Activiti工作流REST方式访问URI的解析

在Activiti工作流中提供一种访问方式为REST方式访问。针对查询字符串的格式采用一个如下一个工具类解析Uri中的提供的各种信息。

package org.activiti.explorer.util;

 

import java.io.UnsupportedEncodingException;

import java.net.URLDecoder;

import java.net.URLEncoder;

import java.util.ArrayList;

import java.util.LinkedHashMap;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import java.util.Scanner;

 

/**

 * @author 'Frederik Heremans'

 */

public class UriUtility {

 

  private static final String PARAMETER_SEPARATOR = "&";

  private static final String QUERY_STRING_SEPARATOR = "?";

  private static final String NAME_VALUE_SEPARATOR = "=";

  private static final String URL_PART_SEPARATOR = "/";

 

  /**

   * Get path fragments. eg: "/task/inbox/123" will return a list with three

   * values: "task", "inbox" and "123" in that order.

   */

  public static List<String> getFragmentParts(String url) {

    if (url != null) {

      List<String> parts = new ArrayList<String>();

      String[] partsArray = url.split(URL_PART_SEPARATOR);

      for (String part : partsArray) {

        if (part.length() > 0) {

          parts.add(part);

        }

      }

      return parts;

    }

    return null;

  }

 

  /**

   * Extracts the query parameters from the given url fragment.

   */

  public static String extractQueryString(String fragment) {

    if (fragment != null) {

      int firstIndex = fragment.indexOf(QUERY_STRING_SEPARATOR);

      if (firstIndex >= 0) {

        return fragment.substring(firstIndex);

      }

    }

    return null;

  }

 

  /**

   * Extracts uri from the given url fragment, without the query params.

   */

  public static String extractUri(String fragment) {

    if (fragment != null) {

      int firstIndex = fragment.indexOf(QUERY_STRING_SEPARATOR);

      if (firstIndex >= 0) {

        return fragment.substring(0, firstIndex);

      } else {

        // No query string present, use full fragment

        return fragment;

      }

    }

    return null;

  }

 

  /**

   * Parses the parameters from the given url query string. When no encoding is

   * passed, default UTF-8 is used. Based on the implementation in Commons

   * httpclient UrlEncodedUtils.

   */

  public static Map<String, String> parseQueryParameters(String queryString, String encoding) {

    Map<String, String> parameters = new LinkedHashMap<String, String>();

    if (queryString != null) {

      // Remove '?' if present at beginning of query-string

      if(queryString.startsWith(QUERY_STRING_SEPARATOR)) {

        queryString = queryString.substring(1);

      }

     

      Scanner scanner = new Scanner(queryString);

      scanner.useDelimiter(PARAMETER_SEPARATOR);

      while (scanner.hasNext()) {

        final String[] nameValue = scanner.next().split(NAME_VALUE_SEPARATOR);

        if (nameValue.length == 0 || nameValue.length > 2)

          throw new IllegalArgumentException("bad parameter");

 

        final String name = decode(nameValue[0], encoding);

        String value = null;

        if (nameValue.length == 2) {

          value = decode(nameValue[1], encoding);

        }

        parameters.put(name, value);

      }

    }

    return parameters;

  }

 

  /**

   * Gets a valid query-string based on the given parameters.

   */

  public static String getQueryString(Map<String, String> parameters) {

    StringBuilder result = new StringBuilder();

 

    if (parameters != null) {

      for (Entry<String, String> param : parameters.entrySet()) {

        final String encodedName = encode(param.getKey(), null);

        final String value = param.getValue();

        final String encodedValue = value != null ? encode(value, null) : "";

        if (result.length() > 0) {

          result.append(PARAMETER_SEPARATOR);

        } else {

          result.append(QUERY_STRING_SEPARATOR);

        }

        result.append(encodedName);

        result.append(NAME_VALUE_SEPARATOR);

        result.append(encodedValue);

      }

    }

 

    return result.toString();

  }

 

  /**

   * Gets full path based on the given parts.

   */

  public static String getPath(List<String> parts) {

    if (parts != null) {

      StringBuilder result = new StringBuilder();

      for (String part : parts) {

        if(result.length() > 0) {

          result.append(URL_PART_SEPARATOR);

        }

        result.append(part);

      }

      return result.toString();

    }

    return "";

  }

 

  private static String decode(final String content, final String encoding) {

    try {

      return URLDecoder.decode(content, encoding != null ? encoding : "UTF-8");

    } catch (UnsupportedEncodingException problem) {

      throw new IllegalArgumentException(problem);

    }

  }

 

  private static String encode(final String content, final String encoding) {

    try {

      return URLEncoder.encode(content, encoding != null ? encoding : "UTF-8");

    } catch (UnsupportedEncodingException problem) {

      throw new IllegalArgumentException(problem);

    }

  }

}