Java分析讲解序列化与字典功能的序列化
两种解决方案
- 前端查询字典数据然后前端转码
- 后端查询字典值，然后再转码返回给前段。
本文及时针对方案2 进行的改进
目标：
在需要返回给前段的字段上添加指定的注解例如：@DictDesc 则根据该字段定义的值结合注解配置生成 xxxDesc字段并自动赋值为注解属性值所对应的字典描述；
具体使用的技术涉及到jackson序列化与反序列化，其他JSON工具包也类型的效果;
字典注解定义
@Inherited
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@JacksonAnnotationsInside
@jsonSerialize(using = DictDescSerializer.class)
@JsonDeserialize(using = DictDescDeserializer.class)
public @interface DictDesc {
Class<? extends Enum<? extends DictEnum>>[] enumType() default {};
String[] dictType() default {};
String defaultValue() default "";
boolean throwException() default false;
}该注解中定义了解析该注解需要序列化器与返序列化器：
@JsonSerialize(using = DictDescSerializer.class)
@JsonDeserialize(using = DictDescDeserializer.class)
字典序列化与返序列化器的实现
import com.fasterxml.jackson.core.JacksonException;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.BeanProperty;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.deser.ContextualDeserializer;
import com.aimilin.common.dict.annotation.DictDesc;
import com.aimilin.common.dict.service.impl.DictDescSerializerUtils;
import lombok.NoArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeanUtils;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.DefaultConversionService;
import java.beans.PropertyDescriptor;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.Objects;
@Slf4j
@NoArgsConstructor
public class DictDescDeserializer extends JsonDeserializer<Object> implements ContextualDeserializer {
private static final String LABEL_SUFFIX = "Desc";
private Class<?> rawClass;
private ConversionService converter;
private Method writeMethod;
private DictDesc dict;
public DictDescDeserializer(DictDesc dict, BeanProperty property) {
this.dict = dict;
this.rawClass = property.getType().getRawClass();
this.converter = new DefaultConversionService();
Class<?> targetClass = property.getMember().getDeclarinGClass();
String writeField = property.getName() + LABEL_SUFFIX;
PropertyDescriptor propertyDescriptor = BeanUtils.getPropertyDescriptor(targetClass, writeField);
this.writeMethod = Objects.isNull(propertyDescriptor) ? null : propertyDescriptor.getWriteMethod();
if (Objects.isNull(this.writeMethod)) {
log.info("类：{}，字典属性：{}，没有写入方法：{}，不设置值！", targetClass.getName(), property.getName(), writeField);
}
}
@Override
public JsonDeserializer<?> createContextual(DeserializationContext ctxt, BeanProperty property) throws JsonMappingException {
DictDesc dict = property.getAnnotation(DictDesc.class);
if (dict != null) {
return new DictDescDeserializer(dict, property);
}
return this;
}
@Override
public Object deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JacksonException {
Object result = this.getValue(p.getText());
this.setDictDesc(result, p.getCurrentName(), p.getCurrentValue());
return result;
}
public Object getValue(String value) throws IOException {
return converter.convert(value, this.rawClass);
}
private void setDictDesc(Object result, String currentName, Object currentValue) {
try {
if (this.writeMethod != null) {
writeMethod.invoke(currentValue, DictDescSerializerUtils.getDesc(this.dict, currentName, result));
}
} catch (Exception e) {
log.error("类：{}，字典属性：{}，回显异常：{}", currentValue.getClass(), currentName, e.getMessage(), e);
}
}
}import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.BeanProperty;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.ContextualSerializer;
import com.aimilin.common.dict.annotation.DictDesc;
import com.aimilin.common.dict.service.impl.DictDescSerializerUtils;
import lombok.NoArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import java.io.IOException;
@Slf4j
@NoArgsConstructor
public class DictDescSerializer extends JsonSerializer<Object> implements ContextualSerializer {
private static final String LABEL_SUFFIX = "Desc";
private DictDesc dict;
public DictDescSerializer(DictDesc dict) {
this.dict = dict;
}
@Override
public JsonSerializer<?> createContextual(SerializerProvider prov, BeanProperty property) throws JsonMappingException {
DictDesc dict = property.getAnnotation(DictDesc.class);
if (dict != null) {
return new DictDescSerializer(dict);
}
return this;
}
@Override
public void serialize(Object value, JsonGenerator gen, SerializerProvider provider) throws IOException {
provider.defaultSerializeValue(value, gen);
if (dict != null) {
String fieldName = gen.getOutputContext().getCurrentName();
// 添加转换之后的字段：xxxDesc
gen.writeStringField(fieldName.concat(LABEL_SUFFIX), DictDescSerializerUtils.getDesc(dict, fieldName, value));
}
}
}字典序列化与反序列工具类
import cn.hutool.extra.spring.SpringUtil;
import com.aimilin.common.core.pojo.system.SysDict;
import com.aimilin.common.dict.annotation.DictDesc;
