SAP PI Java Mapping中使用GSON实现XML转JSON遇问题求助

你的核心问题在于没有先解析XML结构，而是直接把XML字符串当成普通文本传给Gson，所以Gson只是把整个XML转成了JSON格式的字符串（带转义字符），而不是按照XML的层级结构生成对应的JSON对象。

要解决这个问题，我们需要分三步走：把XML解析成Java对象（POJO），再用Gson把POJO转成JSON。下面是具体实现：

第一步：定义对应XML结构的POJO类 #

首先要创建和源XML结构完全匹配的Java类，Gson可以直接把这些对象转换成JSON：

package xmlgsonjson;

import java.util.List;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

// 对应根节点<data>
@XmlRootElement(name = "data")
public class Data {
    private String ERP;
    private String Shiptoparty;
    private String Shippingpoint;
    private String Issuedate;
    private List<Product> products;

    @XmlElement(name = "ERP")
    public String getERP() { return ERP; }
    public void setERP(String ERP) { this.ERP = ERP; }

    @XmlElement(name = "Shiptoparty")
    public String getShiptoparty() { return Shiptoparty; }
    public void setShiptoparty(String shiptoparty) { Shiptoparty = shiptoparty; }

    @XmlElement(name = "Shippingpoint")
    public String getShippingpoint() { return Shippingpoint; }
    public void setShippingpoint(String shippingpoint) { Shippingpoint = shippingpoint; }

    @XmlElement(name = "Issuedate")
    public String getIssuedate() { return Issuedate; }
    public void setIssuedate(String issuedate) { Issuedate = issuedate; }

    @XmlElement(name = "products")
    public List<Product> getProducts() { return products; }
    public void setProducts(List<Product> products) { this.products = products; }
}

// 对应<products>节点
class Product {
    private String Unit;
    private Double QTY;
    private String SKUno;

    @XmlElement(name = "Unit")
    public String getUnit() { return Unit; }
    public void setUnit(String unit) { Unit = unit; }

    @XmlElement(name = "QTY")
    public Double getQTY() { return QTY; }
    public void setQTY(Double QTY) { this.QTY = QTY; }

    @XmlElement(name = "SKUno")
    public String getSKUno() { return SKUno; }
    public void setSKUno(String SKUno) { this.SKUno = SKUno; }
}

第二步：修改Mapping类的转换逻辑 #

替换你原来的transform方法，用JAXB解析XML到POJO，再用Gson转成JSON：

package xmlgsonjson;

import java.io.InputStream;
import java.io.OutputStream;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.sap.aii.mapping.api.AbstractTransformation;
import com.sap.aii.mapping.api.StreamTransformationException;
import com.sap.aii.mapping.api.TransformationInput;
import com.sap.aii.mapping.api.TransformationOutput;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;

public class MakeItJSONByGSON extends AbstractTransformation {

    @Override
    public void transform(TransformationInput in, TransformationOutput out) throws StreamTransformationException {
        try {
            InputStream inputStream = in.getInputPayload().getInputStream();
            OutputStream outputStream = out.getOutputPayload().getOutputStream();

            // 1. 用JAXB把XML解析成Data对象
            JAXBContext jaxbContext = JAXBContext.newInstance(Data.class);
            Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
            Data data = (Data) unmarshaller.unmarshal(inputStream);

            // 2. 用Gson把Data对象转成格式化的JSON
            Gson gson = new GsonBuilder().setPrettyPrinting().create();
            String jsonOutput = gson.toJson(data);

            // 3. 输出JSON到PI的payload
            outputStream.write(jsonOutput.getBytes());

        } catch (Exception e) {
            // 抛出PI能识别的异常，方便排查问题
            throw new StreamTransformationException("XML to JSON transformation failed", e);
        }
    }
}

关键注意事项 #

1. 依赖配置：确保SAP PI的映射库中添加了Gson的jar包（gson-x.x.x.jar），JAXB在Java EE环境中默认自带，不需要额外添加。
2. 字段类型选择：如果需要保留ERP、Shiptoparty等字段的前导0，必须用String类型；如果转成Long/Integer会丢失前导0。
3. XML空格处理：JAXB会自动忽略XML中的空白字符（比如QTY字段的末尾空格），解析时会正确转换成Double类型。

修正后的预期输出 #

（注：你给出的预期输出有语法错误，比如对象属性间缺少逗号，且data不应该是数组，以下是正确的输出）：

{
  "ERP": "0080001",
  "Shiptoparty": "0088000",
  "Shippingpoint": "503",
  "Issuedate": "20181102",
  "products": [
    {
      "Unit": "L",
      "QTY": 2.0,
      "SKUno": "000000000011"
    },
    {
      "Unit": "L",
      "QTY": 0.0,
      "SKUno": "000000000011000078"
    }
  ]
}

内容的提问来源于stack exchange，提问作者Kaushik