无法从 [Source: (String)][UsersPajo{website='hildegard.org' 处的 START_ARRAY 令牌中反序列化 `model.UsersPajo` 的实例

Question

我不明白为什么反序列化不起作用。

public static String readUserFile(String titleFile) {
    String pathJSONFile = "src/main/resources/" + titleFile + ".json";
    ObjectMapper objectMapper = new ObjectMapper();
    File jsonFile = new File(pathJSONFile);
    UsersPajo[] usersPajos2= null;

    try {
        usersPajos2 = objectMapper.readValue(jsonFile, UsersPajo[].class);
        System.out.println("_usersPajos2___" + usersPajos2);
    } catch (JsonProcessingException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    String information = Arrays.toString(usersPajos2);

    try {
        usersPajo = objectMapper.readValue(information, UsersPajo.class);
    } catch (JsonProcessingException e) {
        e.printStackTrace();
    } 
    }

我已经尝试了各种选择，但看起来我 confused.Here 是个错误。

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of 
`model.UsersPajo` out of START_ARRAY token
at [Source: (String)"[UsersPajo{website='hildegard.org', address=Address{zipcode='92998- 
3874', geo=Geo{lng='81.1496', lat='-37.3159'}, suite='Apt. 556', city='Gwenborough', 
street='Kulas Light'}, phone='1-770-736-8031 x56442', name='Leanne Graham', 
company=Company{bs='harness real-time e-markets', catchPhrase='Multi-layered client-server 
neural-net', name='Romaguera-Crona'}, id=1, email='Sincere@april.biz', username='Bret'}, 
UsersPajo{website='anastasia.net', address=Address{zipcode='90566-7771', 
geo=Geo{lng='-34.46"[truncated 3643 chars]; line: 1, column: 1]
at

这里是class模型

public class UsersPajo{
private String website;
private Address address;
private String phone;
private String name;
private Company company;
private int id;
private String email;
private String username;

public String getWebsite(){
    return website;
}

public Address getAddress(){
    return address;
}

public String getPhone(){
    return phone;
}

public String getName(){
    return name;
}

public Company getCompany(){
    return company;
}

public int getId(){
    return id;
}

public String getEmail(){
    return email;
}

public String getUsername(){
    return username;
}

@Override
public String toString() {
    return "UsersPajo{" +
            "website='" + website + '\'' +
            ", address=" + address +
            ", phone='" + phone + '\'' +
            ", name='" + name + '\'' +
            ", company=" + company +
            ", id=" + id +
            ", email='" + email + '\'' +
            ", username='" + username + '\'' +
            '}';
         }
       }

我的JSON文件

[ {
 "id" : 1,
 "name" : "Leanne Graham",
 "username" : "Bret",
 "email" : "Sincere@april.biz",
  "address" : {
     "street" : "Kulas Light",
     "suite" : "Apt. 556",
     "city" : "Gwenborough",
     "zipcode" : "92998-3874",
     "geo" : {
     "lat" : "-37.3159",
     "lng" : "81.1496"
    }
   },
 "phone" : "1-770-736-8031 x56442",
 "website" : "hildegard.org",
 "company" : {
    "name" : "Romaguera-Crona",
    "catchPhrase" : "Multi-layered client-server neural-net",
    "bs" : "harness real-time e-markets"
   }
}, ...
]

我从文件中读取信息，然后将其写入字符串。之后，我想使用反序列化从此行中获取我的 java 对象。告诉我为什么反序列化不起作用？需要修复什么

Answer 1

问题出在以下代码行：

try {
    usersPajo = objectMapper.readValue(information, UsersPajo.class);
} catch (JsonProcessingException e) {
    e.printStackTrace();
}

变量 information 包含以下内容：

[UsersPajo{website='hildegard.org', address=Address{zipcode='92998- 
3874', geo=Geo{lng='81.1496', lat='-37.3159'}, suite='Apt. 556', city='Gwenborough', 
street='Kulas Light'}, phone='1-770-736-8031 x56442', name='Leanne Graham', 
company=Company{bs='harness real-time e-markets', catchPhrase='Multi-layered client-server 
neural-net', name='Romaguera-Crona'}, id=1, email='Sincere@april.biz', username='Bret'}, 
UsersPajo{website='anastasia.net', address=Address{zipcode='90566-7771', 
geo=Geo{lng='-34.46"....

这基本上是 usersPajos2 映射到一个字符串。这显然不能反序列化为单个 UsersPajo 实例。所以摆脱这些代码行并保留所有其他代码：

public static String readUserFile(String titleFile) {
    String pathJSONFile = "src/main/resources/" + titleFile + ".json";
    ObjectMapper objectMapper = new ObjectMapper();
    File jsonFile = new File(pathJSONFile);
    UsersPajo[] usersPajos2= null;

    try {
        usersPajos2 = objectMapper.readValue(jsonFile, UsersPajo[].class);
        System.out.println("_usersPajos2___" + usersPajos2);
    } catch (JsonProcessingException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    return Arrays.toString(usersPajos2);
}

无法从 [Source: (String)][UsersPajo{website='hildegard.org' 处的 START_ARRAY 令牌中反序列化 `model.UsersPajo` 的实例

Cannot deserialize instance of `model.UsersPajo` out of START_ARRAY token at [Source: (String)"[UsersPajo{website='hildegard.org'

java

json

jackson