[Java] [Microsoft] Things to be aware of when including the JDBC driver for SQL Server in one jar

First stage

Maven Shade Plugin That's convenient. You can start the program with a single jar file without writing a lengthy classpath.

It happened when I tried to put the JDBC driver of Microsoft SQL Server in such a jar file.

What i did

• I downloaded sqljdbc4.jar and stored it in my local Maven repository.
• Described the dependency on sqljdbc4.jar in pom.xml.
• The shade plugin is now combined into one jar.

What happened

When I ran it, it failed with this error.

Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.SecurityException: Invalid signature file digest for Manifest main attributes 

People with the same problem → https://social.msdn.microsoft.com/Forums/sqlserver/en-US/f5c69fee-8c68-4601-bfcb-376e21dfa809/sql-server-jdbc-javalangsecurityexception-invalid-signature-file- digest? forum = sqldataaccess

Cause

Is it because the signature is in sqljdbc4.jar? ↑ I don't understand at all.

solution

Do not include the signature file (?) Included in sqljdbc4.jar in the final jar.

pom.xml

(snip)
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
（snip）
                <configuration>
                    <filters>
                        <filter>
                            <artifact>*:*</artifact>
                            <excludes>
                                <exclude>META-INF/*.SF</exclude>
                                <exclude>META-INF/*.DSA</exclude>
                                <exclude>META-INF/*.RSA</exclude>
                            </excludes>
                        </filter>
(snip)

One by one

You have to understand how Java handles and executes jar files. .. ..