Java Play 2.2中的慢速块响应
在基于MyPlay框架的web应用程序中,用户可以下载csv或json格式的不同数据库表的所有行。表相对较大(100k+行),我正在尝试使用Play2.2中的分块来返回结果 然而问题是,尽管println语句显示行被写入Chunks.Out对象,但它们不会显示在客户端!如果我限制返回的行数,它将起作用,但在开始时也会有很大的延迟,如果我尝试返回所有行,则延迟会更大,并导致超时或服务器内存不足 我使用ebeanorm,表被索引,从psql查询不需要太多时间。有人知道可能是什么问题吗 我非常感谢你的帮助 以下是其中一个控制器的代码:Java Play 2.2中的慢速块响应,java,playframework-2.0,ebean,chunking,Java,Playframework 2.0,Ebean,Chunking,在基于MyPlay框架的web应用程序中,用户可以下载csv或json格式的不同数据库表的所有行。表相对较大(100k+行),我正在尝试使用Play2.2中的分块来返回结果 然而问题是,尽管println语句显示行被写入Chunks.Out对象,但它们不会显示在客户端!如果我限制返回的行数,它将起作用,但在开始时也会有很大的延迟,如果我尝试返回所有行,则延迟会更大,并导致超时或服务器内存不足 我使用ebeanorm,表被索引,从psql查询不需要太多时间。有人知道可能是什么问题吗 我非常感谢你的
@SecureSocial.UserAwareAction
public static Result showEpex() {
User user = getUser();
if(user == null || user.getRole() == null)
return ok(views.html.profile.render(user, Application.NOT_CONFIRMED_MSG));
DynamicForm form = DynamicForm.form().bindFromRequest();
final UserRequest req = UserRequest.getRequest(form);
if(req.getFormat().equalsIgnoreCase("html")) {
Page<EpexEntry> page = EpexEntry.page(req.getStart(), req.getFinish(), req.getPage());
return ok(views.html.epex.render(page, req));
}
// otherwise chunk result and send back
final ResultStreamer<EpexEntry> streamer = new ResultStreamer<EpexEntry>();
Chunks<String> chunks = new StringChunks() {
@Override
public void onReady(play.mvc.Results.Chunks.Out<String> out) {
Page<EpexEntry> page = EpexEntry.page(req.getStart(), req.getFinish(), 0);
ResultStreamer<EpexEntry> streamer = new ResultStreamer<EpexEntry>();
streamer.stream(out, page, req);
}
};
return ok(chunks).as("text/plain");
}
@SecureSocial.userawa
公共静态结果showEpex(){
User=getUser();
if(user==null | | user.getRole()==null)
返回ok(views.html.profile.render(用户、应用程序、未确认消息));
DynamicForm form=DynamicForm.form().bindFromRequest();
最终UserRequest req=UserRequest.getRequest(表单);
if(req.getFormat().equalsIgnoreCase(“html”)){
Page Page=EpexEntry.Page(req.getStart(),req.getFinish(),req.getPage());
返回ok(views.html.epex.render(page,req));
}
//否则,将结果分块并发送回
最终结果streamer拖缆=新结果streamer();
Chunks Chunks=新的StringChunks(){
@凌驾
public void onReady(play.mvc.Results.Chunks.Out){
Page Page=EpexEntry.Page(req.getStart(),req.getFinish(),0);
ResultStreamer streamer=新的ResultStreamer();
拖缆流(输出,第页,要求);
}
};
返回ok(块).as(“文本/普通”);
}
和拖缆:
public class ResultStreamer<T extends Entry> {
private static ALogger logger = Logger.of(ResultStreamer.class);
public void stream(Out<String> out, Page<T> page, UserRequest req) {
if(req.getFormat().equalsIgnoreCase("json")) {
JsonContext context = Ebean.createJsonContext();
out.write("[\n");
for(T e: page.getList())
out.write(context.toJsonString(e) + ", ");
while(page.hasNext()) {
page = page.next();
for(T e: page.getList())
out.write(context.toJsonString(e) + ", ");
}
out.write("]\n");
out.close();
} else if(req.getFormat().equalsIgnoreCase("csv")) {
for(T e: page.getList())
out.write(e.toCsv(CSV_SEPARATOR) + "\n");
while(page.hasNext()) {
page = page.next();
for(T e: page.getList())
out.write(e.toCsv(CSV_SEPARATOR) + "\n");
}
out.close();
}else {
out.write("Invalid format! Only CSV, JSON and HTML can be generated!");
