Spring使用event-stream进行数据推送
作者：zyydd_
这篇文章主要介绍了Spring使用event-stream进行数据推送,前端使用EventSource方式向后台发送请求,后端接收到之后使用event-stream方式流式返回,文中有相关的代码示例供大家参考,需要的朋友可以参考下
前端使用EventSource方式向后台发送请求，后端接收到之后使用event-stream方式流式返回。可以应用在时钟、逐字聊天等场景。
前端js示例代码（向后台请求数据，并展示到“id=date”的div上）
<script type="text/javascript">
if (typeof (EventSource) !== "undefined") {
var eventSource = new EventSource("${root}/test/getDate");
eventSource.onmessage = function (event) {
document.getElementById("date").innerHTML = event.data;
}
eventSource.addEventListener('error', function (event) {
console.log("错误：" + event);
});
eventSource.addEventListener('open', function (event) {
console.log("建立连接：" + event);
});
} else {
document.getElementById("date").innerHTML = "抱歉，您的浏览器不支持EventSource事件 ...";
}
</script>后端java示例
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.servlet.http.HttpServletResponse;
import java.util.Date;
@Controller
@RequestMapping(value = "/test")
public class TestController {
@ResponseBody
@RequestMapping(value = "/getDate", produces = "text/event-stream;charset=UTF-8")
public void getDate(HttpServletResponse response) throws Exception {
System.out.println("getDate event start");
response.setContentType("text/event-stream");
response.setCharacterEncoding("UTF-8");
response.setStatus(200);
for (int i = 0; i < 10; i++) {
response.getWriter().write("data:" + new Date() + "\n\n");
response.getWriter().flush();
Thread.sleep(1000);
}
response.getWriter().close();
System.out.println("getDate event end");
}
}除了是这个方法，我们也可以使用Spring的定时器定时推送数据
定时器编写
1.在配置文件里添加相关配置
<!-- 定时器开关 -->
<task:annotation-driven />
<!-- 自动扫描的包名 -->
<bean id="myTaskXml" class="定时方法所在的类的完整类名"></bean>
<task:scheduled-tasks>
<task:scheduled ref="myTaskXml" method="appInfoAdd" cron="*/5 * * * * ?"/>
</task:scheduled-tasks>
上面的代码设置的是每5秒执行一次appInfoAdd方法，cron字段表示的是时间的设置，分为：秒，分，时，日，月，周，年。
2.定时方法的编写
Logger log = Logger.getLogger(TimerTask.class);;
public void apiInfoAdd(){
InputStream in = TimerTask.class.getClassLoader().getResourceAsStream("/system.properties");
Properties prop = new Properties();
try {
prop.load(in);
} catch (IOException e) {
e.printStackTrace();
}
String key = prop.getProperty("DLKEY");
log.info("key--" + key);
//锁数据操作
List<GbEsealInfo> list = this.esealService.loadBySendFlag("0");
if (list == null) {
log.info("没有需要推送的锁数据");
}else{
JsonObject json = new JsonObject();
JsonArray ja = new JsonArray();
json.add("esealList", ja);
for(int i = 0; i < list.size(); i++) {
GbEntInfo ent = this.entService.loadByPk(list.get(i).getEntId());
JsonObject esealJson = getEsealJson(list.get(i), ent);
ja.add(esealJson);
}
String data = json.toString();
log.info("锁数据--" + data);
HttpDeal hd = new HttpDeal();
Map<String,String> map = new HashMap<String, String>();
map.put("key",key);
map.put("data", data);
hd.post(prop.getProperty("ESEALURL"), map);
log.info(hd.responseMsg);
JsonObject returnData = new JsonParser().parse(hd.responseMsg).getAsJsonObject();
if (("\"10000\"").equals(returnData.get("code").toString())){
log.info("锁数据推送成功");
for(int i = 0; i < list.size(); i++){
list.get(i).setSendFlag("1");
int res = this.esealService.updateSelectiveByPk(list.get(i));
if(res == 0){
log.info("第" + (i+1) + "条锁数据的sendflag字段的状态值修改失败");
continue;
}
}
}
}这个过程包括读取配置文件里的key，从数据库读取数据（根据数据的字段判断是否需要推送），使用GSON把数据拼装成上一篇文章里的data的形式data={"esealList":[{},{},{}]},使用HttpClient执行带参数的POST方法，访问POST接口，根据返回信息判断状态。
3.HttpClient里的带参POST方法
public class HttpDeal {
public String responseMsg;
public String post(String url,Map<String, String> params){
//实例化httpClient
CloseableHttpClient httpclient = HttpClients.createDefault();
//实例化post方法
HttpPost httpPost = new HttpPost(url);
//处理参数
List<NameValuePair> nvps = new ArrayList <NameValuePair>();
Set<String> keySet = params.keySet();
for(String key : keySet) {
nvps.add(new BasicNameValuePair(key, params.get(key)));
}
//结果
CloseableHttpResponse response = null;
String content="";
try {
//提交的参数
UrlEncodedFormEntity uefEntity = new UrlEncodedFormEntity(nvps, "UTF-8");
//将参数给post方法
httpPost.setEntity(uefEntity);
//执行post方法
response = httpclient.execute(httpPost);
if(response.getStatusLine().getStatusCode()==200){
content = EntityUtils.toString(response.getEntity(),"utf-8");
responseMsg = content;
//System.out.println(content);
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return content;
}
public static void main(String[] args) {
HttpDeal hd = new HttpDeal();
Map<String,String> map = new HashMap();
map.put("key","5c07db6e22c780e76824c88b2e65e9d9");
map.put("data", "{'esealList':[{'esealId':'1','entName':'q','entName':企业,'id':'qqww','id':'123', 'customsCode':'qq','fax':'021-39297127'}]}");
hd.post("http://localhost:8080/EportGnssWebDL/api/CopInfoAPI/esealInfoAdd.json",map);
}
}4.辅助类
/**
* 辅助类：锁接口需要的字段
* @param eseal
* @param ent
* @return
*/
private JsonObject getEsealJson(GbEsealInfo eseal, GbEntInfo ent){
JsonObject j = new JsonObject();
j.addProperty("esealId", eseal.getEsealId());
j.addProperty("vehicleNo", eseal.getVehicleNo());
j.addProperty("customsCode", eseal.getCustomsCode());
j.addProperty("simNo", eseal.getSimNo());
j.addProperty("entName", ent.getEntName());
j.addProperty("customsName", eseal.getCustomsName());
j.addProperty("leadingOfficial", ent.getLeadingOfficial());
j.addProperty("contact", ent.getContact());
j.addProperty("address", ent.getAddress());
j.addProperty("mail", ent.getMail());
j.addProperty("phone", ent.getPhone());
j.addProperty("fax", ent.getFax());
return j;
}以上就是Spring使用event-stream进行数据推送的详细内容，更多关于Spring event-stream数据推送的资料请关注脚本之家其它相关文章！