尝试使用 Spring Boot 从 POST 请求正文中读取嵌套 JSON 时获取 null答案

【问题标题】：Getting null when trying to read nested JSON from POST request body using springboot尝试使用 Spring Boot 从 POST 请求正文中读取嵌套 JSON 时获取 null
【发布时间】：2020-01-20 10:23:01
【问题描述】：

我正在尝试使用 springboot 从请求正文中解析 JSON：

下面是邮递员的请求（请求体，类型为application/json）->

{
"CreditComplex": [{
    "BCNR":"973",                                                      
    "RelationshipName":"Pricing Company BV",
    "Borrowers":[{
        "Borrower ":[{
            "BCNR" : "",
            "CGC":"1174",
            "UCR":"4+",
            "PD":"0.03",
            "AGIC":"1301",
            "BookingLocation":"NL",
            "SalesTurnover":"10000000000",
            "Facilities": [{
                "Facility": [{
                    "gfid " : "",
                    "limit": "1000000",
                    "producttype": "19",
                    "spread": "3.0000",
                    "commitmentFee": "0.3000",
                    "annualfee": "0",
                    "oneOfffee": "5000",
                    "lgd": "0.1800",
                    "outstanding": "500000"
                }]
            }]
            }]
        }]
}]}

post方法处理来自springboot的请求

   @RequestMapping(path = "/checkjson", method = RequestMethod.POST)
    public ResponseEntity<CreditComplex> getBook(@RequestBody CreditComplex creditcomplex) {
       return new ResponseEntity<>(creditcomplex, HttpStatus.OK);
    }

我创建了以下类来映射 JSON 中的值：

    public class CreditComplex {

    private String BCNR;
    private String RelationshipName;
    List<Borrower> borrower;

所有字段都有getter和setter

public class Borrowers {

    List <Borrower> borrower;

所有字段都有getter和setter

public class Borrower {

    private String BCNR;
    private String CGC;
    private String UCR;
    private String PD;
    private String AGIC;
    private String BookingLocation;
    private String SalesTurnover;
    private String Spread;
    private String CommitmentFee;
    private String AnnualFee;
    private String OneOffFee;
    private String LGD;
    private String Outstanding;
    List<Facilities> facilities;

所有字段都有getter和setter

public class Facilities {

    private List<Facility> facility;

所有字段都有getter和setter

public class Facility {

    private String gfid;
    private String limit;
    private String producttype;
    private String spread;
    private String commitmentfee;
    private String annualfee;
    private String oneOfffee;
    private String lgd;
    private String outstanding;
    with getter and setter for all fields

预期响应是实际请求 json 已映射到 Credit 复杂类但得到如下响应：

{
    "borrower": null,
    "bcnr": null,
    "relationshipName": null
}

任何发现/帮助将不胜感激。

【问题讨论】：

你的 JSON 结构很奇怪。我不明白为什么你有像Borrowers 和Facilities 这样的中间类，它们只是包装了Borrower 和Facility 的列表。这可以大大简化
是的，这很奇怪，但他似乎没有使用那些“包装”。这里的问题可能是属性名称不匹配（JSON 与 Java）。当您的序列化程序将查找名称为 Borrowers 的属性时，它不会找到它，因为您在 CreditComplex 类中将其称为 borrower。以这种方式检查您的代码。并且请不要以大写开头的属性名称，这是不可读的。编辑：没有注意第一个模型。按照akortex91的说法，太复杂了，和你的java模型结构不匹配。
嗨，感谢您的 cmets/调查结果。虽然这个例子有一个实时借款人和设施，但会有多个借款人和设施，因此它被命名为单独的。
在我最初的帖子中，有一个错误是我在 Creditcomplex 类中使用了 Borrower 而不是 Borrowers。然而，通过使其成为借款人，它也不起作用。有效的是@akortex91 提到的格式，但在这种情况下，我如何在借款人下拥有多个借款人部分，在设施下拥有多个设施部分。举个例子会有所帮助。

