JENA:端点返回Content-Type:text/html [英] JENA: Endpoint returned Content-Type: text/html

问题描述

当我尝试向某个端点发送sparql查询时，例如:

When I try to send a sparql query to some endpoint, for example:

QueryExecution qe = QueryExecutionFactory.sparqlService("http://data.open.ac.uk/sparql",
                getStringForQuery());
        ResultSet results = qe.execSelect();

我知道

Exception in thread "main" org.apache.jena.query.QueryException: Endpoint returned Content-Type: text/html which is not currently supported for SELECT queries
    at org.apache.jena.sparql.engine.http.QueryEngineHTTP.execResultSetInner(QueryEngineHTTP.java:372)
    at org.apache.jena.sparql.engine.http.QueryEngineHTTP.execSelect(QueryEngineHTTP.java:334)

这不是我无法向其发送查询的唯一一个端点，

And this is not the only one endpoint, to which I can't send query,

我应该怎么做才能得到其他内容类型的结果?我尝试用Google搜索它，但是我发现如果我将查询发送到错误的html(不是sparql端点)，但是

What should I do to get results in other content-type? I try to google it, but I found that it can happen if I send query to bad html (not sparql endpoint), but http://data.open.ac.uk/sparql is good endpoint, I send sparql query to it via python and everything was good.

推荐答案

我不知道它们使用哪种后端，但是由于任何原因，在使用SPARQL端点时必须使用附加的HTTP参数force=true来自外部服务:

I don't know what kind of backend they use, but for whatever reason, you have to use an additional HTTP parameter force=true when using the SPARQL endpoint from external services:

http://data.open.ac.uk/sparql?force=true

根据Apache Jena开发团队的Andy Seaborne的说法，这应该是Jena 3.1.1重定向中的错误.在版本3.1.0中，重定向到?force=true的功能符合预期.另外，后端是Fuseki 2.3.1.

According to Andy Seaborne from the Apache Jena development team, this is supposed to be a bug in the redirect in Jena 3.1.1. In version 3.1.0 the redirect to ?force=true works as expected. In addition, the backend is Fuseki 2.3.1.

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