Olingo分析和实践之ODataImpl详细分析(重要方法详解)

@Override
public EdmAssistedSerializer createEdmAssistedSerializer(final ContentType contentType) throws SerializerException {
    if (contentType != null && contentType.isCompatible(ContentType.APPLICATION_JSON)) {
        return new EdmAssistedJsonSerializer(contentType);
    }
    throw new SerializerException("Unsupported format: " + 
        ((contentType != null) ? contentType.toContentTypeString() : null),
        SerializerException.MessageKeys.UNSUPPORTED_FORMAT, 
        ((contentType != null) ? contentType.toContentTypeString() : null));
}

@Override
public EdmAssistedSerializer createEdmAssistedSerializer(final ContentType contentType, 
        List<String> versions) throws SerializerException {
    IConstants constants = new Constantsv00();
    if(versions!=null && !versions.isEmpty() && getMaxVersion(versions) > 4){
        constants = new Constantsv01() ;
    }
    if (contentType != null && contentType.isCompatible(ContentType.APPLICATION_JSON)) {
        return new EdmAssistedJsonSerializer(contentType, constants);
    }
    throw new SerializerException("Unsupported format: " + 
        ((contentType != null) ? contentType.toContentTypeString() : null),
        SerializerException.MessageKeys.UNSUPPORTED_FORMAT, 
        ((contentType != null) ? contentType.toContentTypeString() : null));
}

private float getMaxVersion(List<String> versions) {
    Float versionValue [] = new Float [versions.size()];
    int i=0;
    Float max=new Float(0);
    for(String version:versions){
        Float ver = Float.valueOf(version);
        versionValue[i++] = ver;
        max = max > ver ? max : ver ;
    }
    return max;
}

if (serializer == null) {
    throw new SerializerException("Unsupported format: " + 
        ((contentType != null) ? contentType.toContentTypeString() : null),
        SerializerException.MessageKeys.UNSUPPORTED_FORMAT, 
        ((contentType != null) ? contentType.toContentTypeString() : null));
}

// 创建 OData 实例
OData odata = OData.newInstance();
// 创建 JSON 序列化器
ContentType jsonContentType = ContentType.APPLICATION_JSON;
ODataSerializer serializer = odata.createSerializer(jsonContentType);
// 创建 XML 序列化器
ContentType xmlContentType = ContentType.APPLICATION_XML;
ODataSerializer xmlSerializer = odata.createSerializer(xmlContentType);

// 创建支持 v4.01 的序列化器
List<String> versions = Arrays.asList("4.01", "4.0");
ODataSerializer serializer = odata.createSerializer(
    ContentType.APPLICATION_JSON, versions);

// 创建 EDM 辅助序列化器（用户选择的重点）
EdmAssistedSerializer edmSerializer = odata.createEdmAssistedSerializer(
    ContentType.APPLICATION_JSON);
// 创建版本感知的 EDM 辅助序列化器
List<String> versions = Arrays.asList("4.01");
EdmAssistedSerializer versionedSerializer = odata.createEdmAssistedSerializer(
    ContentType.APPLICATION_JSON, versions);

// 创建 Delta 序列化器
List<String> versions = Arrays.asList("4.01");
EdmDeltaSerializer deltaSerializer = odata.createEdmDeltaSerializer(
    ContentType.APPLICATION_JSON, versions);

// 创建基础反序列化器
ODataDeserializer deserializer = odata.createDeserializer(
    ContentType.APPLICATION_JSON);
// 创建带元数据的反序列化器
ServiceMetadata metadata = odata.createServiceMetadata(
    edmProvider, references);
ODataDeserializer metadataDeserializer = odata.createDeserializer(
    ContentType.APPLICATION_JSON, metadata);