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| <article class="doc"> |
| <h1 class="page">Log4j IOStreams</h1> |
| <div class="sect1"> |
| <h2 id="_log4j_iostreams"><a class="anchor" href="#_log4j_iostreams"></a>Log4j IOStreams</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>The IOStreams component is a |
| <a href="manual/api.html" class="xref page">Log4j API</a> |
| extension that provides numerous classes from |
| <a href="https://docs.oracle.com/javase/8/docs/api/java/io/package-summary.html"><code>java.io</code></a> |
| that can either write to a |
| <a href="javadoc/log4j-api/org/apache/logging/log4j/Logger.html"><code>Logger</code></a> |
| while writing to another <code>OutputStream</code> or <code>Writer</code>, or the contents read by an <code>InputStream</code> or <code>Reader</code> can be |
| <a href="https://www.enterpriseintegrationpatterns.com/patterns/messaging/WireTap.html">wiretapped</a> |
| by a <code>Logger</code>.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="_requirements"><a class="anchor" href="#_requirements"></a>Requirements</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>The Log4j IOStreams API extension requires the Log4j 2 API. |
| This component was introduced in Log4j 2.1.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="_usage"><a class="anchor" href="#_usage"></a>Usage</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>The main entry point for the IOStreams module is the builder class <code>IoBuilder</code>, and in particular, the <code>IoBuilder.forLogger()</code> methods. |
| One primary usage of this API extension is for setting up loggers in the JDBC API. |
| For example:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">PrintWriter logger = IoBuilder.forLogger(DriverManager.class) |
| .setLevel(Level.DEBUG) |
| .buildPrintWriter(); |
| DriverManager.setLogWriter(logger);</code></pre> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p>Using the <code>IoBuilder</code> class, there are a few more options that can be set. |
| In general, there are six primary classes one can build from it: <code>Reader</code>, <code>Writer</code>, <code>PrintWriter</code>, <code>InputStream</code>, <code>OutputStream</code>, and <code>PrintStream</code>. |
| 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.</p> |
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