最近在项目里面需要从kafka推送的数据读取数据，spark streaming处理，由于推过来的是Json字符串，需要转换成dataFrame做进一步处理，但是Json字符串字段很多，而且还不固定；我想转换代码如下：

val NewsDF = sqlContext.createDataFrame(NewsRdd,classOf[News])

但是怎么吧json字符串转换成JavaBean呢。这么多的字段，有没有偷懒的方法呢？
jackson提供了很好的方法，曾经尝试使用scala中的ObjectMapper，但是我的json是嵌套的复杂类型，出现了一个错误，在网上没有找到很好的方法，无奈放弃了。

import java.io.IOException;import java.text.SimpleDateFormat;import java.util.List;import org.apache.commons.lang3.StringUtils;import org.codehaus.jackson.JsonNode;import org.codehaus.jackson.JsonParser;import org.codehaus.jackson.JsonProcessingException;import org.codehaus.jackson.map.DeserializationConfig;import org.codehaus.jackson.map.ObjectMapper;import org.codehaus.jackson.map.SerializationConfig;import org.codehaus.jackson.map.annotate.JsonSerialize;import org.codehaus.jackson.map.util.JSONPObject;import org.codehaus.jackson.type.JavaType;import org.slf4j.Logger;import org.slf4j.LoggerFactory;public class JsonMapper { private static Logger logger = LoggerFactory.getLogger(JsonMapper.class); private ObjectMapper mapper; public JsonMapper(JsonSerialize.Inclusion inclusion) { mapper = new ObjectMapper(); //设置输出时包含属性的风格 mapper.setSerializationInclusion(inclusion); //设置输入时忽略在JSON字符串中存在但Java对象实际没有的属性 mapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false); //禁止使用int代表Enum的order()來反序列化Enum,非常危險 mapper.configure(DeserializationConfig.Feature.FAIL_ON_NUMBERS_FOR_ENUMS, true); mapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true); } /** * 创建输出全部属性到Json字符串的Mapper. */ public static JsonMapper buildNormalMapper() { return new JsonMapper(JsonSerialize.Inclusion.ALWAYS); } /** * 创建只输出非空属性到Json字符串的Mapper. */ public static JsonMapper buildNonNullMapper() { return new JsonMapper(JsonSerialize.Inclusion.NON_NULL); } /** * 创建只输出初始值被改变的属性到Json字符串的Mapper. * */ public static JsonMapper buildNonDefaultMapper() { return new JsonMapper(JsonSerialize.Inclusion.NON_DEFAULT); } /** * 创建只输出非Null且非Empty(如List.isEmpty)的属性到Json字符串的Mapper. */ public static JsonMapper buildNonEmptyMapper() { return new JsonMapper(JsonSerialize.Inclusion.NON_EMPTY); } /** * 如果对象为Null, 返回"null". * 如果集合为空集合, 返回"[]". */ public String toJson(Object object) { try { return mapper.writeValueAsString(object); } catch (IOException e) { throw NestedException.wrap(e); } } /** * 如果JSON字符串为Null或"null"字符串, 返回Null. * 如果JSON字符串为"[]", 返回空集合. * * 如需读取集合如List/Map, 且不是List<String>这种简单类型时,先使用函數constructParametricType构造类型. * @see #constructParametricType(Class, Class...) */ public <T> T fromJson(String jsonString, Class<T> clazz) { if (StringUtils.isEmpty(jsonString)) { return null; } try { return mapper.readValue(jsonString, clazz); } catch (IOException e) { throw NestedException.wrap(e); } } /** * 如果JSON字符串为Null或"null"字符串, 返回Null. * 如果JSON字符串为"[]", 返回空集合. * * 如需读取集合如List/Map, 且不是List<String>这种简单类型时,先使用函數constructParametricType构造类型. * @see #constructParametricType(Class, Class...) */ @SuppressWarnings("unchecked") public <T> T fromJson(String jsonString, JavaType javaType) { if (StringUtils.isEmpty(jsonString)) { return null; } try { return (T) mapper.readValue(jsonString, javaType); } catch (IOException e) { throw NestedException.wrap(e); } } @SuppressWarnings("unchecked") public <T> T fromJson(String jsonString, Class<?> parametrized, Class<?