tomcat 7 源码分析-1 关于读取properties及注册系统properties

Tomact的启动开始于Bootstrap.java，在其init()中，首先要做的就是

        setCatalinaHome();
        setCatalinaBase();
initClassLoaders();

 目的就是将tomcat启动的环境设置好，在进行classloader。

  private void setCatalinaHome() {

        if (System.getProperty("catalina.home") != null)
            return;
        File bootstrapJar = 
            new File(System.getProperty("user.dir"), "bootstrap.jar");
        if (bootstrapJar.exists()) {
            try {
                System.setProperty
                    ("catalina.home", 
                     (new File(System.getProperty("user.dir"), ".."))
                     .getCanonicalPath());
                
            } catch (Exception e) {
                // Ignore
                System.setProperty("catalina.home",
                                   System.getProperty("user.dir"));
            }
        } else {
            System.setProperty("catalina.home",
                               System.getProperty("user.dir"));
        }
    }

 判断user.dir\bootstrap.jar存在否来设置catalina.home。

 

在initClassLoaders();中调用createClassLoader。loader class之前又要读取properties，于是看String value = CatalinaProperties.getProperty(name + ".loader");

 

public class CatalinaProperties {


    // ------------------------------------------------------- Static Variables

    private static final org.apache.juli.logging.Log log=
        org.apache.juli.logging.LogFactory.getLog( CatalinaProperties.class );

    private static Properties properties = null;


    static {

        loadProperties();

    }


    // --------------------------------------------------------- Public Methods


    /**
     * Return specified property value.
     */
    public static String getProperty(String name) {
	
        return properties.getProperty(name);

    }


    /**
     * Return specified property value.
     */
    public static String getProperty(String name, String defaultValue) {

        return properties.getProperty(name, defaultValue);

    }


    // --------------------------------------------------------- Public Methods


    /**
     * Load properties.
     */
    private static void loadProperties() {

        InputStream is = null;
        Throwable error = null;

        try {
            String configUrl = getConfigUrl();
            if (configUrl != null) {
                is = (new URL(configUrl)).openStream();
            }
        } catch (Throwable t) {
            ExceptionUtils.handleThrowable(t);
        }

        if (is == null) {
            try {
                File home = new File(getCatalinaBase());
                File conf = new File(home, "conf");
                File properties = new File(conf, "catalina.properties");
                is = new FileInputStream(properties);
            } catch (Throwable t) {
                ExceptionUtils.handleThrowable(t);
            }
        }

        if (is == null) {
            try {
                is = CatalinaProperties.class.getResourceAsStream
                    ("/org/apache/catalina/startup/catalina.properties");
            } catch (Throwable t) {
                ExceptionUtils.handleThrowable(t);
            }
        }

        if (is != null) {
            try {
                properties = new Properties();
                properties.load(is);
                is.close();
            } catch (Throwable t) {
                error = t;
            }
        }

        if ((is == null) || (error != null)) {
            // Do something
            log.warn("Failed to load catalina.properties", error);
            // That's fine - we have reasonable defaults.
            properties=new Properties();
        }

        // Register the properties as system properties
        Enumeration<?> enumeration = properties.propertyNames();
        while (enumeration.hasMoreElements()) {
            String name = (String) enumeration.nextElement();
            String value = properties.getProperty(name);
            if (value != null) {
                System.setProperty(name, value);
            }
        }

    }


    /**
     * Get the value of the catalina.home environment variable.
     */
    private static String getCatalinaHome() {
        return System.getProperty("catalina.home",
                                  System.getProperty("user.dir"));
    }
    
    
    /**
     * Get the value of the catalina.base environment variable.
     */
    private static String getCatalinaBase() {
        return System.getProperty("catalina.base", getCatalinaHome());
    }


    /**
     * Get the value of the configuration URL.
     */
    private static String getConfigUrl() {
        return System.getProperty("catalina.config");
    }


}

 CatalinaProperties 的核心是静态函数loadProperties()，在这里读取真正意义上的properties并注册