直接上代码

package com.demo.jackson.utils;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.StringUtils;

@Slf4j
public class JsonUtil {
private static ObjectMapper objectMapper = new ObjectMapper();
static {
//忽略 在json字符串中存在，但是在java对象中不存在对应属性的情况。防止错误
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
}

 /\*\*  
  \* 对象转换成Sting  
  \* @param obj  
  \* @param <T>  
  \* @return  
  \*/  
 public static <T> String obj2String(T obj){  
     if (obj == null) {  
         return null;  
     }  
     try {  
         return obj instanceof String ? (String) obj : objectMapper.writeValueAsString(obj);  
     } catch (JsonProcessingException e) {  
         System.out.println("Parse Object to String error");  
         e.printStackTrace();  
         return null;  
     }  
 }  
 /\*\*  
  \* 规范地将对象转换成Sting  
  \* @param obj  
  \* @param <T>  
  \* @return  
  \*/  
 public static <T> String obj2StringPretty(T obj){  
     if(obj == null){  
         return null;  
     }  
     try {  
         return obj instanceof String ? (String)obj :  objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(obj);  
     } catch (Exception e) {  
         log.warn("Parse Object to String error",e);  
         return null;  
     }  
 }

 /\*\*  
  \* String转换成obj对象  
  \* @param str  
  \* @param clazz  
  \* @param <T>  
  \* @return  
  \*/  
 public  static <T> T str2Obj(String str, Class<T> clazz){  
     if(str==null){  
         return null;  
     }  
     try {  
         return clazz.equals(String.class) ? (T) str : objectMapper.readValue(str, clazz);  
     } catch (Exception e) {  
         e.printStackTrace();  
         return null;  
     }  
 }

 /\*\*  
  \* String转换成对象  
  \* @param str  
  \* @param typeReference  
  \* @param <T>  
  \* @return  
  \*/  
 public static <T> T string2Obj(String str, TypeReference<T> typeReference){  
     if(StringUtils.isEmpty(str) || typeReference == null){  
         return null;  
     }  
     try {  
         return (T)(typeReference.getType().equals(String.class)? str : objectMapper.readValue(str,typeReference));  
     } catch (Exception e) {  
         log.warn("Parse String to Object error",e);  
         return null;  
     }  
 }

 /\*\*  
  \* String转换成对象  
  \* @param str  
  \* @param collectionClass  
  \* @param elementClasses  
  \* @param <T>  
  \* @return  
  \*/  
 public static <T> T string2Obj(String str, Class<?> collectionClass, Class<?>... elementClasses){  
     JavaType javaType = objectMapper.getTypeFactory().constructParametricType(collectionClass,elementClasses);  
     try {  
         return objectMapper.readValue(str,javaType);  
     } catch (Exception e) {  
         log.warn("Parse String to Object error",e);  
         return null;  
     }  
 }  

}

测试：

package com.demo.jackson.test;

import com.demo.jackson.entity.Student;
import com.demo.jackson.utils.JsonUtil;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.Test;

import java.util.*;

@SuppressWarnings("ALL")
public class JacksonTest {
/**
* 序列化
*/
@Test
public void test01(){
Student s = new Student();
s.setName("cjj");
s.setAge(22);
s.setProfileImageUrl("link");
String s1 = JsonUtil.obj2String(s);
System.out.println(s1);

     Map<String, List<Integer>> map = new HashMap<>();  
     map.put("a", Arrays.asList(1, 2, 3));  
     map.put("b", Arrays.asList(1, 2, 3));  
     String result1 = JsonUtil.obj2StringPretty(map);  
     System.out.println(result1);  
 }

 /\*\*  
  \* 反序列化  
  \*/  
 @Test  
 public void Test02(){  
     String str = "{\\"name\\":\\"name\\",\\"age\\":10,\\"profileImageUrl\\":\\"link\\"}";  
     Student student = JsonUtil.str2Obj(str, Student.class);  
     System.out.println(student);  
 }  
 @Test  
 public void test03() throws Exception {

