我想将以下 JSON
字符串转换为 Java
对象:
{
"user": {
"0": {
"firstName": "Monica",
"lastName": "Belluci"
},
"1": {
"firstName": "John",
"lastName": "Smith"
},
"2": {
"firstName": "Owen",
"lastName": "Hargreaves"
}
}
}
为了将其转换为 Java
对象,我创建了以下类:
class User {
private Map<String, MyObject> user = new HashMap<>();
//Getter and Setter is here
}
class MyObject {
private String firstName;
private String lastName;
//Getters and Setters are here
}
我正在使用 Jackson 库将 JSON
转换为 Java
。以下是我如何使用 Jackson 进行转换:
ObjectMapper mapper = new ObjectMapper();
User user = mapper.readValue(jsonString, User.class);
问题是,通过上面的这种转换,User 对象中的 Map
始终为空。我做错了什么?
提前致谢。
最佳答案
我认为它应该有效。我已经执行了这段代码并且运行良好。这是我的例子。
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
public class TestJackson {
public static void main(String[] args) throws IOException {
ObjectMapper mapper = new ObjectMapper();
String testJson = "{\n" + " \"user\": {\n" + " \"0\": {\n" + " \"firstName\": \"Monica\",\n" + " \"lastName\": \"Belluci\"\n" + " },\n" + " \"1\": {\n" + " \"firstName\": \"John\",\n" + " \"lastName\": \"Smith\"\n" + " },\n" + " \"2\": {\n" + " \"firstName\": \"Owen\",\n" + " \"lastName\": \"Hargreaves\"\n" + " }\n" + " }\n" + "}";
User readValue = mapper.readValue(testJson, User.class);
System.out.println("readValue = " + readValue);
}
}
和用户类:
import java.util.HashMap;
import java.util.Map;
class User {
private Map<String, MyObject> user = new HashMap<String, MyObject>();
public Map<String, MyObject> getUser() {
return user;
}
public void setUser(Map<String, MyObject> user) {
this.user = user;
}
@Override
public String toString() {
return "User{" +
"user=" + user +
'}';
}
}
class MyObject {
private String firstName;
private String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
@Override
public String toString() {
return "MyObject{" +
"firstName='" + firstName + '\'' +
", lastName='" + lastName + '\'' +
'}';
}
}
关于java - 如何将以下 JSON 字符串转换为 POJO,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41499935/