maven引用包冲突的时候，使用exclusion的方式解决：
以下为示例：

<!-- apache shiro 相关jar包 -->
        <dependency>
            <groupId>org.apache.shiro</groupId>
            <artifactId>shiro-web</artifactId>
            <version>${shiro.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.shiro</groupId>
            <artifactId>shiro-spring</artifactId>
            <version>${shiro.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.shiro</groupId>
            <artifactId>shiro-core</artifactId>
            <version>${shiro.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.shiro</groupId>
            <artifactId>shiro-aspectj</artifactId>
            <version>${shiro.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.shiro</groupId>
            <artifactId>shiro-cas</artifactId>
            <version>${shiro.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.shiro</groupId>
            <artifactId>shiro-ehcache</artifactId>
            <version>${shiro.version}</version>
            <exclusions>
                <exclusion>
                    <artifactId>ehcache-core</artifactId>
                    <groupId>net.sf.ehcache</groupId>
                </exclusion>
            </exclusions>
        </dependency>


        <dependency>
            <groupId>net.sf.ehcache</groupId>
            <artifactId>ehcache</artifactId>
            <version>2.7.6</version>
        </dependency>
        <dependency>
            <groupId>net.sf.ehcache</groupId>
            <artifactId>ehcache-jgroupsreplication</artifactId>
            <version>1.7</version>
            <exclusions>
                <exclusion>
                    <artifactId>ehcache-core</artifactId>
                    <groupId>net.sf.ehcache</groupId>
                </exclusion>
            </exclusions>
        </dependency>

exclusions写在dependency中