You can't make javascript/Ajax calls across domains (without some serious kludging). What we've done for this in the past is to create a local jsp proxy that we call with our javascript but is just a pass-through to the remote URL.
Here is some example JSP code that is close to what I've used to hit a SOLR instance returning JSON.
final String ENCODING = "UTF-8"; // this is the default unless specified otherwise (in server.xml for Tomcat)
// see http://tomcat.apache.org/tomcat-6.0-doc/config/http.html#Common_Attributes and
// http://wiki.apache.org/tomcat/FAQ/CharacterEncoding#Q2
final String URI_ENCODING = "ISO-8859-1";
HashMap<String, String> defaultSettings = new HashMap<String, String>() {
{
put("wt", "json");
put("rows", "10");
put("start", "0");
}
};
BufferedReader searchResponse = null;
OutputStreamWriter forwardedSearchRequest = null;
// TODO: are there any headers that we need to pass on?
// simply pass on the request to the search server and return any results
try {
URL searchURL = new URL("http://yourdestinationurlhere.com");
HttpURLConnection conn = (HttpURLConnection) searchURL.openConnection();
// read the request data and send it as POST data (unchanged)
conn.setDoOutput(true);
forwardedSearchRequest = new OutputStreamWriter(conn.getOutputStream());
// at least for Tomcat 6.0, the default is really iso-8859-1, although it is reported as UTF-8
// so, we will explicitly set it to URI_ENCODING in both places
request.setCharacterEncoding(URI_ENCODING);
String query = (String) request.getParameter("q");
if ((query != null) && (! "".equals(query.trim()))) {
query = URLEncoder.encode(query, request.getCharacterEncoding()); // we must use the same setting as the container for URI-encoding
forwardedSearchRequest.write("&q=");
forwardedSearchRequest.write(query);
} else {
// empty queries may return all results, so let's circumvent that
forwardedSearchRequest.write("&q=help");
}
for(String key:defaultSettings.keySet()) {
String resultType = (String) request.getParameter(key);
if ((resultType == null) || "".equals(resultType.trim())) resultType = defaultSettings.get(key);
forwardedSearchRequest.write("&"+key+"=");
forwardedSearchRequest.write(resultType);
}
forwardedSearchRequest.flush();
// read and forward the response
// reset anything that may have been sent so far
out.clearBuffer();
// do this only if we have a 200 response code
if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
// the web server may be running as windows-1252, so let's ensure we have the right CS
searchResponse = new BufferedReader(new InputStreamReader(conn.getInputStream(), ENCODING));
String contentType = conn.getHeaderField("Content-Type");
if ((contentType != null) && (! "".equals(contentType))) response.setHeader("Content-Type", contentType);
String buffer;
while ((buffer = searchResponse.readLine()) != null) out.println(buffer);
} else {
// dish out a mock-Solr-JSON response that includes a status and an error
response.setHeader("Content-Type", "application/json");
out.println("{ responseHeader: {status: -1, responseCode: " + conn.getResponseCode() +
", responseMessage: "" + conn.getResponseMessage() + "" } }");
}
} catch (Exception e) {
throw new ServletException("Exception - " + e.getClass().getName(), e);
} finally {
if (forwardedSearchRequest != null) forwardedSearchRequest.close();
if (searchResponse != null) searchResponse.close();
}
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…