jackson json对象、实体类相互转换

json对象转换为实体类，使用jackson 进行jsonObject、实体类对象转换。

首先导入依赖

<dependency>     <groupId>com.fasterxml.jackson.core</groupId>     <artifactId>jackson-databind</artifactId>     <version>2.9.5</version> </dependency> 

常用方法有如下几个：readValue、writer、writeValueAsString

 public <T> T readValue(File src, Class<T> valueType) throws IOException, JsonParseException, JsonMappingException {         return this._readMapAndClose(this._jsonFactory.createParser(src), this._typeFactory.constructType(valueType));     } 

    public ObjectWriter writer() {         return this._newWriter(this.getSerializationConfig());     }  

 public String writeValueAsString(Object value) throws JsonProcessingException {         SegmentedStringWriter sw = new SegmentedStringWriter(this._jsonFactory._getBufferRecycler());          try {             this._configAndWriteValue(this._jsonFactory.createGenerator(sw), value);         } catch (JsonProcessingException var4) {             throw var4;         } catch (IOException var5) {             throw JsonMappingException.fromUnexpectedIOE(var5);         }          return sw.getAndClear();     }