如何使用杰克逊注释将值json映射到对象java

Question

我有一个字符串Json：

{
   "title": "PowerPoint Presentation",
   "author": "Hana",
   "subject": null,
   "keywords": null,
   "created_date": "2016-03-25 15:11:17",
   "modified_date": "2016-03-28 17:27:06",
   "creator": null,
   "producer": "LibreOffice 5.0",
   "pdfversion": null,
   "file_size": 149225,
   "total_page": 24
}

和对象java

public class ContentInfo {

    @JsonProperty("title")
    private String title;

    @JsonProperty("author")
    private String author;

    @JsonProperty("subject")
    private String subject;

    @JsonProperty("keywords")
    private String keywords;

    @JsonProperty("created_date")
    private String createdDate;

    @JsonProperty("modified_date")
    private String modifiedDate;
// (application name that create original file of PDF)

    @JsonProperty("creator")
    private String creator;
// (application name that create PDF)

    @JsonProperty("producer")
    private String producer;

    @JsonProperty("pdfversion")
    private String pdfversion;

    @JsonProperty("file_size")
    private long fileSize;

    @JsonProperty("total_page")
    private long totalPage;

    public ContentInfo() {
    }

    public ContentInfo(String title, String author, String subject, String keywords, String createdDate, String modifiedDate, String creator, String producer, String pdfversion, long fileSize, long totalPage, PageViewSetting page_view_setting) {
        this.title = title;
        this.author = author;
        this.subject = subject;
        this.keywords = keywords;
        this.createdDate = createdDate;
        this.modifiedDate = modifiedDate;
        this.creator = creator;
        this.producer = producer;
        this.pdfversion = pdfversion;
        this.fileSize = fileSize;
        this.totalPage = totalPage;
        this.page_view_setting = page_view_setting;
    }



    public String getTitle() {
        return title;
    }

    public String getAuthor() {
        return author;
    }

    public String getSubject() {
        return subject;
    }

    public String getKeywords() {
        return keywords;
    }

    public String getCreatedDate() {
        return createdDate;
    }

    public String getModifiedDate() {
        return modifiedDate;
    }

    public String getCreator() {
        return creator;
    }

    public String getProducer() {
        return producer;
    }

    public String getPdfversion() {
        return pdfversion;
    }

    public long getFileSize() {
        return fileSize;
    }

    public long getTotalPage() {
        return totalPage;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }

    public void setKeywords(String keywords) {
        this.keywords = keywords;
    }

    public void setCreatedDate(String createdDate) {
        this.createdDate = createdDate;
    }

    public void setModifiedDate(String modifiedDate) {
        this.modifiedDate = modifiedDate;
    }

    public void setCreator(String creator) {
        this.creator = creator;
    }

    public void setProducer(String producer) {
        this.producer = producer;
    }

    public void setPdfversion(String pdfversion) {
        this.pdfversion = pdfversion;
    }

    public void setFileSize(long fileSize) {
        this.fileSize = fileSize;
    }
}

我正在使用下面的代码来映​​射它们：

ObjectMapper objectMapper = new ObjectMapper();
            objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
            data = objectMapper.readValue(this.jsonContentInfoData, ContentInfo.class);

但是结果ResponseBody在某些领域是错误的：

"content_info": {
"title": "PowerPoint Presentation"
"author": "Hana"
"subject": null
"keywords": null
"created_date": "2016-03-25 15:11:17"
"creator": null
"producer": "LibreOffice 5.0"
"pdfversion": null
"modified_date": "2016-03-28 17:27:06"
"file_size": 0
"total_page": 0
}

Answer 1

Jackson会根据您字段的访问修饰符以及可用的和正确命名的getter和setter方法进行序列化和反序列化。

您可以覆盖此功能，以确保使用以下命令对所有私有字段进行序列化/反序列化：

mapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);

但是，它很适合测试，但不是最佳解决方案。 相反，您实际上应该使用私有字段并使用公共获取程序/设置程序来控制序列化和反序列化过程。

• 公共获取者使非公共字段可序列化和反序列化

  直觉上，吸气剂也会使私有字段反序列化-因为一旦有了吸气剂，该字段就被视为属性。

• 公共设置员只能将非公共字段反序列化

在您的代码中，显示获取器/设置器：

1. setPdfversion不正确：应为setPdfVersion
2. getTotalPage(long totalPage) -不正确，旨在设置为setTotalPage(long totalPage)

最后，我认为这将有助于将totalPage和fileSize的类型从原始long更改为包装对象Long 。 还要更改这些字段的getter / setter以匹配Long类型。 由于这两个字段都存在问题并且正在使用基元，因此Jackson（或您的版本）似乎无法处理基元。