JetWebContext.java

/**
 * Copyright 2013-2016 Guoqiang Chen, Shanghai, China. All rights reserved.
 *
 *   Author: Guoqiang Chen
 *    Email: subchen@gmail.com
 *   WebURL: https://github.com/subchen
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package jetbrick.template.web;

import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import jetbrick.web.servlet.map.*;

/**
 * 处理内置 web 对象.
 */
public final class JetWebContext extends HashMap<String, Object> {
    private static final long serialVersionUID = 1L;

    public static final String APPLICATION = "application";
    public static final String SESSION = "session";
    public static final String REQUEST = "request";
    public static final String RESPONSE = "response";

    public static final String APPLICATION_SCOPE = "applicationScope";
    public static final String SESSION_SCOPE = "sessionScope";
    public static final String REQUEST_SCOPE = "requestScope";

    public static final String PARAM = "param";
    public static final String PARAM_VALUES = "paramValues";

    public static final String CONTEXT_PATH = "CONTEXT_PATH";
    public static final String WEBROOT_PATH = "WEBROOT_PATH";
    public static final String BASE_PATH = "BASE_PATH";
    public static final String WEBROOT = "WEBROOT"; // short name for WEBROOT_PATH

    //@formatter:off
    private enum TYPE {
        REQUEST_SCOPE,
        SESSION, SESSION_SCOPE,
        PARAM, PARAM_VALUES,
        CONTEXT_PATH, WEBROOT_PATH, BASE_PATH,
    }
    //@formatter:on

    //-------------------------------------------------------------
    // 在 分布式环境中，一般不用内置的 session 对象，禁掉后可以提升速度
    protected static boolean SESSION_ENABLED = !"false".equals(System.getProperty("JetWebContext.session.enabled"));

    public static void disableSession() {
        SESSION_ENABLED = false;
    }

    //-------------------------------------------------------------
    private final HttpServletRequest request;
    private final Map<String, Object> context;

    public JetWebContext(HttpServletRequest request, HttpServletResponse response) {
        this(request, response, null);
    }

    public JetWebContext(HttpServletRequest request, HttpServletResponse response, Map<String, Object> context) {
        this.request = request;
        this.context = context;

        put(REQUEST, request);
        put(REQUEST_SCOPE, TYPE.REQUEST_SCOPE);

        put(RESPONSE, response);

        if (SESSION_ENABLED) {
            put(SESSION, TYPE.SESSION);
            put(SESSION_SCOPE, TYPE.SESSION_SCOPE);
        }

        put(PARAM, TYPE.PARAM);
        put(PARAM_VALUES, TYPE.PARAM_VALUES);

        put(CONTEXT_PATH, TYPE.CONTEXT_PATH);
        put(WEBROOT_PATH, TYPE.WEBROOT_PATH);
        put(BASE_PATH, TYPE.BASE_PATH);
        put(WEBROOT, TYPE.WEBROOT_PATH);
    }

    @Override
    public Object get(Object key) {
        String name = (String) key;
        if (name == null) return null;

        Object value;

        if (context != null) {
            value = context.get(name);
            if (value != null) {
                return value;
            }
        }

        value = super.get(name);
        if (value != null) {
            if (value instanceof TYPE) {
                value = createImplicitWebObject((TYPE) value);
                put(name, value); // resolved
            }
            return value;
        }

        value = request.getAttribute(name);
        if (value != null) {
            return value;
        }

        if (SESSION_ENABLED) {
            // fixed: cannot create session after response has been committed
            HttpSession session = request.getSession(false);
            if (session != null) {
                value = session.getAttribute(name);
                if (value != null) {
                    return value;
                }
            }
        }

        return request.getServletContext().getAttribute(name);
    }

    private Object createImplicitWebObject(TYPE type) {
        switch (type) {
        case REQUEST_SCOPE:
            return new RequestAttributeMap(request);
        case SESSION:
            return request.getSession();
        case SESSION_SCOPE:
            return new SessionAttributeMap(request);
        case PARAM:
            return new RequestParameterMap(request);
        case PARAM_VALUES:
            return new RequestParameterValuesMap(request);
        case CONTEXT_PATH:
            return request.getContextPath();
        case WEBROOT_PATH:
            return getWebrootPath();
        case BASE_PATH:
            return getWebrootPath().concat("/");
        default:
            return null;
        }
    }

    private String getWebrootPath() {
        StringBuilder sb = new StringBuilder();
        String schema = request.getScheme();
        int port = request.getServerPort();
        sb.append(schema);
        sb.append("://");
        sb.append(request.getServerName());
        if (!(port == 80 && "http".equals(schema)) && !(port == 443 && "https".equals(schema))) {
            sb.append(':').append(request.getServerPort());
        }
        sb.append(request.getContextPath());
        return sb.toString();
    }
}