script type="text/javascript"> document.getElementById('leftEye').addEventListener('mouseover', function (e) { alert('Left Eye'); }); document.getElementById('rightEye').addEventListener('mouseover', function (e) { alert('Right Eye'); }); </script> </body> </html>转化已通过b7131b添加，自Currency开始提供。

请将1.9.0.M1和@ReadingConverter添加到@WritingConverter实施中，以便Converter而不仅仅是基础CustomConversions了解这些内容。

Answer 2

我的坏。问题在于早先在mongodb中插入的数据。早先用不正确的“货币”格式插入mongodb，即，而不仅仅是美元，英镑等字符串值，它具有以下结构：

"currency" : {
                        "currencyCode" : "GBP",
                        "defaultFractionDigits" : 2,
                        "numericCode" : 826
                }

代替简单的代码，如：

 "currency" : "GBP"

在我编写转换器后，mongo无法解析此结构并抛出此异常：

org.springframework.data.mapping.model.MappingException: No property null found on entity class java.util.Currency to bind constructor parameter to!
    at org.springframework.data.mapping.model.PersistentEntityParameterValueProvider.getParameterValue(PersistentEntityParameterValueProvider.java:74)

我认为这种例外具有误导性。无论如何，我想通了。现在两个转换器都被调用了。

最终解决方案对我有用：

@Configuration
public class CustomMongoConfiguration extends AbstractMongoConfiguration {
    @Autowired
    private MongoProperties mongoProps;

    @Bean
    @Override
    public CustomConversions customConversions() {
        System.out.println("***CUSTOM MONGO CONVERSIONS***");
        List<Converter<?, ?>> converters = new ArrayList<>();
        converters.add(new CurrencyToStringConverter());
        converters.add(new StringToCurrencyConverter());

        return new CustomConversions(converters);
    }

    @Override
    protected String getDatabaseName() {
        return mongoProps.getDatabase();
    }

    @Override
    @Bean
    public Mongo mongo() throws Exception {
        return new MongoClient(mongoProps.getHost(), mongoProps.getPort());
    }
}

根据春季文档http://docs.spring.io/spring-data/mongodb/docs/current/reference/html/#mongo.converter-disambiguation，您需要将@ReadingConverter和@WritingConverter放在转换器上，只有源和版本都是如此。 target是本机类型（例如：String to Long或Long to String）。否则，您不需要在转换器上使用它们。在我的情况下，不需要作为货币的那些不是本机mongo类型。

java.util.currency的spring-data-mongodb问题

2 个答案: