Java: Use httpclient for post and get requests and file downloads

1.HttpClient

We can first look at the introduction of httpclient, this blog post is quite good: http://blog.csdn.net/wangpeng047/article/details/19624529

Of course, detailed documentation, you can go to the official website to view and download: http://hc.apache.org/httpclient-3.x/

2. This blog briefly describes the post and get and file download applications.

The code is as follows:

Package Net.mobctrl;import Java.io.bytearrayoutputstream;import Java.io.fileoutputstream;import Java.io.ioexception;import Java.io.inputstream;import Java.util.arraylist;import Java.util.List;import Java.util.map;import Java.util.set;import Java.util.concurrent.executorservice;import Java.util.concurrent.executors;import Org.apache.http.httpentity;import Org.apache.http.namevaluepair;import Org.apache.http.client.entity.urlencodedformentity;import Org.apache.http.client.methods.CloseableHttpResponse; Import Org.apache.http.client.methods.httpget;import Org.apache.http.client.methods.httppost;import Org.apache.http.impl.client.closeablehttpclient;import Org.apache.http.impl.client.httpclients;import Org.apache.http.message.basicnamevaluepair;import org.apache.http.util.entityutils;/** * @web/HTTP// Www.mobctrl.net * @author Zheng Haibo * @Description: File download POST GET */public class Httpclientutils {/** * max thread pool */public s tatic Final int thread_pool_size = 5;public interface Httpclientdownloadprogress {public void onprogress (int progress);} private static httpclientutils httpclientdownload;private Executorservice downloadexcutorservice;private Httpclientutils () {downloadexcutorservice = Executors.newfixedthreadpool (thread_pool_size);} public static Httpclientutils getinstance () {if (httpclientdownload = = null) {httpclientdownload = new httpclientutils (); }return Httpclientdownload;} /** * Download file * * @param URL * @param filePath */public void Download (final string url, final string filePath) {Downloadexcu Torservice.execute (New Runnable () {@Overridepublic void run () {httpdownloadfile (URL, FilePath, null,null);}});} /** * Download file * * @param URL * @param filePath * @param progress * Progress callback */public void download (Final String URL, Final String filepath,final httpclientdownloadprogress progress) {Downloadexcutorservice.execute (new Runnable () {@ overridepublic void Run () {httpdownloadfile (URL, FilePath, progress,null);}}); /** * Download file * * @param URL * @param filePath */private VOID httpdownloadfile (string URL, string filepath,httpclientdownloadprogress progress, map<string, string> Headmap) {Closeablehttpclient httpclient = Httpclients.createdefault (); try {httpget httpget = new HttpGet (URL); Setgethead (HttpGet, Headmap); Closeablehttpresponse response1 = Httpclient.execute (httpget); try {System.out.println (Response1.getstatusline ()); Httpentity httpentity = response1.getentity (); Long contentlength = Httpentity.getcontentlength (); InputStream is = Httpentity.getcontent ();//download file according to InputStream bytearrayoutputstream output = new Bytearrayoutputstream (); byte[] Buffer = new Byte[4096];int r = 0;long Totalread = 0;while ((r = is.read (buffer)) > 0) {output.write (buffer, 0, R); Totalread + = R;if (Progress! = NULL) {//Callback Progress Progress.onprogress ((int) (Totalread * 100/contentlength));}} FileOutputStream fos = new FileOutputStream (FilePath); Output.writeto (FOS); Output.flush (); Output.close (); Fos.close ( ); Entityutils.consume (httpentity);} finally {response1.close ();}} CatcH (Exception e) {e.printstacktrace ();} finally {try {httpclient.close ();} catch (IOException e) {e.printstacktrace ();}}} /** * GET request * * @param URL * @return */public string httpget (string url) {return httpget (URL, null);} /** * HTTP GET request * * @param URL * @return */public string httpget (string url, map<string, string> headmap) {string Responsecontent = null; Closeablehttpclient httpclient = Httpclients.createdefault (); try {httpget httpget = new HttpGet (URL); Closeablehttpresponse response1 = Httpclient.execute (HttpGet); Setgethead (HttpGet, headmap); try {System.out.println ( Response1.getstatusline ()); httpentity entity = response1.getentity (); InputStream is = Entity.getcontent (); StringBuffer strbuf = new StringBuffer () byte[] buffer = new Byte[4096];int r = 0;while ((r = is.read (buffer)) > 0) {St Rbuf.append (new String (buffer, 0, R, "UTF-8")); Responsecontent = Strbuf.tostring (); System.out.println ("debug:" + responsecontent); Entityutils.consume (entity);} finally {response1.close ();}} catch (Exception e) {e.printstacktrace ();} finally {try {httpclient.close ();} catch (IOException e) {e.printstacktrace ( );}} return responsecontent;} public string httppost (string url, map<string, string> paramsmap) {return HttpPost (URL, paramsmap, null);} /** * HTTP POST request * * @param URL * @param paramsmap * @return */public string httppost (string url, map<string, string& Gt Paramsmap,map<string, string> headmap) {String responsecontent = null; Closeablehttpclient httpclient = Httpclients.createdefault (); try {httppost httppost = new HttpPost (URL); Setposthead ( HttpPost, Headmap); Setpostparams (HttpPost, Paramsmap); Closeablehttpresponse response = Httpclient.execute (HttpPost); try {System.out.println (Response.getstatusline ()); httpentity entity = response.getentity (); InputStream is = Entity.getcontent (); StringBuffer strbuf = new StringBuffer () byte[] buffer = new Byte[4096];int r = 0;while ((r = is.read (buffer)) > 0) {St Rbuf.append (new String (buffer, 0, R, "UTF-8")); ResponsEContent = Strbuf.tostring (); Entityutils.consume (entity);} finally {response.close ();}} catch (Exception e) {e.printstacktrace ();} finally {try {httpclient.close ();} catch (IOException e) {e.printstacktrace () ;}} System.out.println ("responsecontent =" + responsecontent); return responsecontent;} /** * Set Post parameters * * @param httppost * @param paramsmap * @throws Exception */private void Setpostparams (HttpPost httppost , map<string, string> paramsmap) throws Exception {if (Paramsmap! = null && paramsmap.size () > 0) {list&lt ; namevaluepair> Nvps = new arraylist<namevaluepair> (); set<string> KeySet = Paramsmap.keyset (); for (String Key:keyset) {nvps.add (New Basicnamevaluepair (Key, Paramsmap.get (key)));} Httppost.setentity (New Urlencodedformentity (Nvps));}} /** * Set HTTP head * * @param httppost * @param headmap */private void Setposthead (HttpPost httppost, map<string, Strin G> headmap) {if (Headmap! = null && headmap.size () > 0) {set<string> keySet = Headmap.keyset (); for (String Key:keyset) {Httppost.addheader (key, Headmap.get (key));}}} /** * Set HTTP head * * @param httpget * @param headmap */private void Setgethead (HttpGet httpget, map<string, String&gt ; Headmap) {if (Headmap! = null && headmap.size () > 0) {set<string> keySet = Headmap.keyset (); for (String K Ey:keyset) {Httpget.addheader (key, Headmap.get (key));}}}}

