JDK8版本过高引起MySQL连接失败：javax.net.ssl.SSLHandshakeException: No appropriate protocol

前几天发现一直跑的项目本地无法启动了：

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.17.jar:8.0.17]
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.17.jar:8.0.17]
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:827) ~[mysql-connector-java-8.0.17.jar:8.0.17]
	at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:447) ~[mysql-connector-java-8.0.17.jar:8.0.17]
	at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:237) ~[mysql-connector-java-8.0.17.jar:8.0.17]
	at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199) ~[mysql-connector-java-8.0.17.jar:8.0.17]
	at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:136) ~[HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:369) ~[HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:198) ~[HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:467) [HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:541) [HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) [HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) [HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.HikariDataSource$$FastClassBySpringCGLIB$$eeb1ae86.invoke(<generated>) [HikariCP-3.2.0.jar:na]

看到Communications link failure初步认为是超时了，网络问题导致的，但在解决了网络问题后发现依旧报相同的错，这就奇怪了，然后一条一条的看报错日志，找到：

javax.net.ssl.SSLHandshakeException: No appropriate protocol (protocol is disabled or cipher suites are inappropriate)
	at sun.security.ssl.HandshakeContext.<init>(HandshakeContext.java:171) ~[na:1.8.0_292]
	at sun.security.ssl.ClientHandshakeContext.<init>(ClientHandshakeContext.java:98) ~[na:1.8.0_292]
	at sun.security.ssl.TransportContext.kickstart(TransportContext.java:220) ~[na:1.8.0_292]
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:428) ~[na:1.8.0_292]
	at com.mysql.cj.protocol.ExportControlled.performTlsHandshake(ExportControlled.java:316) ~[mysql-connector-java-8.0.17.jar:8.0.17]
	at com.mysql.cj.protocol.StandardSocketFactory.performTlsHandshake(StandardSocketFactory.java:188) ~[mysql-connector-java-8.0.17.jar:8.0.17]
	at com.mysql.cj.protocol.a.NativeSocketConnection.performTlsHandshake(NativeSocketConnection.java:99) ~[mysql-connector-java-8.0.17.jar:8.0.17]
	at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:331) ~[mysql-connector-java-8.0.17.jar:8.0.17]
	... 68 common frames omitted

看到SSLHandshakeException，心里打起了问号？这个错误比较反常，最终网上找了一番，问题定位了：

JDK 8高版本导致的，之前用的1.8.0_281，前些天捣鼓Homebrew，发现JDK 8有新版本，就升级了1.8.0_292，然后发现项目无法启动了。

查看/Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home/jre/lib/security/java.security（Mac上；Windows同理，在jre/lib/security/java.security里面）发现：

# Example:
#   jdk.tls.disabledAlgorithms=MD5, SSLv3, DSA, RSA keySize < 2048
jdk.tls.disabledAlgorithms=SSLv3, TLSv1, TLSv1.1, RC4, DES, MD5withRSA, \
    DH keySize < 1024, EC keySize < 224, 3DES_EDE_CBC, anon, NULL, \
    include jdk.disabled.namedCurves

• 方法一：

  此处连接的MySQL，导致的报错，修改jdbcUrl，在其后面加useSSL=false后运行正常

• 方法二：

  删除SSLv3, TLSv1, TLSv1.1并保存java.security文件，重启项目即可解决问题，删除后此处为：

  # Example:
  #   jdk.tls.disabledAlgorithms=MD5, SSLv3, DSA, RSA keySize < 2048
  jdk.tls.disabledAlgorithms=RC4, DES, MD5withRSA, \
      DH keySize < 1024, EC keySize < 224, 3DES_EDE_CBC, anon, NULL, \
      include jdk.disabled.namedCurves
  

• 方法三：

  降低JDK版本，这个相当也容易操作，比如可以从1.8.0_292降到1.8.0_281，甚至是1.8.0_275版本，但个人不建议，因为Oracle对JDK 8的支持一直会到2030年：

即使很长一段时间用JDK 8，但JDK 8本身也是有小版本迭代的，比如你明年换了电脑，安装JDK，基本是1.8.0_292之后的版本，那这个问题会一直存在

• 方法四：

  方法一 能解决由SSL调用权限导致的所有问题，但破坏了安全性
  方法二 针对MySQL的问题，可以快速解决
  方法三 不推荐

  因此，碰到类似问题，基本的思路是兼容JDK 8高版本甚至JDK高版本，比如代码层面的：

  private Socket overrideTlsProtocol(final Socket socket) {
      if (!(socket instanceof SSLSocket)) {
          throw new RuntimeException("Error, an instance of SSLSocket is expected");
      }
      ((SSLSocket) socket).setEnabledProtocols(new String[]{"SSLv3"});
      return socket;
  }
  

  修改为：

  private Socket overrideTlsProtocol(final Socket socket) {
      if (!(socket instanceof SSLSocket)) {
          throw new RuntimeException("Error, an instance of SSLSocket is expected");
      }
      ((SSLSocket) socket).setEnabledProtocols(new String[]{"SSLv3", "TLSv1","TLSv1.1"});
      return socket;
  }
  

有问题直面问题、解决问题，不要拍折腾，经常捣鼓这些东西，相信你也会受益匪浅，希望对你有所帮助～😄😄😄