Java 无法从url解析JSON
编写一段代码，查询返回JSON的URL，并可以解析JSON字符串以提取信息片段。应该解析并返回的信息是pageid和“请参阅”链接列表。这些链接应该被格式化为一个人可以用来找到合适文章的实际链接。 使用WikipediaAPI进行查询。示例查询是： 通过更改查询字符串的“标题”部分，可以生成其他查询。解析JSON和提取“请参阅”链接的代码应该足够通用，可以用于任何维基百科文章 我尝试编写以下代码：Java 无法从url解析JSON,java,json,jakarta-ee,jackson,gson,Java,Json,Jakarta Ee,Jackson,Gson,编写一段代码，查询返回JSON的URL，并可以解析JSON字符串以提取信息片段。应该解析并返回的信息是pageid和“请参阅”链接列表。这些链接应该被格式化为一个人可以用来找到合适文章的实际链接。 使用WikipediaAPI进行查询。示例查询是： 通过更改查询字符串的“标题”部分，可以生成其他查询。解析JSON和提取“请参阅”链接的代码应该足够通用，可以用于任何维基百科文章 我尝试编写以下代码： import java.io.BufferedReader; import java.i
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import org.json.JSONException;
import org.json.JSONObject;
public class JsonRead {
private static String readUrl(String urlString) throws Exception {
BufferedReader reader = null;
try {
URL url = new URL(urlString);
reader = new BufferedReader(new InputStreamReader(url.openStream()));
StringBuffer buffer = new StringBuffer();
int read;
char[] chars = new char[1024];
while ((read = reader.read(chars)) != -1)
buffer.append(chars, 0, read);
return buffer.toString();
} finally {
if (reader != null)
reader.close();
}
}
public static void main(String[] args) throws IOException, JSONException {
JSONObject json;
try {
json = new JSONObject(readUrl("https://en.wikipedia.org/w/api.php?format=json&action=query&titles=SMALL&prop=revisions&rvprop=content"));
System.out.println(json.toString());
System.out.println(json.get("pageid"));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
org.json.JSONException: JSONObject["pageid"] not found.
at org.json.JSONObject.get(JSONObject.java:471)
at JsonRead.main(JsonRead.java:35)
{
"batchcomplete":"",
"query":{
"pages":{
"1808130":{
"pageid":1808130,
"ns":0,
"title":"SMALL",
"revisions":[
{
"contentformat":"text/x-wiki",
"contentmodel":"wikitext",
"*":"{{About|the ALGOL-like programming language|the scripting language formerly named Small|Pawn (scripting language)}}\n\n'''SMALL''', Small Machine Algol Like Language, is a [[computer programming|programming]] [[programming language|language]] developed by Dr. [[Nevil Brownlee]] of [[Auckland University]].\n\n==History==\nThe aim of the language was to enable people to write [[ALGOL]]-like code that ran on a small machine. It also included the '''string''' type for easier text manipulation.\n\nSMALL was used extensively from about 1980 to 1985 at [[Auckland University]] as a programming teaching aid, and for some internal projects. Originally written to run on a [[Burroughs Corporation]] B6700 [[Main frame]] in [[Fortran]] IV, subsequently rewritten in SMALL and ported to a DEC [[PDP-10]] Architecture (on the [[Operating System]] [[TOPS-10]]) and IBM S360 Architecture (on the Operating System VM/[[Conversational Monitor System|CMS]]).\n\nAbout 1985, SMALL had some [[Object-oriented programming|object-oriented]] features added to handle structures (that were missing from the early language), and to formalise file manipulation operations.\n\n==See also==\n*[[ALGOL]]\n*[[Lua (programming language)]]\n*[[Squirrel (programming language)]]\n\n==References==\n*[http://www.caida.org/home/seniorstaff/nevil.xml Nevil Brownlee]\n\n[[Category:Algol programming language family]]\n[[Category:Systems programming languages]]\n[[Category:Procedural programming languages]]\n[[Category:Object-oriented programming languages]]\n[[Category:Programming languages created in the 1980s]]"
}
]
}
}
}
}
如果您仔细阅读您的
异常Exception in thread "main" org.json.JSONException: A JSONObject text must begin with '{' at 1 [character 2 line 1]
at org.json.JSONTokener.syntaxError(JSONTokener.java:433)
异常JSONObject文本必须以“{”api因此，我建议您调试代码，并尝试找出字符串变量
jsonText异常Exception in thread "main" org.json.JSONException: A JSONObject text must begin with '{' at 1 [character 2 line 1]
at org.json.JSONTokener.syntaxError(JSONTokener.java:433)
异常JSONObject文本必须以“{”api因此，我建议您调试代码，并尝试找出在字符串变量
jsonTextorg.json.JSONException:JSONObject[“pageid”]未找到。json.get（“pageid”）时pageidint pid = json.getJSONObject("query")
.getJSONObject("pages")
.getJSONObject("1808130")
.getInt("pageid");
数组String s = json.getJSONObject("query")
.getJSONObject("pages")
.getJSONObject("1808130")
.getJSONArray("revisions")
.getJSONObject(0)
.getString("*");
生成的字符串不包含有效的JSON。您必须手动解析它。您会得到异常
org.JSON.JSONException:JSONObject[“pageid”]未找到。JSON.get（“pageid”）时pageidint pid = json.getJSONObject("query")
.getJSONObject("pages")
.getJSONObject("1808130")
.getInt("pageid");
数组String s = json.getJSONObject("query")
.getJSONObject("pages")
.getJSONObject("1808130")
.getJSONArray("revisions")
.getJSONObject(0)
.getString("*");
生成的字符串不包含有效的JSON。您必须手动对其进行分析。是否调试应用程序？并尝试获取字符串变量“jsonText”实际包含的内容。.尝试在
字符串jsonText=readAll（rd）；jsonTextString jsonText=readAll（rd）；jsonTextURLURL