使用elasticsearch 2.4 版本，想分页遍历所有的文档，因为 from + size 有范围限制，且效率低下，因此采用 scroll,代码如下，结果每次打印出来的数据一模一样，但是scroll_id 的值是最新的
public static void main(String[] args) { try { String url = "http://ip:port/index/type/_search"; String oldEsResult = sendGet(url, "scroll=20s&search_type=scan&size=10"); ObjectMapper mapper1 = new ObjectMapper(); String scroll_id; int totalCount = NumberUtils.toInt(mapper1.readTree(oldEsResult).findValue("hits").findValue("total").toString()); scroll_id = mapper1.readTree(oldEsResult).findValue("_scroll_id").toString(); System.out.println("totalCount is-------" + totalCount); int size = 100; int numbers = totalCount / size; //页数 String params = "scroll=20s&scroll_id="; for(int i = 0; i < numbers; i++){ String param = params + scroll_id; oldEsResult = sendGet(url, param); if(StringUtils.isBlank(oldEsResult)){ continue; } ObjectMapper mapper2 = new ObjectMapper(); scroll_id = mapper2.readTree(oldEsResult).findValue("_scroll_id").toString(); JsonNode node = mapper2.readTree(oldEsResult).findValue("hits").findValue("hits"); for (int j = 0; j < node.size(); j++) { System.out.println(node.get(j).get("_source")); } } } catch (Exception e) { e.printStackTrace(); } } public static String sendGet(String url, String param) { String result = ""; BufferedReader in = null; try { String urlNameString = url + "?" + param; URL realUrl = new URL(urlNameString); // 打开和URL之间的连接 URLConnection connection = realUrl.openConnection(); // 设置通用的请求属性 connection.setRequestProperty("accept", "*/*"); connection.setRequestProperty("connection", "Keep-Alive"); connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)"); // 建立实际的连接 connection.connect(); // 获取所有响应头字段 Map<String, List<String>> map = connection.getHeaderFields(); // 定义 BufferedReader输入流来读取URL的响应 in = new BufferedReader(new InputStreamReader( connection.getInputStream())); String line; while ((line = in.readLine()) != null) { result += line; } } catch (Exception e) { System.out.println("发送GET请求出现异常！" + e); e.printStackTrace(); } // 使用finally块来关闭输入流 finally { try { if (in != null) { in.close(); } } catch (Exception e2) { e2.printStackTrace(); } } return result; }
