Fastson,Gson,fasterxml Jackson的比较，Demo示例

小咪咪 2023-02-14 15:33 9阅读 0赞

### jackson 的使用示例 ###

*   *  写在前面
     *  一、简单比较
     *  二 、fastJson
     *   *  2.1、示例一
         *  2.2、示例二
         *  2.3、示例三
         *  2.4、示例四,name ,value 过滤
         *  2.5、demo5, @JSONField 使用
         *  2.6、demo 6
         *  2.7、DefaultJSONParser
         *  2.8、从文件中解析
         *  2.9、Null 处理
     *  三、Gson
     *  四、Jackson

## 写在前面 ##

关于 java 对象的序列化与反序列化的问题，最近 阿里的fastJson在网上嘘声一片，很多遗留的Bug、issue都未解决等等…

其实也不要太警惕，java 的基本开发中，web开发、大数据开发，我目前接触、了解的也就这两个主流开发方向，关于对象的构造不是很复杂的话，阿里的FastJson就可以很方便的准确序列化，但是，目前中国，也存在一些真正的大牛、团队（类似阿里。腾讯，网易、百度等等大厂）在高级的框架设计中，会有频繁的序列化与反序列化的对象操作，这样可能对序列化要有更加准确的解析，类似 Spring ，Mybatis,apache 等等，他们都是基于 Jackson（fasterxml ）封装的对象序列化实现方案…

## 一、简单比较 ##

这里比较下，FastJson、Gson、fasterxml jackson的相关基础

*  FastJson  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMTA1NjI5_size_16_color_FFFFFF_t_70]
 *  Gson  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMTA1NjI5_size_16_color_FFFFFF_t_70 1]
 *  jackson

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMTA1NjI5_size_16_color_FFFFFF_t_70 2]  
基本性能测试、有兴趣的可以去自己测试，序列化/反序列化最重要的准确解析数据。速度不是最重要的

## 二 、fastJson ##

### 2.1、示例一 ###

/** * {"id":123,"name":"一级部门"} * @throws Exception */
        public void test_0() throws Exception { 
            Department dep = new Department();
            dep.setId(123);
            dep.setName("一级部门");
            dep.setParent(dep);        
    
            String text = JSON.toJSONString(dep);
            System.out.println(text);
            
            JSON.parseObject(text, Department.class);
        }
    
        public static class Department { 
    
            private int                  id;
            private String               name;
            private Department parent;
            private transient List<Department> children = new ArrayList<Department>();
    
            public int getId() {  return id; }
            public void setId(int id) {  this.id = id; }
            public String getName() {  return name; }
            public void setName(String name) {  this.name = name; }
            @JSONField(serialize=false)
            public Department getParent() {  return parent; }
            public void setParent(Department parent) {  this.parent = parent; }
            public List<Department> getChildren() {  return children; }
            public void setChildren(List<Department> children) {  this.children = children; }
        }

### 2.2、示例二 ###

/** * {"name":"Jobs","salary":8000,"age":50} * @throws Exception */
        public void test_0() throws Exception { 
            JSONObject jsonObject = new JSONObject();
            jsonObject.put("name", "Jobs");
            jsonObject.put("age", 50);
            jsonObject.put("salary", new BigDecimal(8000));
    
            String text = jsonObject.toJSONString();
            System.out.println(text);
        }

### 2.3、示例三 ###

/** * {"id":0,"name":"admin","users":[{"id":2,"name":"guest"},{"id":3,"name":"root"}]} * @throws Exception */
        public void test_encode() throws Exception { 
            Group group = new Group();
            group.setId(0L);
            group.setName("admin");
    
            User guestUser = new User();
            guestUser.setId(2L);
            guestUser.setName("guest");
    
            User rootUser = new User();
            rootUser.setId(3L);
            rootUser.setName("root");
    
            group.getUsers().add(guestUser);
            group.getUsers().add(rootUser);
    
            String jsonString = JSON.toJSONString(group);
    
            System.out.println(jsonString);
            
            JSON.parseObject(jsonString, Group.class);
        }

### 2.4、示例四,name ,value 过滤 ###

public void test_secure() throws Exception { 
    
            ValueFilter filter = new ValueFilter() { 
    
                public Object process(Object source, String name, Object value) { 
                    if (name.equals("name")) { 
                        return "WSJ";
                    }
                    return value;
                }
            };
    
