如何使用Jackson来反序列化对象数组

 

 

Jackson数据绑定文档表明Jackson支持反序列化“所有受支持类型的数组”，但是我无法确定确切的语法。

对于单个对象，我可以这样做：

//json input { "id" : "junk", "stuff" : "things" } //Java MyClass instance = objectMapper.readValue(json, MyClass.class);

现在，对于数组，我想这样做：

//json input [{ "id" : "junk", "stuff" : "things" }, { "id" : "spam", "stuff" : "eggs" }] //Java List<MyClass> entries = ?

有人知道是否有不可思议的命令吗？ 如果没有，那么解决方案是什么？

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#1楼 (guyue: 推荐, 既演示了反序列为 数组, 又演示了转换成 列表)

从Eugene Tskhovrebov

List<MyClass> myObjects = Arrays.asList(mapper.readValue(json, MyClass[].class))

这个解决方案似乎对我来说是最好的

 

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#2楼

try { ObjectMapper mapper = new ObjectMapper(); JsonFactory f = new JsonFactory(); List<User> lstUser = null; JsonParser jp = f.createJsonParser(new File("C:\\maven\\user.json")); TypeReference<List<User>> tRef = new TypeReference<List<User>>() {}; lstUser = mapper.readValue(jp, tRef); for (User user : lstUser) { System.out.println(user.toString()); } } catch (JsonGenerationException e) { e.printStackTrace(); } catch (JsonMappingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); }

 

 

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#3楼

对于通用实现：

public static <T> List<T> parseJsonArray(String json, Class<T> classOnWhichArrayIsDefined) throws IOException, ClassNotFoundException { ObjectMapper mapper = new ObjectMapper(); Class<T[]> arrayClass = (Class<T[]>) Class.forName("[L" + classOnWhichArrayIsDefined.getName() + ";"); T[] objects = mapper.readValue(json, arrayClass); return Arrays.asList(objects); }

 

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#4楼

首先创建一个线程安全的ObjectReader实例。

ObjectMapper objectMapper = new ObjectMapper(); ObjectReader objectReader = objectMapper.reader().forType(new TypeReference<List<MyClass>>(){});

然后使用它：

List<MyClass> result = objectReader.readValue(inputStream);

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#5楼

这是一个可以转换json2object或Object2json的实用程序，无论您的pojo（实体T）如何

  import java.io.IOException; import java.io.StringWriter; import java.util.List; import com.fasterxml.jackson.core.JsonGenerationException; import com.fasterxml.jackson.core.JsonParseException; import com.fasterxml.jackson.core.type.TypeReference; import com.fasterxml.jackson.databind.DeserializationFeature; import com.fasterxml.jackson.databind.JsonMappingException; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.SerializationFeature; /** * * @author TIAGO.MEDICI * */ public class JsonUtils { public static boolean isJSONValid(String jsonInString) { try { final ObjectMapper mapper = new ObjectMapper(); mapper.readTree(jsonInString); return true; } catch (IOException e) { return false; } } public static String serializeAsJsonString(Object object) throws JsonGenerationException, JsonMappingException, IOException { ObjectMapper objMapper = new ObjectMapper(); objMapper.enable(SerializationFeature.INDENT_OUTPUT); objMapper.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS); StringWriter sw = new StringWriter(); objMapper.writeValue(sw, object); return sw.toString(); } public static String serializeAsJsonString(Object object, boolean indent) throws JsonGenerationException, JsonMappingException, IOException { ObjectMapper objMapper = new ObjectMapper(); if (indent == true) { objMapper.enable(SerializationFeature.INDENT_OUTPUT); objMapper.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS); } StringWriter stringWriter = new StringWriter(); objMapper.writeValue(stringWriter, object); return stringWriter.toString(); } public static <T> T jsonStringToObject(String content, Class<T> clazz) throws JsonParseException, JsonMappingException, IOException { T obj = null; ObjectMapper objMapper = new ObjectMapper(); obj = objMapper.readValue(content, clazz); return obj; } @SuppressWarnings("rawtypes") public static <T> T jsonStringToObjectArray(String content) throws JsonParseException, JsonMappingException, IOException { T obj = null; ObjectMapper mapper = new ObjectMapper(); obj = mapper.readValue(content, new TypeReference<List>() { }); return obj; } public static <T> T jsonStringToObjectArray(String content, Class<T> clazz) throws JsonParseException, JsonMappingException, IOException { T obj = null; ObjectMapper mapper = new ObjectMapper(); mapper = new ObjectMapper().configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true); obj = mapper.readValue(content, mapper.getTypeFactory().constructCollectionType(List.class, clazz)); return obj; }

 

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#6楼

首先创建一个映射器：

import com.fasterxml.jackson.databind.ObjectMapper;// in play 2.3 ObjectMapper mapper = new ObjectMapper();

​​​​​​​

作为数组：

MyClass[] myObjects = mapper.readValue(json, MyClass[].class);

作为列表, 方法1：

List<MyClass> myObjects = mapper.readValue(jsonInput, new TypeReference<List<MyClass>>(){});

作为列表, 方法2：

List<MyClass> myObjects = mapper.readValue(jsonInput, mapper.getTypeFactory().constructCollectionType(List.class, MyClass.class));

 

 

 

 

如何使用Jackson来反序列化对象数组_asdfgh0077的博客-博客_jackson 反序列化 数组 https://blog.csdn.net/asdfgh0077/article/details/103888370