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# 在没有 DynamoDB 的情况下使用 `EnhancedDocument`
<a name="ddb-en-client-doc-api-standalone"></a>

尽管您通常使用 `EnhancedDocument` 的实例来读取和写入文档类型的 DynamoDB 项目，但它也可以独立于 DynamoDB 使用。

您可以使用 `EnhancedDocuments` 的功能，在 JSON 字符串或自定义对象之间，执行到 `AttributeValues` 的低级映射的转换，如以下示例所示。

```
    public static void conversionWithoutDynamoDbExample() {
        Address address = new Address();
        address.setCity("my city");
        address.setState("my state");
        address.setStreet("my street");
        address.setZipCode("00000");

        // Build an EnhancedDocument instance for its conversion functionality alone.
        EnhancedDocument addressEnhancedDoc = EnhancedDocument.builder()
                // Important: You must specify attribute converter providers when you build an EnhancedDocument instance not used with a DynamoDB table.
                .attributeConverterProviders(new CustomAttributeConverterProvider(), DefaultAttributeConverterProvider.create())
                .put("addressDoc", address, Address.class)
                .build();

        // Convert address to a low-level item representation.
        final Map<String, AttributeValue> addressAsAttributeMap = addressEnhancedDoc.getMapOfUnknownType("addressDoc");
        logger.info("addressAsAttributeMap: {}", addressAsAttributeMap.toString());

        // Convert address to a JSON string.
        String addressAsJsonString = addressEnhancedDoc.getJson("addressDoc");
        logger.info("addressAsJsonString: {}", addressAsJsonString);
        // Convert addressEnhancedDoc back to an Address instance.
        Address addressConverted =  addressEnhancedDoc.get("addressDoc", Address.class);
        logger.info("addressConverted: {}", addressConverted.toString());
    }

   /* Console output:
          addressAsAttributeMap: {zipCode=AttributeValue(S=00000), state=AttributeValue(S=my state), street=AttributeValue(S=my street), city=AttributeValue(S=my city)}
          addressAsJsonString: {"zipCode":"00000","state":"my state","street":"my street","city":"my city"}
          addressConverted: Address{street='my street', city='my city', state='my state', zipCode='00000'}
   */
```

**注意**  
当您独立于 DynamoDB 表使用增强型文档时，请务必在生成器上明确设置属性转换器提供程序。  
相比之下，当增强型文档与 DynamoDB 表结合使用时，文档表架构会提供转换器提供程序。