72 lines
2.7 KiB
Markdown
72 lines
2.7 KiB
Markdown
# Spring Boot JSON
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## Spring Boot JSON简介
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在Spring Boot中为JSON提供了三个集成的内置库：Gson、Jackson、JSON-B。
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> 其中，Jackson是Spring Boot推荐并且默认的JSON库。
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Spring Boot项目为Jackson提供了自动装配，并且Jackson是spring-boot-starter-json启动器的一部分。当Jackson依赖在classpath下时，ObjectMapper的bean对象会自动的被配置。
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## 自定义序列化器和反序列化器
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如果使用Jackson进行json数据的序列化和反序列化，你可能需要实现自己的序列化类和反序列化类。可以通过@JsonComponent注解来定义自己的JsonSerializer, JsonDeserializer,JsonObjectSerializer,JsonObjectDeserializer
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```java
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@JsonComponent
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public class MyJsonComponent {
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public static class Serializer extends JsonSerializer<MyObject> {
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@Override
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public void serialize(MyObject value, JsonGenerator jgen, SerializerProvider serializers) throws IOException {
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jgen.writeStartObject();
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jgen.writeStringField("name", value.getName());
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jgen.writeNumberField("age", value.getAge());
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jgen.writeEndObject();
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}
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}
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public static class Deserializer extends JsonDeserializer<MyObject> {
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@Override
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public MyObject deserialize(JsonParser jsonParser, DeserializationContext ctxt) throws IOException {
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ObjectCodec codec = jsonParser.getCodec();
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JsonNode tree = codec.readTree(jsonParser);
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String name = tree.get("name").textValue();
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int age = tree.get("age").intValue();
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return new MyObject(name, age);
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}
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}
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}
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@JsonComponent
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public class MyJsonComponent {
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public static class Serializer extends JsonObjectSerializer<MyObject> {
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@Override
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protected void serializeObject(MyObject value, JsonGenerator jgen, SerializerProvider provider)
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throws IOException {
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jgen.writeStringField("name", value.getName());
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jgen.writeNumberField("age", value.getAge());
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}
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}
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public static class Deserializer extends JsonObjectDeserializer<MyObject> {
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@Override
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protected MyObject deserializeObject(JsonParser jsonParser, DeserializationContext context, ObjectCodec codec,
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JsonNode tree) throws IOException {
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String name = nullSafeValue(tree.get("name"), String.class);
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int age = nullSafeValue(tree.get("age"), Integer.class);
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return new MyObject(name, age);
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}
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}
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}
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```
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## Jackson使用
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Jackson使用ObjectMapper来将json转化为java对象，或者将java对象转化为json。
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### ObjectMapper处理json域字段和java类域字段的映射关系
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