com.itpro.restws.helper.MultipartFromWrapper.java Source code

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Here is the source code for com.itpro.restws.helper.MultipartFromWrapper.java

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package com.itpro.restws.helper;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * Wrapper for a file upload request (before Servlet 3.0).
 * 
 * <P>
 * This class uses the Apache Commons
 * <a href='http://commons.apache.org/fileupload/'>File Upload tool</a>. The
 * generous Apache License will very likely allow you to use it in your
 * applications as well.
 */
public class MultipartFromWrapper extends HttpServletRequestWrapper {

    /** Store regular params only. May be multivalued (hence the List). */
    private final Map<String, List<String>> fRegularParams = new LinkedHashMap<>();

    /** Store file params only. */
    private final Map<String, FileItem> fFileParams = new LinkedHashMap<>();
    private static final int FIRST_VALUE = 0;

    /** Constructor. */
    public MultipartFromWrapper(HttpServletRequest aRequest) throws IOException {
        super(aRequest);
        ServletFileUpload upload = new ServletFileUpload(new DiskFileItemFactory());
        try {
            List<FileItem> fileItems = upload.parseRequest(aRequest);
            convertToMaps(fileItems);
        } catch (FileUploadException ex) {
            throw new IOException("Cannot parse underlying request: " + ex.toString());
        }
    }

    /**
     * Return all request parameter names, for both regular controls and file
     * upload controls.
     */
    @Override
    public Enumeration<String> getParameterNames() {
        Set<String> allNames = new LinkedHashSet<>();
        allNames.addAll(fRegularParams.keySet());
        allNames.addAll(fFileParams.keySet());
        return Collections.enumeration(allNames);
    }

    /**
     * Return the parameter value. Applies only to regular parameters, not to
     * file upload parameters.
     * 
     * <P>
     * If the parameter is not present in the underlying request, then
     * <tt>null</tt> is returned.
     * <P>
     * If the parameter is present, but has no associated value, then an empty
     * string is returned.
     * <P>
     * If the parameter is multivalued, return the first value that appears in
     * the request.
     */
    @Override
    public String getParameter(String aName) {
        String result = null;
        List<String> values = fRegularParams.get(aName);
        if (values == null) {
            // you might try the wrappee, to see if it has a value
        } else if (values.isEmpty()) {
            // param name known, but no values present
            result = "";
        } else {
            // return first value in list
            result = values.get(FIRST_VALUE);
        }
        return result;
    }

    /**
     * Return the parameter values. Applies only to regular parameters, not to
     * file upload parameters.
     */
    @Override
    public String[] getParameterValues(String aName) {
        String[] result = null;
        List<String> values = fRegularParams.get(aName);
        if (values != null) {
            result = values.toArray(new String[values.size()]);
        }
        return result;
    }

    /**
     * Return a {@code Map<String, List<String>>} for all regular parameters.
     * Does not return any file upload parameters at all.
     */
    @Override
    public Map<String, String[]> getParameterMap() {
        Map<String, String[]> map = new LinkedHashMap<>();
        for (Entry<String, List<String>> entry : fRegularParams.entrySet()) {
            String key = entry.getKey();
            List<String> value = entry.getValue();
            if (value != null && value.size() > 0) {
                String[] arr = (String[]) value.toArray();
                map.put(key, arr);
            }
        }
        return map;
    }

    /**
     * Return a {@code List<FileItem>}, in the same order as they appear in the
     * underlying request.
     */
    public List<FileItem> getFileItems() {
        return new ArrayList<FileItem>(fFileParams.values());
    }

    /**
     * Return the {@link FileItem} of the given name.
     * <P>
     * If the name is unknown, then return <tt>null</tt>.
     */
    public FileItem getFileItem(String aFieldName) {
        return fFileParams.get(aFieldName);
    }

    // PRIVATE

    private void convertToMaps(List<FileItem> aFileItems) {
        for (FileItem item : aFileItems) {
            if (isFileUploadField(item)) {
                fFileParams.put(item.getFieldName(), item);
            } else {
                if (alreadyHasValue(item)) {
                    addMultivaluedItem(item);
                } else {
                    addSingleValueItem(item);
                }
            }
        }
    }

    private boolean isFileUploadField(FileItem aFileItem) {
        return !aFileItem.isFormField();
    }

    private boolean alreadyHasValue(FileItem aItem) {
        return fRegularParams.get(aItem.getFieldName()) != null;
    }

    private void addSingleValueItem(FileItem aItem) {
        List<String> list = new ArrayList<>();
        list.add(aItem.getString());
        fRegularParams.put(aItem.getFieldName(), list);
    }

    private void addMultivaluedItem(FileItem aItem) {
        List<String> values = fRegularParams.get(aItem.getFieldName());
        values.add(aItem.getString());
    }
    ////////////////////

    // tag::getRequestBody[]
    public String getRequestBody() {
        if (fRegularParams != null) {
            return fRegularParams.toString();
        }
        return "";

    }

}