在上一篇博客springMVC源码分析--容器初始化（二）DispatcherServlet中，我们队SpringMVC整体生命周期有一个简单的说明，并没有进行详细的源码分析，接下来我们会根据博客中提供的springMVC的生命周期图来详细的对SpringMVC的相关源码进行分析。
在上一篇博客中我们了解到，SpringMVC初始化配置是在父类HttpServletBean的init方法中，其实HttServletBean是一个比较简单的类，在这个类中并没有太复杂的功能，主要的函数是init函数中，源码如下：
主要工作就是设置我们在web.xml中配置的contextConfigLocation属性，当然这个属性是springMVC文件的配置文件地址，当然也可以不用配置，使用默认名称加载。
initBeanWrapper 函数并没有具体实现
initServletBean（）是模板方法，是在子类FrameworkServlet中实现的，接下来我们会详细分析，这样HttpServletBean的主体功能就介绍完了。
public final void init() throws ServletException {
if (logger.isDebugEnabled()) {
logger.debug("Initializing servlet '" + getServletName() + "'");
}
// Set bean properties from init parameters.
try {
//获得web.xml中的contextConfigLocation配置属性，就是spring MVC的配置文件
PropertyValues pvs = new ServletConfigPropertyValues(getServletConfig(), this.requiredProperties);
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);
//获取服务器的各种信息
ResourceLoader resourceLoader = new ServletContextResourceLoader(getServletContext());
bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader, getEnvironment()));
//模板方法，可以在子类中调用，做一些初始化工作，bw代表DispatcherServelt
initBeanWrapper(bw);
//将配置的初始化值设置到DispatcherServlet中
bw.setPropertyValues(pvs, true);
}
catch (BeansException ex) {
logger.error("Failed to set bean properties on servlet '" + getServletName() + "'", ex);
throw ex;
}
// Let subclasses do whatever initialization they like.
//模板方法，子类初始化的入口方法
initServletBean();
if (logger.isDebugEnabled()) {
logger.debug("Servlet '" + getServletName() + "' configured successfully");
}
}
当然HttpServletBean还是提供了一些其他方法的，其实都是一些比较简单的get和set方法，就不做过多介绍了，HttpServletBean的完整源码如下：
/**
*HttpServlet的一个简单扩展类
*/
@SuppressWarnings("serial")
public abstract class HttpServletBean extends HttpServlet
implements EnvironmentCapable, EnvironmentAware {
protected final Log logger = LogFactory.getLog(getClass());
private final Set<String> requiredProperties = new HashSet<String>();
private ConfigurableEnvironment environment;
protected final void addRequiredProperty(String property) {
this.requiredProperties.add(property);
}
@Override
public final void init() throws ServletException {
if (logger.isDebugEnabled()) {
logger.debug("Initializing servlet '" + getServletName() + "'");
}
// Set bean properties from init parameters.
try {
//获得web.xml中的contextConfigLocation配置属性，就是spring MVC的配置文件
PropertyValues pvs = new ServletConfigPropertyValues(getServletConfig(), this.requiredProperties);
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);
//获取服务器的各种信息
ResourceLoader resourceLoader = new ServletContextResourceLoader(getServletContext());
bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader, getEnvironment()));
//模板方法，可以在子类中调用，做一些初始化工作，bw代表DispatcherServelt
initBeanWrapper(bw);
//将配置的初始化值设置到DispatcherServlet中
bw.setPropertyValues(pvs, true);
}
catch (BeansException ex) {
logger.error("Failed to set bean properties on servlet '" + getServletName() + "'", ex);
throw ex;
}
// Let subclasses do whatever initialization they like.
//模板方法，子类初始化的入口方法
initServletBean();
if (logger.isDebugEnabled()) {
logger.debug("Servlet '" + getServletName() + "' configured successfully");
}
}
/**
* Initialize the BeanWrapper for this HttpServletBean,
* possibly with custom editors.
* <p>This default implementation is empty.
* @param bw the BeanWrapper to initialize
* @throws BeansException if thrown by BeanWrapper methods
* @see org.springframework.beans.BeanWrapper#registerCustomEditor
*/
protected void initBeanWrapper(BeanWrapper bw) throws BeansException {
}
//获取servletName
@Override
public final String getServletName() {
return (getServletConfig() != null ? getServletConfig().getServletName() : null);
}
//获取ServletContext
@Override
public final ServletContext getServletContext() {
return (getServletConfig() != null ? getServletConfig().getServletContext() : null);
}
protected void initServletBean() throws ServletException {
}
@Override
public void setEnvironment(Environment environment) {
Assert.isInstanceOf(ConfigurableEnvironment.class, environment);
this.environment = (ConfigurableEnvironment) environment;
}
@Override
public ConfigurableEnvironment getEnvironment() {
if (this.environment == null) {
this.environment = this.createEnvironment();
}
return this.environment;
}
protected ConfigurableEnvironment createEnvironment() {
return new StandardServletEnvironment();
}
private static class ServletConfigPropertyValues extends MutablePropertyValues {
public ServletConfigPropertyValues(ServletConfig config, Set<String> requiredProperties)
throws ServletException {
Set<String> missingProps = (requiredProperties != null && !requiredProperties.isEmpty()) ?
new HashSet<String>(requiredProperties) : null;
Enumeration<String> en = config.getInitParameterNames();
while (en.hasMoreElements()) {
String property = en.nextElement();
Object value = config.getInitParameter(property);
addPropertyValue(new PropertyValue(property, value));
if (missingProps != null) {
missingProps.remove(property);
}
}
// Fail if we are still missing properties.
if (missingProps != null && missingProps.size() > 0) {
throw new ServletException(
"Initialization from ServletConfig for servlet '" + config.getServletName() +
"' failed; the following required properties were missing: " +
StringUtils.collectionToDelimitedString(missingProps, ", "));
}
}
}
}