标签： java json api post nested

【解决方案1】：

您的 JSON 架构错误。预期字段和 JSON 请求正文之间存在命名差异。

此外，没有必要使用这些不增加任何价值的复杂包装器（否则会使生成的 JSON 更难阅读）。只需将您的代码重构为如下所示：

public class Facility {

    private String gfid;
    public String getGfid() { return gfid; }
    public void setGfid(String gfid) { this.gfid = gfid; }

    private Integer limit;
    public Integer getLimit() { return limit; }
    public void setLimit(Integer limit) { this.limit = limit; }

    private Integer productType;
    public Integer getProductType() { return productType; }
    public void setProductType(Integer productType) { this.productType = productType; }

    private Double spread;
    public Double getSpread() { return spread; }
    public void setSpread(Double spread) { this.spread = spread; }

    private Double commitmentFee;
    public Double getCommitmentFee() { return commitmentFee; }
    public void setCommitmentFee(Double commitmentFee) { this.commitmentFee = commitmentFee; }

    private Double annualFee;
    public Double getAnnualFee() { return annualFee; }
    public void setAnnualFee(Double annualFee) { this.annualFee = annualFee; }

    private Double oneOffFee;
    public Double getOneOffFee() { return oneOffFee; }
    public void setOneOffFee(Double oneOffFee) { this.oneOffFee = oneOffFee; }

    private Double lgd;
    public Double getLgd() { return lgd; }
    public void setLgd(Double lgd) { this.lgd = lgd; }

    private Integer outstanding;
    public Integer getOutstanding() { return outstanding; }
    public void setOutstanding(Integer outstanding) { this.outstanding = outstanding; }

}

借款人：

public class Borrower {

    private String bncr;
    public String getBncr() { return bncr; }
    public void setBncr(String bncr) { this.bncr = bncr; }

    private Integer cgc;
    public Integer getCgc() { return cgc; }
    public void setCgc(Integer cgc) { this.cgc = cgc; }

    private String ucr;
    public String getUcr() { return ucr; }
    public void setUcr(String ucr) { this.ucr = ucr; }

    private Double pd;
    public Double getPd() { return pd; }
    public void setPd(Double pd) { this.pd = pd; }

    private Integer agic;
    public Integer getAgic() { return agic; }
    public void setAgic(Integer agic) { this.agic = agic; }

    private String bookingLocation;
    public String getBookingLocation() { return bookingLocation; }
    public void setBookingLocation(String bookingLocation) { this.bookingLocation = bookingLocation; }

    private Integer salesTurnover;
    public Integer getSalesTurnover() { return salesTurnover; }
    public void setSalesTurnover(Integer salesTurnover) { this.salesTurnover = salesTurnover; }

    private List<Facility> faciliies;
    public List<Facility> getFaciliies() { return faciliies; }
    public void setFaciliies(List<Facility> faciliies) { this.faciliies = faciliies; }

}

信用综合体：

public class CreditComplex {

    private String bcnr;
    public String getBcnr() { return bcnr; }
    public void setBcnr(String bcnr) { this.bcnr = bcnr; }

    private String relationshipName;
    public String getRelationshipName() { return relationshipName; }
    public void setRelationshipName(String relationshipName) { this.relationshipName = relationshipName; }

    private List<Borrower> borrowers;
    public List<Borrower> getBorrowers() { return borrowers; }
    public void setBorrowers(List<Borrower> borrowers) { this.borrowers = borrowers; }

}

将此传递给对象映射器将生成以下 JSON 正文：

{
  "bcnr" : "973",
  "relationshipName" : "Pricing Company BV",
  "borrowers" : [ {
    "bncr" : "",
    "cgc" : 1174,
    "ucr" : "4+",
    "pd" : 0.03,
    "agic" : 1301,
    "bookingLocation" : "NL",
    "salesTurnover" : 10000000,
    "faciliies" : [ {
      "gfid" : "",
      "limit" : 10000,
      "productType" : 19,
      "spread" : 3.0,
      "commitmentFee" : 0.3,
      "annualFee" : 0.0,
      "oneOffFee" : 5000.0,
      "lgd" : 0.18,
      "outstanding" : 50000
    } ]
  } ]
}

【讨论】：