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java-Spring MVC转换如何

2019-10-10 03:07:38  阅读:22  来源: 互联网

标签:java spring-mvc thymeleaf type-conversion converter



我的车辆服务包括零件清单.添加新服务不是问题,查看服务也不是问题,但是当我尝试实现编辑时,它不会预先选择零件列表.因此,考虑到这是Thymeleaf的问题,我发布了问题here.

我得到的答案是尝试实现spring转换服务.我只是这样做了(我认为),现在我需要帮助才能摆脱困境.问题在于,视图将服务中的零件实例与包含所有零件的partsAttribute零件形式的实例进行比较,并且从不使用转换器,因此它不起作用.我没有收到任何错误…在视图中,未选择零件.
在下面,您可以找到转换器,WebMVCConfig,PartRepository,ServiceController和带有百里香叶的html,供您参考.我究竟做错了什么???

转换器:

PartToString:

    public class PartToStringConverter implements  Converter<Part, String> {   
    /** The string that represents null. */
    private static final String NULL_REPRESENTATION = "null";

    @Resource
    private PartRepository partRepository;

    @Override
    public String convert(final Part part) {
        if (part.equals(NULL_REPRESENTATION)) {
                return null;
        }
        try {
          return part.getId().toString();
        }
        catch (NumberFormatException e) {
            throw new RuntimeException("could not convert `" + part + "` to an valid id");
        }
    }
}

StringToPart:

public class StringToPartConverter implements  Converter<String, Part> {   
        /** The string that represents null. */
        private static final String NULL_REPRESENTATION = "null";

        @Resource
        private PartRepository partRepository;

        @Override
        public Part convert(final String idString) {
            if (idString.equals(NULL_REPRESENTATION)) {
                    return null;
            }
            try {
              Long id = Long.parseLong(idString);
              return this.partRepository.findByID(id);
            }
            catch (NumberFormatException e) {
                throw new RuntimeException("could not convert `" + id + "` to an valid id");
            }
        }
    }

WebMvcConfig的相关部分:

@Configuration
public class WebMvcConfig extends WebMvcConfigurationSupport {
...
    @Bean(name="conversionService")
    public ConversionService getConversionService(){
        ConversionServiceFactoryBean bean = new ConversionServiceFactoryBean();
        bean.setConverters(getConverters());
        bean.afterPropertiesSet();
        ConversionService object = bean.getObject();
        return object;
    }
    private Set<Converter> getConverters() {
        Set<Converter> converters = new HashSet<Converter>();

        converters.add(new PartToStringConverter());
        converters.add(new StringToPartConverter());
        System.out.println("converters added");
        return converters;
    }
}

零件存储库如下所示:

@Repository
@Transactional(readOnly = true)
public class PartRepository {

protected static Logger logger = Logger.getLogger("repo");

    @PersistenceContext
    private EntityManager entityManager;

    @Transactional
    public Part update(Part part){
        try {
            entityManager.merge(part);
            return part;
        } catch (PersistenceException e) {
            return null;
        }
    }

    @SuppressWarnings("unchecked")
    public List<Part> getAllParts(){
        try {
            return entityManager.createQuery("from Part").getResultList();
        } catch (Exception e) {
            return new ArrayList<Part>();
        }
    }

    public Part findByID(Long id){
        try {
            return entityManager.find(Part.class, id);
        } catch (Exception e) {
            return new Part();
        }
    }
}

编辑ServiceController的一部分:

    @Controller
    @RequestMapping("/")
    public class ServisController {

        protected static Logger logger = Logger.getLogger("controller");

        @Autowired
        private ServisRepository servisRepository;
        @Autowired
        private ServisTypeRepository servisTypeRepo;
        @Autowired
        private PartRepository partRepo;
        @Autowired
        private VehicleRepository2 vehicleRepository;   

        /*-- **************************************************************** -*/
    /*--  Editing servis methods                                          -*/
    /*--                                                                  -*/
    /*-- **************************************************************** -*/

