[Java] Spring Boot 2.0 配置属性自定义转换的方法

package com.paderlol.spring.practice.properties.editor;
 
import com.paderlol.spring.practice.properties.pojo.movie;
import java.beans.propertyeditorsupport;
import lombok.extern.slf4j.slf4j;
import org.springframework.beans.propertyeditorregistrar;
import org.springframework.beans.propertyeditorregistry;
 
/**
 * @author pader propertyeditor 在不同的包下面
 */
@slf4j
public class custommovieeditor extends propertyeditorsupport
implements propertyeditorregistrar {
 
  @override
  public string getastext() {
  movie movie = (movie) getvalue();
  return movie == null ? "" : movie.getname();
  }
 
  @override
  public void setastext(string text) throws illegalargumentexception {
  log.info("继承[propertyeditorsupport]类,转换数据={}", text);
  string[] data = text.split("-");
  movie movie = movie.builder().name(data[0]
  .touppercase()).seat(integer.parseint(data[1]))
  .build();
  setvalue(movie);
  }
 
 
  @override
  public void registercustomeditors(propertyeditorregistry registry) {
  registry.registercustomeditor(movie.class,this);
  }
}

@bean
public customeditorconfigurer customeditorconfigurer() {
  customeditorconfigurer customeditorconfigurer = new customeditorconfigurer();   
   // 有两种注册方式 这是第一种
  customeditorconfigurer.setpropertyeditorregistrars( 
  new propertyeditorregistrar[]{ new custommovieeditor() });
   // 第二 种
  map<class<?>,class<? extends propertyeditor>> maps = new hashmap<>();
  maps.put(movie.class,custommovieeditor.class);
 
  return customeditorconfigurer;
}

//注意
@component
@configurationpropertiesbinding
public class stringtopersonconverter implements converter<string, person> {
 
  @override
  public person convert(string from) {
  log.info("使用[converter]接口,转换数据={}", from);
  string[] data = from.split(",");
  return person.builder().name(data[0]).age(integer.parseint(data[1])).build();
  }
}

• 以上两种实现方式结果,但是converter接口相比propertyeditor接口更加灵活一些,propertyeditor接口仅限于string转换,converter可以自定义别的,并且propertyeditor接口通常用于controller中的接收参数的转换。
  
• @configurationpropertiesbinding是限定符注解@qualifier的派生类而已,参考org.springframework.boot.context.properties.conversionservicededucer，以下是源代码片段
  

@autowired(required = false)
@configurationpropertiesbinding
public void setconverters(list<converter<?, ?>> converters) {
   this.converters = converters;
}
 
/**
* a list of custom converters (in addition to the defaults) to use when
* converting properties for binding.
* @param converters the converters to set
*/
@autowired(required = false)
@configurationpropertiesbinding
public void setgenericconverters(list<genericconverter> converters) {
this.genericconverters = converters;
 }

• formatter接口是不能对属性完成转换的,因为conversionservicededucer初始化的时候只获取genericconverter和converter接口
  
• 官方文档上还介绍了可以使用实现org.springframework.core.convert.conversionservice并且bean名称也必须叫conversionservice，不过大部分情况不推荐自己通过这种方式去实现这个接口,因为自己实现的conversionservice会替代默认的。具体参考conversionservicededucer源码：
  

public conversionservice getconversionservice() {
  try {
    //默认首先寻找bean名称叫conversionservice的conversionservice的bean类
    return this.applicationcontext.getbean(
      configurableapplicationcontext.conversion_service_bean_name,
      conversionservice.class);
  }
  catch (nosuchbeandefinitionexception ex) {
    //找不到就默认生成applicationconversionservice类
    return this.applicationcontext.getautowirecapablebeanfactory()
      .createbean(factory.class).create();
  }
}