将json URL导入java并使用jackson库解析
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Import json URL to java and parse it using Hymanson library
提问by zahra
I am trying to read a json link in java and parse it so I can use it for other matters, but the problem is that I get errors that I really don't know waht to do about them. Here is the code:
我正在尝试在 Java 中读取 json 链接并解析它，以便我可以将它用于其他事项，但问题是我遇到了我真的不知道该怎么做的错误。这是代码：
package weather.data;
import weather.data;
import com.fasterxml.Hymanson.core.JsonParseException;
//import com.fasterxml.Hymanson.annotation.JsonMappingException;
import com.fasterxml.Hymanson.databind.ObjectMapper;
import com.fasterxml.Hymanson.databind.JsonMappingException;
import java.io.File;
import java.net.URI;
import java.io.IOException;
public class usertest {
public static void main() throws JsonParseException, JsonMappingException, IOException
{
URI jsonUrl = new URI("https://gist.githubusercontent.com/anonymous/4b32c7ef1ceb5dd48bf5/raw/ef1987551faa3fb61473bb0e7aad70a228dc36d6/gistfile1.txt");
ObjectMapper mapper = new ObjectMapper();
City = mapper.readValue(jsonUrl, data.class);
}
}
Here are the errors: about import weather.data:Multiple markers at this line - Only a type can be imported. weather.data resolves to a package - The import weather.data is never used
以下是错误： about import weather.data: 在这一行有多个标记 - 只能导入一个类型。weather.data 解析为一个包 - 从未使用过导入 weather.data
about City = mapper.readValue(jsonUrl, data.class):Multiple markers at this line - data cannot be resolved to a type - City cannot be resolved to a variable - The method readValue(JsonParser, Class) in the type ObjectMapper is not applicable for the arguments (URI, Class) - The method readValue(JsonParser, Class) in the type ObjectMapper is not applicable for the arguments (URI, Class) - City cannot be resolved to a variable - data cannot be resolved to a type
关于 City = mapper.readValue(jsonUrl, data.class): 这一行有多个标记 - 数据无法解析为类型 - 城市无法解析为变量 - ObjectMapper 类型中的 readValue(JsonParser, Class) 方法不是适用于参数 (URI, Class) - ObjectMapper 类型中的 readValue(JsonParser, Class) 方法不适用于参数 (URI, Class) - 城市无法解析为变量 - 数据无法解析为类型
Any Ideas? Also I really do not understand the concept of using mapper.readValue. would any one help me please?
有任何想法吗？另外我真的不明白使用mapper.readValue的概念。有人可以帮我吗？
Note: I have used json gen to generate the data objects inside the link and now I have object data java files: City, Coord, List1, Temp and Weather with the following contents.
注意：我已经使用 json gen 生成链接内的数据对象，现在我有对象数据 java 文件：City、Coord、List1、Temp 和 Weather 具有以下内容。
For City.java as a sample:
以 City.java 为例：
package weather.data;
import java.util.List;
public class City{
private Coord coord;
private String country;
private Number id;
private String name;
private Number population;
public Coord getCoord(){
return this.coord;
}
public void setCoord(Coord coord){
this.coord = coord;
}
public String getCountry(){
return this.country;
}
public void setCountry(String country){
this.country = country;
}
public Number getId(){
return this.id;
}
public void setId(Number id){
this.id = id;
}
public String getName(){
return this.name;
}
public void setName(String name){
this.name = name;
}
public Number getPopulation(){
return this.population;
}
public void setPopulation(Number population){
this.population = population;
}
}
Thanks in advance
提前致谢
采纳答案by jcragun
You need to import weather.data.City(specific class) instead of import weather.data(a package).
你需要import weather.data.City（特定的类）而不是import weather.data（一个包）。
And then do as @jdiver says:
然后按照@jdiver 说的做：
City city = mapper.readValue(jsonUrl, City.class);
回答by jdiver
If gistfile1.txtfile in the URL includes a JSON object of City, then replace the line
如果gistfile1.txtURL 中的文件包含 City 的 JSON 对象，则替换该行
City = mapper.readValue(jsonUrl, data.class);
with
和
City = mapper.readValue(jsonUrl, City.class);
You should give object class to readValuemethod.
您应该为readValue方法提供对象类。
