英文:
Map JSON key-value to class in java
问题
我需要将字符串JSON按键值映射到POJO类中，但我不确定是否有更简单的方法来进行转换。
我的类：
class Colors {
private String name;
private String color;
public String getName() { return name; }
public String getColor() { return color; }
}
JSON示例：
{
"white": "FFFFFF",
"red": "FF0000",
"black": "000000"
}
是否有任何方法（而不是使用foreach循环）可以将上述JSON放入List<Colors>中？
附：我尝试过使用objectMapper.readValue来解决相同的问题，但没有成功。
英文:
I need to map string JSON by key-value into the POJO class, but I'm not sure there is an easier way to convert this.
My class:
class Colors {
private String name;
private String color;
public String getName() { return name; }
public String getColor() { return color; }
}
Example of JSON:
{
"white": "FFFFFF",
"red": "FF0000",
"black": "000000"
}
Is there any way (instead of using foreach loop) to have the above JSON in List<Colors>?
P.s: I tried some same issue with objectMapper.readValue, but didn't succeed.
答案1
得分: 3
您可以使用 com.fasterxml.jackson.annotation.JsonAnySetter 注解来处理每个 键值对：
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
public class JsonApp {
public static void main(String[] args) throws Exception {
File jsonFile = new File("./src/main/resources/test.json");
ObjectMapper mapper = new ObjectMapper();
Colors colors = mapper.readValue(jsonFile, Colors.class);
System.out.println(colors.getColors());
}
}
class Colors {
private final List<Color> colors = new ArrayList<>();
@JsonAnySetter
public void setAny(String key, String value) {
colors.add(new Color(key, value));
}
public List<Color> getColors() {
return colors;
}
}
class Color {
private String name;
private String color;
public Color(String name, String color) {
this.name = name;
this.color = color;
}
public String getName() {
return name;
}
public String getColor() {
return color;
}
@Override
public String toString() {
return "Color{" +
"name='" + name + '\'' +
", color='" + color + '\'' +
'}';
}
}
以上代码打印：
[Color{name='white', color='FFFFFF'}, Color{name='red', color='FF0000'}, Color{name='black', color='000000'}]
另请参阅：
英文:
You can use com.fasterxml.jackson.annotation.JsonAnySetter annotation which will allow you to handle each key-value pair:
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
public class JsonApp {
public static void main(String[] args) throws Exception {
File jsonFile = new File("./src/main/resources/test.json");
ObjectMapper mapper = new ObjectMapper();
Colors colors = mapper.readValue(jsonFile, Colors.class);
System.out.println(colors.getColors());
}
}
class Colors {
private final List<Color> colors = new ArrayList<>();
@JsonAnySetter
public void setAny(String key, String value) {
colors.add(new Color(key, value));
}
public List<Color> getColors() {
return colors;
}
}
class Color {
private String name;
private String color;
public Color(String name, String color) {
this.name = name;
this.color = color;
}
public String getName() {
return name;
}
public String getColor() {
return color;
}
@Override
public String toString() {
return "Color{" +
"name='" + name + '\'' +
", color='" + color + '\'' +
'}';
}
}
Above code prints:
[Color{name='white', color='FFFFFF'}, Color{name='red', color='FF0000'}, Color{name='black', color='000000'}]
See also:
答案2
得分: 0
改变你的 JSON 对象为：
{
"listcolors": [
{
"name": "white",
"color": "FFFFFF"
},
{
"name": "red",
"color": "FF0000"
},
{
"name": "black",
"color": "000000"
}
]
}
你的颜色类应该实现序列化：
import java.io.Serializable;
class Colors implements Serializable {
private String name;
private String color;
public String getName() { return name; }
public String getColor() { return color; }
}
现在创建一个颜色类的列表来接收你对象的反序列化：
import java.io.Serializable;
import java.util.ArrayList;
class ListColors implements Serializable {
ArrayList<Colors> ListColors = new ArrayList<Colors>();
}
然后：
ListColors objColors = new Gson().fromJson(
// 将你的 JSON 对象字符串放在这里,
Colors.class);
在这里了解更多关于 GSON 库的信息：这里
英文:
change your json object to:
{
"listcolors": [
{
"name": "white",
"color": "FFFFFF"
},
{
"name": "red",
"color": "FF0000"
},
{
"name": "black",
"color": "000000"
}
]}
your color class should implement serializable
class Colors implements Serializable {
private String name;
private String color;
public String getName() { return name; }
public String getColor() { return color; }
}
Now create a list of colors class to receive the deserialization of your object
class ListColors implements Serializable {
ArrayList<Color> ListColors = new ArrayList<Color>();
}
then:
ListColors objColors = new Gson().fromJson(<
put your json object string here>, Colors.class);
See more about the GSON library here
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