How can I suppress java compiler warnings about Su

问题:

This question already has an answer here:

• Suppress javac warning “…is internal proprietary API and may be removed in a future release” 6 answers

I'm using the encode() method from the sun.misc.BASE64Encoder package. How do I suppress the compiler warnings that it generates?

sun.misc.BASE64Encoder is Sun proprietary API and may be removed in

And as a followup, why don't I see this warning in Eclipse?

回答1:

You could switch to a different Base64 implementation, e.g., http://commons.apache.org/codec/apidocs/org/apache/commons/codec/binary/Base64.html which is part of the Apache commons packages, which you might already have included in your classpath, or http://iharder.sourceforge.net/current/java/base64/ which you could just take the implementation and stick in your source tree if you don't want another Jar on the path.

回答2:

There is a totally undocumented way to suppress the sun proprietary API warnings! Add -XDignore.symbol.file to the javac command line.

I found this at http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6476630 (scroll all the way to the very last comment). We all need to think kind thoughts about "xfournet" who added that last comment!

回答3:

because you cannot disable this warning

回答4:

Eclipse does have a setting which (should) pick this up, see e.g. the desciption in the Eclipse 3.1 release notes:

Preferences → Java → Compiler → Errors/Warnings → Deprecated And Restricted API → Forbidden/Discouraged Reference

(and the project properties page to allow project-specific overrides of this setting)

回答5:

You can't switch them off, Eclipse simply filters them for you (if told to do so).

Quick interim fix on Linux:

javac *.java 2>&1 | pcregrep -v -M ".*Sun proprietary API.*\n.*\n.*\^"

2>&1 ... puts STDERR into STDOUT, so the pipeline "|" will work

pcregrep might or might not be present on your system - if not, use your package utility (e.g. on Debian, Ubuntu etc: "sudo apt-get install pcregrep")

The expression searches for the "Sun proprietary API" warning and the following two lines (containing the line and the "^" indicating the position of the error in the line).

I leave the "XY warnings." line in at the end, lest I forget there were warnings ;o) Note that if you have other warnings as well, the number reported there will of course not be correct :o)

NOTE also that standard "grep" does not work as well, because it can't span multiple lines.

回答6:

If you understand the inherent problems with using a proprietary API and decide to do it anyway, and if you are using maven, you might be interested in adding the following to your pom.xml file:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>2.3.2</version>
    <configuration>
        <compilerArgument>-XDignore.symbol.file</compilerArgument>
    </configuration>
</plugin>

回答7:

Encapsulate the call in a class which you place in a library jar on your classpath. Then the warning only shows when that library is recompiled.

回答8:

If you are using jdk 1.8 then you can use the below

java.util.Base64

回答9:

The javac option -Xlint:unchecked does do the trick: it disables the warnings, see the javac manual for details