        @RequestMapping(value="/admin/servisi/editServis", method = RequestMethod.GET)
        public String getEditServis(@RequestParam(value="id", required=true) Long id, Model model){
            logger.debug("Received request to show edit page");

            List<ServisType> servisTypeList = servisTypeRepo.getAllST();
            List<Part> partList = partRepo.getAllParts();
            List<Part> selectedParts = new ArrayList<Part>();
            Servis s = servisRepository.getById(id);
            for (Part part : partList) {
                for (Part parts : s.getParts()) {
                    if(part.getId()==parts.getId()){
                        selectedParts.add(part);
                        System.out.println(part);
                    }
                }
            }
            s.setParts(selectedParts);

            logger.debug("radjeni dijelovi " + s.getParts().toString());
            logger.debug("radjeni dijelovi " + s.getParts().size());
            s.setVehicle(vehicleRepository.findByVin(s.getVehicle().getVin()));
            model.addAttribute("partsAtribute", partList);
            model.addAttribute("servisTypesAtribute", servisTypeList);
            model.addAttribute("servisAttribute", s);

            return "/admin/servis/editServis";
        }

        @RequestMapping(value="/admin/servisi/editServis", method = RequestMethod.POST)
        public String saveEditServis(@ModelAttribute("servisAttribute") @Valid Servis servis, BindingResult result){
            logger.debug("Received request to save edit page");
            if (result.hasErrors()) 
            {
                String ret = "/admin/servis/editServis";
                return ret;
            }

            servisRepository.update(servis);

            return "redirect:/admin/servisi/listServis?id="+servis.getVehicle().getVin();
        }
}

视图正确显示了服务,只是它没有预选零件.

editService:

<!DOCTYPE html SYSTEM "http://www.thymeleaf.org/dtd/xhtml1-strict-thymeleaf-spring3-3.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:th="http://www.thymeleaf.org">
<head th:include="fragments/common :: headFragment">
<title>Edit Vehicle Service</title>
</head>
<body>

<div th:include="fragments/common :: adminHeaderFragment"></div>

<div class="container">

<section id="object">
  <div class="page-header">
    <h1>Edit service</h1>
  </div>

<div class="row">

    <form action="#" th:object="${servisAttribute}"
        th:action="@{/admin/servisi/editServis}" method="post" class="form-horizontal well">

