Java 如何使用camel-jackson将JSONArray转换为对象列表
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how to convert JSONArray to List of Object using camel-Hymanson
提问by Abhijeet
Am having the String of json array as follow
我有 json 数组的字符串如下
{"Compemployes":[
{
"id":1001,
"name":"jhon"
},
{
"id":1002,
"name":"jhon"
}
]}
i want to convert this this jsonarray to List<Empolyee>. for this i had added the the maven dependency "camel-Hymanson" and also write the pojo class for employee . but when i try to run my below code
我想将此 jsonarray 转换为List<Empolyee>. 为此，我添加了 maven 依赖项“ camel-Hymanson”，并为员工编写了 pojo 类。但是当我尝试运行下面的代码时
ObjectMapper mapper = new ObjectMapper();
List<Employe> list = mapper.readValue(jsonString, TypeFactory.collectionType(List.class, Employe.class));
am getting the following exception.
我收到以下异常。
org.codehaus.Hymanson.map.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
at [Source: java.io.StringReader@43caa144; line: 1, column: 1]
can someone pls tell what am missing or doing anyting wrong
有人可以告诉我遗漏了什么或做错了什么吗
采纳答案by Frederic Close
The problem is not in your code but in your json:
问题不在您的代码中，而在您的 json 中：
{"Compemployes":[{"id":1001,"name":"jhon"}, {"id":1002,"name":"jhon"}]}
this represents an object which contains a property Compemployes which is a list of Employee. In that case you should create that object like:
这表示一个对象，其中包含一个属性 Compemployes，它是一个 Employee 列表。在这种情况下，您应该创建该对象，如：
class EmployeList{
private List<Employe> compemployes;
(with getter an setter)
}
and to deserialize the json simply do:
并反序列化 json 只需执行以下操作：
EmployeList employeList = mapper.readValue(jsonString,EmployeList.class);
If your json should directly represent a list of employees it should look like:
如果您的 json 应直接表示员工列表，则它应如下所示：
[{"id":1001,"name":"jhon"}, {"id":1002,"name":"jhon"}]
Last remark:
最后备注：
List<Employee> list2 = mapper.readValue(jsonString,
TypeFactory.collectionType(List.class, Employee.class));
TypeFactory.collectionTypeis deprecatedyou should now use something like:
TypeFactory.collectionType已弃用，您现在应该使用以下内容：
List<Employee> list = mapper.readValue(jsonString,
TypeFactory.defaultInstance().constructCollectionType(List.class,
Employee.class));
回答by Marlon Leite de Albuquerque
/*
It has been answered in http://stackoverflow.com/questions/15609306/convert-string-to-json-array/33292260#33292260
* put string into file jsonFileArr.json
* [{"username":"Hello","email":"[email protected]","credits"
* :"100","twitter_username":""},
* {"username":"Goodbye","email":"[email protected]"
* ,"credits":"0","twitter_username":""},
* {"username":"mlsilva","email":"[email protected]"
* ,"credits":"524","twitter_username":""},
* {"username":"fsouza","email":"[email protected]"
* ,"credits":"1052","twitter_username":""}]
*/
public class TestaGsonLista {
public static void main(String[] args) {
Gson gson = new Gson();
try {
BufferedReader br = new BufferedReader(new FileReader(
"C:\Temp\jsonFileArr.json"));
JsonArray jsonArray = new JsonParser().parse(br).getAsJsonArray();
for (int i = 0; i < jsonArray.size(); i++) {
JsonElement str = jsonArray.get(i);
Usuario obj = gson.fromJson(str, Usuario.class);
//use the add method from the list and returns it.
System.out.println(obj);
System.out.println(str);
System.out.println("-------");
}
} catch (IOException e) {
e.printStackTrace();
}
}
回答by KalKi
I also faced the similar problem with JSON output format. This code worked for me with the above JSON format.
我也遇到了 JSON 输出格式的类似问题。这段代码适用于上述 JSON 格式。
package com.test.ameba;
import java.util.List;
public class OutputRanges {
public List<Range> OutputRanges;
public String Message;
public String Entity;
/**
* @return the outputRanges
*/
public List<Range> getOutputRanges() {
return OutputRanges;
}
/**
* @param outputRanges the outputRanges to set
*/
public void setOutputRanges(List<Range> outputRanges) {
OutputRanges = outputRanges;
}
/**
* @return the message
*/
public String getMessage() {
return Message;
}
/**
* @param message the message to set
*/
public void setMessage(String message) {
Message = message;
}
/**
* @return the entity
*/
public String getEntity() {
return Entity;
}
/**
* @param entity the entity to set
*/
public void setEntity(String entity) {
Entity = entity;
}
}
package com.test;
public class Range {
public String Name;
/**
* @return the name
*/
public String getName() {
return Name;
}
/**
* @param name the name to set
*/
public void setName(String name) {
Name = name;
}
public Object[] Value;
/**
* @return the value
*/
public Object[] getValue() {
return Value;
}
/**
* @param value the value to set
*/
public void setValue(Object[] value) {
Value = value;
}
}
package com.test.ameba;
import java.io.IOException;
import com.fasterxml.Hymanson.core.JsonParseException;
import com.fasterxml.Hymanson.databind.JsonMappingException;
import com.fasterxml.Hymanson.databind.ObjectMapper;
public class JSONTest {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String jsonString ="{\"OutputRanges\":[{\"Name\":\"ABF_MEDICAL_RELATIVITY\",\"Value\":[[1.3628407124839714]]},{\"Name\":\" ABF_RX_RELATIVITY\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_Unique_ID_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_FIRST_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_AMEBA_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_Effective_Date_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_AMEBA_MODEL\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_UC_ER_COPAY_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_INN_OON_DED_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_COINSURANCE_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_PCP_SPEC_COPAY_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_INN_OON_OOP_MAX_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_IP_OP_COPAY_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_PHARMACY_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]},{\"Name\":\" ABF_PLAN_ADMIN_ERR\",\"Value\":[[\"CPD\",\"SL Limit\",\"Concat\",1,1.5,2,2.5,3]]}],\"Message\":\"\",\"Entity\":null}";
ObjectMapper mapper = new ObjectMapper();
OutputRanges OutputRanges=null;
try {
OutputRanges = mapper.readValue(jsonString, OutputRanges.class);
} catch (JsonParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JsonMappingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("OutputRanges :: "+OutputRanges);;
System.out.println("OutputRanges.getOutputRanges() :: "+OutputRanges.getOutputRanges());;
for (Range r : OutputRanges.getOutputRanges()) {
System.out.println(r.getName());
}
}
}
回答by Kun
private static String readAll(Reader rd) throws IOException {
StringBuilder sb = new StringBuilder();
int cp;
while ((cp = rd.read()) != -1) {
sb.append((char) cp);
}
return sb.toString();
}
String jsonText = readAll(inputofyourjsonstream);
JSONObject json = new JSONObject(jsonText);
JSONArray arr = json.getJSONArray("Compemployes");
Your arr would looks like: [ { "id":1001, "name":"jhon" }, { "id":1002, "name":"jhon" } ] You can use:
你的 arr 看起来像： [ { "id":1001, "name":"jhon" }, { "id":1002, "name":"jhon" } ] 你可以使用：
arr.getJSONObject(index)
to get the objects inside of the array.
获取数组内的对象。
回答by Ravi
I had similar json response coming from client. Created one main list class, and one POJO class.
我有来自客户端的类似 json 响应。创建了一个主列表类和一个 POJO 类。
