com.fasterxml.jackson将对象序列化成json时，出现在json里的属性名称是怎么来的

如果不考虑用任何annotation指定出现在json string里的属性名称的话，默认的逻辑是将getter方法里，“get”之后的字符串的首字母小写。

比如：

getJerDryContent()

提取出的属性名为jerDryContent.

getDiabloId()

提取成diabloId.

请看测试代码：

package jacksonTest;

public class BrandName {
// Jerry 2017-08-25 9:19PM: after I change id to id2, the deserialization from string
// to object can still work, which proves that the conversion is not done 
// based on ATTRIBUTE NAME
    private Integer id2; 
    private String content5;
    public Integer getDiabloId() {
        return id2;
    }
    
    public BrandName(Integer id3, String content3){
    	this.id2 = id3;
    	this.content5 = content3;
    	
    }
// Exception in thread "main" com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "id" (class jacksonTest.BrandName), not marked as ignorable (2 known properties: , "pp", "content"])
        
//    public void setPP(Integer id) {
    public void setJerry2Id(Integer id4){
        this.id2 = id4;
    }
    public String getJerDryContent() {
        return content5;
    }
    public void setTomcontent(String name) {
        this.content5 = name;
    }
    @Override
    public String toString() {
        return "BrandName [id4=" + id2 + ", content4=" + content5 + "]";
    }
}

package jacksonTest;

import java.io.IOException;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonTest {

	@SuppressWarnings("unused")
	private static void string2Object() throws JsonParseException, JsonMappingException, IOException{
		ObjectMapper objectMapper = new ObjectMapper();
        String DATA = "{\r\n" + 
                "  \"id\": 123,\r\n" + 
                "  \"name\": \"The Best Product\",\r\n" + 
                "  \"brand\": {\r\n" + 
                "     \"id\": 234,\r\n" + 
                "     \"content\": \"ACME Products\"\r\n" + 
                "  }\r\n" + 
                "}";

        ProductTest productTest = objectMapper.readValue(DATA, ProductTest.class);
        System.out.println(productTest.toString());
	}
	
	private static void object2String() throws JsonProcessingException{
		BrandName b = new BrandName(11, "sap");
		ProductTest p = new ProductTest(12, "Jerry", b);
		
		ObjectMapper mapper = new ObjectMapper();
		
		String jsonInString = mapper.writeValueAsString(p);
		System.out.println("JSON: " + jsonInString);
		
	}
    public static void main(String[] args) throws JsonParseException, JsonMappingException, IOException {
    	// string2Object();
    	object2String();
    }

}

package jacksonTest;

import com.fasterxml.jackson.annotation.JsonProperty;

public class ProductTest {

    private int productId;
    private String productName;
    private BrandName brandName;
    
    public ProductTest(int id, String Name, BrandName brandName){
    	this.productId = id;
    	this.productName = Name;
    	this.brandName = brandName;
    }

    @JsonProperty("id") // this should match the attribute in JSON file
    public int getProductId() {
        return productId;
    }
    public void setProductId(int productId) {
        this.productId = productId;
    }

    @JsonProperty("name")
    public String getProductName() {
        return productName;
    }
    public void setProductName(String productName) {
        this.productName = productName;
    }

    @JsonProperty("brand")
    public BrandName getBrandName() {
        return brandName;
    }
    public void setBrandName(BrandName brandName) {
        this.brandName = brandName;
    }

    @Override
    public String toString() {
        return "ProductTest [productId=" + productId + ", productName=" + productName + ", brandName=" + brandName
                + "]";
    }
}

输出结果：

JSON: {“id”:12,“name”:“Jerry”,“brand”:{“diabloId”:11,“jerDryContent”:“sap”}}