Java编译器如何允许此类定义

Question

I am deeply investigating Java EE world. Application server manifacturers announced new versions even after Java EE released new specs. I know that all spec implemantations exist in Application Server Lib and compiled war file does not need that jar additionally. In addition to that, while developing a JAVA EE lets say web project we need following dependecy

    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-api</artifactId>
        <version>6.0</version>
    </dependency>

when looked at javaee-api-6.0.jar you can realise that it is just 957KB, in other words it consists of class method definitions.

With the fact that above I have decompiled one of the class file in javaee-api-6.0.jar and here is the one: I was expecting all class files should be interfaces and abstract. But it is not. And What I want to understand is that how compiler allows such Java Class having method definition like:

public ActivationDataFlavor(Class paramClass, String paramString1, String paramString2);

Decompiled Class File:

package javax.activation;

import java.awt.datatransfer.DataFlavor;

public class ActivationDataFlavor extends DataFlavor
{
  private String mimeType;
  private MimeType mimeObject;
  private String humanPresentableName;
  private Class representationClass;

  public ActivationDataFlavor(Class paramClass, String paramString1, String paramString2);

  public ActivationDataFlavor(Class paramClass, String paramString);

  public ActivationDataFlavor(String paramString1, String paramString2);

  public String getMimeType();

My Java Compiler give such error that all you are expecting.

I do not think that java compiler does not work properly since all class file is just 1KB.

Answer 1

This jar only exist to fit compile dependency, isn't expected to run in jvm. so all bytecode is stripped, the decompiler can't work properly in this case.

https://java.net/jira/browse/GLASSFISH-11389