使用 jackson 数据绑定序列化对象时出现 Java InvalidDefinition
我正在尝试使用 Jackson 的 ObjectMapper 将以下 Player 对象编写为 String。
package models.Game;
import models.Game.Enums.SnowballState;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import java.util.ArrayList;
import java.util.List;
public class Player {
private Circle circle;
private String name;
private Color color;
private int points = 0;
public int getLives() {
return lives;
}
private int lives = 3;
private List<Snowball> snowballs;
private Circle oldCircle;
private int stepSize = 10;
public Player(String name, Color color) {
this.name = name;
circle = new Circle();
oldCircle = new Circle();
this.color = color;
snowballs = new ArrayList<>();
snowballs.add(new Snowball(this));
snowballs.add(new Snowball(this));
snowballs.add(new Snowball(this));
}
public Player() {
}
private void removeLife() {
this.lives--;
}
public int getHit() {
removeLife();
return getLives();
}
public int shotSuccess() {
points+= 50;
return points;
}
public int getSnowballAmount() {
int balls = 0;
for (Snowball ball : snowballs) {
if (ball.getState() == SnowballState.CREATED) {
balls++;
}
}
return balls;
}
public List<Snowball> getSnowballs() {
return snowballs;
}
public Snowball getNextSnowball() {
for (Snowball ball : snowballs) {
if (ball.getState() == SnowballState.CREATED) {
return ball;
}
}
return null;
}
public void createSnowball() {
if (getSnowballAmount() < 3) {
snowballs.add(new Snowball(this));
}
}
public Color getColor() {
return this.color;
}
public Circle getCircle() {
return this.circle;
}
public void moveLeft() {
saveOld();
circle.setTranslateX(circle.getTranslateX() - stepSize);
}
public void moveRight() {
saveOld();
circle.setTranslateX(circle.getTranslateX() + stepSize);
}
慕田峪73311742回答
-
米琪卡哇伊
您正在尝试存储Circle类，它是一个 JavaFX 类，它实际上不是一个数据类（它是一个 UI 元素），具有许多属性（如半径、厚度、颜色、填充、边框等）。因此，它以各种方式与 JavaFX 系统捆绑在一起，并且不会很好地存储。相反，只需将您想要的信息存储在您自己的一个简单类中，Circle当您读回它时，它具有您再次创建对象所需的信息。 -
繁星淼淼
通常在课堂Jackson上效果最好。POJO当您想要序列化业务对象时，可能会发生许多意外错误。可能最好的解决方案是创建代表和状态的新模型类。和之类的东西。这两个类应该遵循规则：, , , 等。当你需要保存状态时，你可以将你的业务模型转换为状态模型并序列化状态模型。当您需要反序列化时，您需要将其反序列化为状态模型，然后再将其转换为业务模型。为了PlayerSnowballPlayerStateSnowballStatePOJOgetterssettersno-arg constructorJSONJSONJavaFX如果需要，您需要实现自定义序列化器和反序列化器的类。他们也不是正规POJO班级，需要特殊对待。让我们实现两个序列化器和一个反序列化器：class CircleJsonSerializer extends JsonSerializer<Circle> { @Override public void serialize(Circle value, JsonGenerator gen, SerializerProvider serializers) throws IOException { gen.writeStartObject(); gen.writeNumberField("radius", value.getRadius()); gen.writeNumberField("centerX", value.getCenterX()); gen.writeNumberField("centerY", value.getCenterY()); gen.writeEndObject(); }}class CircleJsonDeserializer extends JsonDeserializer<Circle> { @Override public Circle deserialize(JsonParser p, DeserializationContext ctxt) throws IOException { TreeNode node = p.readValueAsTree(); NumericNode radius = (NumericNode) node.get("radius"); NumericNode centerX = (NumericNode) node.get("centerX"); NumericNode centerY = (NumericNode) node.get("centerY"); return new Circle(centerX.doubleValue(), centerY.doubleValue(), radius.doubleValue()); }}class ColorJsonDeserializer extends JsonDeserializer<Color> { @Override public Color deserialize(JsonParser p, DeserializationContext ctxt) throws IOException { TreeNode node = p.readValueAsTree(); NumericNode red = (NumericNode) node.get("red"); NumericNode green = (NumericNode) node.get("green"); NumericNode blue = (NumericNode) node.get("blue"); NumericNode opacity = (NumericNode) node.get("opacity"); return Color.color(red.doubleValue(), green.doubleValue(), blue.doubleValue(), opacity.doubleValue()); }}您可以按如下方式使用它们：import com.fasterxml.jackson.annotation.JsonIgnore;import com.fasterxml.jackson.core.JsonGenerator;import com.fasterxml.jackson.core.JsonParser;import com.fasterxml.jackson.core.TreeNode;import com.fasterxml.jackson.databind.DeserializationContext;import com.fasterxml.jackson.databind.JsonDeserializer;import com.fasterxml.jackson.databind.JsonSerializer;import com.fasterxml.jackson.databind.ObjectMapper;import com.fasterxml.jackson.databind.SerializationFeature;import com.fasterxml.jackson.databind.SerializerProvider;import com.fasterxml.jackson.databind.module.SimpleModule;import com.fasterxml.jackson.databind.node.NumericNode;import javafx.scene.paint.Color;import javafx.scene.shape.Circle;import java.io.IOException;import java.util.ArrayList;import java.util.List;public class JsonApp { public static void main(String[] args) throws Exception { Player player = new Player("N1", Color.BLUE); SimpleModule javafxModule = new SimpleModule(); javafxModule.addSerializer(Circle.class, new CircleJsonSerializer()); javafxModule.addDeserializer(Circle.class, new CircleJsonDeserializer()); javafxModule.addDeserializer(Color.class, new ColorJsonDeserializer()); ObjectMapper mapper = new ObjectMapper(); mapper.registerModule(javafxModule); mapper.enable(SerializationFeature.INDENT_OUTPUT); String json = mapper.writeValueAsString(player); System.out.println(json); System.out.println(mapper.readValue(json, Player.class)); }}上面的代码打印：{ "circle" : { "radius" : 1.0, "centerX" : 0.0, "centerY" : 0.0 }, "color" : { "red" : 0.0, "green" : 0.0, "blue" : 1.0, "opacity" : 1.0, "opaque" : true, "hue" : 240.0, "saturation" : 1.0, "brightness" : 1.0 }, "lives" : 3, "snowballs" : [ { "state" : "CREATED", "direction" : 0.0, "circle" : null }, { "state" : "CREATED", "direction" : 0.0, "circle" : null }, { "state" : "CREATED", "direction" : 0.0, "circle" : null } ]}//ToStringPlayer{circle=Circle[centerX=0.0, centerY=0.0, radius=1.0, fill=0x000000ff], name='null', color=0x0000ffff, points=0, lives=3, snowballs=[Snowball{player=null, state=CREATED, direction=0.0, circle=null}, Snowball{player=null, state=CREATED, direction=0.0, circle=null}, Snowball{player=null, state=CREATED, direction=0.0, circle=null}], oldCircle=null, stepSize=10}如您所见，我们可以序列化和反序列化Player类，但它需要做很多额外的工作。同样对于每个getter执行业务逻辑的方法，我都忽略了它们，如下所示：@JsonIgnorepublic int getHit() { removeLife(); return getLives();}另一个提示：getHint方法有副作用。它消除了生命——不管它意味着什么。这通常是一种不好的做法，但这个问题与命名无关。
随时随地看视频慕课网APP
相关分类
Java