Java Jackson将map,list转换成json

1. map对象转换成json

public static void main(String[] args) {
    try {
        ObjectMapper objectMapper = new ObjectMapper();
        JsonGenerator jsonGenerator = objectMapper.getJsonFactory().createJsonGenerator(System.out, JsonEncoding.UTF8);
        //map转JSON
        Map < String,Object > map = new HashMap < String,Object > ();
        map.put("one", new User("张", 12, "深圳"));
        map.put("two", new User("李", 22, "武汉"));
        map.put("three", new User("王", 32, "北京"));
        System.out.println("ObjectMapper方式");
        objectMapper.writeValue(System.out, map);  System.out.println("JsonGenerator方式");
        jsonGenerator.writeObject(map);
    } catch(IOException e) {
        e.printStackTrace();
    }
}

2. list对象转换成json

public static void main(String[] args) {
    try {
        ObjectMapper objectMapper = new ObjectMapper();
        JsonGenerator jsonGenerator = objectMapper.getJsonFactory().createJsonGenerator(System.out, JsonEncoding.UTF8);
        //list转JSON
        List < User > list = new ArrayList < User > ();
        list.add(new User("张", 12, "深圳"));
        list.add(new User("李", 22, "武汉"));
        list.add(new User("王", 32, "北京"));
        System.out.println("ObjectMapper方式");
        objectMapper.writeValue(System.out, list);
        System.out.println("JsonGenerator方式");
        jsonGenerator.writeObject(list);
    } catch(IOException e) {
        e.printStackTrace();
    }
}