JSON与对象的相互转换

一、fastjson

		//1、maven依赖
		<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.75</version>
        </dependency>

			//2、实体类

			import lombok.*;
			@Getter
			@Setter
			@NoArgsConstructor
			@AllArgsConstructor
			@ToString
			public class User {
				private String name;
				private Integer age;
			}

		//3.测试

		User xx = new User("xx", 12);
        User ll = new User("ll", 12);
        User jj = new User("jj", 12);
        List<User> users = Arrays.asList(xx, ll, jj);
      
        //对象转JSON字符串
        String jsonString = JSON.toJSONString(users);
        System.out.println(jsonString); //[{"age":12,"name":"xx"},{"age":12,"name":"ll"},{"age":12,"name":"jj"}]

        //json字符串
        //对象类型
        System.out.println(JSON.parseArray(jsonString, User.class)); 
        //[User(name=xx, age=12), User(name=ll, age=12),User(name=jj, age=12)]
       
        System.out.println(JSON.parseObject(jsonString,List.class));
        //[{"name":"xx","age":12}, {"name":"ll","age":12}, {"name":"jj","age":12}]

二、jackson

		//1、maven依赖
		<dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.11.4</version>
        </dependency>
		//2、测试
		 private final ObjectMapper objectMapper = new ObjectMapper();
	    @Test
	    public void test() throws JsonProcessingException {
	        User xx = new User("xx", 12);
	        User ll = new User("ll", 12);
	        User jj = new User("jj", 12);
	        List<User> users = Arrays.asList(xx, ll, jj);
	
	        //将对象转换为JSON
	        System.out.println(objectMapper.writeValueAsString(users));
	        //[{"name":"xx","age":12},{"name":"ll","age":12},{"name":"jj","age":12}]
	
	        //将JSON转换成对象
	        List<User> user = objectMapper.readValue(objectMapper.writeValueAsString(users), List.class);
	        System.out.println(user);
	        //[{name=xx, age=12}, {name=ll, age=12}, {name=jj, age=12}]
	
	    }