GSON 示例代码 实用版

去除所有格式的json字符串

{"data":[{"friend":[{"address":"广州","name":"好友1"},{"address":"深圳","name":"好友2"}],"username":"包青天"},{"friend":[],"username":"bqt"}],"num":2}

添加转义字符后的json字符串

{"data":[{"friend":[{"address":"广州","name":"好友1"},{"address":"深圳","name":"好友2"}],"username":"包青天"},{"friend":[],"username":"bqt"}],"num":2}

{ "data": [ { "friend": [ { "address": "广州", "name": "好友1" }, { "address": "深圳", "name": "好友2" } ], "username": "包青天" }, { "friend": [], "username": "bqt" } ], "num": 2 }

public class GsonDemo {

    // 将 java 对象 格式化为 Json 字符串.

    public static void main(String[] args) {

        Gson gson = new Gson();

        String json = "{"data":[{"friend":[{"address":"广州","name":"好友1"},{"address":"深圳","name":"好友2"}],"username":"包青天"},{"friend":[],"username":"bqt"}],"num":2}";

        GsonBean bean = gson.fromJson(json, GsonBean.class);

        System.out.println(bean.toString());

        System.out.println(bean.data.get(0).username);

        String json2 = gson.toJson(bean);

        System.out.println("Json字符串 = " + json2);

        //******************************************************************************************

        ArrayList<Person> list_person = new ArrayList<Person>();

        list_person.add(new Person("好友1", "广州"));

        list_person.add(new Person("好友2", "深圳"));

        ArrayList<Account> list_account = new ArrayList<Account>();

        list_account.add(new GsonBean().new Account("包青天", list_person));//外部类GsonBean要有一个无参的构造方法，不然怎么创建内部类对象？

        list_account.add(new GsonBean().new Account("bqt", new ArrayList<Person>()));//可以是空的集合，或者直接是空对象null

        GsonBean bean2 = new GsonBean(2, list_account);

        String json3 = gson.toJson(bean2);

        System.out.println("Json字符串 = " + json3);

    }

}

public class Person {

    //不要求一定有get、set方法，也不要求一定有无参构造方法，甚至不要求其成员是public还是private

    //但要求所有字段名必须和json字符串中的一致

    public String name;

    public String address;

    public Person(String name, String address) {

        this.name = name;

        this.address = address;

    }

    @Override

    public String toString() {

        return "name=" + name + " & " + "address=" + address;

    }

}

public class GsonBean {

    public GsonBean() {

    }

    public GsonBean(int num, ArrayList<Account> data) {

        super();

        this.num = num;

        this.data = data;

    }

    public int num;

    public ArrayList<Account> data;

    /**data数组里的对象*/

    public class Account {

        public String username;

        public ArrayList<Person> friend;

        @Override

        public String toString() {

            return "账户【username=" + username + "，friend=" + friend + "】";

        }

        public Account(String username, ArrayList<Person> friend) {

            super();

            this.username = username;

            this.friend = friend;

        }

    }

    @Override

    public String toString() {

        return "Gson 【num=" + num + "，data=" + data + "】";

    }

}

来自为知笔记(Wiz)