fastjson是阿里巴巴的开源JSON解析库，它可以解析JSON格式的字符串，支持将Java Bean序列化为JSON字符串，也可以从JSON字符串反序列化到JavaBean。fastjson地址
引用
<!-- fastjson -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
</dependency>
下面例子中所使用的对象：
@Data
public class EmployeeVo implements Serializable {
private Long id;
private String name;
private Short sex;
private Date birthday;
private String telephone;
private BigDecimal salary;
private Boolean isOfficial;
private String hobby;
public String getAbc() {
return "abc方法";
}
}
默认序列化(JSON.toJSONString)
@Test
public void serializeTest() {
EmployeeVo employeeVo = new EmployeeVo();
employeeVo.setId(1000L)
.setName("haha")
.setBirthday(new Date())
.setSalary(new BigDecimal("19865.32"))
.setIsOfficial(true)
.setSex(new Short("0"))
.setTelephone("021-2546589");
String jsonStr = JSON.toJSONString(employeeVo);
log.info(jsonStr);
}
结果：
{"abc":"abc方法","birthday":1595037120123,"id":1000,"isOfficial":true,"name":"haha","salary":19865.32,"sex":0,"telephone":"021-2546589"}
默认反序列化(JSON.parseObject)
@Test
public void deserializeTest() {
String jsonStr = "{\"abc\":\"abc方法\",\"birthday\":1592872441001,\"id\":1000,\"isOfficial\":true,\"name\":\"haha\",\"salary\":19865.32,\"sex\":0,\"telephone\":\"021-2546589\"}";
EmployeeVo employeeVo = JSON.parseObject(jsonStr, EmployeeVo.class);
log.info(employeeVo.toString());
}
结果：EmployeeVo(id=1000, name=haha, sex=0, birthday=Tue Jun 23 08:34:01 CST 2020, telephone=021-2546589, salary=19865.32, isOfficial=true, hobby=null)
序列化个性化设置(SerializerFeature)
API接口：(JSON.toJSONString)
public static String toJSONString(Object object, SerializerFeature... features) {
return toJSONString(object, DEFAULT_GENERATE_FEATURE, features);
}
常用的SerializerFeature在jar包中com.alibaba.fastjson.serializer.SerializerFeature枚举中都有定义，常用的有如配置：
- SerializerFeature.SortField 按字段名称排序后输出，默认为false不排序
- SerializerFeature.PrettyFormat 结果是否格式化，默认为false不格式化
- SerializerFeature.WriteDateUseDateFormat 全局修改日期格式，默认为false不使用全局日期格式
- SerializerFeature.WriteMapNullValue 将空值属性输出为null，默认空值属性不输出
- SerializerFeature.WriteNullStringAsEmpty 将空值属性输出为“”(空字符串)，默认空值属性不输出
序列化过滤器设置(SerializeFilter)
SerializeFilter可以序列化前和后做一些定制，如PropertyFilter，PropertyPreFilter，BeforeFilter，AfterFilter，LabelFilter，NameFilter，ValueFilter
-
PropertyFilter 根据PropertyName和PropertyValue来判断是否序列化,接口定义如下：
public class SamplePropertyFilter implements PropertyFilter { /** * 根据 属性的name与value判断是否进行序列化 * * @param object * @param name * @param value * @return */ @Override public boolean apply(Object object, String name, Object value) { if("telephone".equals(name)){ return false; } return true; } }
-
AfterFilter 在序列化对象的所有属性之后执行某些操作
public class SampleAfterFilter extends AfterFilter { @Override public void writeAfter(Object object) { log.info("writeAfter==" + object); } }
使用：
@Test
public void propertyFilterTest() {
EmployeeVo employeeVo = new EmployeeVo();
employeeVo.setId(1000L).setName("haha").setBirthday(new Date()).setSalary(new BigDecimal("19865.32")).setIsOfficial(true).setSex(new Short("0")).setTelephone("021-2546589");
SamplePropertyFilter samplePropertyFilter = new SamplePropertyFilter();
SampleAfterFilter sampleAfterFilter = new SampleAfterFilter();
String jsonStr1 = JSON.toJSONString(employeeVo, new SerializeFilter[]{samplePropertyFilter, sampleAfterFilter});
// {"abc":"abc方法","birthday":1592873561942,"id":1000,"isOfficial":true,"name":"haha","salary":19865.32,"sex":0,"telephone":"021-2546589"}
log.info(jsonStr1);
}
自定义序列化、反序列化及@JSONField和@JSONType
-
自定义的序列化
