我试图将json数据转换为使用Jackson的POJO对象。这里是MainActivity和我的POJO类代码。我基本上得到一个JsonMappingException错误。我也附上了整个日志
MainActivity.java:
ObjectMapper mapper = new ObjectMapper();
mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
try {
List<Entries> results = mapper.readValue(new URL("http://collegewires.com/android/jacksoncw.json"), new TypeReference<List<Entries>>(){});
for(int i=0;i<results.size();++i){
System.out.println(results.get(i).getName());
out = out + " ## " + results.get(i).getName();
txt.setText("1111");
}
} catch (JsonParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JsonMappingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Entries.java(这是POJO)
package com.collegewires.jackson;
public class Entries {
public Entries(){
}
private String id, name, email, address, gender;
private Phone phone;
public Phone getPhone() {
return phone;
}
public void setPhone(Phone phone) {
this.phone = phone;
}
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 String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
@Override
public String toString() {
return "Entries:{id: " + id + ", name: " + name +
", email: " + email + ", address: " + address + ", gender: " + gender + ", phone: " + phone + "}";
}
public class Phone {
public Phone(){
}
public String mobile, home, office;
public String getMobile() {
return mobile;
}
public void setMobile(String mobile) {
this.mobile = mobile;
}
public String getHome() {
return home;
}
public void setHome(String home) {
this.home = home;
}
public String getOffice() {
return office;
}
public void setOffice(String office) {
this.office = office;
}
@Override
public String toString() {
return "Phone:{mobile: " + mobile + ", home: " + home +
", office: " + office + "}";
}
}
}
现在，我在日志中得到以下错误。因此，我无法继续我的工作。日志如下:
07-12 12:06:13.206: W/System.err(30593):
com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
07-12 12:06:13.206: W/System.err(30593): at [Source: http://collegewires.com/android/jacksoncw.json; line: 1, column: 1]
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:575)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:569)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.handleNonArray(CollectionDeserializer.java:259)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:217)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:207)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:23)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2888)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2018)
07-12 12:06:13.211: W/System.err(30593): at com.collegewires.jackson.MainActivity.onCreate(MainActivity.java:81)
07-12 12:06:13.211: W/System.err(30593): at android.app.Activity.performCreate(Activity.java:5250)
07-12 12:06:13.211: W/System.err(30593): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
07-12 12:06:13.211: W/System.err(30593): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
07-12 12:06:13.211: W/System.err(30593): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2297)
07-12 12:06:13.211: W/System.err(30593): at android.app.ActivityThread.access$700(ActivityThread.java:152)
07-12 12:06:13.211: W/System.err(30593): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1282)
07-12 12:06:13.211: W/System.err(30593): at android.os.Handler.dispatchMessage(Handler.java:99)
07-12 12:06:13.211: W/System.err(30593): at android.os.Looper.loop(Looper.java:137)
07-12 12:06:13.211: W/System.err(30593): at android.app.ActivityThread.main(ActivityThread.java:5328)
07-12 12:06:13.211: W/System.err(30593): at java.lang.reflect.Method.invokeNative(Native Method)
07-12 12:06:13.211: W/System.err(30593): at java.lang.reflect.Method.invoke(Method.java:511)
07-12 12:06:13.211: W/System.err(30593): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
07-12 12:06:13.211: W/System.err(30593): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
07-12 12:06:13.211: W/System.err(30593): at dalvik.system.NativeStart.main(Native Method)
07-12 12:06:13.251: D/libEGL(30593): loaded /vendor/lib/egl/libEGL_POWERVR_SGX544_115.so
07-12 12:06:13.261: D/libEGL(30593): loaded /vendor/lib/egl/libGLESv1_CM_POWERVR_SGX544_115.so
07-12 12:06:13.266: D/libEGL(30593): loaded /vendor/lib/egl/libGLESv2_POWERVR_SGX544_115.so
07-12 12:06:13.271: I/(30593): !@IMGSRV: DATE: 2013.04.23(11:19:33) | BUILDER: LSI3D | REVISION: e9cd1377d8225457ae40
07-12 12:06:13.346: D/OpenGLRenderer(30593): Enabling debug mode 0
07-12 12:06:31.521: W/IInputConnectionWrapper(30593): setComposingText on inactive InputConnection
Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
您只能将JSON对象的数组反序列化为POJO的数组或集合。请注意，JSON对象由{ }大括号分隔，而数组由[ ]大括号分隔，其中包含一些对象。
-
删除Entries &手机
-
GetEntries results = mapper.readValue(new URL("http://collegewires.com/android/jacksoncw.json"), GetEntries.class); -
Entries似乎是JSON中的一个参数
GetEntries.java
package com.collegewires.jackson;
import java.util.List;
public class GetEntries{
private List<Entries> entries;
public List<Entries> getEntries(){
return this.entries;
}
public void setEntries(List<Entries> entries){
this.entries = entries;
}
}
Entries.java
package com.collegewires.jackson;
import java.util.List;
public class Entries{
private String address;
private String email;
private String gender;
private String id;
private String name;
private Phone phone;
public String getAddress(){
return this.address;
}
public void setAddress(String address){
this.address = address;
}
public String getEmail(){
return this.email;
}
public void setEmail(String email){
this.email = email;
}
public String getGender(){
return this.gender;
}
public void setGender(String gender){
this.gender = gender;
}
public String getId(){
return this.id;
}
public void setId(String id){
this.id = id;
}
public String getName(){
return this.name;
}
public void setName(String name){
this.name = name;
}
public Phone getPhone(){
return this.phone;
}
public void setPhone(Phone phone){
this.phone = phone;
}
}
Phone.java
package com.collegewires.jackson;
import java.util.List;
public class Phone{
private String home;
private String mobile;
private String office;
public String getHome(){
return this.home;
}
public void setHome(String home){
this.home = home;
}
public String getMobile(){
return this.mobile;
}
public void setMobile(String mobile){
this.mobile = mobile;
}
public String getOffice(){
return this.office;
}
public void setOffice(String office){
this.office = office;
}
}
json的构造函数意味着您可以像这样在对象中读取它:
class Response{
private List<Entries> entries = ....
public setEntries(List<Entrie> e)
public getEntries()....
}
并像这样加载
Response results = mapper.readValue(new URL("http://collegewires.com/android/jacksoncw.json"), Response.class);
只需将数据放入[]而不是{}，它就会工作。
[
{
"id": "1",
"name":"exemple"
}
]