线程"main“json异常:尝试将com/fasterxml/jackson/annotation/JsonAutoDetect转换为POJO时出现java.lang.NoClassDefFoundError错误
线程"main“json异常:尝试将com/fasterxml/jackson/annotation/JsonAutoDetect转换为POJO时出现java.lang.NoClassDefFoundError错误
提问于 2013-11-08 18:08:29
我需要将json转换为POJO，为此我决定使用JACKSON库，我将jackson-databind-2.2.3.jar和jackson-core-2.0.6.jar添加到我的路径中，然后创建了以下类：
1-数据绑定类：
package Distributed;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
public class DataBinding {
public static void main(String[] args) throws JsonParseException, JsonMappingException, MalformedURLException, IOException {
String url = "http://frstmwarwebsrv.orsyptst.com:9000/duobject?searchString=TSK(ZTA010OU05)(000)&filtercheck=nameSWF&p.index=0&p.size=8";
ObjectMapper mapper = new ObjectMapper();
mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
DuObject duobject = mapper.readValue(new URL(url), DuObject.class);
Dataset[] datasets = duobject.getDataset();
for (Dataset dataset : datasets) {
System.out.println(dataset.getName());
}
}
}2-数据集类：
package Distributed;
import java.util.HashMap;
import java.util.Map;
public class Dataset {
private String id, name;
private Map<String , Object> otherProperties = new HashMap<String , Object>();
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Object get(String name) {
return otherProperties.get(name);
}
}3- DuObject类：
package Distributed;
public class DuObject {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Dataset[] getDataset() {
return dataset;
}
public void setDataset(Dataset[] dataset) {
this.dataset = dataset;
}
private Dataset[] dataset;
}下面是我在启动URL时使用的json对象：
{
"facets": {
"application": [
{
"name": "u_",
"distribution": 2
}
],
"node": [
{
"name": "frstlwardu03_05",
"distribution": 2
}
],
"area": [
{
"name": "x",
"distribution": 2
}
],
"company": [
{
"name": "war001",
"distribution": 2
}
]
},
"duObjects": [
{
"id": "TASK|TSK(ZTA010OU05)(000)|ZECPFICO00",
"name": "TSK(ZTA010OU05)(000)",
"mu": "ZECPFICO00",
"label": "",
"uprocHeader": "ZTA010OU05|000",
"uprocHeaderLabel": "Uproc Tech Planif ne pas supprimer tous les jours f\u00c3\u00a9ri\u00c3\u00a9s",
"uprocHeaderType": "CL_INT",
"domain": "I",
"domainLabel": "Internal Activities",
"application": "U_",
"applicationLabel": "DU",
"highlightResult": {
"name": "name",
"word": "TSK"
}
},
{
"id": "TASK|TSK(ZTA010OU05)(000)|ZECPSDA000",
"name": "TSK(ZTA010OU05)(000)",
"mu": "ZECPSDA000",
"label": "",
"uprocHeader": "ZTA010OU05|000",
"uprocHeaderLabel": "Uproc Tech Planif ne pas supprimer tous les jours f\u00c3\u00a9ri\u00c3\u00a9s",
"uprocHeaderType": "CL_INT",
"domain": "I",
"domainLabel": "Internal Activities",
"application": "U_",
"applicationLabel": "DU",
"highlightResult": {
"name": "name",
"word": "TSK"
}
}
],
"totalCount": 2,
"pageSize": 10,
"pageCurrent": 1,
"pageNb": 1
}我想要做的是获取DuObject.name并将其存储在一个DataSet表中；然而，当我运行Databinding类时，我得到了以下错误：
Exception in thread "main" java.lang.NoClassDefFoundError: com/fasterxml/jackson/annotation/JsonAutoDetect
at com.fasterxml.jackson.databind.introspect.VisibilityChecker$Std.<clinit> (VisibilityChecker.java:172)
at com.fasterxml.jackson.databind.ObjectMapper.<clinit>(ObjectMapper.java:193)
at Distributed.DataBinding.main(DataBinding.java:16)
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.annotation.JsonAutoDetect
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 3 more我是jackson livbrary的新手，我不知道为什么我会有这个错误。
提前感谢您的帮助。
在添加注释jar之后，我遇到了以下错误：
Exception in thread "main" java.lang.NoSuchMethodError: com.fasterxml.jackson.core.JsonFactory.createParser(Ljava/net/URL;)Lcom/fasterxml/jackson/core/JsonParser;
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2011)
at Distributed.DataBinding.main(DataBinding.java:18)我已经将这三个JARS更改为2.1.2版本，我现在得到的错误是：
Exception in thread "main" java.lang.NullPointerException
at Distributed.DataBinding.main(DataBinding.java:21)实际上数据集表返回的是null，你知道为什么数据集不包含json name字段吗？
回答 1
Stack Overflow用户
回答已采纳
发布于 2013-11-08 18:29:32
您必须添加一个jar :jackson-annotations 2.1.2.jar
你可以从here下载
编辑：
此外，由于您的json中有数组，因此需要遍历它：
ObjectMapper mapper = new ObjectMapper();
mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
JsonNode node = mapper.readTree(new URL(url));
node = node.get("duObjects");
TypeReference<List<Dataset>> typeRef = new TypeReference<List<Dataset>>() {
};
List<Dataset> list = mapper.readValue(node.traverse(), typeRef);
for (int i = 0; i < list.size(); i++) {
Dataset dataSet = list.get(i);
System.out.println(dataSet.getName());
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/19856363
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