【技术累积】【点】【java】【27】@JSONField

时间 2019-12-11

原文原文链接

@JSONField

该注解隶属于阿里fastjson，方便fastjson处理对象时的一些操做html

源码java

@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.METHOD, ElementType.FIELD, ElementType.PARAMETER })
public @interface JSONField {
    /**
     * config encode/decode ordinal
     * @since 1.1.42
     * @return
     */
    int ordinal() default 0;

    String name() default "";

    String format() default "";

    boolean serialize() default true;

    boolean deserialize() default true;

    SerializerFeature[] serialzeFeatures() default {};

    Feature[] parseFeatures() default {};
    
    String label() default "";
    
    /**
     * @since 1.2.12
     */
    boolean jsonDirect() default false;
    
    /**
     * Serializer class to use for serializing associated value.
     * 
     * @since 1.2.16
     */
    Class<?> serializeUsing() default Void.class;
    
    /**
     * Deserializer class to use for deserializing associated value. 
     * 
     * @since 1.2.16 
     */
    Class<?> deserializeUsing() default Void.class;

    /**
     * @since 1.2.21
     * @return the alternative names of the field when it is deserialized
     */
    String[] alternateNames() default {};

    /**
     * @since 1.2.31
     */
    boolean unwrapped() default false;
}

ordinal() 顺序设置。git

缺省fastjson序列化一个java bean，是根据fieldName的字母序进行序列化的，你能够经过ordinal指定字段的顺序。这个特性须要1.1.42以上版本github
name() 指定名字。指定后，序列化后字段名变为指定名称，反序列化同理；
format() 指定日期格式；
serialize() deserialize() 是否序列化和反序列化，默认true。
serialzeFeatures() 序列化特性选择，具体参考后面文章吧；经过枚举选择
parseFeatures() 解释特性选择；经过枚举选择
label() 打标记，可定制化输出json

@JSONField(label = "normal")
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
        
    @JSONField(label = "normal")
    public String getName() {
        return name;
    }
System.out.println(JSON.toJSONString(v, Labels.includes("normal")));

jsonDirect() 直接输出而不通过json转译session

在fastjson-1.2.12版本中，JSONField支持一个新的配置项jsonDirect，它的用途是：当你有一个字段是字符串类型，里面是json格式数据，你但愿直接输入，而不是通过转义以后再输出。app
serializeUsing() deserializeUsing() 指定序列化、反序列化使用自定义Serialize、Parser（注意，直接写在类中便可，格式固定，关键是取值）ide

//示例1
public static class TimeStampDeserializer implements ObjectDeserializer {

        @Override
        public <T> T deserialze(DefaultJSONParser parser, Type type, Object fieldName) {
            String time = parser.getLexer().stringVal();
            if (StringUtils.isBlank(time)) {
                return (T)String.valueOf(new Date().getTime());
            } else {
                return (T)(time + "000");
            }
        }

        @Override
        public int getFastMatchToken() {
            return 0;
        }
    }
    
//示例2
public static class Model {
    @JSONField(serializeUsing = ModelValueSerializer.class)
    public int value;
}

public static class ModelValueSerializer implements ObjectSerializer {
    @Override
    public void write(JSONSerializer serializer, Object object, Object fieldName, Type fieldType,
                      int features) throws IOException {
        Integer value = (Integer) object;
        String text = value + "元";
        serializer.write(text);
    }
}

alternateNames() 多名字。容许多个名字的变量转成一个

@JSONField(alternateNames = {"user", "person"})
public String name;

unwrapped() 不封箱

搭配JSON.parseObject

给输出结构体中field配置上@JSONField(name="aaa")等，直接转出获得的json串this

Response response = JSON.parseObject(res, Response.class);

@Setter
@Getter
@NoArgsConstructor
@ToString
public class Response {
    
    @JSONField(name = "answerList")
    private List<Answer> answers;
    
    @JSONField(name = "timeStamp")
    private String timeStamp;
    
    @JSONField(name = "type")
    private String answerType;
    
    @JSONField(name = "id")
    private String erp;
    
    @JSONField(name = "session")
    private String sessionId;
    
    @JSONField(name = "topic")
    private String topic;
    
    @JSONField(deserialize = false, serialize = false)
    private String answerType = AnswerTypeEnum.ANSWER.getCode();
}

【技术累积】【点】【java】【27】@JSONField

@JSONField

搭配JSON.parseObject

参考文章