language:类“java.lang.Class”上的未知属性“language”

Question

我得到了以下错误：

java.lang.NoSuchMethodException: Unknown property 'language' on class 'class java.lang.Class'

使用的Rest调用: /Test/rest/Languages/insertobj/Japanese/Swedish%206

我正在使用: org.apache.commons.beanutils.PropertyUtils；

我确实在我的Languages类中有指定的属性'language‘，所以我不确定为什么它会抛出这个错误。当我这样声明它时，它就可以工作了：

Languages lanobj = new Lanaguages()；

//Languages类

public class Languages implements java.io.Serializable {
    private String language;
    private String displayName;

public Languages() {
        this.language = null;
        this.displayName = null;
    }


public Languages(String language, String displayName) {
    this.language = language;
    this.displayName = displayName;
}

public void setLanguageId(Long languageId) {
    this.languageId = languageId;
}

@Column(name = "language", nullable = false, length = 50)
public String getLanguage() {
    return this.language;
}

public void setLanguage(String language) {
    this.language = language;
}

@Column(name = "displayName", nullable = false, length = 50)
public String getDisplayName() {
    return this.displayName;
}

public void setDisplayName(String displayName) {
    this.displayName = displayName;
}

}

/资源管理器代码

@Path("{subResources}/insertobj/{language-id}/{displayname-id}")
//@POST 
@GET // Using get for the sake of making rest call with browser
@Produces(MediaType.TEXT_HTML)
public String getLanguageById(@PathParam("subResources") String id,
                            @PathParam("language-id") String language_id,
                            @PathParam("displayname-id") String displayname_id) 
{
    try{
        Class<?> c = Class.forName("com.test."+id);
        PropertyUtils.setProperty(c, "language",language_id);
        PropertyUtils.setProperty(c, "displayName",displayname_id);
        TransactionManager.createObject(c);     

    }catch (Exception exc){
        exc.printStackTrace();      
    }

}

//TransactionManager代码片段：

public static void createObject(Object entityObject) {
    Transaction tx = null;
    //SessionFactoryUtil.getInstance().openSession();
    Session session =  SessionFactoryUtil.openSession();
    try {
      tx = session.beginTransaction();        
      session.save(entityObject);         
      tx.commit();
    } 
    catch (RuntimeException e)
    {
      if (tx != null && tx.isActive())
      {
        try 
        {
            // Second try catch as the rollback could fail as well
            tx.rollback();
        } 
        catch (HibernateException e1) {
            //logger.debug(“Error rolling back transaction”);
        }
        // throw again the first exception
        throw e;
      }
    }
    finally
    {
        session.close();
    }
  }

Answer 1

setProperty需要一个实例，而您传递的是类，请参见documentation

Class<?> c = Class.forName("com.test."+id);
Language language = (Language)c.newInstance();
PropertyUtils.setProperty(language , "language",language_id);

要么特定地强制转换为Language，要么就将其保留为Object

Object object  = Class.forName("com.test."+id).newInstance();
PropertyUtils.setProperty(object, "language",language_id);

Answer 2

您正尝试在"com.test."+id的类对象上设置属性language。你需要创建一个这个类的实例来设置值。类似于：

try{
    Class<?> c = Class.forName("com.test."+id);
    Object o = c.newInstance();
    PropertyUtils.setProperty(o, "language",language_id);
    PropertyUtils.setProperty(o, "displayName",displayname_id);
    TransactionManager.createObject(o);     

}catch (Exception exc){
    exc.printStackTrace();      
}

c引用的类必须具有零参数构造函数，此代码才能工作。

Answer 3

因为您的类Languages没有定义默认的构造函数，所以beanutils无法执行reflection.make，确保您的类中定义了默认的构造函数。