JSON 转换为特定格式

Question

我有一个 Java 对象并试图将其转换为特定的 JSON 格式

    public class Audit {
       String auditId;
       String auditData;
    }

及以上对象需要转换为以下JSON格式

{
    "event":"auditId=100,auditData=purchase order"
}

我们如何使用 Jackson 解析器转换上述格式

Answer 1

您需要为 Audit class.

编写自定义序列化程序

public class AuditSerializer extends StdSerializer<Audit> {

    public AuditSerializer() {
        super(Audit.class);
    }

    protected AuditSerializer(Class<Audit> auditClass) {
        super(auditClass);
    }

    @Override
    public void serialize(Audit audit, JsonGenerator gen, SerializerProvider provider) throws IOException {
        gen.writeStartObject();
        String key = "event";
        String value = String.format("auditId=%s,auditData=%s", audit.auditId, audit.auditData);
        gen.writeStringField(key, value);
        gen.writeEndObject();   
    }
}

然后使用此自定义序列化程序为 Audit 获取 JSON 字符串：

SimpleModule module = new SimpleModule();
module.addSerializer(new AuditSerializer(Audit.class));

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(module);

Audit audit = new Audit();
audit.auditId = "100";
audit.auditData = "purchase Order";
System.out.println(mapper.writeValueAsString(audit));
// {"event":"auditId=100,auditData=purchase Order"}

如果用@JsonSerialize(using=AuditSerializer.class)注解Auditclass，则不需要显式注册AuditSerializer.

@JsonSerialize(using=AuditSerializer.class)
public class Audit {
    ...

而你直接使用ObjectMapper。

Audit audit = new Audit();
audit.auditId = "100";
audit.auditData = "purchase Order";

ObjectMapper mapper = new ObjectMapper();
System.out.println(mapper.writeValueAsString(audit));
// {"event":"auditId=100,auditData=purchase Order"}

JSON 转换为特定格式

JSON conversion to a specific format

spring

json

spring-boot

jackson-databind