在Pojo響應中排除空字段

Question

我想從pojo中排除空字段

**** TransactionHistoryBO Pojo **

 package main.java.com.as.model; import com.fasterxml.jackson.annotation.JsonInclude; @JsonInclude(JsonInclude.Include.NON_NULL) public class TransactionHistoryBO { private String processId; private String dateTime; private Integer status; private Double pointsEarned; private String productName; private String receiptNumber; public String getProcessId() { return processId; } public void setProcessId(String processId) { this.processId = processId; } public String getDateTime() { return dateTime; } public void setDateTime(String dateTime) { this.dateTime = dateTime; } public Integer getStatus() { return status; } public void setStatus(Integer status) { this.status = status; } public Double getPointsEarned() { return pointsEarned; } public void setPointsEarned(Double pointsEarned) { this.pointsEarned = pointsEarned; } public String getProductName() { return productName; } public void setProductName(String productName) { this.productName = productName; } public String getReceiptNumber() { return receiptNumber; } public void setReceiptNumber(String receiptNumber) { this.receiptNumber = receiptNumber; } } 

**

交易紀錄回應pojo

 public class TransactionHistoryResponse { private ArrayList<TransactionHistoryBO> transactions; @JsonInclude(JsonInclude.Include.NON_NULL) public ArrayList<TransactionHistoryBO> getTransactions() { return transactions; } @JsonInclude(Include.NON_NULL) public void setTransactions(ArrayList<TransactionHistoryBO> transactions) { this.transactions = transactions; } } 

交易歷史記錄響應pojo中使用了交易歷史記錄BO類型的數組列表。這是我在響應中顯示的確切pojo。我想在交易歷史記錄BO中排除具有空值的字段。 我嘗試使用@JsonInclude（JsonInclude.Include.NON_NULL）。它不起作用。也嘗試使用JsonSerialize，但已棄用。使用的傑克遜版本為2.2.2。

任何幫助，將不勝感激..請幫助..

Answer 1

@JsonInclude(JsonInclude.Include.NON_NULL)
public class TransactionHistoryBO { ... }

@JsonInclude(JsonInclude.Include.NON_NULL)
public class TransactionHistoryResponse { ... }

public class App {

    public static void main(String... args) throws JsonProcessingException {

        ObjectMapper om = new ObjectMapper();

        TransactionHistoryResponse thr = new TransactionHistoryResponse();
        TransactionHistoryBO thbo = new TransactionHistoryBO();
        thbo.setProductName("TEST");
        thr.setTransactions(new ArrayList<TransactionHistoryBO>());
        thr.getTransactions().add(thbo);
        System.out.print(om.writerWithDefaultPrettyPrinter().writeValueAsString(thr));
    }

}

產生輸出：

{
  "transactions" : [ {
    "productName" : "TEST"
  } ]
}

不使用其他注釋。 只需將@JsonInclude注釋添加到類而不是屬性。

---

更新：

將自定義JacksonJsonProvider添加到您的應用程序

@Provider
public class CustomJsonProvider extends ResteasyJackson2Provider {

    @Override
    public void writeTo(Object value, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) throws IOException {

        ObjectMapper mapper = locateMapper(type, mediaType);
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);

        super.writeTo(value, type, genericType, annotations, mediaType, httpHeaders, entityStream);
    }

}

在您的web.xml中注冊此提供程序

<context-param> 
    <param-name>resteasy.providers</param-name> 
    <param-value>com.package.CustomJsonProvider</param-value> 
</context-param>

經過和不經過測試，都可以正常工作。