使用了Spring boot devtools, dozer轉換嵌套對象失敗解決記錄

業務背景:

添加商品以及價格,一個商品會有多個價格(針對不一樣用戶等級).

代碼:

先在controller中使用dozer將goodsForm-->Goods,而後保存商品, 以後遍歷商品價格列表,注入商品ID,接着保存商品價格.

GoodsForm:
List<GoodsPriceForm> priceList;
Goods:
List<GoodsPrice> priceList;

Controller:
Goods goods = BeanMapper.map(goodsForm, Goods.class);
save(goods);
goods.getPriceList().forEach(p->p.setGoodsId(goods.getId()));
save(goods.getPriceList());

在遍歷商品價格列表時報錯, 錯誤信息:

java.lang.ClassCastException: com.foo.goods.model.GoodsPrice cannot be cast to com.foo.goods.model.GoodsPrice
at com.foo.goods.service.GoodsService$$Lambda$11/310447431.accept(Unknown Source) ~[na:na]
at java.util.ArrayList.forEach(ArrayList.java:1249) ~[na:1.8.0_51]
at com.foo.goods.service.GoodsService.saveGoods(GoodsService.java:34) ~[classes/:na]

對這一異常描述有些摸不着頭腦, 經提醒有多是不一樣的類加載器加載致使, 在Eclipse debug模式中Expression視圖下,輸出了goods和goodsPrice的類加載器名

Goods: org.springframework.boot.devtools.restart.classloader.RestartClassLoader@41aa15ea
GoodsPrice:  sun.misc.Launcher$AppClassLoader@58644d46

果真涉及到不一樣的類加載器. 

嘗試了在pom.xml中註釋掉spring-boot-devtools, 再啓動後沒有上述異常. 但如何在保留devtools的狀況下解決該問題呢? 查詢官方文檔:

By default, any open project in your IDE will be loaded using the 「restart」 classloader, and any regular .jar file will be loaded using the 「base」 classloader. If you work on a multi-module project, and not each module is imported into your IDE, you may need to customize things. To do this you can create aMETA-INF/spring-devtools.properties file.

The spring-devtools.properties file can contain restart.exclude. and restart.include. prefixed properties. The include elements are items that should be pulled-up into the 「restart」 classloader, and the exclude elements are items that should be pushed down into the 「base」 classloader. The value of the property is a regex pattern that will be applied to the classpath.

因而在工程的resources目錄下添加了META-INF/spring-devtools.properties,內容爲

restart.include.dozer=/dozer-5.5.1.jar

即dozer代碼也使用RestartClassLoader,能夠解決上述問題.

補充:

在該工程中的Application類中有以下一段代碼

  @Bean
  public Mapper fooDozerBeanMapper() {
    DozerBeanMapper mapper = BeanMapper.getDozerBeanMapper();
    List<String> mappingFiles = Lists.newArrayList(mapper.getMappingFiles());
    mappingFiles.add("foo-dozer-custom-convert.xml");
    mapper.setMappingFiles(mappingFiles);
    return mapper;
  }

其中BeanMapper是依賴另外一個工程(bar), 當在Eclipse中關閉該依賴工程(bar)後, 會報錯

Caused by: java.lang.LinkageError: loader constraint violation: loader (instance of org/springframework/boot/devtools/restart/classloader/RestartClassLoader) previously initiated loading for a different type with name "org/dozer/DozerBeanMapper"
	at java.lang.ClassLoader.defineClass1(Native Method) ~[na:1.8.0_05]
	at java.lang.ClassLoader.defineClass(ClassLoader.java:760) ~[na:1.8.0_05]
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[na:1.8.0_05]

解決方法

修改spring-devtools.properties,再增長一個配置

restart.include.bar=/bar.jar
restart.include.dozer=/dozer-5.5.1.jar