（Java）HTTP GET请求不断获得400响应代码，尽管链接在浏览器中工作得很好

Question

我想从使用HTTP的Google Trends获取JSON响应。这是我的代码片段：

public class TestClass { 
    public static void main(String[] args) throws Exception{ 

    String address = "https://trends.google.com/trends/api/explore?hl=en-US&tz=240&req={\"comparisonItem\":[{\"keyword\":\"Miley\",\"geo\":\"US\",\"time\":\"2012-01-01 2014-01-01\"},{\"keyword\":\"Hannah Montana\",\"geo\":\"US\",\"time\":\"2012-01-01 2014-01-01\"}],\"category\":0,\"property\":\"\"}"; 

    URL url = new URL(address); 

    HttpURLConnection con = (HttpURLConnection) url.openConnection(); 

    con.setRequestMethod("GET"); 

    int responseCode = con.getResponseCode(); 

    System.out.println("URL is "+address); 

    System.out.println("Response code is " + responseCode); } 
} 

这是输出：

URL is https://trends.google.com/trends/api/explore?hl=en-US&tz=240&req={"comparisonItem":[{"keyword":"Miley","geo":"US","time":"2012-01-01 2014-01-01"},{"keyword":"Hannah Montana","geo":"US","time":"2012-01-01 2014-01-01"}],"category":0,"property":""} 

Response code is 400 

如果我直接在浏览器中键入URL，谷歌给我也没有问题的JSON文件。但是，如果我尝试使用Java访问该URL，则会收到错误的请求。我怎么解决这个问题？提前致谢。

Answer 1

您需要URL编码URL的查询字符串部分。请查看this question/answer以了解实现此目的的一些方法。

Answer 2

我解决了你的问题。我建议使用apache http api构建http-request。

private static final HttpRequest<String> REQUEST = 
     HttpRequestBuilder.createGet("https://trends.google.com/trends/api/explore", String.class) 
       .addDefaultRequestParameter("hl", "en-US") 
       .addDefaultRequestParameter("tz", "240") 
       .responseDeserializer(ResponseDeserializer.ignorableDeserializer()) 
       .build(); 

public void send() { 
    ResponseHandler<String> responseHandler = REQUEST.execute("req", "{\"comparisonItem\":[{\"keyword\":\"Miley\",\"geo\":\"US\",\"time\":\"2012-01-01 2014-01-01\"},{\"keyword\":\"Hannah Montana\",\"geo\":\"US\",\"time\":\"2012-01-01 2014-01-01\"}],\"category\":0,\"property\":\"\"}"); 
    System.out.println(responseHandler.getStatusCode()); 
    responseHandler.ifHasContent(System.out::println); 
} 

该代码打印您通过浏览器得到的响应代码200和响应正文。