>... parameterClasses) { return (T) this.fromJson(jsonString, constructParametricType(parametrized, parameterClasses)); } @SuppressWarnings("unchecked") public <T> List<T> fromJsonToList(String jsonString, Class<T> classMeta){ return (List<T>) this.fromJson(jsonString,constructParametricType(List.class, classMeta)); } @SuppressWarnings("unchecked") public <T> T fromJson(JsonNode node, Class<?> parametrized, Class<?>... parameterClasses) { JavaType javaType = constructParametricType(parametrized, parameterClasses); try { return (T) mapper.readValue(node, javaType); } catch (IOException e) { throw NestedException.wrap(e); } } @SuppressWarnings("unchecked") public <T> T pathAtRoot(String json, String path, Class<?> parametrized, Class<?>... parameterClasses){ JsonNode rootNode = parseNode(json); JsonNode node = rootNode.path(path); return (T) fromJson(node, parametrized, parameterClasses); } @SuppressWarnings("unchecked") public <T> T pathAtRoot(String json, String path, Class<T> clazz){ JsonNode rootNode = parseNode(json); JsonNode node = rootNode.path(path); return (T) fromJson(node, clazz); } /** * 構造泛型的Type如List<MyBean>, 则调用constructParametricType(ArrayList.class,MyBean.class) * Map<String,MyBean>则调用(HashMap.class,String.class, MyBean.class) */ public JavaType constructParametricType(Class<?> parametrized, Class<?>... parameterClasses) { return mapper.getTypeFactory().constructParametricType(parametrized, parameterClasses); } /** * 當JSON裡只含有Bean的部分屬性時，更新一個已存在Bean，只覆蓋該部分的屬性. */ @SuppressWarnings("unchecked") public <T> T update(T object, String jsonString) { try { return (T) mapper.readerForUpdating(object).readValue(jsonString); } catch (JsonProcessingException e) { logger.warn("update json string:" + jsonString + " to object:" + object + " error.", e); } catch (IOException e) { logger.warn("update json string:" + jsonString + " to object:" + object + " error.", e); } return null; } /** * 輸出JSONP格式數據. */ public String toJsonP(String functionName, Object object) { return toJson(new JSONPObject(functionName, object)); } /** * 設定是否使用Enum的toString函數來讀寫Enum, * 為False時時使用Enum的name()函數來讀寫Enum, 默認為False. * 注意本函數一定要在Mapper創建後, 所有的讀寫動作之前調用. */ public void setEnumUseToString(boolean value) { mapper.configure(SerializationConfig.Feature.WRITE_ENUMS_USING_TO_STRING, value); mapper.configure(DeserializationConfig.Feature.READ_ENUMS_USING_TO_STRING, value); } /** * 取出Mapper做进一步的设置或使用其他序列化API. */ public ObjectMapper getMapper() { return mapper; } public JsonNode parseNode(String json){ try { return mapper.readValue(json, JsonNode.class); } catch (IOException e) { throw NestedException.wrap(e); } } /** * 输出全部属性 * @param object * @return */ public static String toNormalJson(Object object){ return new JsonMapper(JsonSerialize.Inclusion.ALWAYS).toJson(object); } /** * 输出非空属性 * @param object * @return */ public static String toNonNullJson(Object object){ return new JsonMapper(JsonSerialize.Inclusion.NON_NULL).toJson(object); } /** * 输出初始值被改变部分的属性 * @param object * @return */ public static String toNonDefaultJson(Object object){ return new JsonMapper(JsonSerialize.Inclusion.NON_DEFAULT).toJson(object); } /** * 输出非Null且非Empty(如List.isEmpty)的属性 * @param object * @return */ public static String toNonEmptyJson(Object object){ return new JsonMapper(JsonSerialize.Inclusion.NON_EMPTY).toJson(object); } public void setDateFormat(String dateFormat){ mapper.setDateFormat(new SimpleDateFormat(dateFormat)); } public static String toLogJson(Object object){ JsonMapper jsonMapper = new JsonMapper(JsonSerialize.Inclusion.NON_EMPTY); jsonMapper.setDateFormat("yyyy-MM-dd HH:mm:ss"); return jsonMapper.toJson(object); }