Fastjson SerializerFeature&@JSONField的使用

原创已于 2022-04-28 09:49:45 修改 · 624 阅读

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于 2021-06-29 09:47:55 首次发布

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本文详细介绍了 FastJSON 的使用方法及技巧，包括 SerializerFeature 的各项功能、JSONField 注解的使用方式，以及 JSONPath 的基本操作。

文章目录

依赖
SerializerFeature
@JSONField
JSONPath

依赖

 <dependency>
       <groupId>com.alibaba</groupId>
       <artifactId>fastjson</artifactId>
       <version>1.2.7</version>
 </dependency>

SerializerFeature

 public static void main(String[] args) {
        @Data
        @Accessors
        @AllArgsConstructor
        class Xsd{
            private Integer id;
            private String name;
            private Date brDate;
            private String clazz;
            private Integer size;
            private List list;
        }
        Xsd xsd=new Xsd(1,"\"张林\"",new Date(),null,null,null);
        System.out.println("===========================");
        System.out.println(JSON.toJSONString(xsd));

        System.out.println("显示为null的字段===========================");
        System.out.println(JSON.toJSONString(xsd,SerializerFeature.WriteMapNullValue));

        System.out.println("null显示''===========================");
        System.out.println(JSON.toJSONString(xsd,SerializerFeature.WriteNullStringAsEmpty));

        System.out.println("转换array===========================");
        System.out.println(JSON.toJSONString(xsd,SerializerFeature.BeanToArray));

        System.out.println("全局修改日期格式,默认为false===========================");
        JSON.DEFFAULT_DATE_FORMAT = "yyyy-MM-dd";
        System.out.println(JSON.toJSONString(xsd,SerializerFeature.WriteDateUseDateFormat));

        System.out.println("PrettyFormat格式化json===========================");
        System.out.println(JSON.toJSONString(xsd,SerializerFeature.PrettyFormat));

        System.out.println("按字段名称排序后输出===========================");
        System.out.println(JSON.toJSONString(xsd,SerializerFeature.SortField));

        System.out.println("Date使用ISO8601格式输出===========================");
        System.out.println(JSON.toJSONString(xsd, SerializerFeature.UseISO8601DateFormat));

        System.out.println("单引号UseSingleQuotes=====双引号QuoteFieldNames========");
        System.out.println(JSON.toJSONString(xsd, SerializerFeature.UseSingleQuotes));

        System.out.println("数字为null输出0========");
        System.out.println(JSON.toJSONString(xsd, SerializerFeature.WriteNullNumberAsZero));

        System.out.println("中文转义支持IE6========");
        System.out.println(JSON.toJSONString(xsd, SerializerFeature.BrowserCompatible));

        System.out.println("特殊字符转义========");
        System.out.println(JSON.toJSONString(xsd, SerializerFeature.DisableCheckSpecialChar));

        System.out.println("list为null转[]========");
        System.out.println(JSON.toJSONString(xsd, SerializerFeature.WriteNullListAsEmpty));

    }

@JSONField

注意：1、若属性是私有的，必须有set*方法。否则无法反序列化。

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.annotation.JSONField;
import com.alibaba.fastjson.serializer.SerializerFeature;
import lombok.Data;
import lombok.experimental.Accessors;

import java.util.Date;
import java.util.List;