We can test it with the following code:

Import Java.util.hashmap;import Java.util.map;import Net.mobctrl.httpclientutils;import net.mobctrl.httpclientutils.httpclientdownloadprogress;/** * @date January 14, 2015 PM 1:49:50 * @author Zheng Haibo * @ Description: Test */public class Main {public static void main (string[] args) {/** * Test download file asynchronous download */httpclientutils.getinstan CE (). Download ("Http://newbbs.qiniudn.com/phone.png", "Test.png", new Httpclientdownloadprogress () {@Overridepublic void OnProgress (int progress) {System.out.println ("Download progress =" + progress);}); /POST synchronization method map<string, string> params = new hashmap<string, string> ();p arams.put ("username", "admin"); Params.put ("Password", "admin"); Httpclientutils.getinstance (). HttpPost ("Http://localhost:8080/sshmysql/register", params);//GET Synchronization method Httpclientutils.getinstance (). HttpGet ("http://wthrcdn.etouch.cn/weather_mini?city= Beijing");}

The result of the operation is:

http/1.1 okresponsecontent = {"id": "2", "MSG": "Add failed!" user name already exists! "}http/1.1 okdebug:{" desc ":" OK "," status ": +," data ": {" Wendu ":" 1 "," Ganmao ":" The weather turns cool, the air humidity is bigger, the cold is easy to occur, The weaker of the friend please pay attention to appropriate protection. "," forecast ": [{" Fengxiang ":" No continuous Wind Direction "," Fengli ":" Breeze Level "," High ":" Hot 2 ℃ "," type ":" Snow "," Low ":" Cryogenic -5℃ "," date ":" 14th Wed "},{" Fengxiang ":" No continuous Wind Direction "," Fengli ":" Breeze Level "," High ":" Hot 3 ℃ "," type ":" Haze "," Low ":" Cryogenic -3℃ "," date ":" 15th Thursday "},{" Fengxiang ":" North Wind "," Fengli ":" 4-5 "," High ":" 5 ℃ "," type ":" Sunny "," Low ":" Cryogenic -6℃ "," date ":" 16th Friday "},{" Fengxiang ":" No continuous Wind Direction "," Fengli ":" Breeze "," High ":" 4 ℃ "," type ":" Cloudy "," Low ":" -5℃ "," date ":" 17th Saturday "},{" Fengxiang ":" No continuous Wind Direction "," Fengli ":" Breeze Level "," High ":" Hot 6 ℃ "," Type ":" Cloudy "," Low ":" Lo -4℃ "," date ":" 18th Sunday "}]," Yesterday ": {" fl ":" Breeze "," FX ":" No continuous Wind Direction "," High ":" Temperature 4 ℃ "," type ":" Haze "," lower ": "Low Temperature -4℃", "date": "13th Tuesday"}, "AQI": "309", "City": "Beijing"}}http/1.1 okdownload progress = 2download progress = 6download Progress = 8download Progress = 10download Progress = 12download Progress = 15download Progress = 17download progress = 20 Download progress = 22downloAd progress = 27download Progress = 29download Progress = 31download Progress = 33download progress = 36download Progress  = 38download Progress = 40download Progress = 45download Progress = 47download Progress = 49download progress = 51download Progress = 54download Progress = 56download Progress = 58download Progress = 60download Progress = 62download progress = 69download progress = 75download Progress = 81download Progress = 87download Progress = 89download progress = 91download P Rogress = 93download Progress = 96download progress = 100

The download process has a progress callback.

The relevant LIBS package can be downloaded in the following link: http://download.csdn.net/detail/nuptboyzhb/8362801

The above code, which can be used in J2SE,J2EE or Android, requires relevant permissions when used in Android.

Not permitted for commercial purposes without permission

Java: Use httpclient for post and get requests and file downloads