IDEA 搭建mybatis程序时，运行时出现下面的报错：
org.apache.ibatis.exceptions.PersistenceException: ### Error building SqlSession. ### The error may exist in mapper/UserMapper.xml ### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error creating document instance. Cause: com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException: 2 字节的 UTF-8 序列的字节 2 无效。 at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30) at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:52) at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:36) at Test.UserTest.userFindByIdTest(UserTest.java:28) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68) at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33) at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230) at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58) Caused by: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error creating document instance. Cause: com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException: 2 字节的 UTF-8 序列的字节 2 无效。 at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:121) at org.apache.ibatis.builder.xml.XMLConfigBuilder.parse(XMLConfigBuilder.java:98) at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:50) ... 24 more Caused by: org.apache.ibatis.builder.BuilderException: Error creating document instance. Cause: com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException: 2 字节的 UTF-8 序列的字节 2 无效。 at org.apache.ibatis.parsing.XPathParser.createDocument(XPathParser.java:260) at org.apache.ibatis.parsing.XPathParser.<init>(XPathParser.java:126) at org.apache.ibatis.builder.xml.XMLMapperBuilder.<init>(XMLMapperBuilder.java:80) at org.apache.ibatis.builder.xml.XMLConfigBuilder.mapperElement(XMLConfigBuilder.java:373) at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:119) ... 26 more Caused by: com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException: 2 字节的 UTF-8 序列的字节 2 无效。 at com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.invalidByte(UTF8Reader.java:701) at com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.read(UTF8Reader.java:372) at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.load(XMLEntityScanner.java:1895) at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.scanData(XMLEntityScanner.java:1375) at com.sun.org.apache.xerces.internal.impl.XMLScanner.scanComment(XMLScanner.java:801) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanComment(XMLDocumentFragmentScannerImpl.java:1034) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:899) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:602) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:505) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:841) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:770) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141) at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:243) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339) at org.apache.ibatis.parsing.XPathParser.createDocument(XPathParser.java:258)
1.错误原因及解决办法
（1）xml文件编码设置问题
打开你的xml文件，查看编码是不是UTF-8
（2）xml文件中出现其他符号
这个一般是因为你复制代码的时候复制了一些多余的空格，或者其他的中文字符，删除掉所有的中文字符，建议把注释的中文字符也都删掉。
虽然是注释，不影响结论，但是建议删掉，有的时候会有一些奇奇怪怪的报错。