webutils.java

一个在线学习系统的服务端SERVLET程序

package eols.tools.binder;

/**
 * 该类重写了Spring框架提供的WebUtils类的getParametersStartingWith方法. 主要是为了提供额外的
 * request中文参数值的编码转换功能.
 */
import java.util.Map;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Enumeration;
import java.util.List;
import javax.servlet.ServletRequest;
import eols.tools.ChineseSwitcher;

public class WebUtils {
        /**
         * Return a map containing all parameters with the given prefix.
         * Maps single values to String and multiple values to String array.
         * <p>For example, with a prefix of "spring_", "spring_param1" and
         * "spring_param2" result in a Map with "param1" and "param2" as keys.
         * <p>Similar to Servlet 2.3's <code>ServletRequest.getParameterMap</code>,
         * but more flexible and compatible with Servlet 2.2.
         * @param request HTTP request in which to look for parameters
         * @param prefix the beginning of parameter names
         * (if this is null or the empty string, all parameters will match)
         * @return map containing request parameters <b>without the prefix</b>,
         * containing either a String or a String array as values
         * @see javax.servlet.ServletRequest#getParameterNames
         * @see javax.servlet.ServletRequest#getParameterValues
         * @see javax.servlet.ServletRequest#getParameterMap
         */
        public static Map getParametersStartingWith(ServletRequest request, String prefix, boolean isResultNeedTranslate) {
                Enumeration enum = request.getParameterNames();
                Map params = new HashMap();
                if (prefix == null) {
                        prefix = "";
                }
                while (enum != null && enum.hasMoreElements()) {
                        String paramName = (String) enum.nextElement();
                        if ("".equals(prefix) || paramName.startsWith(prefix)) {
                                String unprefixed = paramName.substring(prefix.length());
                                String[] values = request.getParameterValues(paramName);
                                if (values == null) {
                                        // do nothing, no values found at all
                                }
                                //else if (values.length > 1) {
                                        //params.put(unprefixed, ChineseSwitcher.toStore(values));
                                        //params.put(unprefixed, values);
                                //}
                                else {
                                        if (isResultNeedTranslate){
                                                params.put(unprefixed,
                                                    ChineseSwitcher.
                                                    ISO8859TOGB2312(values[0]));
                                        }
                                        else {
                                                params.put(unprefixed, values[0]);

                                        }
                                        //params.put(unprefixed, values[0]);
                                }
                        }
                }
                return params;
        }

        /**
         * Return a map containing all needed parameters with the given prefix.
         * Maps multiple values with the given name to String array.
         *
         * This method is mainly used to values of multiple bean properties. For example,
         * suppose a client submits a form with many rows of datas, also suppose we want to
         * fetch all these datas in one step, to realize this aim, we should first get all
         * the request parameters(that is, form datas), then we fetch one row a time to instantialize
         * and set property values of the given bean class, and add the result bean object into
         * a List(ArrayList), finally, we return such a List to request controllers who need
         * this object arraylist.
         *
         * @param request HTTP request in which to look for parameters
         * @param parametersName parameters' name whose values are needed to be fetched
         * @return map containing request parameters <b>without the prefix</b>,
         * containing either a String or a String array as values
         *
         * @see javax.servlet.ServletRequest#getParameterNames
         * @see javax.servlet.ServletRequest#getParameterValues
         * @see javax.servlet.ServletRequest#getParameterMap
         */
        public static Map getSpecifiedParameterValues(ServletRequest request, String[] parametersName) {
                Map result = new HashMap();
                // First, check whether the given parameters are valid
                if (parametersName == null || parametersName.length == 0) {
                        return result;
                }
                // Second, fetch values of the specified parameter name
                int size = parametersName.length;
                // Variable indicating the row count of the datas submitted by the client
                int rowCount = 0;
                String paramName = null;
                String[] values = null;
                for (int i = 0; i < size; i++) {
                        paramName = parametersName[i];
                        values = request.getParameterValues(paramName);
                        if (values != null && values.length > rowCount) {
                                rowCount = values.length;
                        }
                        result.put(paramName, values);
                }
                result.put("rowCount", new Integer(rowCount));
                return result;
        }

}