问题
I am using commons HttpClient to make an http call to a Spring servlet. I need to add a few parameters in the query string. So I do the following:
HttpRequestBase request = new HttpGet(url);
HttpParams params = new BasicHttpParams();
params.setParameter("key1", "value1");
params.setParameter("key2", "value2");
params.setParameter("key3", "value3");
request.setParams(params);
HttpClient httpClient = new DefaultHttpClient();
httpClient.execute(request);
However when i try to read the parameter in the servlet using
((ServletRequestAttributes) RequestContextHolder.currentRequestAttributes()).getRequest().getParameter("key");
it returns null. In fact the parameterMap is completely empty. When I manually append the parameters to the url before creating the HttpGet request, the parameters are available in the servlet. Same when I hit the servlet from the browser using the URL with queryString appended.
What's the error here? In httpclient 3.x, GetMethod had a setQueryString() method to append the querystring. What's the equivalent in 4.x?
回答1:
Here is how you would add query string parameters using HttpClient 4.2 and later:
URIBuilder builder = new URIBuilder("http://example.com/");
builder.setParameter("parts", "all").setParameter("action", "finish");
HttpPost post = new HttpPost(builder.build());
The resulting URI would look like:
http://example.com/?parts=all&action=finish
回答2:
If you want to add a query parameter after you have created the request, try casting the HttpRequest to a HttpBaseRequest. Then you can change the URI of the casted request:
HttpGet someHttpGet = new HttpGet("http://google.de");
URI uri = new URIBuilder(someHttpGet.getURI()).addParameter("q",
"That was easy!").build();
((HttpRequestBase) someHttpGet).setURI(uri);
回答3:
The HttpParams interface isn't there for specifying query string parameters, it's for specifying runtime behaviour of the HttpClient object.
If you want to pass query string parameters, you need to assemble them on the URL yourself, e.g.
new HttpGet(url + "key1=" + value1 + ...);
Remember to encode the values first (using URLEncoder).
回答4:
I am using httpclient 4.4.
For solr query I used the following way and it worked.
NameValuePair nv2 = new BasicNameValuePair("fq","(active:true) AND (category:Fruit OR category1:Vegetable)");
nvPairList.add(nv2);
NameValuePair nv3 = new BasicNameValuePair("wt","json");
nvPairList.add(nv3);
NameValuePair nv4 = new BasicNameValuePair("start","0");
nvPairList.add(nv4);
NameValuePair nv5 = new BasicNameValuePair("rows","10");
nvPairList.add(nv5);
HttpClient client = HttpClientBuilder.create().build();
HttpGet request = new HttpGet(url);
URI uri = new URIBuilder(request.getURI()).addParameters(nvPairList).build();
request.setURI(uri);
HttpResponse response = client.execute(request);
if (response.getStatusLine().getStatusCode() != 200) {
}
BufferedReader br = new BufferedReader(
new InputStreamReader((response.getEntity().getContent())));
String output;
System.out.println("Output .... ");
String respStr = "";
while ((output = br.readLine()) != null) {
respStr = respStr + output;
System.out.println(output);
}
回答5:
This approach is ok but will not work for when you get params dynamically , sometimes 1, 2, 3 or more, just like a SOLR search query (for example)
Here is a more flexible solution. Crude but can be refined.
public static void main(String[] args) {
String host = "localhost";
String port = "9093";
String param = "/10-2014.01?description=cars&verbose=true&hl=true&hl.simple.pre=<b>&hl.simple.post=</b>";
String[] wholeString = param.split("\\?");
String theQueryString = wholeString.length > 1 ? wholeString[1] : "";
String SolrUrl = "http://" + host + ":" + port + "/mypublish-services/carclassifications/" + "loc";
GetMethod method = new GetMethod(SolrUrl );
if (theQueryString.equalsIgnoreCase("")) {
method.setQueryString(new NameValuePair[]{
});
} else {
String[] paramKeyValuesArray = theQueryString.split("&");
List<String> list = Arrays.asList(paramKeyValuesArray);
List<NameValuePair> nvPairList = new ArrayList<NameValuePair>();
for (String s : list) {
String[] nvPair = s.split("=");
String theKey = nvPair[0];
String theValue = nvPair[1];
NameValuePair nameValuePair = new NameValuePair(theKey, theValue);
nvPairList.add(nameValuePair);
}
NameValuePair[] nvPairArray = new NameValuePair[nvPairList.size()];
nvPairList.toArray(nvPairArray);
method.setQueryString(nvPairArray); // Encoding is taken care of here by setQueryString
}
}
回答6:
This is how I implemented my URL builder. I have created one Service class to provide the params for the URL
public interface ParamsProvider {
String queryProvider(List<BasicNameValuePair> params);
String bodyProvider(List<BasicNameValuePair> params);
}
The Implementation of methods are below
@Component
public class ParamsProviderImp implements ParamsProvider {
@Override
public String queryProvider(List<BasicNameValuePair> params) {
StringBuilder query = new StringBuilder();
AtomicBoolean first = new AtomicBoolean(true);
params.forEach(basicNameValuePair -> {
if (first.get()) {
query.append("?");
query.append(basicNameValuePair.toString());
first.set(false);
} else {
query.append("&");
query.append(basicNameValuePair.toString());
}
});
return query.toString();
}
@Override
public String bodyProvider(List<BasicNameValuePair> params) {
StringBuilder body = new StringBuilder();
AtomicBoolean first = new AtomicBoolean(true);
params.forEach(basicNameValuePair -> {
if (first.get()) {
body.append(basicNameValuePair.toString());
first.set(false);
} else {
body.append("&");
body.append(basicNameValuePair.toString());
}
});
return body.toString();
}
}
When we need the query params for our URL, I simply call the service and build it. Example for that is below.
Class Mock{
@Autowired
ParamsProvider paramsProvider;
String url ="http://www.google.lk";
// For the query params price,type
List<BasicNameValuePair> queryParameters = new ArrayList<>();
queryParameters.add(new BasicNameValuePair("price", 100));
queryParameters.add(new BasicNameValuePair("type", "L"));
url = url+paramsProvider.queryProvider(queryParameters);
// You can use it in similar way to send the body params using the bodyProvider
}
来源：https://stackoverflow.com/questions/9907161/commons-httpclient-adding-query-string-parameters-to-get-post-request