HttpClient4.3使用总结

1.Get

public static String getResultWithGet(HttpServletRequest request, String url) throws Exception{
    String result =  null;
    HttpClient client =getClient();
    try{
        HttpGet get = new HttpGet(url);
        HttpResponse response = client.execute(get);
        result = getResponseBodyAsString(response);
    }finally{
        client.getConnectionManager().shutdown();
    }
    return result;
}

2、Post

public static String getResultWithPost(HttpServletRequest request, String url) throws Exception{
        String json = null;
        HttpClient client =getClient();
        try{
            HttpPost post = new HttpPost(url);
            @SuppressWarnings("unchecked")
            Map<String, String[]> map = request.getParameterMap();
            Set<String> keySet = map.keySet();
            JSONObject jo = new JSONObject();
            for(String s : keySet){
                if(!"".equals(map.get(s)[0])){
                    jo.element(s, map.get(s)[0]);
                }

            }
            StringEntity reqEntity = new StringEntity(jo.toString(),"UTF-8");
            reqEntity.setContentType("application/json");
            post.setEntity(reqEntity);
            HttpResponse response = client.execute(post);
            json = getResponseBodyAsString(response);
        }finally{
            client.getConnectionManager().shutdown();
        }
        return json;
    }

3、Put

public static String getResultWithPut(HttpServletRequest request, String url) throws Exception{
        String json = null;
        HttpClient client =getClient();
        try{
            HttpPut put = new HttpPut（url);
            @SuppressWarnings("unchecked")
            Map<String, String[]> map = request.getParameterMap();
            Set<String> keySet = map.keySet();
            JSONObject jo = new JSONObject();
            for(String s : keySet){
                if(!"".equals(map.get(s)[0])){
                    jo.element(s, map.get(s)[0]);
                }

            }
            StringEntity reqEntity = new StringEntity(jo.toString(),"UTF-8");
            reqEntity.setContentType("application/json");
            put.setEntity(reqEntity);
            HttpResponse response = client.execute(put);
            json = getResponseBodyAsString(response);
        }finally{
            client.getConnectionManager().shutdown();
        }
        return json;
    }

4、Delete

public static String getResultWithDelete(HttpServletRequest request, String url) throws Exception{
        String result = null;
        HttpClient client =getClient();
        try{
            HttpDelete delete = new HttpDelete(url);
            HttpResponse response  = client.execute(delete);
            result = getResponseBodyAsString(response);
        }finally{
            client.getConnectionManager().shutdown();
        }
        return result;
    }

5、getResponseBodyAsString

public static String getResponseBodyAsString(HttpResponse response) throws Exception {
        StringBuilder sb = new StringBuilder();
        HttpEntity httpEntity = response.getEntity();
        if(httpEntity != null){
            httpEntity = new BufferedHttpEntity(httpEntity);
            InputStream is = httpEntity.getContent();
            BufferedReader br = new BufferedReader(new InputStreamReader(is,"UTF-8"));
            String str;
            while((str=br.readLine())!=null){
                sb.append(str);
            }
            is.close();
        }
        return sb.toString();
    }

6、文件上传

public String uploadAttachment(HttpServletRequest request){
    String json = null;
    HttpClient client = TicketUtils.getClient();
    try {

        HttpPost post = new HttpPost(url);

        DiskFileItemFactory fac = new DiskFileItemFactory();
        ServletFileUpload upload = new ServletFileUpload(fac);
        upload.setHeaderEncoding("UTF-8");
        @SuppressWarnings("unchecked")
        List<FileItem> fileList = upload.parseRequest(request);
        Iterator<FileItem> it = fileList.iterator();
        List<File> tempFileList = new ArrayList<File>();
        while (it.hasNext()) {
            FileItem item = it.next();
            if (!item.isFormField()) {
                String fileName = item.getName();
                if (fileName != null)
                 {
                  File file = new File(fileName);
                  item.write(file);
                  MultipartEntity multipartEntity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE, null,Charset.forName("UTF-8"));
                  FileBody fileBody = new FileBody(file);
                  multipartEntity.addPart(fileName, fileBody);
                  post.setEntity(multipartEntity);
                  tempFileList.add(file);
                 }
            }
        }
        HttpResponse response = client.execute(post);
        json = TicketUtils.getResponseBodyAsString(response);
        //delete temp files
        for(File file : tempFileList){
            file.delete();
        }
    } catch (Exception e) {
        log.error(e);
        json = JsonUtil.getJsonString(Const.ERROR_MESSAGE, EM.TICKET_EXCEPTION);
    }finally{
        client.getConnectionManager().shutdown();
    }
       return json;
   }

7、文件下载

public void downloadAttachment(HttpServletRequest request, HttpServletResponse response, @PathVariable("fileId") Integer fileId){
    HttpClient client = TicketUtils.getClient();
    try {
        HttpGet get = new HttpGet(urlStr);

        ResponseHandler<byte[]> handler = new ResponseHandler<byte[]>() {
               public byte[] handleResponse(HttpResponse response)
                       throws ClientProtocolException, IOException {
                   HttpEntity entity = response.getEntity();
                   if (entity != null) {
                       return EntityUtils.toByteArray(entity);
                   } else {
                       return null;
                   }
               }
           };
           byte[] charts = client.execute(get, handler);

        URL url = new URL(urlStr);
        HttpURLConnection uc = (HttpURLConnection)url.openConnection();
        response.reset();
        response.addHeader("Content-disposition",uc.getHeaderField("Content-disposition"));
        OutputStream output = new BufferedOutputStream(response.getOutputStream());
        output.write(charts);
        output.flush();
        output.close();
        get.releaseConnection();
    } catch (Exception e) {
        log.error(e);
    }finally{
        client.getConnectionManager().shutdown();
    }
   }