org.argeo.slc.core/src/main/java/org/argeo/slc/logging/Log4jUtils.java

   1 package org.argeo.slc.logging;
   2
   3 import java.io.IOException;
   4 import java.io.InputStream;
   5 import java.util.Properties;
   6
   7 import org.apache.commons.io.IOUtils;
   8 import org.apache.log4j.LogManager;
   9 import org.apache.log4j.PropertyConfigurator;
  10 import org.argeo.slc.core.SlcException;
  11 import org.springframework.core.io.DefaultResourceLoader;
  12 import org.springframework.util.ResourceUtils;
  13 import org.springframework.util.SystemPropertyUtils;
  14
  15 public class Log4jUtils {
  16
  17         /**
  18          * Configure log4j based on properties, with the following priorities (from
  19          * highest to lowest):<br>
  20          * 1. System properties<br>
  21          * 2. configuration file itself
  22          */
  23         public static void initLog4j(String configuration) {
  24                 // clears previous configuration
  25                 shutDownLog4j();
  26
  27                 ClassLoader cl = Log4jUtils.class.getClassLoader();
  28                 Properties properties = new Properties();
  29                 if (configuration != null) {
  30                         InputStream in = null;
  31                         try {
  32                                 if (configuration
  33                                                 .startsWith(ResourceUtils.CLASSPATH_URL_PREFIX)) {
  34                                         String path = configuration
  35                                                         .substring(ResourceUtils.CLASSPATH_URL_PREFIX
  36                                                                         .length());
  37                                         in = cl.getResourceAsStream(path);
  38                                 } else {
  39                                         in = new DefaultResourceLoader(cl).getResource(
  40                                                         configuration).getInputStream();
  41                                 }
  42
  43                                 properties.load(in);
  44                         } catch (IOException e) {
  45                                 throw new SlcException("Cannot load properties from "
  46                                                 + configuration);
  47                         } finally {
  48                                 IOUtils.closeQuietly(in);
  49                         }
  50                 }
  51
  52                 // Overrides with System properties
  53                 overrideLog4jProperties(properties, System.getProperties());
  54
  55                 PropertyConfigurator.configure(properties);
  56         }
  57
  58         private static void overrideLog4jProperties(Properties target,
  59                         Properties additional) {
  60                 for (Object obj : additional.keySet()) {
  61                         String key = obj.toString();
  62                         if (key.startsWith("log4j.")) {
  63                                 if (!key.equals("log4j.configuration")) {
  64                                         String value = SystemPropertyUtils
  65                                                         .resolvePlaceholders(additional.getProperty(key));
  66                                         target.put(key, value);
  67                                 }
  68                         }
  69                 }
  70         }
  71
  72         public static void shutDownLog4j() {
  73                 LogManager.shutdown();
  74         }
  75
  76         private Log4jUtils() {
  77
  78         }
  79 }