@Data
@Accessors
public class TestCor {
    /**
     *     int ordinal() default 0  字段排序
     *     String name() default ""; 重命名
     *     String format() default ""; 格式化
     *     boolean serialize() default true; 是否序列化
     *     boolean deserialize() default true;是否反序列化
     *     SerializerFeature[] serialzeFeatures() default {}; 序列化枚举
     *     Feature[] parseFeatures() default {}; 控制反序列化的一些规则
     *     String label() default ""; 批量处理某一类的属性，比如不序列化某一类属性。
     *     boolean jsonDirect() default false; 可直接赋值为JSON  xxx="{'size':1}"
     *     Class<?> serializeUsing() default Void.class;  定制序列化
     *     Class<?> deserializeUsing() default Void.class; 定制反序列化
     *     String[] alternateNames() default {}; 反序列化时使用多个不同的字段名称  AJSON{"AField":1} BJSON{"BField":2}
     *                                          alternateNames={"AField","BField"}  那么2个key都会相应的赋值到当前字段
     *     boolean unwrapped() default false;  把子对象的内容放到父对象里面
     *     String defaultValue() default "";  默认值
     */
        @JSONField(ordinal = 3,label = "b")
        private Integer id=5;
        @JSONField(ordinal = 2,name = "othername",label = "a",alternateNames={"othername"})
        private String name="张";
        @JSONField(ordinal = 1,format = "yyyy-MM-dd",label = "a",deserialize =false)
        private Date format=new Date();
        @JSONField(ordinal = 4,jsonDirect = true)
        private String jsonDirect="{'size':1}";
        @JSONField(ordinal = 5,serializeUsing = NumberCon.class,label = "b",deserializeUsing =NumberConUn.class )
        private Double hight=175.2;
        @JSONField(ordinal = 6,serialzeFeatures = SerializerFeature.WriteNullListAsEmpty)
        private List list=null;
        @JSONField(ordinal = 7,defaultValue = "--")
        private String defaultValue;
        @JSONField(ordinal = 9,unwrapped = false)
        private Objs testCor2=new Objs();

        @JSONField(unwrapped = true)
        private Objs testCor1=new Objs();
        @Data
        @Accessors
        class Objs{
            private String childObj="childObj";
        }
    public static void main(String[] args) {
        TestCor t=new TestCor();
        System.out.println(JSON.toJSONString(t));

        String str="{\"childObj\":\"childObj\",\"format\":\"2021-06-29\",\"othername\":\"张\",\"id\":5,\"jsonDirect\":{\"size\":1},\"hight\":\"175.2CM\",\"list\":[],\"defaultValue\":\"--\",\"testCor2\":{\"childObj\":\"childObj\"}}";
        TestCor testCor = JSONObject.parseObject(str, TestCor.class);
        System.out.println(JSON.toJSONString(testCor,SerializerFeature.PrettyFormat));
    }

public class DecimalUtil extends JsonSerializer<BigDecimal> {
    @Override
    public void serialize(BigDecimal bigDecimal, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
        jsonGenerator.writeString(bigDecimal.setScale(2, RoundingMode.HALF_UP).toString());
//        jsonGenerator.writeNumber(bigDecimal.setScale(2));
    }
}

JSONPath

  public static void main(String[] args) {
        String str="{\"asd\":[{\"id\":1,\"name\":\"小明\"},{\"id\":2,\"name\":\"张3\"}]}";
        String str2="[{\"id\":1,\"name\":\"小明\"},{\"id\":2,\"name\":\"张3\"},{\"id\":3,\"name\":null}]";
        JSONObject json1=JSONObject.parseObject(str);
        JSONArray json2=JSONArray.parseArray(str2);
        //数组全部对象
        System.out.println(JSONPath.eval(json1, "$"));
        //访问数组
        System.out.println(JSONPath.eval(json2, "$"));
        //访问数组第一个
        System.out.println(JSONPath.eval(json2, "$[0]"));
        //访问数组第一个的id
        System.out.println(JSONPath.eval(json2, "$[0].id"));
        //访问数组下标0-1的id
        System.out.println(JSONPath.eval(json2, "$[0,1].id"));
        //访问对象非空过滤
        System.out.println(JSONPath.eval(json2, "$[?(name)]"));
        //过滤id>1
        System.out.print(JSONPath.eval(json2, "$[id>1]"));
        System.out.println(JSONPath.eval(json1, "$.asd[id>1]"));
        //过滤比较
        System.out.print(JSONPath.eval(json2, "$[name='张3']"));
        System.out.println(JSONPath.eval(json1, "$.asd[name='张3']"));
        //字符匹配
        System.out.print(JSONPath.eval(json2, "$[name like '%张%']"));
        System.out.println(JSONPath.eval(json1, "$.asd[name='张3']"));
        //in 包含
        System.out.print(JSONPath.eval(json2, "$[name in ('张三','张3')]"));
        System.out.println(JSONPath.eval(json1, "$.asd[name in ('张三','张3')]"));
        // 数组长度
        System.out.println(JSONPath.eval(json1, "$.asd.size()"));

    }