背景
微信退款接口需要使用到证书，我参考微信的官方Demo进行，部分代码如下：
char[] password = config.getMchID().toCharArray();InputStream certStream = config.getCertStream();KeyStore ks = KeyStore.getInstance("PKCS12");ks.load(certStream, password);上面的代码，在本地调试的时候正常跑过，没有出现任何异常，但是放到测试环境之后便会出现下面的异常，这三种异常都是从ks.load(certStream, password)这里抛出来的。定位这个问题花费了一些时间，且让我小小总结一下，供大家遇到相同问题时有个参考。
异常类型1
java.io.IOException: Short read of DER length at sun.security.util.DerInputStream.getLength(DerInputStream.java:582) at sun.security.util.DerValue.init(DerValue.java:391) at sun.security.util.DerValue.<init>(DerValue.java:332) at sun.security.util.DerValue.<init>(DerValue.java:345) at sun.security.pkcs12.PKCS12KeyStore.engineLoad(PKCS12KeyStore.java:1914) at java.security.KeyStore.load(KeyStore.java:1445) at com.lingyejun.authenticator.ReadPKCS12File$LoadCertInputStream.run(ReadPKCS12File.java:53) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748)异常类型2
java.io.IOException: DerInputStream.getLength(): lengthTag=7, too big. at sun.security.util.DerInputStream.getLength(DerInputStream.java:599) at sun.security.util.DerValue.init(DerValue.java:391) at sun.security.util.DerValue.<init>(DerValue.java:332) at sun.security.util.DerValue.<init>(DerValue.java:345) at sun.security.pkcs12.PKCS12KeyStore.engineLoad(PKCS12KeyStore.java:1914) at java.security.KeyStore.load(KeyStore.java:1445) at com.lingyejun.authenticator.ReadPKCS12File$LoadCertInputStream.run(ReadPKCS12File.java:53) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748)异常类型3
java.io.IOException: toDerInputStream rejects tag type 54 at sun.security.util.DerValue.toDerInputStream(DerValue.java:874) at sun.security.pkcs12.PKCS12KeyStore.engineLoad(PKCS12KeyStore.java:1915) at java.security.KeyStore.load(KeyStore.java:1445) at com.lingyejun.authenticator.ReadPKCS12File$LoadCertInputStream.run(ReadPKCS12File.java:53) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)结论：keyStore.load(InputStream stream, char[] password)中的InputStream在尝试加载的过程中，如果有其他的线程正在使用或者进行同样的读加载，那么就会抛出上面的异常。
模拟复现
package com.lingyejun.authenticator; import javax.net.ssl.KeyManagerFactory;import javax.net.ssl.SSLContext;import java.io.IOException;import java.io.InputStream;import java.security.*;import java.security.cert.CertificateException;import java.util.concurrent.ExecutorService;import java.util.concurrent.LinkedBlockingQueue;import java.util.concurrent.ThreadPoolExecutor;import java.util.concurrent.TimeUnit; /** * 模拟加载certStream问题 * * @Author: lingyejun * @Date: 2019/6/24 * @Describe: * @Modified By: */public class ReadPKCS12File { // 线程个数 private static final int THREAD_POOL_SIZE = 10; // 初始化线程池 private ExecutorService executorService = new ThreadPoolExecutor(THREAD_POOL_SIZE, THREAD_POOL_SIZE, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>()); // HTTPS证书的本地路径 private static final String CERT_LOCAL_PATH = "apiclient_cert.p12"; // HTTPS证书密码，默认密码等于商户号MCHID private static final String CERT_PASSWORD = "1509107311"; private static InputStream certStream = ReadPKCS12File.class.getClassLoader().getResourceAsStream(CERT_LOCAL_PATH); public static void main(String[] args) { ReadPKCS12File readPKCS12File = new ReadPKCS12File(); for (int threadNo = 0; threadNo < THREAD_POOL_SIZE; threadNo++) { readPKCS12File.executorService.execute(readPKCS12File.new LoadCertInputStream()); } readPKCS12File.executorService.shutdown(); } public class LoadCertInputStream implements Runnable { @Override public void run() { // 证书 char[] password = CERT_PASSWORD.toCharArray(); InputStream certStream = ReadPKCS12File.certStream; try { KeyStore ks = KeyStore.getInstance("PKCS12"); ks.load(certStream, password); // 实例化密钥库 & 初始化密钥工厂 KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm()); kmf.init(ks, password); // 创建 SSLContext SSLContext sslContext = SSLContext.getInstance("TLS"); sslContext.init(kmf.getKeyManagers(), null, new SecureRandom()); // 余下代码就不写了，，， System.out.println("初始化SSL成功！"); } catch (IOException e) { e.printStackTrace(); } catch (CertificateException e) { e.printStackTrace(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (UnrecoverableKeyException e) { e.printStackTrace(); } catch (KeyStoreException e) { e.printStackTrace(); } catch (KeyManagementException e) { e.printStackTrace(); } } }}知道问题之后，我们只需要将certStream由全局唯一更改为方法的局部变量即可
InputStream certStream = ReadPKCS12File.certStream改为
InputStream certStream = ReadPKCS12File.class.getClassLoader().getResourceAsStream(CERT_LOCAL_PATH)究其原因
微信的官方Demo中的，InputStream certStream = config.getCertStream()，这行代码把我给'误导'了，我是在外部读取的pkcs12文件输入流且config对象是单例的，导致多个线程共同访问这行代码时，certStream不能被正常加载，故出现了上面的问题。