Catching multiple types of exceptions when writing JSON
It is okay to just catch Exception and print the stack trace.
However rather than catching the top level Exception class, you may want to look at the Java 7 exception handling: http://docs.oracle.com/javase/7/docs/technotes/guides/language/catch-multiple.html

In your case:

try {
    mapper.writeValue(outStream, myVal);
} catch (JsonGenerationException | JsonMappingException | IOException e) {
    e.printStackTrace();
}