总结/朱季谦

业余在一个SpringBoot项目集成Swagger2时，启动过程一直出现以下报错信息——

An attempt was made to call a method that does not exist. The attempt was made from the following location:

​ springfox.documentation.schema.DefaultModelDependencyProvider.dependentModels(DefaultModelDependencyProvider.java:79)

The following method did not exist:

​ com.google.common.collect.FluentIterable.concat(Ljava/lang/Iterable;Ljava/lang/Iterable;)Lcom/google/common/collect/FluentIterable;

The method's class, com.google.common.collect.FluentIterable, is available from the following locations:

​ jar:file:/C:/Users/92493/.m2/repository/com/google/guava/guava/18.0/guava-18.0.jar!/com/google/common/collect/FluentIterable.class

The class hierarchy was loaded from the following locations:

​ com.google.common.collect.FluentIterable: file:/C:/Users/92493/.m2/repository/com/google/guava/guava/18.0/guava-18.0.jar

Action:

Correct the classpath of your application so that it contains a single, compatible version of com.google.common.collect.FluentIterable

出现这个问题，大概猜测到，应该是Maven依赖冲突导致的，忽然想到，是否有可以检查maven依赖冲突的插件呢，一查发现还真有，而且极方便。

这个Idea插件，叫Maven Helper，根据File -> Settings -> Plugins -> Marketplace 输入Maven Helper即可找到。
 

下载后，重启IDEA，这时点击pom.xml文件，会发现多了一栏【Dependency Analyzer】——

切换至【Dependency Analyzer】栏，在搜索框输入冲突包guava，即会出现，guava都被哪些包依赖了，当多个组件包都依赖了同一个包但又不同版本时，很容易久出现各种冲突。红色部分即是导致启动报异常的地方，可见，springfox-core已经依赖的是20.0包，但其他还依赖18版本的包，这里可以把报错提示的18.0版本的通过exclusion去除即可。

选中对应想去除的包，右击即可一键exclusion——

再切换至Text栏，即可发现已经自动增加了exclusions模块——

<dependency>
    <groupId>io.shardingsphere</groupId>
    <artifactId>sharding-jdbc-spring-namespace</artifactId>
    <version>3.1.0</version>
    <exclusions>
        <exclusion>
            <artifactId>guava</artifactId>
            <groupId>com.google.guava</groupId>
        </exclusion>
    </exclusions>
</dependency>