本文共 4598 字，大约阅读时间需要 15 分钟。

jackson 介绍

官方地址: https://github.com/FasterXML/jackson-core

常用使用方法

maven引入

           
    
     2.9.9
        
       ...        
           
                
                 
                     
      
       com.fasterxml.jackson.core
                      
      
       jackson-core
                      
      
       ${jackson-version}
                  
                 
                     
      
       com.fasterxml.jackson.core
                      
      
       jackson-databind
                      
      
       ${jackson-version}
                  
                 
                     
      
       com.fasterxml.jackson.core
                      
      
       jackson-annotations
                      
      
       ${jackson-version}
                  
     
    
   

JAVA对象转JSON[JSON序列化]

ObjectMapper是JSON操作的核心，Jackson的所有JSON操作都是在ObjectMapper中实现。

ObjectMapper有多个JSON序列化的方法，可以把JSON字符串保存File、OutputStream等不同的介质中。

1. writeValue(File arg0, Object arg1)把arg1转成json序列，并保存到arg0文件中。
2. writeValue(OutputStream arg0, Object arg1)把arg1转成json序列，并保存到arg0输出流中。
3. writeValueAsBytes(Object arg0)把arg0转成json序列，并把结果输出成字节数组。
4. writeValueAsString(Object arg0)把arg0转成json序列，并把结果输出成字符串。

JSON转Java类[JSON反序列化]

JSON转对象

objectMapping.readValue(str, ojb.class)

• 如果json字符串中的属性个数小于java对象中的属性个数，可以顺利转换，java中多的那个属性为null

• 如果json字符串中出现java对象中没有的属性，则在将json转换为java对象时会报错：Unrecognized field, not marked as ignorable

demo

public class JacksonTest {
       public static void main(String args[]) {
           Student student = new Student();        student.setAge(20);        student.setName("she");        ObjectMapper mapper = new ObjectMapper();        try {
               //Java类转JSON            String json = mapper.writeValueAsString(student);            System.out.println(json);        } catch (JsonProcessingException e) {
               e.printStackTrace();        }        //Java集合转JSON        List
   
     studentList = new ArrayList
    
     ();        studentList.add(student);        String jsonlist = null;        try {
               jsonlist = mapper.writeValueAsString(studentList);        } catch (JsonProcessingException e) {
               e.printStackTrace();        }        System.out.println(jsonlist);        String json = "{\"name\":\"she\",\"age\":20}";        /**         * ObjectMapper支持从byte[]、File、InputStream、字符串等数据的JSON反序列化。         */        ObjectMapper mapper1 = new ObjectMapper();        Student student1 = null;        try {
               student1 = mapper1.readValue(json, Student.class);        } catch (IOException e) {
               e.printStackTrace();        }        System.out.println(student1);    }    static class Student {
           private String name;        private int age;        public Student() {
           }        public String getName() {
               return name;        }        public void setName(String name) {
               this.name = name;        }        public int getAge() {
               return age;        }        public void setAge(int age) {
               this.age = age;        }    }}
    
   

SpringBoot Jackson

SpringBoot JSON工具包默认是Jackson，只需要引入spring-boot-starter-web依赖包，自动引如下相应依赖包:

           
    
     com.fasterxml.jackson.core
            
    
     jackson-databind
     -->数据绑定依赖于下面两个包        
    
     2.8.7
    
   
           
    
     com.fasterxml.jackson.core
            
    
     jackson-annotations
     -->注解包        
    
     2.8.0
    
   
           
    
     com.fasterxml.jackson.core
            
    
     jackson-core
     -->核心包        
    
     2.8.7
    
   

Jackson两种配置方式

1. application.properties文件

# 日期格式化spring.jackson.date-format=yyyy-MM-dd HH:mm:ss# 日期时区spring.jackson.time-zone=GMT+8# 返回值null不显示spring.jackson.default-property-inclusion=non_null

2. bean配置

import com.fasterxml.jackson.annotation.JsonInclude;import com.fasterxml.jackson.databind.ObjectMapper;import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Primary;import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;@Configurationpublic class JacksonConfig {
      @Bean   @Primary   @ConditionalOnMissingBean(ObjectMapper.class)   public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
         ObjectMapper objectMapper = builder.createXmlMapper(false).build();      // 返回值过滤null或""值      objectMapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY).setSerializationInclusion(JsonInclude.Include.NON_NULL);      return objectMapper;   }}

转载地址：https://docker.blog.csdn.net/article/details/105747959 如侵犯您的版权，请留言回复原文章的地址，我们会给您删除此文章，给您带来不便请您谅解！