Java 解析 xml 之 Digester

看了Tomcat的源代码，发现Tomcat是通过Digester方式来解析server.xml的

Catalina中：

/**
 * Create and configure the Digester we will be using for startup.
 */
protected Digester createStartDigester() {
    long t1=System.currentTimeMillis();
    // Initialize the digester
    Digester digester = new Digester();
    digester.setValidating(false);
    digester.setRulesValidation(true);
    HashMap<Class, List<String>> fakeAttributes = new HashMap<Class, List<String>>();
    ArrayList<String> attrs = new ArrayList<String>();
    attrs.add("className");
    fakeAttributes.put(Object.class, attrs);
    digester.setFakeAttributes(fakeAttributes);
    digester.setClassLoader(StandardServer.class.getClassLoader());

    // Configure the actions we will be using
    digester.addObjectCreate("Server",
                             "org.apache.catalina.core.StandardServer",
                             "className");
    digester.addSetProperties("Server");
    digester.addSetNext("Server",
                        "setServer",
                        "org.apache.catalina.Server");

    digester.addObjectCreate("Server/GlobalNamingResources",
                             "org.apache.catalina.deploy.NamingResources");
    digester.addSetProperties("Server/GlobalNamingResources");
    digester.addSetNext("Server/GlobalNamingResources",
                        "setGlobalNamingResources",
                        "org.apache.catalina.deploy.NamingResources");

    digester.addObjectCreate("Server/Listener",
                             null, // MUST be specified in the element
                             "className");
    digester.addSetProperties("Server/Listener");
    digester.addSetNext("Server/Listener",
                        "addLifecycleListener",
                        "org.apache.catalina.LifecycleListener");

    digester.addObjectCreate("Server/Service",
                             "org.apache.catalina.core.StandardService",
                             "className");
    digester.addSetProperties("Server/Service");
    digester.addSetNext("Server/Service",
                        "addService",
                        "org.apache.catalina.Service");

    digester.addObjectCreate("Server/Service/Listener",
                             null, // MUST be specified in the element
                             "className");
    digester.addSetProperties("Server/Service/Listener");
    digester.addSetNext("Server/Service/Listener",
                        "addLifecycleListener",
                        "org.apache.catalina.LifecycleListener");

    //Executor
    digester.addObjectCreate("Server/Service/Executor",
                     "org.apache.catalina.core.StandardThreadExecutor",
                     "className");
    digester.addSetProperties("Server/Service/Executor");

    digester.addSetNext("Server/Service/Executor",
                        "addExecutor",
                        "org.apache.catalina.Executor");

    
    digester.addRule("Server/Service/Connector",
                     new ConnectorCreateRule());
    digester.addRule("Server/Service/Connector", 
                     new SetAllPropertiesRule(new String[]{"executor"}));
    digester.addSetNext("Server/Service/Connector",
                        "addConnector",
                        "org.apache.catalina.connector.Connector");
    
    


    digester.addObjectCreate("Server/Service/Connector/Listener",
                             null, // MUST be specified in the element
                             "className");
    digester.addSetProperties("Server/Service/Connector/Listener");
    digester.addSetNext("Server/Service/Connector/Listener",
                        "addLifecycleListener",
                        "org.apache.catalina.LifecycleListener");

    // Add RuleSets for nested elements
    digester.addRuleSet(new NamingRuleSet("Server/GlobalNamingResources/"));
    digester.addRuleSet(new EngineRuleSet("Server/Service/"));
    digester.addRuleSet(new HostRuleSet("Server/Service/Engine/"));
    digester.addRuleSet(new ContextRuleSet("Server/Service/Engine/Host/"));
    digester.addRuleSet(ClusterRuleSetFactory.getClusterRuleSet("Server/Service/Engine/Host/Cluster/"));
    digester.addRuleSet(new NamingRuleSet("Server/Service/Engine/Host/Context/"));

    // When the 'engine' is found, set the parentClassLoader.
    digester.addRule("Server/Service/Engine",
                     new SetParentClassLoaderRule(parentClassLoader));
    digester.addRuleSet(ClusterRuleSetFactory.getClusterRuleSet("Server/Service/Engine/Cluster/"));

    long t2=System.currentTimeMillis();
    if (log.isDebugEnabled())
        log.debug("Digester for server.xml created " + ( t2-t1 ));
    return (digester);

}

Digester 是通过堆栈，来实现解析xml的

hello world

public boolean parserXml(InputStream is) throws Exception {
	Digester d = createDigester();
	d.parse(is);

	return true;
}

public Digester createDigester() {
	Digester digester = new Digester();

	digester.push(document);
	// <description>information of users</description>
	digester.addBeanPropertySetter("users/description", "description");

	// <user>
	digester.addObjectCreate("users/user", "test.xue.xml.model.User");
	digester.addSetNext("users/user", "addUser", "test.xue.xml.model.User");

	// digester.addBeanPropertySetter("users/user/dead", "dead");
	digester.addSetProperties("users/user");

	// <user>
	// <name>LiLei</name>
	digester.addBeanPropertySetter("users/user/name", "name");

	// <user>
	// <sex>1</sex>
	digester.addBeanPropertySetter("users/user/sex", "sex");

	// <user>
	// <age>19</age>
	digester.addBeanPropertySetter("users/user/age", "age");

	return digester;
}

详细代码svn： https://hsuehfeng.googlecode.com/svn/trunk/xml/XMLParse