SpringMVC使用JSON

小鱼儿 2023-10-01 20:16 3阅读 0赞

### JSON ###

>  *  JSON(JavaScript Object Notation, JS对象标记)是一种轻量级的数据交换格式，目前使用特别广泛。
>  *  采用完全独立于编程语言的文本格式来存储和表示数据。
>  *  简洁松清晰的层次结构使得JSON成为理想的数据交换语言。
>  *  易于人阅读和编写，同时也易于机器解析和生成，并有效地提升网络传输效率。

#### JackSon ####

1.  导入依赖
    
        
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.13.1</version>
        </dependency>
2.  实体类
    
        @Data
        @AllArgsConstructor
        @NoArgsConstructor
        public class User {
              
            private String name;
            private int age;
            private String sex;
        }
3.  springmvc-servlet.xml配置中加入防止json乱码配置
    
        
            <mvc:annotation-driven>
                <mvc:message-converters register-defaults="true">
                    <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                        <constructor-arg value="UTF-8"/>
                    </bean>
                    <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                        <property name="objectMapper">
                            <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                                <property name="failOnEmptyBeans" value="false"/>
                            </bean>
                        </property>
                    </bean>
                </mvc:message-converters>
            </mvc:annotation-driven>
4.  控制器测试
    
        //@Controller
        @RestController//这个类不会走视图解析器
        public class UserController {
              
            @RequestMapping(value = "/j1",produces = "application/json;charset=utf-8")//如果没有在spring配置防json乱码，需要加入produces防止乱码
        //    @ResponseBody//它就不会走视图解析器，会直接返回一个字符串
            public String json1() throws JsonProcessingException {
              
                //jackson,ObjectMapper
                ObjectMapper mapper = new ObjectMapper();
                //创建一个对象
                User user = new User("lzj", 18, "男");
                String str = mapper.writeValueAsString(user);
                return str;//new ObjectMapper().writeValueAsString(user)
            }
            
                @RequestMapping("/j2")
            public String json2() throws JsonProcessingException {
              
                //jackson,ObjectMapper
                ObjectMapper mapper = new ObjectMapper();
                Date date = new Date();
                //自定义日期格式
                SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                String format = simpleDateFormat.format(date);
                //ObjectMapper,时间解析后的默认格式为：Timestamp,时间戳
                String str = mapper.writeValueAsString(format);
                return str;//new ObjectMapper().writeValueAsString(user)
            }
            
             @RequestMapping("/j3")
            public String json3() throws JsonProcessingException {
              
                //jackson,ObjectMapper
                ObjectMapper mapper = new ObjectMapper();
                //不使用时间戳的方式
                mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);
                //自定义日期格式
                SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                mapper.setDateFormat(simpleDateFormat);
        
                Date date = new Date();
                String str = mapper.writeValueAsString(date);
                return str;//new ObjectMapper().writeValueAsString(user)
            }
        }

#### 抽为工具类 ####

public class JsonUtils {
        
        public static String getJson(Object object){
        
            return getJson(object,"yyyy-MM-dd HH:mm:ss");
        }
    
        public static String getJson(Object object,String deteFormat){
        
            ObjectMapper mapper = new ObjectMapper();
            //不使用时间戳的方式
            mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);
            //自定义日期格式
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            mapper.setDateFormat(simpleDateFormat);
            try {
        
                return mapper.writeValueAsString(object);
            } catch (JsonProcessingException e) {
        
                e.printStackTrace();
            }
            return null;
        }
    }

#### FastSon ####

1.  导入依赖
    
        
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.79</version>
        </dependency>
2.  编写控制器
    
        @RequestMapping("/j4")
            public String json4() throws JsonProcessingException {
              
                ArrayList<User> list = new ArrayList<>();
                User user1 = new User("lzj",18,"男");
                User user2 = new User("lzj2",18,"男");
                User user3 = new User("lzj3",18,"男");
                list.add(user1);
                list.add(user2);
                list.add(user3);
        
        //        System.out.println("*******Jay对象转JSON字符*******");
        //        String str1 = JSON. toJSONString(list);
        //        System.out.println( "ISON. toJSoNString(list)==>"+str1);
        //        String str2 = JSON.toJSONString(user1);
        //        System.out.println( "ISON toJSoNString(user1)==>"+str2);
        //        System.out.println("****** JSON字符串转Java对 象*****");
        //        User jp_user1=JSON. parseObject(str2,User . class);
        //        System.out.println( "JSON. parse0bject(str2,User .class)=>"+jp_user1);
        //        System.out.println("****** Java对象转JSON对象*****");
        //        JSONObject jsonobject1 = (JSONObject) JSON. toJSON(user2);
        //        System.out.println(" (JSONObject) JSON. toJSON(user2)==>"+jsonobject1.getString( "name"));
        //        System.out.println( "***** JSON对象转Java对象****");
        //        User to_java_user = JSON.toJavaObject(jsonobject1, User.class);
        //        System.out.println( "ISON. toJavaobject(json0bject1, User .class)==>"+to_java_user);
        
                String s = JSON.toJSONString(list);
                return s;
            }