        <input type="hidden" th:field="*{vehicle.vin}" class="form-control input-xlarge" />
          <div class="form-group" th:class="${#fields.hasErrors('vehicle.vin')} ? 'form-group has-error' : 'form-group'">
          <label for="vehicle.licensePlate" class="col-lg-2 control-label">License Plate</label>
            <div class="col-lg-10">
                <input type="text" th:field="*{vehicle.licensePlate}" class="form-control input-xlarge" placeholder="License Plate" readonly="readonly"/>
              <p th:if="${#fields.hasErrors('vehicle.licensePlate')}" class="label label-danger" th:errors="*{vehicle.licensePlate}">Incorrect LP</p>
            </div>
          </div>    
          <div class="form-group" th:class="${#fields.hasErrors('serviceDate')} ? 'form-group has-error' : 'form-group'">
          <label for="serviceDate" class="col-lg-2 control-label">Servis Date: </label>
            <div class="col-lg-10">
              <input type="date" th:field="*{serviceDate}" class="form-control input-xlarge" placeholder="Servis Date" />
              <p th:if="${#fields.hasErrors('serviceDate')}" class="label label-danger" th:errors="*{serviceDate}">Incorrect Date</p>
            </div>
          </div>
          <div class="form-group" th:class="${#fields.hasErrors('serviceType.id')} ? 'form-group has-error' : 'form-group'">
          <label for="serviceType.id" class="col-lg-2 control-label">Vrsta Servisa</label>
            <div class="col-lg-10">
                <select th:field="*{serviceType.id}" class="form-control">
                <option th:each="servisType : ${servisTypesAtribute}" 
                        th:value="${servisType.id}" th:selected="${servisType.id==servisAttribute.serviceType.id}"
                        th:text="${servisType.name}">Vrsta Servisa</option>
                </select>
              <p th:if="${#fields.hasErrors('serviceType.id')}" class="label label-danger" th:errors="${serviceType.id}">Incorrect VIN</p>
            </div>
          </div>
          <div class="form-group" th:class="${#fields.hasErrors('parts')} ? 'form-group has-error' : 'form-group'">
          <label for="parts" class="col-lg-2 control-label">Parts</label>
            <div class="col-lg-10">
                <select class="form-control" th:field="*{parts}" multiple="multiple" >
                <option th:each="part : ${partsAtribute}" 
                        th:field="*{parts}"
                        th:value="${part.id}"
                        th:text="${part.Name}">Part name and serial No.</option>
                </select>
              <p th:if="${#fields.hasErrors('parts')}" class="label label-danger" th:errors="*{parts}">Incorrect part ID</p>
            </div>
          </div>
          <div class="form-group" th:class="${#fields.hasErrors('completed')} ? 'form-group has-error' : 'form-group'">
          <label for="completed" class="col-lg-2 control-label">Is service completed?</label>
            <div class="col-lg-10">
              <select th:field="*{completed}" class="form-control">
                <option value="true">Yes</option>
                <option value="false">No</option>
              </select>
              <p th:if="${#fields.hasErrors('completed')}" class="label label-danger" th:errors="*{completed}">Incorrect checkbox</p>
            </div>
          </div>
        <hr/>
          <div class="form-actions">
            <button type="submit" class="btn btn-primary">Edit Service</button>
            <a class="btn btn-default" th:href="@{/admin/servisi/listServis(id=${servisAttribute.vehicle.vin})}">Cancel</a>
          </div>
    </form>

</div>
</section>

<div class="row right">
  <a class="btn btn-primary btn-large" th:href="@{/admin/part/listPart}">Back to list</a>
</div> 

<div th:include="fragments/common :: footerFragment"></div>
</div>
<!-- /.container -->
<div th:include="fragments/common :: jsFragment"></div>

</body>
</html>

更新:
在Avnish的帮助下,我进行了几处更改,这就是我的回馈:

添加转换服务不起作用,因此在研究和阅读文档后,返回并更改了我的WebMvcConfig文件,因此代替了@Bean,我添加了此文件(我要做的就是查看WebMvcConfigurationSupport上的文档:

@Override
    protected void addFormatters(FormatterRegistry registry){
        registry.addFormatter(new PartTwoWayConverter());
    }

然后,我删除了转换器,仅制作了一个能起到神奇作用的格式化程序.请勿混淆名称,它是格式化程序:

public class PartTwoWayConverter implements Formatter<Part>{

    /** The string that represents null. */
    private static final String NULL_REPRESENTATION = "null";

    @Resource
    private PartRepository partRepository;

    public PartTwoWayConverter(){
        super();
    }

    public Part parse(final String text, final Locale locale) throws ParseException{
        if (text.equals(NULL_REPRESENTATION)) {
            return null;
        }
        try {
            Long id = Long.parseLong(text);
        // Part part = partRepository.findByID(id); // this does not work with controller
        Part part = new Part(); // this works
        part.setId(id);         // 
        return part;
        }
        catch (NumberFormatException e) {
            throw new RuntimeException("could not convert `" + text + "` to an valid id");
        }       
    }

    public String print(final Part part, final Locale locale){
        if (part.equals(NULL_REPRESENTATION)) {
            return null;
        }
        try {
            return part.getId().toString();
        }
        catch (NumberFormatException e) {
            throw new RuntimeException("could not convert `" + part + "` to an valid id");
        }
    }

}

然后,我编辑了HTML.无法解决百里香的问题,所以我这样做是这样的:

