springMVC基础（配置开发）

public class SimpleControllerHandlerAdapter implements HandlerAdapter {

	@Override
	public boolean supports(Object handler) {
		return (handler instanceof Controller);
	}

	@Override
	@Nullable
	public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		//强转后，就会调用我们自己定义的处理器的 handleRequest()方法
		return ((Controller) handler).handleRequest(request, response);
	}

	@Override
	public long getLastModified(HttpServletRequest request, Object handler) {
		if (handler instanceof LastModified) {
			return ((LastModified) handler).getLastModified(request);
		}
		return -1L;
	}

}

public interface Controller {

	/**
	 * Process the request and return a ModelAndView object which the DispatcherServlet
	 * will render. A {@code null} return value is not an error: it indicates that
	 * this object completed request processing itself and that there is therefore no
	 * ModelAndView to render.
	 * @param request current HTTP request
	 * @param response current HTTP response
	 * @return a ModelAndView to render, or {@code null} if handled directly
	 * @throws Exception in case of errors
	 */
	@Nullable
	ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception;

}

public interface HttpRequestHandler {

	/**
	 * Process the given request, generating a response.
	 * @param request current HTTP request
	 * @param response current HTTP response
	 * @throws ServletException in case of general errors
	 * @throws IOException in case of I/O errors
	 */
	void handleRequest(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException;

}

public class MyController implements HttpRequestHandler {
    @Override
    public void handleRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setAttribute("welcome","welcome to china");
        request.getRequestDispatcher("/WEB-INF/jsp/welcome.jsp").forward(request,response);
    }
}

/**
	 * Set the HTTP methods that this content generator should support.
	 * <p>Default is GET, HEAD and POST for simple form controller types;
	 * unrestricted for general controllers and interceptors.
	 */
	public final void setSupportedMethods(@Nullable String... methods) {
		if (!ObjectUtils.isEmpty(methods)) {
			this.supportedMethods = new LinkedHashSet<>(Arrays.asList(methods));
		}
		else {
			this.supportedMethods = null;
		}
		initAllowHeader();
	}

/**
	 * Template method. Subclasses must implement this.
	 * The contract is the same as for {@code handleRequest}.
	 * @see #handleRequest
	 */
	@Nullable
	protected abstract ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)
			throws Exception;

@Override
	@Nullable
	public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response)
			throws Exception {

		if (HttpMethod.OPTIONS.matches(request.getMethod())) {
			response.setHeader("Allow", getAllowHeader());
			return null;
		}

		// Delegate to WebContentGenerator for checking and preparing.
		checkRequest(request);
		prepareResponse(response);

		// Execute handleRequestInternal in synchronized block if required.
		if (this.synchronizeOnSession) {
			HttpSession session = request.getSession(false);
			if (session != null) {
				Object mutex = WebUtils.getSessionMutex(session);
				synchronized (mutex) {
					return handleRequestInternal(request, response);
				}
			}
		}

		return handleRequestInternal(request, response);
	}

public class MyController extends AbstractController {

    @Override
    protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView mv = new ModelAndView();
        mv.addObject("welcome","hello springmvc");
        mv.setViewName("welcome");
        return mv;
    }
}

public class MyController extends MultiActionController  {

    
    protected ModelAndView doFirst(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView mv = new ModelAndView();
        mv.addObject("method","doFirst()");
        mv.setViewName("show");
        return mv;
    }
    
    protected ModelAndView doSecond(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView mv = new ModelAndView();
        mv.addObject("method","doSecond()");
        mv.setViewName("show");
        return mv;
    }
}

//InternalPathMethodNameResolver:方法名解析器（默认）
//该方法名解析器要求方法名以 URI 中资源名称的身份出现，即方法作为一种可以被请求的资源出现。也就是前面的写法：/xxx/方法名
private MethodNameResolver methodNameResolver = new InternalPathMethodNameResolver();

public class ParameterMethodNameResolver implements MethodNameResolver {
    public static final String DEFAULT_PARAM_NAME = "action";

//ModelAndView类的addObject方法
public ModelAndView addObject(Object attributeValue) {
        this.getModelMap().addAttribute(attributeValue);
        return this;
    }

//获取ModelMap
public ModelMap getModelMap() {
        if (this.model == null) {
            this.model = new ModelMap();
        }

        return this.model;
    }
//而 ModelMap 的本质就是个 HashMap
public class ModelMap extends LinkedHashMap<String, Object>
//而 ModelMap 的本质就是个 HashMap
public class LinkedHashMap<K,V> extends HashMap<K,V> implements Map<K,V>

 /**
     * The table, initialized on first use, and resized as
     * necessary. When allocated, length is always a power of two.
     * (We also tolerate length zero in some operations to allow
     * bootstrapping mechanics that are currently not needed.)
     */
    transient Node<K,V>[] table;

static class Node<K,V> implements Map.Entry<K,V> {
        final int hash;
        final K key;
        V value;
        Node<K,V> next;

transient LinkedHashMap.Entry<K,V> head;

static class Entry<K,V> extends HashMap.Node<K,V> {
        Entry<K,V> before, after;
        Entry(int hash, K key, V value, Node<K,V> next) {
            super(hash, key, value, next);
        }
    }

//ModelAndView类中有个成员变量：private Object view;
public void setViewName(String viewName) {
        this.view = viewName;
    }

public ModelAndView(String viewName) {
        this.view = viewName;
    }

mv.addObject("method","doSecond()");
//向ModelAndView对象中添加view，即要跳转的页面
mv.setViewName("show");

//这样写需要配置视图解析器

//如果不配置视图解析器也可以这样写
mv.addObject("method","doSecond()");
//向ModelAndView对象中添加view，即要跳转的页面
mv.setViewName("/WEB-INF/admin/show.jsp");