JFinal 初始化过程浅析

Posted 2020-07-14

从 web 容器进行初始化。

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
	<filter>
		<filter-name>jfinal</filter-name>
		<filter-class>com.jfinal.core.JFinalFilter</filter-class>
		<init-param>
			<param-name>configClass</param-name>
			<param-value>com.fw.config.MppConfig</param-value>
		</init-param>
	</filter>
	
	<filter-mapping>
		<filter-name>jfinal</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>	
</web-app>

从 web.xml 可以看出，容器初始化的时候会加载 JFinalFilter 这个类（调用其 init 方法）。下面来看看 JFinalFilter 类做了些什么。

public final class JFinalFilter implements Filter {
	
	private Handler handler;
	private String encoding;
	private JFinalConfig jfinalConfig;
	private Constants constants;
	private static final JFinal jfinal = JFinal.me();
	private static Log log;
	private int contextPathLength;
	
	public void init(FilterConfig filterConfig) throws ServletException {
		createJFinalConfig(filterConfig.getInitParameter("configClass"));
		
		if (jfinal.init(jfinalConfig, filterConfig.getServletContext()) == false)
			throw new RuntimeException("JFinal init error!");
		
		handler = jfinal.getHandler();
		constants = Config.getConstants();
		encoding = constants.getEncoding();
		jfinalConfig.afterJFinalStart();
		
		String contextPath = filterConfig.getServletContext().getContextPath();
		contextPathLength = (contextPath == null || "/".equals(contextPath) ? 0 : contextPath.length());
	}
	
	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest)req;
		HttpServletResponse response = (HttpServletResponse)res;
		request.setCharacterEncoding(encoding);
		
		String target = request.getRequestURI();
		if (contextPathLength != 0)
			target = target.substring(contextPathLength);
		
		boolean[] isHandled = {false};
		try {
			handler.handle(target, request, response, isHandled);
		}
		catch (Exception e) {
			if (log.isErrorEnabled()) {
				String qs = request.getQueryString();
				log.error(qs == null ? target : target + "?" + qs, e);
			}
		}
		
		if (isHandled[0] == false)
			chain.doFilter(request, response);
	}
	
	public void destroy() {
		jfinalConfig.beforeJFinalStop();
		jfinal.stopPlugins();
	}
	
	private void createJFinalConfig(String configClass) {
		if (configClass == null)
			throw new RuntimeException("Please set configClass parameter of JFinalFilter in web.xml");
		
		Object temp = null;
		try {
			temp = Class.forName(configClass).newInstance();
		} catch (Exception e) {
			throw new RuntimeException("Can not create instance of class: " + configClass, e);
		}
		
		if (temp instanceof JFinalConfig)
			jfinalConfig = (JFinalConfig)temp;
		else
			throw new RuntimeException("Can not create instance of class: " + configClass + ". Please check the config in web.xml");
	}
	
	static void initLog() {
		log = Log.getLog(JFinalFilter.class);
	}
}

1. createJFinalConfig 创建自定义配置类的一个实例

这个方法中的参数正是 web.xml 中的 JFinalFilter 的初始化参数，它继承于 JFinalConfig。

调用此方法会创建出一个 JFinalConfig 实例。

2. jfinal.init 加载配置并且初始化各个 JFinal 组件

代码如下：

boolean init(JFinalConfig jfinalConfig, ServletContext servletContext) {
	this.servletContext = servletContext;
	this.contextPath = servletContext.getContextPath();
	
	initPathUtil();
	
	Config.configJFinal(jfinalConfig);
	constants = Config.getConstants();
	
	initActionMapping();
	initHandler();
	initRender();
	initOreillyCos();
	initTokenManager();
	
	return true;
}

(1) 初始化项目根路径 contextPath

(2) Config.configJFinal 加载自定义配置（配置常量、添加 handler、添加 routes、添加插件、开启插件、添加 Interceptor），代码如下：

static void configJFinal(JFinalConfig jfinalConfig) {
	jfinalConfig.configConstant(constants);				initLogFactory();
	jfinalConfig.configRoute(routes);
	jfinalConfig.configPlugin(plugins);					startPlugins();	// very important!!!
	jfinalConfig.configInterceptor(interceptors);
	jfinalConfig.configHandler(handlers);
}

public class MppConfig extends JFinalConfig {
	
	//配置常量
	public void configConstant(Constants me) {
		PropKit.use("jdbc.properties");
		me.setDevMode(PropKit.getBoolean("devMode", false));
	}
	
	//配置路由
	public void configRoute(Routes me) {
		me.add(new RoutesMapping());		
	}
	
	public static C3p0Plugin createC3p0Plugin() {
		return new C3p0Plugin(PropKit.get("jdbcUrl"), PropKit.get("user"), PropKit.get("password").trim());
	}
	
	//配置插件
	public void configPlugin(Plugins me) {
		// 配置C3p0数据库连接池插件
		C3p0Plugin C3p0Plugin = createC3p0Plugin();
		me.add(C3p0Plugin);
		
		// 配置ActiveRecord插件
		ActiveRecordPlugin arp = new ActiveRecordPlugin(C3p0Plugin);
		me.add(arp);
		
		// 配置属性名(字段名)大小写不敏感容器工厂 oracle
		arp.setContainerFactory(new CaseInsensitiveContainerFactory());
		
		//缓存插件
		me.add(new EhCachePlugin());
		
		// 所有配置在 MappingKit 中搞定
		ModelMapping.mapping(arp);
	}
	
	//配置全局拦截器
	public void configInterceptor(Interceptors me) {
		  me.add(new SessionInViewInterceptor());//session拦截器，用于在View模板中取出session值
	}
	
	//配置处理器，接管所有 web 请求
	public void configHandler(Handlers me) {
		me.add(new ContextPathHandler("contextPath"));//设置上下文路径
	}
	
	//系统启动完成后回调,如创建调度线程
	public void afterJFinalStart(){}
	
	//系统关闭前回调,如写回缓存
	public void beforeJFinalStop(){}
}

(3) 初始化 ActionMapping、Handler、Render、等。

来自为知笔记(Wiz)