// 将性别0和1序列化成“男”和“女” public class SexSerializer implements ObjectSerializer { @Override public void write(JSONSerializer serializer, Object object, Object fieldName, Type fieldType, int features) throws IOException { Short value = (Short) object; String text; if (value != null && value == 0) { text = "男"; } else { text = "女"; } serializer.write(text); } } -
自定义的反序列化
// 将性别“男”和“女”反序列化成0和1 public class SexDeserialize implements ObjectDeserializer { @Override public <T> T deserialze(DefaultJSONParser parser, Type type, Object fieldName) { String sex = parser.parseObject(String.class); if ("男".equals(sex)) { return (T) new Short("0"); } else { return (T) new Short("1"); } } @Override public int getFastMatchToken() { return 0; } }使用：配合@JSONField定义的属性上表示对该class适用
@JSONField(serializeUsing = SexSerializer.class, deserializeUsing = SexDeserialize.class) private Short sex;
-
@JSONField，标注在属性上，部分配置如下：
@Retention(RetentionPolicy.RUNTIME) @Target({ ElementType.METHOD, ElementType.FIELD, ElementType.PARAMETER }) public @interface JSONField { // 配置序列化和反序列化的顺序 int ordinal() default 0; // 指定字段的名称 String name() default ""; // 指定字段的格式，对日期格式有用 String format() default ""; // 是否序列化 boolean serialize() default true; // 是否反序列化 boolean deserialize() default true; // 字段级别的SerializerFeature SerializerFeature[] serialzeFeatures() default {}; Feature[] parseFeatures() default {}; // 给属性打上标签， 相当于给属性进行了分组 String label() default ""; boolean jsonDirect() default false; // 自定义的序列化类 Class<?> serializeUsing() default Void.class; // 自定义的反序列化类 Class<?> deserializeUsing() default Void.class; String[] alternateNames() default {}; boolean unwrapped() default false; } -
@JSONType，标注在类上面
@Retention(RetentionPolicy.RUNTIME) @Target({ ElementType.TYPE }) public @interface JSONType { boolean asm() default true; // 输出json的字段顺序 String[] orders() default {}; // 包含的字段 String[] includes() default {}; // 不包含的字段 String[] ignores() default {}; // 类级别的序列化特性定义 SerializerFeature[] serialzeFeatures() default {}; Feature[] parseFeatures() default {}; // 按字母顺序进行输出 boolean alphabetic() default true; Class<?> mappingTo() default Void.class; Class<?> builder() default Void.class; String typeName() default ""; String typeKey() default ""; Class<?>[] seeAlso() default{}; // 序列化类 Class<?> serializer() default Void.class; // 反序列化类 Class<?> deserializer() default Void.class; boolean serializeEnumAsJavaBean() default false; PropertyNamingStrategy naming() default PropertyNamingStrategy.CamelCase; Class<? extends SerializeFilter>[] serialzeFilters() default {}; }
泛型反序列化(TypeReference)
泛型反序列化是指反序列化结果的对象是一个泛型，如ResponseVO<BaseVo>
public class ResponseVO<T extends BaseVo> {
private int resultCode;
private BaseVo resultData;
}
public class EmployeeVo extends BaseVo {
// ...
}
如果对：{"resultCode":100,"resultData":{"abc":"abc方法","birthday":1595040655594,"id":1000,"isOfficial":true,"name":"haha","salary":19865.32,"sex":0,"telephone":"021-2546589"}} JSON串反序列化成ResponseVO<EmployeeVo>对象则需要：
ResponseVO<EmployeeVo> response = JSON.parseObject(jsonString, new TypeReference<ResponseVO<EmployeeVo>>(){});
综合API及相关概念
最全的JSON.toJSONString()方法：
public static String toJSONString(Object object, // 对象
SerializeConfig config, // 配置并记录每种Java类型对应的序列化类
SerializeFilter[] filters, // 序列化过滤器
String dateFormat, // 日期的格式化
int defaultFeatures, // 默认的格式化设置
SerializerFeature... features) {// 对于对输出的json做各种格式化设置
// ...
}
public static <T> T parseObject(String input, //json串
Type clazz, //对象clazz
ParserConfig config, //保存各种ObjectDeserializer
ParseProcess processor,//定制反序列化，类似于SerializeFilter
int featureValues,
Feature... features) {//反序列化的特性
// ...
}
网友评论