java.text.ParseException: Failed to parse date ["未知']

先把"未知"替换为""

直接new 出来的Gson 对象是无法解析为""的Date属性的,需要通过GsonBuilder来进行创建

Gson ignoreDateGson=new GsonBuilder().registerTypeAdapterFactory(new DateNullAdapterFactory<>()).create();

这个registerTypeAdapterFactory()方法就是添加自己的适配器,来对某些特定的类型进行处理.new 出来的这个DateNullAdapterFactory.class 需要自己写.

import java.util.Date;
 
import com.google.gson.Gson;
import com.google.gson.TypeAdapter;
import com.google.gson.TypeAdapterFactory;
import com.google.gson.reflect.TypeToken;
 
public class DateNullAdapterFactory<T> implements TypeAdapterFactory {
    
    @SuppressWarnings("unchecked")
    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
        Class<T> rawType = (Class<T>) type.getRawType();
        if (rawType != Date.class) {
            return null;
        }
        return (TypeAdapter<T>) new DateNullAdapter();
    }
}

import java.io.IOException;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.ParsePosition;
import java.util.Date;
import java.util.Locale;
 
import com.google.gson.Gson;
import com.google.gson.JsonSyntaxException;
import com.google.gson.TypeAdapter;
import com.google.gson.TypeAdapterFactory;
import com.google.gson.internal.bind.DateTypeAdapter;
import com.google.gson.internal.bind.util.ISO8601Utils;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;
import com.google.gson.stream.JsonWriter;
import com.zxtc.common.utils.StringUtils;
 
public class DateNullAdapter extends TypeAdapter<Date>{
    
      public static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
            @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
            @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
              return typeToken.getRawType() == Date.class ? (TypeAdapter<T>) new DateTypeAdapter() : null;
            }
          };
 
          private final DateFormat enUsFormat
              = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, Locale.US);
          private final DateFormat localFormat
              = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT);
 
          @Override public Date read(JsonReader in) throws IOException {
              
            if (in.peek() == JsonToken.NULL) {
              in.nextNull();
              return null;
            }
            String jsonStr = in.nextString();
            if(StringUtils.isBlank(jsonStr)) {
                return null;
            }else {
                return deserializeToDate(jsonStr);
            }
          }
 
          private synchronized Date deserializeToDate(String json) {
            try {
              return localFormat.parse(json);
            } catch (ParseException ignored) {
            }
            try {
              return enUsFormat.parse(json);
            } catch (ParseException ignored) {
            }
            try {
                return ISO8601Utils.parse(json, new ParsePosition(0));
            } catch (ParseException e) {
              throw new JsonSyntaxException(json, e);
            }
          }
 
          @Override public synchronized void write(JsonWriter out, Date value) throws IOException {
            if (value == null) {
              out.nullValue();
              return;
            }
            String dateFormatAsString = enUsFormat.format(value);
            out.value(dateFormatAsString);
          }
          
          
}

可能还会出现报错:Invalid time zone indicator

两种结合:

Gson gson = new GsonBuilder().registerTypeAdapterFactory(new DateNullAdapterFactory<>()).setDateFormat("yyyy-MM-dd HH:mm:ss").create();