org.xml.sax.SAXParseException: schema_reference.4: Failed to read schema document 'http://code.alibabatech.com/schema/dubbo/dubbo.xsd', because 1) could not find the document; 2) the document could not be read; 3) the root element of the document is not <xsd:schema>.
解決方案
下載dubbo.xsd文件並將改文件添加到XML catalog element 中key值為xml文件中的連接，location為下載的文件路徑
如果還不行進行如下操作
解決方案：
添加dubbo框架的jar包
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
<version>2.5.5</version>
</dependency>