extensions/servlet/src/com/google/inject/servlet/ServletsModuleBuilder.java

/**
 * Copyright (C) 2008 Google Inc.
 *
 * 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 com.google.inject.servlet;

import com.google.common.collect.Sets;
import com.google.inject.Binder;
import com.google.inject.Key;
import com.google.inject.internal.UniqueAnnotations;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.servlet.http.HttpServlet;

/**
 * Builds the guice module that binds configured servlets, with their
 * wrapper ServletDefinitions. Is part of the binding EDSL. Very similar to
 * {@link com.google.inject.servlet.FiltersModuleBuilder}.
 *
 * @author Dhanji R. Prasanna (dhanji@gmail.com)
 */
class ServletsModuleBuilder {
  
  private final Set<String> servletUris = Sets.newHashSet();
  private final Binder binder;
  
  public ServletsModuleBuilder(Binder binder) {
    this.binder = binder;
  }

  //the first level of the EDSL--
  public ServletModule.ServletKeyBindingBuilder serve(List<String> urlPatterns) {
    return new ServletKeyBindingBuilderImpl(urlPatterns, UriPatternType.SERVLET);
  }

  public ServletModule.ServletKeyBindingBuilder serveRegex(List<String> regexes) {
    return new ServletKeyBindingBuilderImpl(regexes, UriPatternType.REGEX);
  }

  //non-static inner class so it can access state of enclosing module class
  class ServletKeyBindingBuilderImpl implements ServletModule.ServletKeyBindingBuilder {
    private final List<String> uriPatterns;
    private final UriPatternType uriPatternType;

    private ServletKeyBindingBuilderImpl(List<String> uriPatterns, UriPatternType uriPatternType) {
      this.uriPatterns = uriPatterns;
      this.uriPatternType = uriPatternType;
    }

    public void with(Class<? extends HttpServlet> servletKey) {
      with(Key.get(servletKey));
    }

    public void with(Key<? extends HttpServlet> servletKey) {
      with(servletKey, new HashMap<String, String>());
    }

    public void with(HttpServlet servlet) {
      with(servlet, new HashMap<String, String>());
    }

    public void with(Class<? extends HttpServlet> servletKey,
        Map<String, String> initParams) {
      with(Key.get(servletKey), initParams);
    }

    public void with(Key<? extends HttpServlet> servletKey,
        Map<String, String> initParams) {
      with(servletKey, initParams, null);
    }

    private void with(Key<? extends HttpServlet> servletKey, Map<String, String> initParams,
        HttpServlet servletInstance) {
      for (String pattern : uriPatterns) {
        // Ensure two servlets aren't bound to the same pattern.
        if (!servletUris.add(pattern)) {
          binder.addError("More than one servlet was mapped to the same URI pattern: " + pattern);
        } else {
          binder.bind(Key.get(ServletDefinition.class, UniqueAnnotations.create())).toProvider(
              new ServletDefinition(pattern, servletKey, UriPatternType
                  .get(uriPatternType, pattern), initParams, servletInstance));
        }
      }
    }

    public void with(HttpServlet servlet,
        Map<String, String> initParams) {
      Key<HttpServlet> servletKey = Key.get(HttpServlet.class, UniqueAnnotations.create());
      binder.bind(servletKey).toInstance(servlet);
      with(servletKey, initParams, servlet);
    }
  }
}