out.close();
}
}
public static final String CSV_SEPARATOR = ";";
}
公共类ResultStreamer{
私有静态ALogger logger=logger.of(ResultStreamer.class);
公共无效流(Out Out、Page Page、UserRequest req){
if(req.getFormat().equalsIgnoreCase(“json”)){
JsonContext context=Ebean.createJsonContext();
输出。写入(“[\n”);
对于(te:page.getList())
out.write(context.toJsonString(e)+“,”);
while(page.hasNext()){
page=page.next();
对于(te:page.getList())
out.write(context.toJsonString(e)+“,”);
}
out.write(“]\n”);
out.close();
}else if(req.getFormat().equalsIgnoreCase(“csv”)){
对于(te:page.getList())
out.write(e.toCsv(CSV_分隔符)+“\n”);
while(page.hasNext()){
page=page.next();
对于(te:page.getList())
out.write(e.toCsv(CSV_分隔符)+“\n”);
}
out.close();
}否则{
write(“格式无效!只能生成CSV、JSON和HTML!”);
out.close();
}
}
公共静态最终字符串CSV_分隔符=“;”;
}
模型:
@Entity
@Table(name="epex")
public class EpexEntry extends Model implements Entry {
@Id
@Column(columnDefinition = "pg-uuid")
private UUID id;
private DateTime start;
private DateTime finish;
private String contract;
private String market;
private Double low;
private Double high;
private Double last;
@Column(name="weight_avg")
private Double weightAverage;
private Double index;
private Double buyVol;
private Double sellVol;
private static final String START_COL = "start";
private static final String FINISH_COL = "finish";
private static final String CONTRACT_COL = "contract";
private static final String MARKET_COL = "market";
private static final String ORDER_BY = MARKET_COL + "," + CONTRACT_COL + "," + START_COL;
public static final int PAGE_SIZE = 100;
public static final String HOURLY_CONTRACT = "hourly";
public static final String MIN15_CONTRACT = "15min";
public static final String FRANCE_MARKET = "france";
public static final String GER_AUS_MARKET = "germany/austria";
public static final String SWISS_MARKET = "switzerland";
public static Finder<UUID, EpexEntry> find =
new Finder(UUID.class, EpexEntry.class);
public EpexEntry() {
}
public EpexEntry(UUID id, DateTime start, DateTime finish, String contract,
String market, Double low, Double high, Double last,
Double weightAverage, Double index, Double buyVol, Double sellVol) {
this.id = id;
this.start = start;
this.finish = finish;
this.contract = contract;
this.market = market;
this.low = low;
this.high = high;
this.last = last;
this.weightAverage = weightAverage;
this.index = index;
this.buyVol = buyVol;
this.sellVol = sellVol;
}
public static Page<EpexEntry> page(DateTime from, DateTime to, int page) {
if(from == null && to == null)
return find.order(ORDER_BY).findPagingList(PAGE_SIZE).getPage(page);
ExpressionList<EpexEntry> exp = find.where();
if(from != null)
exp = exp.ge(START_COL, from);
if(to != null)
exp = exp.le(FINISH_COL, to.plusHours(24));
return exp.order(ORDER_BY).findPagingList(PAGE_SIZE).getPage(page);
}
@Override
public String toCsv(String s) {
return id + s + start + s + finish + s + contract +
s + market + s + low + s + high + s +
last + s + weightAverage + s +
index + s + buyVol + s + sellVol;
}
@实体
@表(name=“epex”)
公共类EpexEntry扩展模型实现入口{
@身份证
@列(columnDefinition=“pg uuid”)