            NameFilter nameFilter = new NameFilter() { 
                public String process(Object source, String name, Object value) { 
                    if (name.equals("id")) { 
                        return "ID";
                    }
                    return name;
                }
            };
    
            String text = "{\"id\":123,\"name\":\"WJH\"}";
    
            Object object = JSON.parse(text);
    
            SerializeWriter out = new SerializeWriter();
            JSONSerializer serializer = new JSONSerializer(out);
            serializer.getValueFilters().add(filter);
            serializer.getNameFilters().add(nameFilter);
    
            serializer.write(object);
    
            String outText = out.toString();
            System.out.println(outText);
        }

### 2.5、demo5, @JSONField 使用 ###

public static class User { 
    
            private int    id;
            private String name;
    
            @JSONField(name = "uid")
            public int getId() {  return id; }
    
            @JSONField(name = "uid")
            public void setId(int id) {  this.id = id; }
    
            public String getName() {  return name; }
    
            public void setName(String name) {  this.name = name; }
        }
    
        /** * {"name":"毛头","uid":123} * @throws Exception */
        public void test_0() throws Exception { 
            User user = new User();
            user.setId(123);
            user.setName("毛头");
    
            String text = JSON.toJSONString(user);
            Assert.assertEquals("{\"name\":\"毛头\",\"uid\":123}", text);
            System.out.println(text);
        }

### 2.6、demo 6 ###

/** * {"name":"张三","id":123} * {name=张三, id=123} */
    public class MapDemo extends TestCase { 
        public void test_0 () throws Exception { 
            Map<String, Object> map = new HashMap<String, Object>();
            map.put("id", 123);
            map.put("name", "张三");
            
            String text = JSON.toJSONString(map);
            System.out.println(text);
            System.out.println(map.toString());
        }
    }

### 2.7、DefaultJSONParser ###

public void test_reuse() throws Exception { 
            Model model = new Model();
    
            { 
                DefaultJSONParser parser = new DefaultJSONParser("{\"id\":123,\"name\":\"wangsai-silence\"}");
                parser.parseObject(model);
                parser.close(); // 调用close能重用buf，提升性能
    
                assertEquals(123, model.id);
                assertEquals("wangsai-silence", model.name);
            }
    
            { 
                DefaultJSONParser parser = new DefaultJSONParser("{\"id\":234,\"name\":\"wenshao\"}");
                parser.parseObject(model);
                parser.close(); // 调用close能重用buf，提升性能
    
                assertEquals(234, model.id);
                assertEquals("wenshao", model.name);
            }
        }
    
        public static class Model { 
            public int id;
            public String name;
        }

### 2.8、从文件中解析 ###

public void test_for_maiksagill() throws Exception { 
            String resource = "json/maiksagill.json";
            InputStream is = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
            String text = IOUtils.toString(is);
    
            System.out.println(text);
            JSON.parseObject(text, WareHouseInfo[].class);
        }

### 2.9、Null 处理 ###

public void test_boolean() throws Exception { 
            Model model = new Model();
    // String json = JSON.toJSONString(model, SerializerFeature.IgnoreNonFieldGetter); //{}
            String json = JSON.toJSONString(model,SerializerFeature.WriteNullStringAsEmpty); // {"available":true,"name":""}
    // String json = JSON.toJSONString(model,SerializerFeature.WriteMapNullValue); // {"age":null,"available":true,"name":null}
            System.out.println(json);
        }
    
        public static class Model { 
            private String name;
            private Long age;
    
            public String getName() { 
                return name;
            }
    
            public void setName(String name) { 
                this.name = name;
            }
    
            public Long getAge() { 
                return age;
            }
    
            public void setAge(Long age) { 
                this.age = age;
            }
    
            public boolean isAvailable() { 
                return true;
            }
        }

简单列出这么多，其实 FastJson还是很强大的，比Gson ,Jackson 丰富很多序列化的实现

## 三、Gson ##

这里可参考这里，[***链接***][Link 1]

## 四、Jackson ##

Jackson是框架设计中首选的，是可以肯定的

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[Link 1]: https://blog.csdn.net/qq_42105629/article/details/106431645