springboot post 请求异常

引言

在测试spring boot 的post传递实体类的过程中发现了一个反向序列化的异常。

异常

JSON parse error: Cannot construct instance of `com.**` (although at least one Creator exists): cannot deserialize from Object value (no delegate- or property-based Creator); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `com.**` (although at least one Creator exists): cannot deserialize from Object value (no delegate- or property-based Creator)
 at [Source: (PushbackInputStream); line: 2, column: 2]]
 

解决方案

在实体类中添加无参构造函数。

 

原因

jackson的反序列化需要无参构造函数,而我在实体类中添加了有参数的构造函数。

在实体类中添加无参构造函数即可。

 

修改前


import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

import java.io.Serializable;

@Data
@TableName("user")
public class User implements Serializable {

    @TableId("id")
    private String id;
    @TableField("user_id")
    private String userId;
    @TableField("device_id")
    private String deviceId;

    public User(String deviceId) {
        this.deviceId= deviceId;
    }
}

修改后


import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

import java.io.Serializable;

@Data
@TableName("user")
public class User implements Serializable {

    @TableId("id")
    private String id;
    @TableField("user_id")
    private String userId;
    @TableField("device_id")
    private String deviceId;

    public User() {
        super();
    }

    public User(String deviceId) {
        this.deviceId= deviceId;
    }
}

 

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