     Student student1 = new Student();  
     student1.setAge(10);  
     student1.setName("name1");  
     student1.setProfileImageUrl("link1");

     Student student2 = new Student();  
     student2.setAge(20);  
     student2.setName("name2");  
     student2.setProfileImageUrl("link2");

     List<Student> studentList = new ArrayList<>();  
     studentList.add(student1);  
     studentList.add(student2);  
     String result = JsonUtil.obj2String(studentList);  
     // \[{"name":"name1","age":10,"profileImageUrl":"link1"},{"name":"name2","age":20,"profileImageUrl":"link2"}\]  
     System.out.println(result);

     List<Student> finalList = JsonUtil.string2Obj(result, new TypeReference<List<Student>>() {});  
     // \[{name=name1, age=10, profileImageUrl=link1}, {name=name2, age=20, profileImageUrl=link2}\]  
     System.out.println(finalList);  
 }  
 @Test  
 public void test04() throws Exception {

     Student student1 = new Student();  
     student1.setAge(10);  
     student1.setName("name1");  
     student1.setProfileImageUrl("link1");

     Student student2 = new Student();  
     student2.setAge(20);  
     student2.setName("name2");  
     student2.setProfileImageUrl("link2");

     List<Student> studentList = new ArrayList<>();  
     studentList.add(student1);  
     studentList.add(student2);  
     String result = JsonUtil.obj2String(studentList);  
     // \[{"name":"name1","age":10,"profileImageUrl":"link1"},{"name":"name2","age":20,"profileImageUrl":"link2"}\]  
     System.out.println(result);

     List<Student> finalList = JsonUtil.string2Obj(result, List.class, Student.class);  
     // \[{name=name1, age=10, profileImageUrl=link1}, {name=name2, age=20, profileImageUrl=link2}\]  
     System.out.println(finalList);  
 }  
 @Test  
 public void jsonProperty() throws Exception {

     String str = "{\\"name\\":\\"name\\",\\"age\\":10,\\"setImage\\":\\"link\\"}";  
     Student student1 = JsonUtil.string2Obj(str, Student.class);  
     // name  
     System.out.println(student1.getName());  
     //  
     System.out.println(student1.getAge());  
     // link  
     System.out.println(student1.getProfileImageUrl());  
     // {"name":"name","age":10,"getImage":"link"}  
     System.out.println(JsonUtil.obj2String(student1));  
 }

 /\*\*  
  \* 除了将json转为对象外，还可以用Tree Mode方式解析JSON，全程无脑操作，  
  \* 除了一些特别复杂的JSON，或者只取JSON中的一部分，千万不要用这种二B方式解析JSON。  
  \* 正确的方式是将JSON直接转为对象。  
  \* @throws Exception  
  \*/  
 @Test  
 public void parseJson() throws Exception {  
     String jsonStr = "{\\"name\\":\\"zhansan\\",\\"age\\":100,\\"schools\\":\[{\\"name\\":\\"tsinghua\\",\\"location\\":\\"beijing\\"},{\\"name\\":\\"pku\\",\\"location\\":\\"beijing\\"}\]}";

     ObjectMapper objectMapper = new ObjectMapper();  
     JsonNode jsonNode = objectMapper.readTree(jsonStr);

     String name = jsonNode.get("name").asText();  
     int age = jsonNode.get("age").asInt();  
     // name is zhansan age is 100  
     System.out.println("name is " + name + " age is " + age);

     JsonNode schoolsNode = jsonNode.get("schools");  
     for (int i = 0; i < schoolsNode.size(); i++) {  
         String schooleName = schoolsNode.get(i).get("name").asText();  
         String schooleLocation = schoolsNode.get(i).get("location").asText();  
         // schooleName is tsinghua schooleLocation is beijing  
         // schooleName is pku schooleLocation is beijing  
         System.out.println("schooleName is " + schooleName + " schooleLocation is " + schooleLocation);  
     }  
 }  

}