How does spring boot configure the JSON data format of the input and output parameters of the request

This article mainly introduces how spring boot configures the JSON data format of the input and output parameters of the request. It is introduced in great detail through the example code, which has a certain reference value for everyone's study or work. Friends in need can refer to it

Request input parameter data format configuration, taking date format as an example:

Edit date editor class:

import first.zxz.tools.DateUtil;
import java.beans.propertyeditorSupport;
/**
 * 日期编辑器
 *
 * @author zhangxz
 * @date 2019-11-12 20:01
 */
public class DateEditor extends propertyeditorSupport {
 /**
  * 是否将null转换为空字符串
  */
 private final boolean nullAsEmpty;
 public DateEditor() {
  this(true);
 }
 public DateEditor(boolean nullAsEmpty) {
  this.nullAsEmpty = nullAsEmpty;
 }
 @Override
 public void setAsText(String text) {
  if (text == null) {
   if (nullAsEmpty) {
    setValue("");
   } else {
    setValue(null);
   }
  } else {
   setValue(DateUtil.parse(text));
  }
 }

}

The date tools used are as follows:

public class DateUtil {

 private static final String DATE_FORMAT_1 = "yyyy-MM-dd";
 private static final String DATE_FORMAT_2 = "yyyy/MM/dd";
 private static final String DATE_FORMAT_3 = "yyyyMMdd";
 private static final String DATE_TIME_FORMAT_1 = DATE_FORMAT_1 + " HH:mm:ss";
 private static final String DATE_TIME_FORMAT_2 = DATE_FORMAT_2 + " HH:mm:ss";
 private static final String DATE_TIME_FORMAT_3 = DATE_FORMAT_3 + "HHmmss";

 //key为正则表达式，value为对应的日期格式
 private static final HashMap<String,String> DATE_REGEX_FORMATTER_MAP = new HashMap<>();

 static {
  DATE_REGEX_FORMATTER_MAP.put(DateRegexConst.DATE_1,DATE_FORMAT_1);
  DATE_REGEX_FORMATTER_MAP.put(DateRegexConst.DATE_2,DATE_FORMAT_2);
  DATE_REGEX_FORMATTER_MAP.put(DateRegexConst.DATE_3,DATE_FORMAT_3);
  DATE_REGEX_FORMATTER_MAP.put(DateRegexConst.DATE_TIME_1,DATE_TIME_FORMAT_1);
  DATE_REGEX_FORMATTER_MAP.put(DateRegexConst.DATE_TIME_2,DATE_TIME_FORMAT_2);
  DATE_REGEX_FORMATTER_MAP.put(DateRegexConst.DATE_TIME_3,DATE_TIME_FORMAT_3);
 }

 //提示语：所有可用的日期格式
 public static final String ALL_USABLE_DATE_FORMATS = DATE_REGEX_FORMATTER_MAP.values().toString() + "，以及时间戳；";

 /**
  * 根据输入的字符串，进行格式化，并输入日期数据
  * 注意：格式化之前，会进行null和空字符串过滤；格式化时，会去除字符串两端的空字符串
  *
  * @param formattedDateStr 日期字符串数据
  * @return java.util.Date
  * @author Zxz
  * @date 2019/11/6 15:07
  **/
 public static Date parse(String formattedDateStr) {
  if (formattedDateStr == null || formattedDateStr.trim().length() <= 0) {
   throw new StringEmptyException();
  }

  for (Map.Entry<String,String> entry : DATE_REGEX_FORMATTER_MAP.entrySet()) {
   if (formattedDateStr.trim().matches(entry.getKey())) {
    SimpleDateFormat simpleDateFormat = new SimpleDateFormat(entry.getValue());
    try {
     return simpleDateFormat.parse(formattedDateStr.trim());
    } catch (ParseException e) {
     e.printStackTrace();
     throw new DateFormatException();
    }
   }
  }

  try {
   Long aLong = Long.valueOf(formattedDateStr);
   return new Date(aLong);
  } catch (NumberFormatException e) {
   //格式不匹配
   throw new DateFormatException();
  }

 }
}

Add the editor to the web binding initialization configuration:

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.format.support.FormattingConversionService;
import org.springframework.validation.Validator;
import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
import simple.proj.zxz.play.config.editor.DateEditor;

import java.util.Date;

/**
 * 配置请求 bean数据接收格式，例如date格式
 *
 * @author zhangxz
 * @date 2019-11-12 19:56
 */

@Configuration
public class WebBindingInitializerConfig {

 /**
  * 配置请求入参数据格式，参考{@link simple.proj.zxz.play.config.editor.DateEditor}
  *
  * @param mvcConversionService mvc版本业务
  * @param mvcValidator   mvc校验器
  * @return org.springframework.web.bind.support.ConfigurableWebBindingInitializer
  * @author zhangxz
  * @date 2019/11/13 10:40
  */
 @Bean
 public ConfigurableWebBindingInitializer configurableWebBindingInitializer(FormattingConversionService mvcConversionService,Validator mvcValidator) {
  ConfigurableWebBindingInitializer initializer = new ConfigurableWebBindingInitializer();
  initializer.setConversionService(mvcConversionService);
  initializer.setValidator(mvcValidator);

  initializer.setpropertyeditorRegistrar(propertyeditorRegistry -> {
   //propertyeditor 非线程安全
   propertyeditorRegistry.registerCustomEditor(Date.class,new DateEditor());
  });
  return initializer;
 }
}

The date data format of the input parameter is configured. The date formats that can be received can be seen in the date tool class, including yyyy MM DD, timestamp, yyyy MM DD HH: mm: SS, etc.

