[英]How to read json file into java with GSON library
我想使用GSON库用java读取这个JSON文件。 我是新手使用gson libray。 有人请更正我的代码我的JSON文件如下所示:
{
"tableRows":[
{
"id":"100",
"mailContent":"Test mail content 123",
"sentiment":"0"
},
{
"id":"200",
"mailContent":"Test mail content 123",
"sentiment":"0"
},
{
"id":"300",
"mailContent":"Test mail content 123",
"sentiment":"0"
}
]
}
这是我为阅读此文件而编写的java代码:
import java.io.FileNotFoundException;
import java.io.FileReader;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonIOException;
import com.google.gson.JsonParser;
import com.google.gson.JsonSyntaxException;
import com.google.gson.JsonObject;
public class Sample {
public static void main(String[] args) {
JsonParser parser = new JsonParser();
try {
JsonElement jsontree = parser.parse(
new FileReader(
"/Users/kesavan-4688/Desktop/JSP-Eclipse/Sample/src/Demo/sample.json"
)
);
JsonElement je = jsontree.getAsJsonObject();
JsonArray ja = je.getAsJsonArray();
for (Object o : ja)
{
JsonObject person = (JsonObject) o;
String id = person.get("id").getAsString();
System.out.println(id);
String mail = person.get("mailcontent").getAsString();
System.out.println(mail);
String sentiment = person.get("sentiment").getAsString();
System.out.println(sentiment);
}
}
catch (JsonIOException e) {
e.printStackTrace();
} catch (JsonSyntaxException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
}
但我得到以下异常:
Exception in thread "main" java.lang.IllegalStateException: This is not a JSON Array.
at com.google.gson.JsonElement.getAsJsonArray(JsonElement.java:106)
at Demo.Sample.main(Sample.java:18)
您尝试将JsonObject
转换为无法工作的JsonArray
,您需要先获取根JsonObject
然后使用getAsJsonArray(String memberName)
将属性tableRows作为JsonArray
作为下一个:
...
// Get the root JsonObject
JsonObject je = jsontree.getAsJsonObject();
// Get the property tableRows as a JsonArray
JsonArray ja = je.getAsJsonArray("tableRows");
for (Object o : ja) {
...
// Warning JSON is case sensitive so use mailContent instead of mailcontent
String mail = person.get("mailContent").getAsString();
...
}
输出:
100
Test mail content 123
0
200
Test mail content 123
0
300
Test mail content 123
0
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