我是作者之一，所以答案可能有偏见。它是开源的(Apache 2.0)，但是插件不是免费的。如果你克隆并在本地构建它，你就不需要付费。

在Intellij IDEA上，ZenUML可以从Java代码生成序列图。

请登录https://plugins.jetbrains.com/plugin/12437-zenuml-support查看

源代码:https://github.com/ZenUml/jetbrains-zenuml

使用IntelliJ IDEA。要生成类图，选择package并按Ctrl + Alt + U:

默认情况下，它只显示类名，而不显示所有依赖项。要更改它:右键单击->显示类别…和显示依赖项:

要生成依赖关系图(UML部署图)，使用maven go View -> Tool Windows -> maven Projects，并按Ctrl + Alt + U:

结果:

此外，还可以生成更多其他图表。见文档。

我注意到Intellij的SequenceDiagram插件也是一个不错的选择。

有一个名为binarydoc的免费工具，它可以从Java方法的字节码(而不是源代码)生成UML序列图或控制流图(CFG)。

下面是为java方法java.net.AbstractPlainSocketImpl.getInputStream生成的示例图binarydoc:

方法控制流图:

方法的UML序列图:

ObjectAid UML Explorer

是我用的。它很容易从存储库安装:

Name:     ObjectAid UML Explorer
Location: http://www.objectaid.com/update/current

并生成相当不错的UML图:

网站描述:

The ObjectAid UML Explorer is different from other UML tools. It uses the UML notation to show a graphical representation of existing code that is as accurate and up-to-date as your text editor, while being very easy to use. Several unique features make this possible: Your source code and libraries are the model that is displayed, they are not reverse engineered into a different format. If you update your code in Eclipse, your diagram is updated as well; there is no need to reverse engineer source code. Refactoring updates your diagram as well as your source code. When you rename a field or move a class, your diagram simply reflects the changes without going out of sync. All diagrams in your Eclipse workspace are updated with refactoring changes as appropriate. If necessary, they are checked out of your version control system. Diagrams are fully integrated into the Eclipse IDE. You can drag Java classes from any other view onto the diagram, and diagram-related information is shown in other views wherever applicable.

您也可以尝试使用netbeans UML建模器。我用它来生成我在eclipse项目中使用的javcode。您甚至可以在netbeans中导入eclipse项目，并保持eclipse设置与netbeans项目设置同步。

我尝试了几个用于eclipse的UML建模器，但都不满意。它们要么不稳定，要么复杂，要么丑陋不堪。: -)