Request parameter format configuration, including empty string, empty array, and date formatted output

Write an empty string sequencer:

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;

import java.io.IOException;

/**
 * 空字符串序列器
 *
 * @author zhangxz
 * @date 2019-11-12 22:05
 */
public class NullStringSerializer extends JsonSerializer {

 @Override
 public void serialize(Object o,JsonGenerator jsonGenerator,SerializerProvider serializerProvider)
   throws IOException,JsonProcessingException {
  jsonGenerator.writeString("");
 }
}

Write an empty array sequencer

/**
 * 空数组或集合序列器
 *
 * @author zhangxz
 * @date 2019-11-12 22:04
 */

public class NullArraySerializer extends JsonSerializer {

 @Override
 public void serialize(Object value,JsonGenerator jgen,SerializerProvider provider) throws IOException,JsonProcessingException {
  jgen.writeStartArray();
  jgen.writeEndarray();
 }
}

Write date sequencer

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;

import java.io.IOException;
import java.util.Date;

/**
 * 日期序列器
 *
 * @author zhangxz
 * @date 2019-11-12 23:01
 */
public class DateSerializer extends JsonSerializer {

 /**
  * 日期序列化方法，返回时间戳格式
  *
  * @param o     数值
  * @param jsonGenerator  json生成器
  * @param serializerProvider 序列器
  * @author zhangxz
  * @date 2019/11/13 10:41
  */
 @Override
 public void serialize(Object o,SerializerProvider serializerProvider) throws IOException {
  jsonGenerator.writeNumber(((Date) o).getTime());
 }
}

Write total sequencer

import com.fasterxml.jackson.databind.BeanDescription;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializationConfig;
import com.fasterxml.jackson.databind.ser.BeanPropertyWriter;
import com.fasterxml.jackson.databind.ser.BeanSerializerModifier;

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

/**
 * 总序列器
 *
 * @author zhangxz
 * @date 2019-11-12 22:07
 */

public class GeneralSerializer extends BeanSerializerModifier {

 //空数组
 private JsonSerializer _nullArraySerializer = new NullArraySerializer();
 //空字符串
 private JsonSerializer _nullStringSerializer = new NullStringSerializer();
 //日期类型
 private JsonSerializer dateSerializer = new DateSerializer();

 @Override
 public List<BeanPropertyWriter> changeProperties(SerializationConfig config,BeanDescription beanDesc,List<BeanPropertyWriter> beanProperties) {
  for (BeanPropertyWriter beanProperty : beanProperties) {
   if (isArrayType(beanProperty)) {
    beanProperty.assignNullSerializer(this._nullArraySerializer);
   } else if (isStringType(beanProperty)) {
    beanProperty.assignNullSerializer(this._nullStringSerializer);
   } else if (isDateType(beanProperty)) {
    beanProperty.assignSerializer(this.dateSerializer);
   }
  }
  return beanProperties;
 }

 private boolean isStringType(BeanPropertyWriter writer) {
  Class clazz = writer.getType().getRawClass();
  return clazz == String.class;
 }

 private boolean isDateType(BeanPropertyWriter writer) {
  return Date.class == writer.getType().getRawClass();
 }

 private boolean isArrayType(BeanPropertyWriter writer) {
  Class clazz = writer.getType().getRawClass();
  return clazz.isArray() || Collection.class.isAssignableFrom(clazz);
 }
}

Add the total sequencer to the web configuration:

import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import simple.proj.zxz.play.config.serializer.GeneralSerializer;

/**
 * @description: 配置jackson 序列器
 * @author: zhangxz
 * @create: 2019-11-12 22:02
 */

@Configuration
public class JacksonConfig {

 /**
  * 出参数据格式配置，参考类 {@link simple.proj.zxz.play.config.serializer.GeneralSerializer}
  *
  * @return org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
  * @author zhangxz
  * @date 2019/11/13 10:34
  */
 @Bean
 public MappingJackson2HttpMessageConverter mappingJacksonHttpMessageConverter() {

  final MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
  ObjectMapper mapper = converter.getObjectMapper();
  mapper.setSerializerFactory(mapper.getSerializerFactory().withSerializerModifier(new GeneralSerializer()));

  return converter;
 }
}

The request parameter output configuration is completed. The parameter output format is as follows: null string output is empty string, null array output is empty array, and date data format output is timestamp.

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