MyBatis报错 ：Failed to read external DTD 'mybatis-3-config.dtd'... http ... accessExternalDTD...

　　当前我的解决方式是在MyBatis源码基础上，因为需要修改一点点源码，如果不是使用源码则另寻它法。报错如图所示：

java.lang.ExceptionInInitializerError
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at org.junit.platform.commons.util.ReflectionUtils.newInstance(ReflectionUtils.java:500)
    at org.junit.jupiter.engine.execution.ConstructorInvocation.proceed(ConstructorInvocation.java:56)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:125)
    at org.junit.jupiter.api.extension.InvocationInterceptor.interceptTestClassConstructor(InvocationInterceptor.java:69)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:104)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:62)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:43)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:35)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:77)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.invokeTestClassConstructor(ClassBasedTestDescriptor.java:329)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.instantiateTestClass(ClassBasedTestDescriptor.java:276)
    at org.junit.jupiter.engine.descriptor.ClassTestDescriptor.instantiateTestClass(ClassTestDescriptor.java:77)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.instantiateAndPostProcessTestInstance(ClassBasedTestDescriptor.java:258)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$2(ClassBasedTestDescriptor.java:252)
    at java.util.Optional.orElseGet(Optional.java:267)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$3(ClassBasedTestDescriptor.java:251)
    at org.junit.jupiter.engine.execution.TestInstancesProvider.getTestInstances(TestInstancesProvider.java:29)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$prepare$0(TestMethodTestDescriptor.java:106)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:105)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:69)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$prepare$1(NodeTestTask.java:107)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.prepare(NodeTestTask.java:107)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:75)
    at java.util.ArrayList.forEach(ArrayList.java:1257)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80)
    at java.util.ArrayList.forEach(ArrayList.java:1257)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:229)
    at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$6(DefaultLauncher.java:197)
    at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:211)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:191)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:128)
    at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:69)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: org.apache.ibatis.exceptions.PersistenceException: 
### Error building SqlSession.
### Cause: org.apache.ibatis.builder.BuilderException: Error creating document instance.  Cause: org.xml.sax.SAXParseException; lineNumber: 3; columnNumber: 26; External DTD: Failed to read external DTD 'mybatis-3-config.dtd', because 'file' access is not allowed due to restriction set by the accessExternalDTD property.
    at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
    at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:80)
    at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:64)
    at wy.hanyufang.cn.mybatis.MyBatisApplication.<clinit>(MyBatisApplication.java:34)
    ... 63 more
Caused by: org.apache.ibatis.builder.BuilderException: Error creating document instance.  Cause: org.xml.sax.SAXParseException; lineNumber: 3; columnNumber: 26; External DTD: Failed to read external DTD 'mybatis-3-config.dtd', because 'file' access is not allowed due to restriction set by the accessExternalDTD property.
    at org.apache.ibatis.parsing.XPathParser.createDocument(XPathParser.java:263)
    at org.apache.ibatis.parsing.XPathParser.<init>(XPathParser.java:127)
    at org.apache.ibatis.builder.xml.XMLConfigBuilder.<init>(XMLConfigBuilder.java:82)
    at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:77)
    ... 65 more
Caused by: org.xml.sax.SAXParseException; lineNumber: 3; columnNumber: 26; External DTD: Failed to read external DTD 'mybatis-3-config.dtd', because 'file' access is not allowed due to restriction set by the accessExternalDTD property.
    at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:203)
    at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(ErrorHandlerWrapper.java:177)
    at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:400)
    at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:327)
    at com.sun.org.apache.xerces.internal.impl.XMLScanner.reportFatalError(XMLScanner.java:1472)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.dispatch(XMLDocumentScannerImpl.java:1157)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.next(XMLDocumentScannerImpl.java:1045)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:959)
    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:842)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:771)
    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:261)
    ... 68 more

　　1.方法一：（你可能会使用到的解决方法：https://blog.csdn.net/dingshuo168/article/details/103317453 ）

　　2. 最简单的方式，修改应用启动类的JVM，添加启动参数：缺点是如果使用Spring的@Test进行测试的，那么每次调用都要重新添加，非常烦～

-Djavax.xml.accessExternalDTD=all

　　3.直接修改源码，通过调试可以找到程序报错的位置（详细步骤就不写了...）

　　　　· myBatis配置加载和运行位置：

@RunWith(SpringRunner.class)
class MyBatisApplication {
    private static SqlSessionFactoryBuilder factoryBuilder;
    private static SqlSessionFactory sqlSessionFactory;
    private static Transaction transaction;
    private static Connection connection;
    static{
        //获取配置文件
        factoryBuilder = new SqlSessionFactoryBuilder();
        sqlSessionFactory = factoryBuilder.build(HanServerApplication.class.getClassLoader()
                .getResourceAsStream("mybatis-config.xml"));

        Environment environment = sqlSessionFactory.getConfiguration().getEnvironment();
        try {
            connection= environment.getDataSource().getConnection();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        transaction = new JdbcTransaction(connection);
    }

　　//程序调用位置
    @Test
    void test1() throws Exception{
        SimpleExecutor simpleExecutor = new SimpleExecutor(sqlSessionFactory.getConfiguration(),transaction);
        MappedStatement mapper = sqlSessionFactory.getConfiguration()
                .getMappedStatement("wy.hanyufang.cn.mybatis.dao.testMapper.selectByPrimaryKey");
        List<Object> objects = simpleExecutor.doQuery(mapper, 5075937, RowBounds.DEFAULT,
                SimpleExecutor.NO_RESULT_HANDLER, mapper.getBoundSql(5075937));

