Jackson对泛型的序列化和反序列化方法汇总

朴灿烈づ我的快乐病毒、 2023-02-27 12:22 4阅读 0赞

转载自：https://www.cnblogs.com/EasonJim/p/7919422.html

> 说明：Jackson对于简单泛型是可以正常操作的，但是如果对于太过于复杂的泛型类有时会不成功。目前还在找着更合适的Json库。不过这一点在dotnet原生方案JavaScriptSerializer可以完美解决这一些问题，无论泛型多复杂。

例子如下：

package com.jsoft.springboottest.springboottest1.controller;
    
    import java.io.IOException;
    import java.lang.reflect.Type;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    import com.fasterxml.jackson.core.type.TypeReference;
    import com.fasterxml.jackson.databind.JavaType;
    import com.fasterxml.jackson.databind.ObjectMapper;
    import com.jsoft.springboottest.springboottest1.Pager;
    import com.jsoft.springboottest.springboottest1.PagerAppoint;
    import com.jsoft.springboottest.springboottest1.User;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    import sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl;
    
    @RestController
    public class TestController {
    
        private static final Logger logger = LoggerFactory.getLogger(TestController.class);
    
        @RequestMapping("/show")
        public String show() throws IOException {
            ObjectMapper mapper = new ObjectMapper();
            User user = new User();
            user.setId(1);
            Pager<User> pager = new Pager<User>();
            List<User> users = new ArrayList<User>();
            users.add(user);
            pager.setDatas(users);
            String json = mapper.writeValueAsString(pager);
            // 方式1
            Pager<User> userPager1 = mapper.readValue(json, new TypeReference<Pager<User>>() {
            });
            // 方式2
            Type[] types = new Type[1];
            types[0] = User.class;
            final ParameterizedTypeImpl type = ParameterizedTypeImpl.make(Pager.class, types, Pager.class.getDeclaringClass());
            TypeReference typeReference = new TypeReference<Pager>() {
                @Override
                public Type getType() {
                    return type;
                }
            };
            Pager<User> userPager2 = mapper.readValue(json, typeReference);
            // 方式3
            JavaType javaType = mapper.getTypeFactory().constructParametrizedType(Pager.class, Pager.class, User.class);
            Pager<User> userPager3 = mapper.readValue(json, javaType);
            // 方式4
            JavaType javaType1 = mapper.getTypeFactory().constructParametricType(Pager.class, User.class);
            Pager<User> userPager4 = mapper.readValue(json, javaType1);
            // 方式5，新建另一个指定具体泛型T的参数的类
            PagerAppoint userPager5 = mapper.readValue(json, PagerAppoint.class);
            // 数组泛型的序列化和反序列化
            String json1 = mapper.writeValueAsString(users);
            JavaType javaType2 = mapper.getTypeFactory().constructParametricType(List.class, User.class);
            List<User> users1 = mapper.readValue(json1, javaType2);
            // HashMap
            Map<String, User> map = new HashMap<String, User>(16);
            map.put("test", user);
            String json2 = mapper.writeValueAsString(map);
            // 1
            Map<String, User> users2 = mapper.readValue(json2, new TypeReference<Map<String, User>>() {
            });
            // 2
            JavaType javaType3 = mapper.getTypeFactory().constructParametricType(HashMap.class, String.class, User.class);
            Map<String, User> users3 = mapper.readValue(json2, javaType3);
    
            return "hello world";
        }
    }

示例工程：https://github.com/easonjim/5\_java\_example/tree/master/springboottest/springboottest10

参考：

http://www.yiibai.com/jackson/jackson\_data\_binding\_generics.html

http://blog.csdn.net/z69183787/article/details/46235905

http://bbs.csdn.net/topics/391823803

https://www.cnblogs.com/quanyongan/archive/2013/04/16/3024993.html

http://www.hankcs.com/program/json-to-map-java-demo-code.html

http://huangyunbin.iteye.com/blog/2352243

http://www.jianshu.com/p/ca03c2fe36e3

http://www.yiibai.com/jackson/jackson\_data\_binding\_generics.html

http://bbs.csdn.net/topics/391823803

https://www.cnblogs.com/quanyongan/archive/2013/04/16/3024993.html