import com.aimilin.common.dict.annotation.DictEnum;
import com.aimilin.common.dict.exception.DictException;
import com.aimilin.common.dict.exception.enums.DictExceptionEnum;
import com.aimilin.common.dict.service.SysDictService;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.collections4.CollectionUtils;
import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.StringUtils;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
@Slf4j
public class DictDescSerializerUtils {
public static String getDesc(DictDesc dict, String field, Object value) {
if (ArrayUtils.isEmpty(dict.dictType()) && ArrayUtils.isEmpty(dict.enumType())) {
throw new DictException(DictExceptionEnum.REQUEST_DICT_TYPE, field);
}
try {
if (value == null) {
throw new DictException(DictExceptionEnum.REQUEST_NOT_NULL, field);
}
if (ArrayUtils.isNotEmpty(dict.enumType())) {
return getEnumDesc(dict, field, value);
}
return getDictDesc(dict, field, value);
} catch (Exception e) {
log.error("字典转换异常, field:{}, enumType:{}, dictType:{}, 值：{}, 异常：{}",
field, dict.enumType(), dict.dictType(), value, e.getMessage(), e);
if (dict.throwException()) {
throw e instanceof DictException ? (DictException) e : new DictException(DictExceptionEnum.DICT_EXCEPTION, e);
}
return dict.defaultValue();
}
}
public static String getEnumDesc(DictDesc dict, String field, Object value) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
for (Class<? extends Enum<? extends DictEnum>> dictEnum : dict.enumType()) {
Method getCode = dictEnum.getMethod("getCode");
Method getMessage = dictEnum.getMethod("getMessage");
for (Enum<? extends DictEnum> e : dictEnum.getEnumConstants()) {
if (value.equals(getCode.invoke(e))) {
return Objects.toString(getMessage.invoke(e));
}
}
}
throw new DictException(DictExceptionEnum.UNKNOWN_ENUM_DICT_VALUE,
String.fORMat("Field:%s, EnumType: %s, Value: %s", field, Arrays.toString(dict.enumType()), value));
}
public static String getDictDesc(DictDesc dict, String field, Object value) {
if (ArrayUtils.isEmpty(dict.dictType())) {
throw new DictException(DictExceptionEnum.REQUEST_DICT_TYPE, field);
}
List<SysDict> sysDictList = SpringUtil.getBean(SysDictService.class).getDictByDictTypeCode(dict.dictType());
if (CollectionUtils.isEmpty(sysDictList)) {
throw new DictException(DictExceptionEnum.NO_DICT_DATA, field, Arrays.toString(dict.dictType()));
}
for (SysDict sysDict : sysDictList) {
if (StringUtils.equals(sysDict.getCode(), Objects.toString(value))) {
return sysDict.getValue();
}
}
throw new DictException(DictExceptionEnum.UNKNOWN_DICT_VALUE, field, Arrays.toString(dict.dictType()));
}
}字典转换服务类
public interface SysDictService {
public List<SysDict> getDictByDictTypeCode(String... dictTypeCodes);
}服务实现类：
@Service
public class SysDictServiceImpl implements SysDictService {
@Resource
private SystemContextServiceapi systemContextServiceApi;
@Resource
private SysDictCache sysDictCache;
@Override
public List<SysDict> getDictByDictTypeCode(String... dictTypeCodes) {
List<SysDict> dictTypeCache = sysDictCache.getDictTypeCache(dictTypeCodes);
if (CollectionUtils.isNotEmpty(dictTypeCache)) {
return dictTypeCache;
}
return systemContextServiceApi.getDictByDictTypeCode(dictTypeCodes).getData();
}
}字典缓存服务
可以修改为使用本地缓存方式
@Slf4j
@Service
public class SysDictCache {
@Resource
private RedisService redisService;
public List<SysDict> getDictTypeCache(String... dictTypes) {
if (Objects.isNull(redisService)) {
log.info("redisService 为空，不使用字典缓存");
return null;
}
List<List<SysDict>> dictValues = redisService.getMultiCacheMapValue(CommonConstant.DICT_CACHE_KEY, Arrays.asList(dictTypes));
if (CollectionUtils.isEmpty(dictValues)) {
return null;
}
List<SysDict> result = new ArrayList<>();
dictValues.stream().filter(Objects::nonNull).forEach(result::addAll);
log.debug("查询字典缓存，dictTypes:{}, 结果：{}", dictTypes, result);
return result;
}
public void cleanDictTypeCache(String... dictTypes) {
if (Objects.isNull(redisService)) {
return;
}
redisService.deleteCacheMapValue(CommonConstant.DICT_CACHE_KEY, dictTypes);
log.info("清除字典缓存，dictTypes:{}", StringUtils.join(dictTypes));
}
public void putDictTypeCache(List<SysDict> sysDictList) {
if (Objects.isNull(redisService) || CollectionUtils.isEmpty(sysDictList)) {
return;
}
Map<String, List<SysDict>> collect = sysDictList.stream().collect(Collectors.groupingBy(SysDict::getTypeCode));
for (Map.Entry<String, List<SysDict>> entry : collect.entrySet()) {
redisService.setCacheMapValue(CommonConstant.DICT_CACHE_KEY, entry.geTKEy(), entry.getValue());
log.info("设置字典缓存，dictType：{}，结果：{}", entry.getKey(), entry.getValue());
}
}
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