java json转换工具类 json转换java对象

先创建一个实体类。

public class User {

    private String name;
    
    private Integer age;
    
    private String address;

    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;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

一、FastJson的转换

1、对象转json

public void beanToJosnString() {
        User user = new User();
        user.setName("Json");
        user.setAge(18);
        user.setAddress("杭州");
        User user1 = new User();
        user1.setName("Java");
        user1.setAge(19);
        user1.setAddress("上海");
        List<User> userList = new ArrayList<>();
        userList.add(user);
        userList.add(user1);
        //java对象转json字符串
        String json = JSONObject.toJSONString(user);
        //java对象数组转json字符串
        String jsonArray = JSONArray.toJSONString(userList);
        System.out.println("json: "+json);
        System.out.println("jsonArray: "+jsonArray);

    }

输出结果：

json: {"address":"杭州","age":18,"name":"Json"}
jsonArray: [{"address":"杭州","age":18,"name":"Json"},{"address":"上海","age":19,"name":"Java"}]

2、json字符串转java对象

public void beanToJosnString() {
        User user = new User();
        user.setName("Json");
        user.setAge(18);
        user.setAddress("杭州");
        User user1 = new User();
        user1.setName("Java");
        user1.setAge(19);
        user1.setAddress("上海");
        List<User> userList = new ArrayList<>();
        userList.add(user);
        userList.add(user1);
        //java对象转json字符串
        String json = JSONObject.toJSONString(user);
        //java对象数组转json字符串
        String jsonArray = JSONArray.toJSONString(userList);

        User user2 = JSON.parseObject(json, User.class);
        System.out.println(user2.getName()+"  "+user2.getAge()+"  "+user2.getAddress());
        System.out.println("----------------------------");
        List<User> list = JSON.parseArray(jsonArray, User.class);
        for (User user3:list) {
            System.out.println(user3.getName()+"   "+user3.getAddress());
        }

    }

输出内容：

Json  18  杭州
--------------
Json   杭州
Java   上海

二、Json-Lib

1、java对象转成json字符串

public void beanToJosnString() {
        User user = new User();
        user.setName("Json");
        user.setAge(18);
        user.setAddress("杭州");
        User user1 = new User();
        user1.setName("Java");
        user1.setAge(19);
        user1.setAddress("上海");
        List<User> userList = new ArrayList<>();
        userList.add(user);
        userList.add(user1);
        //java对象转json字符串
        String json = JSONObject.fromObject(user).toString();
        //java对象数组转json字符串
        String jsonArray = JSONArray.fromObject(userList).toString();
        System.out.println("json: "+json);
        System.out.println("jsonArray: "+jsonArray);
    }

输出内容：

json: {"address":"杭州","age":18,"name":"Json"}
jsonArray: [{"address":"杭州","age":18,"name":"Json"},{"address":"上海","age":19,"name":"Java"}]

2、json字符串转java对象

public void beanToJosnString() {
        User user = new User();
        user.setName("Json");
        user.setAge(18);
        user.setAddress("杭州");
        User user1 = new User();
        user1.setName("Java");
        user1.setAge(19);
        user1.setAddress("上海");
        List<User> userList = new ArrayList<>();
        userList.add(user);
        userList.add(user1);
        //java对象转json字符串
        String json = JSONObject.fromObject(user).toString();
        //java对象数组转json字符串
        String jsonArray = JSONArray.fromObject(userList).toString();

        //json字符串转java对象
        User userBean = (User) JSONObject.toBean(JSONObject.fromObject(json),User.class);
        System.out.println(userBean.getName()+"  "+userBean.getAddress());
        System.out.println("--------------------");
        //json字符串转java对象数组
        List<User> list = (List<User>) JSONArray.toList(JSONArray.fromObject(jsonArray),User.class);
        for (User user2:list) {
            System.out.println(user2.getName()+"  "+user2.getAge()+"  "+user2.getAddress());
        }
    }

输出内容：

Json  杭州
--------------
Json  18  杭州
Java  19  上海