        System.out.println(JSON.toJSONString(objects));
    }
}

　　· 程序异常位置以及修改的位置（标红）：

　　　　解决办法就是：无论是读取 ...config.dtd 文件、还是读取 ...apper.dtd文件，都让它去读取项目resurce文件夹下的资源文件。

　　　　如下所示：

　　　　　　1.需要将 mybatis-3-config.dtd、mybatis-3-mapper.dtd 两个文件放到resource资源目录下。
　　　　　　　　http://mybatis.org/dtd/mybatis-3-config.dtd

　　　　　　　　http://mybatis.org/dtd/mybatis-3-mapper.dtd

　　　　　　　　如图：
 
　　　　　　　　　　

　　　　　　2.我添加了两行代码，并且修改了 if 判断：

  　　　　　　private static final String MYBATIS_CONFIG_SYSTEM_local = "config/mybatis-3-config.dtd";
  　　　　　　private static final String MYBATIS_MAPPER_SYSTEM_local = "config/mybatis-3-mapper.dtd";

　　　　　　如果需要读取 config.dtd 则让它去 MYBATIS_CONFIG_SYSTEM_local 路径下读取。
　　　　　　如果需要读取 mapper.dtd 则让它去 MYBATIS_MAPPER_SYSTEM_local 路径下读取。

package org.apache.ibatis.builder.xml;

import java.io.IOException;
import java.io.InputStream;
import java.util.Locale;

import org.apache.ibatis.io.Resources;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * Offline entity resolver for the MyBatis DTDs.
 *
 * @author Clinton Begin
 * @author Eduardo Macarron
 */
public class XMLMapperEntityResolver implements EntityResolver {

  private static final String IBATIS_CONFIG_SYSTEM = "ibatis-3-config.dtd";
  private static final String IBATIS_MAPPER_SYSTEM = "ibatis-3-mapper.dtd";
  private static final String MYBATIS_CONFIG_SYSTEM = "mybatis-3-config.dtd";
  private static final String MYBATIS_CONFIG_SYSTEM_local = "config/mybatis-3-config.dtd";
  private static final String MYBATIS_MAPPER_SYSTEM_local = "config/mybatis-3-mapper.dtd";
  private static final String MYBATIS_MAPPER_SYSTEM = "mybatis-3-mapper.dtd";

  private static final String MYBATIS_CONFIG_DTD = "org/apache/ibatis/builder/xml/mybatis-3-config.dtd";
  private static final String MYBATIS_MAPPER_DTD = "org/apache/ibatis/builder/xml/mybatis-3-mapper.dtd";

  /**
   * Converts a public DTD into a local one.
   *
   * @param publicId
   *          The public id that is what comes after "PUBLIC"
   * @param systemId
   *          The system id that is what comes after the public id.
   * @return The InputSource for the DTD
   *
   * @throws org.xml.sax.SAXException
   *           If anything goes wrong
   */
  @Override
  public InputSource resolveEntity(String publicId, String systemId) throws SAXException {
    try {
      if (systemId != null) {
        String lowerCaseSystemId = systemId.toLowerCase(Locale.ENGLISH);
        if (lowerCaseSystemId.contains(MYBATIS_CONFIG_SYSTEM) || lowerCaseSystemId.contains(IBATIS_CONFIG_SYSTEM)) {
          return getInputSource(MYBATIS_CONFIG_SYSTEM_local, publicId, systemId);
        } else if (lowerCaseSystemId.contains(MYBATIS_MAPPER_SYSTEM) || lowerCaseSystemId.contains(IBATIS_MAPPER_SYSTEM)) {
          return getInputSource(MYBATIS_MAPPER_SYSTEM_local, publicId, systemId);
        }
      }
      return null;
    } catch (Exception e) {
      throw new SAXException(e.toString());
    }
  }

  private InputSource getInputSource(String path, String publicId, String systemId) {
    InputSource source = null;
    if (path != null) {
      try {
        InputStream in = Resources.getResourceAsStream(path);
        source = new InputSource(in);
        source.setPublicId(publicId);
        source.setSystemId(systemId);
      } catch (IOException e) {
        // ignore, null is ok
      }
    }
    return source;
  }

}

　　3.修改后重新测试，完成，返回结果

　

Connected to the target VM, address: '127.0.0.1:51594', transport: 'socket'
11:58:29.803 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
11:58:29.840 [main] DEBUG org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
11:58:29.840 [main] DEBUG org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
11:58:29.840 [main] DEBUG org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
11:58:29.840 [main] DEBUG org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
11:58:33.785 [main] DEBUG org.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 688593710.

11:58:33.826 [main] DEBUG wy.hanyufang.cn.mybatis.dao.testMapper.selectByPrimaryKey - ==>  Preparing: select id, title, author from test where id = ?
11:58:33.887 [main] DEBUG wy.hanyufang.cn.mybatis.dao.testMapper.selectByPrimaryKey - ==> Parameters: 5075937(Integer)
11:58:33.934 [main] DEBUG wy.hanyufang.cn.mybatis.dao.testMapper.selectByPrimaryKey - <==      Total: 1
[{"author":"用户：3","id":5075937,"title":"hello world:2"}]