## Log4j IOStreams The IOStreams component is a Log4j API extension that provides numerous classes from java.io that can either write to a Logger while writing to another `OutputStream` or `Writer`, or the contents read by an `InputStream` or `Reader` can be wiretapped by a `Logger`. ## Requirements The Log4j IOStreams API extension requires Java 6 and the Log4j API. This component was introduced in Log4j 2.1. ## Usage The main entry point for the IOStreams module is the builder class IoBuilder, and in particular, the `IoBuilder.forLogger()` methods. One primary usage of this API extension is for setting up loggers in the JDBC API. For example:
    PrintWriter logger = IoBuilder.forLogger(DriverManager.class)
                                  .setLevel(Level.DEBUG)
                                  .buildPrintWriter();
    DriverManager.setLogWriter(logger);
Using the `IoBuilder` class, there are a few more options that can be set. In general, there are six primary classes one can build from it: `Reader`, `Writer`, `PrintWriter`, `InputStream`, `OutputStream`, and `PrintStream`. The input-oriented classes are for wiretapping, and the output-oriented classes are for creating either an output class that solely outputs its lines as log messages, or an output filter class that logs all lines output through it to its delegate output class.