poi-4.x中对加密excel文件(xlsx,xls)的解密，适用于JRE 8u111或更高版本
所使用的jar包： poi-4.0.1.jar poi-ooxml-4.0.1.jar poi-ooxml-schemas-4.0.1.jar poi-scratchpad-4.0.1.jar
/** * JCE * 此版本适用于JRE 8u111或更高版本。 */ private static void removeCryptographyRestrictions() { LOGGER.info("reflect analysis JceSecurity"); if (!isRestrictedCryptography()) { return; } try { /* * Do the following, but with reflection to bypass access checks: * * JceSecurity.isRestricted = false; JceSecurity.defaultPolicy.perms.clear(); * JceSecurity.defaultPolicy.add(CryptoAllPermission.INSTANCE); */ final Class<?> jceSecurity = Class.forName("javax.crypto.JceSecurity"); final Class<?> cryptoPermissions = Class.forName("javax.crypto.CryptoPermissions"); final Class<?> cryptoAllPermission = Class.forName("javax.crypto.CryptoAllPermission"); Field isRestrictedField = jceSecurity.getDeclaredField("isRestricted"); isRestrictedField.setAccessible(true); setFinalStatic(isRestrictedField, true); isRestrictedField.set(null, false); final Field defaultPolicyField = jceSecurity.getDeclaredField("defaultPolicy"); defaultPolicyField.setAccessible(true); final PermissionCollection defaultPolicy = (PermissionCollection) defaultPolicyField.get(null); final Field perms = cryptoPermissions.getDeclaredField("perms"); perms.setAccessible(true); ((Map<?, ?>) perms.get(defaultPolicy)).clear(); final Field instance = cryptoAllPermission.getDeclaredField("INSTANCE"); instance.setAccessible(true); defaultPolicy.add((Permission) instance.get(null)); } catch (final Exception e) { e.printStackTrace(); } } static void setFinalStatic(Field field, Object newValue) throws Exception { field.setAccessible(true); Field modifiersField = Field.class.getDeclaredField("modifiers"); modifiersField.setAccessible(true); modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL); field.set(null, newValue); } private static boolean isRestrictedCryptography() { // This simply matches the Oracle JRE, but not OpenJDK. return "Java(TM) SE Runtime Environment".equals(System.getProperty("java.runtime.name")); }