jackson - 从GET Api返回JSON POJO时找不到MessageBodyWriter

问题描述

我试图使用jackson返回一个简单的json响应。

I was trying to return a simple json response using jackson.

@GET
    @Produces(MediaType.APPLICATION_JSON)
    public FMSResponseInfo test(){
        System.out.println("Entered the function");
        FMSResponseInfo fmsResponseInfo = new FMSResponseInfo();
        List<SearchDetailsDTO> searchDetailsDtoList = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            SearchDetailsDTO searchDetailsDto = new SearchDetailsDTO();
            searchDetailsDto.setBarcode("barcode" + i);
            searchDetailsDto.setDocNo("docNo" + i);
            searchDetailsDto.setDocType("docType" + i);
            searchDetailsDtoList.add(searchDetailsDto);
        }
        fmsResponseInfo.setStatus("200");
        fmsResponseInfo.setMessage("Success");
        fmsResponseInfo.setData(searchDetailsDtoList);
        System.out.println("Exiting the function");
        return fmsResponseInfo;
    }

这是代码。当函数尝试返回FMSResponseInfo时，它是POJO：

This is the code. When the function tries to return the FMSResponseInfo which is POJO :

package com.fms.core;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({ "status", "message", "data" })
public class FMSResponseInfo {
    @JsonProperty("status")
    private String status;
    @JsonProperty("message")
    private String message;
    @JsonProperty("data")
    private Object data;
    //Getters and Setters
}

这是pojo，它将是发回来。

This is the pojo which will be sent back.

但是当函数试图返回这个时，我得到了这个例外：

But as soons as the function tries to return this , I get this exception :

我已经包含了jackson-annotation-2.4.2.jar，jackson-core-2.4.2.jar和jackson-databind-2.4.2.jar。这些是我已经包含的三个杰克逊罐以及球衣2.16和hibernate和mysql所需的其他罐子。

I have included jackson-annotation-2.4.2.jar, jackson-core-2.4.2.jar and jackson-databind-2.4.2.jar. These are the three jackson jars I have included along with the other jars required by jersey 2.16 and hibernate and mysql.

请帮我解决这个问题！

Please help me resolve this issue !!

推荐答案

您需要的不仅仅是杰克逊，还需要Jackson JAX-RS提供商。

You need more than just Jackson, you need the Jackson JAX-RS provider.

然后在web.xml中注册

Then register it either in web.xml

<init-param>
    <param-name>jersey.config.server.provider.packages</param-name>
    <param-value>
        your.resource.provider.package,
        com.fasterxml.jackson.jaxrs.json
    </param-value>
</init-param>

或者在你的 ResourceConfig

packages("your.resource.provider.packgae",
         "com.fasterxml.jackson.jaxrs.json");

这篇关于jackson - 从GET Api返回JSON POJO时找不到MessageBodyWriter的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！