<div class="form-group" th:class="${#fields.hasErrors('parts')} ? 'form-group has-error' : 'form-group'">
      <label for="parts" class="col-lg-2 control-label">Parts</label>
        <div class="col-lg-10">
            <select class="form-control" id="parts" name="parts" multiple="multiple" >
            <option th:each="part : ${partsAtribute}" 
                    th:selected="${servisAttribute.parts.contains(part)}"
                    th:value="${part.id}"
                    th:text="${part.name}">Part name and serial No.</option>
            </select>
          <p th:if="${#fields.hasErrors('parts')}" class="label label-danger" th:errors="*{parts}">Incorrect part ID</p>
        </div>
      </div>

最后,在遇到许多麻烦和无法识别的转换错误后,更改了控制器更新方法:

@RequestMapping(value="/admin/servisi/editServis", method = RequestMethod.POST)
    public String saveEditServis(@ModelAttribute("servisAttribute") @Valid Servis servis, BindingResult result){
        logger.debug("Received request to save edit page");
        if (result.hasErrors()) 
        {
            logger.debug(result);
            String ret = "/admin/servis/editServis";
            return ret;
        }
        List<Part> list = new ArrayList<Part>();
        for (Part part : servis.getParts()) {
            list.add(partRepo.findByID(part.getId()));
        }
        Servis updating = servisRepository.getById(servis.getId());

        updating.setCompleted(servis.getCompleted());
        updating.setParts(list); // If just setting servis.getParts() it does not work
        updating.setServiceDate(servis.getServiceDate());
        updating.setServiceType(servis.getServiceType());

        servisRepository.update(updating);

        return "redirect:/admin/servisi/listServis?id="+servis.getVehicle().getVin();
    }

尽管这行得通,但我仍然不满意,因为这段代码看起来更像是修补程序,而不是适当的编码.仍然困惑为什么从partRepository返回Part无效.以及为什么百里香无法工作…如果有人可以将我送往正确的方向,我将不胜感激!

解决方法:

Thymeleaf使用Spring框架SelectedValueComparator.isSelected比较值(用于在选项html中包含selected =“ selected”标记),该框架固有地首先依赖于Java相等性.如果失败,则返回两个值的字符串表示形式.以下是其文档摘录

用于测试候选值是否与数据绑定值匹配的实用程序类.急于尝试通过多种途径来证明比较,以解决实例不平等,逻辑(基于字符串表示)的相等性和基于PropertyEditor的比较等问题.
提供了全面的比较数组,集合和映射的支持.
平等合同
对于单值对象,首先使用标准Java相等性测试相等性.因此,用户代码应努力实现Object.equals以加快比较过程.如果Object.equals返回false,则尝试进行详尽的比较,目的是证明平等而不是证明平等.
接下来,尝试比较候选值和绑定值的字符串表示形式.由于在显示给用户时两个值都将表示为字符串,因此在许多情况下这可能会导致结果为true.
接下来,如果候选值为字符串,则尝试将绑定值与将对应的PropertyEditor应用于候选的结果进行比较.该比较可以执行两次,一次是针对直接的String实例,然后是第一次的比较结果为false时,针对字符串表示形式.

对于您的特定情况,我会记下转换服务,以便将我的零件对象转换为字符串,如http://www.thymeleaf.org/doc/html/Thymeleaf-Spring3.html#configuring-a-conversion-service中的VarietyFormatter所述.发布此内容后,我将使用th:value =“ ${part}”并让SelectedValueComparator做比较对象的魔术,并在html中添加selected =“ selected”部分.

同样在我的设计中,我总是基于主键实现equals方法(通常是在所有其他实体都从其继承的顶级抽象实体上执行).这进一步增强了整个系统中域对象的自然比较.您是否在设计中做了类似的事情?

希望能帮助到你!!



标签:java,spring-mvc,thymeleaf,type-conversion,converter

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