我最终写了我自己的。它可以像

  URIUtils.withQuery（uri，param1，value1，param2，value2 ）; 
 

这不是很糟糕。

  / ** 
 *连接< code> uri< / code>具有从
 *< code> params< / code&gt ;.生成的查询字符串。 
 * 
 * @param uri基本URI 
 * @param params a< code> Map< / code>键/值对
 * @返回一个新的< code> URI< / code> 
 * / 

 public static URI withQuery（URI uri，Map< String，String> params）{
 StringBuilder query = new StringBuilder（）; 
 char separator ='？'; 
 for（Entry< String，String> param：params.entrySet（））{
 query.append（separator）; 
 separator ='&'; 
 try {
 query.append（URLEncoder.encode（param.getKey（），UTF-8））; 
 if（！StringUtils.isEmpty（param.getValue（）））{
 query.append（'='）; 
 query.append（URLEncoder.encode（param.getValue（），UTF-8））; 
} 
} catch（UnsupportedEncodingException e）{
 throw new RuntimeException（e）; 
} 
} 
返回URI.create（uri.toString（）+ query.toString（））; 
} 

 / ** 
 *连接< code> uri< / code>具有从
 *< code> params< / code&gt ;.生成的查询字符串。 < code> params< / code>的成员将
 *解释为{key1，val1，key2，val2}。空值可以被赋予
 * as< code>< / code>或< code> null< / code&gt ;. 
 * 
 * @param uri基本URI 
 * @param按顺序对键/值对进行参数
 * @返回一个新的< code> URI< / code> 
 * / 
 public static URI withQuery（URI uri，String ... params）{
 Map< String，String> map = new LinkedHashMap< String，String>（）; （int i = 0; i< params.length; i + = 2）
 {
 String key = params [i]; 
 String val = i + 1< params.length？ params [i + 1]：; 
 map.put（key，val）; 
} 
返回withQuery（uri，map）; 
} 
 

Is there a widely-used Java library that does something like what dojo.objectToQuery() does? E.g. (assuming the use of HttpCore's HttpParams object, but any key-value mapping will do):

HttpParams params = new BasicHttpParams()
    .setParameter("foo", "bar")
    .setParameter("thud", "grunt");
UnknownLibrary.toQueryString(params);

should yield "foo=bar&thud=grunt".

I know it's not hard to write but it seems like it should have already been written. I just can't find it.

I ended up writing my own. It can be called like

URIUtils.withQuery(uri, "param1", "value1", "param2", "value2");

which isn't so bad.

/**
 * Concatenates <code>uri</code> with a query string generated from
 * <code>params</code>.
 *
 * @param uri the base URI
 * @param params a <code>Map</code> of key/value pairs
 * @return a new <code>URI</code>
 */

public static URI withQuery(URI uri, Map<String, String> params) {
    StringBuilder query = new StringBuilder();
    char separator = '?';
    for (Entry<String, String> param : params.entrySet()) {
        query.append(separator);
        separator = '&';
        try {
            query.append(URLEncoder.encode(param.getKey(), "UTF-8"));
            if (!StringUtils.isEmpty(param.getValue())) {
                query.append('=');
                query.append(URLEncoder.encode(param.getValue(), "UTF-8"));
            }
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        }
    }
    return URI.create(uri.toString() + query.toString());
}

/**
 * Concatenates <code>uri</code> with a query string generated from
 * <code>params</code>.  The members of <code>params</code> will be
 * interpreted as {key1, val1, key2, val2}.  Empty values can be given
 * as <code>""</code> or <code>null</code>.
 *
 * @param uri the base URI
 * @param params the key/value pairs in sequence
 * @return a new <code>URI</code>
 */
public static URI withQuery(URI uri, String... params) {
    Map<String, String> map = new LinkedHashMap<String, String>();
    for (int i = 0; i < params.length; i += 2) {
        String key = params[i];
        String val = i + 1 < params.length ? params[i + 1] : "";
        map.put(key, val);
    }
    return withQuery(uri, map);
}