私有UUID;
私有日期时间开始;
私人约会时间完成;
私人串合同;
私人市场;
私人双低;
私人双高;
私人双末;
@列(名称=“平均重量”)
私人双重平均;
私人双指数;
私人双重购买;
私人双重销售;
私有静态最终字符串START\u COL=“START”;
私有静态最终字符串FINISH\u COL=“FINISH”;
私有静态最终字符串合同\u COL=“合同”;
私有静态最终字符串市场\u COL=“市场”;
私有静态最终字符串订单\按=市场\列+”,“+合同\列+”,“+开始\列;
公共静态最终整版页面大小=100;
公共静态最终字符串HOURLY\u CONTRACT=“HOURLY”;
公共静态最终字符串MIN15_CONTRACT=“15min”;
公共静态最终字符串FRANCE_MARKET=“FRANCE”;
公共静态最终字符串geru AUS_MARKET=“德国/奥地利”;
公共静态最终字符串SWISS_MARKET=“swissand”;
公共静态查找器查找=
新查找程序(UUID.class、EpexEntry.class);
公共电子出口{
}
公共EpexEntry(UUID id、DateTime start、DateTime finish、String contract、,
弦乐市场,双低,双高,双末,
双权重平均、双指数、双买入量、双卖出量){
this.id=id;
this.start=start;
this.finish=完成;
本合同=合同;
这个市场=市场;
这个.低=低;
这个高=高;
this.last=last;
this.weightAverage=weightAverage;
这个指数=指数;
this.buyVol=buyVol;
this.sellVol=sellVol;
}
公共静态页面(DateTime-from、DateTime-to、int-Page){
if(from==null&&to==null)
返回find.order(order_BY).findPagingList(PAGE_SIZE).getPage(PAGE);
ExpressionList exp=find.where();
if(from!=null)
exp=exp.ge(起始列,起始);
如果(到!=null)
exp=exp.le(饰面颜色,至plusHours(24));
返回exp.order(order_BY).findPagingList(PAGE_SIZE).getPage(PAGE);
}
@凌驾
公共字符串toCsv(字符串s){
返回id+s+开始+s+结束+s+合同+
s+市场+s+低+s+高+s+
最后+s+权重平均值+s+
指数+s+buyVol+s+sellVol;
}
1.大多数浏览器在显示任何结果之前都会等待1-5 kb的数据。您可以使用命令curl检查Play Framework是否确实发送数据http://localhost:9000
2.创建拖缆两次,首先删除final ResultStreamer streamer=new ResultStreamer();
public static QueryIterator<EpexEntry> all() {
return find.order(ORDER_BY).findIterate();
}
public void stream(Out<String> out, QueryIterator<T> iterator, UserRequest req) {
if(req.getFormat().equalsIgnoreCase("json")) {
JsonContext context = Ebean.createJsonContext();
out.write("[\n");
while (iterator.hasNext()) {
out.write(context.toJsonString(iterator.next()) + ", ");
}
iterator.close(); // its important to close iterator
out.write("]\n");
out.close();
} else // csv implementation here
QueryIterator<EpexEntry> iterator = EpexEntry.all();
ResultStreamer<EpexEntry> streamer = new ResultStreamer<EpexEntry>();
streamer.stream(new BuffOut(out, 10000), iterator, req); // notice buffering here
public class Application extends Controller {
public static Result showEpex() {
Chunks<String> chunks = new StringChunks() {
@Override
public void onReady(play.mvc.Results.Chunks.Out<String> out) {
new ResultStreamer().stream(out);
}
};
return ok(chunks).as("text/plain");
}
}
public class BuffOut {
private StringBuilder sb;
private Out<String> dst;
public BuffOut(Out<String> dst, int bufSize) {
this.dst = dst;
this.sb = new StringBuilder(bufSize);
}
public void write(String data) {
if ((sb.length() + data.length()) > sb.capacity()) {
dst.write(sb.toString());
sb.setLength(0);
}
sb.append(data);
}
public void close() {
if (sb.length() > 0)
dst.write(sb.toString());
dst.close();
}
}
public class ResultStreamer {
public void stream(Out<String> out) {
for (int i = 0; i < 10000; i++) {
out.write("TEST" + i + "\n");
}
out.close();
}
}
public class ResultStreamer {
public void stream(Out<String> out) {
BuffOut out2 = new BuffOut(out, 1000);
for (int i = 0; i < 10000; i++) {
out2.write("TEST" + i + "\n");
}
out2.close();
}
}