将JSON转换为特定格式

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;
    }

上面的对象需要转换为下面的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

您需要为

Audit

类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();   
    }
}

---

如果使用

@JsonSerialize（使用=AuditSerializer.class）

注释

Audit

类，则不需要显式注册

AuditSerializer

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

您可以直接使用

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"}

---

您需要为

Audit

类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();   
    }
}

---

如果使用

@JsonSerialize（使用=AuditSerializer.class）

注释

Audit

类，则不需要显式注册

AuditSerializer

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

您可以直接使用

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"}