Jackson：将JSON格式的字符串数组转成List

朱雀 2021-09-11 08:06 468阅读 0赞

首先，在项目中引入 Jackson 的依赖：

<dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.9.1</version>
    </dependency>

再来看 JSON 格式的字符串数组：

[{"name":"沉默王二", "age":18}, {"name":"沉默王三", "age":16}]

根据 JSON 的字段创建一个对象：

public class Cmower {
        private String name;
        private Integer age;
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        @Override
        public String toString() {
            return "Cmower{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    '}';
        }
    }

准备转：

ObjectMapper mapper = new ObjectMapper();
    String json = "[{\"name\":\"沉默王二\", \"age\":18}, {\"name\":\"沉默王三\", \"age\":16}]";
    
    try {
    
        // 1. 把 JSON 数组转成对象数组
        Cmower[] pp1 = mapper.readValue(json, Cmower[].class);
    
        System.out.println("JSON 数组转成对象数组...");
        for (Cmower cmower : pp1) {
            System.out.println(cmower);
        }
    
        // 2. 把 JSON 数组转成 List
        List<Cmower> ppl2 = Arrays.asList(mapper.readValue(json, Cmower[].class));
    
        System.out.println("\nJSON 数组转成 List");
        ppl2.stream().forEach(x -> System.out.println(x));
    
        // 3. TypeReference
        List<Cmower> pp3 = mapper.readValue(json, new TypeReference<List<Cmower>>() {});
    
        System.out.println("\nTypeReference...");
        pp3.stream().forEach(x -> System.out.println(x));
    
    } catch (
            IOException e) {
        e.printStackTrace();
    }

输出：

JSON 数组转成对象数组...
    Cmower{name='沉默王二', age=18}
    Cmower{name='沉默王三', age=16}
    
    JSON 数组转成 List
    Cmower{name='沉默王二', age=18}
    Cmower{name='沉默王三', age=16}
    
    TypeReference...
    Cmower{name='沉默王二', age=18}
    Cmower{name='沉默王三', age=16}