import com.fasterxml.jackson.databind.ObjectMapper;
// 定義實(shí)體類
class User {
    private Integer id;
    private String name;
    private String email;
    // 必須提供無(wú)參構(gòu)造函數(shù)（Jackson反射依賴）
    public User() {}
    // Getter和Setter省略
}
public class JacksonDemo {
    public static void main(String[] args) throws Exception {
        ObjectMapper objectMapper = new ObjectMapper();
        String jsonStr = "{\"id\":1,\"name\":\"張三\",\"email\":\"zhangsan@example.com\"}";
        // JSON轉(zhuǎn)對(duì)象（反序列化）
        User user = objectMapper.readValue(jsonStr, User.class);
        System.out.println("反序列化結(jié)果：" + user.getName());
        // 對(duì)象轉(zhuǎn)JSON（序列化）
        User newUser = new User();
        newUser.setId(2);
        newUser.setName("李四");
        newUser.setEmail("lisi@example.com");
        String newJsonStr = objectMapper.writeValueAsString(newUser);
        System.out.println("序列化結(jié)果：" + newJsonStr);
    }
}

import com.fasterxml.jackson.annotation.*;
import java.util.Date;
class AdvancedUser {
    @JsonProperty("user_id") // JSON字段名映射（解決駝峰與下劃線沖突）
    private Integer id;
    @JsonIgnore // 序列化時(shí)忽略該字段
    private String password;
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") // 日期格式化
    private Date createTime;
    // Getter和Setter省略
}
// 序列化示例
AdvancedUser user = new AdvancedUser();
user.setId(3);
user.setPassword("123456");
user.setCreateTime(new Date());
String json = new ObjectMapper().writeValueAsString(user);
// 輸出：{"user_id":3,"createTime":"2025-08-01 15:30:00"}

import com.google.gson.Gson;
import java.util.List;
public class GsonDemo {
    public static void main(String[] args) {
        Gson gson = new Gson();
        String jsonStr = "{\"id\":1,\"name\":\"王五\",\"age\":25}";
        // JSON轉(zhuǎn)對(duì)象
        User user = gson.fromJson(jsonStr, User.class);
        System.out.println("反序列化結(jié)果：" + user.getAge());
        // 對(duì)象轉(zhuǎn)JSON
        String newJsonStr = gson.toJson(user);
        System.out.println("序列化結(jié)果：" + newJsonStr);
        // 泛型對(duì)象轉(zhuǎn)換（List為例）
        String listJson = "[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]";
        List<User> userList = gson.fromJson(listJson, new com.google.gson.reflect.TypeToken<List<User>>() {}.getType());
        System.out.println("List反序列化大?。? + userList.size());
    }
}

import com.google.gson.annotations.Expose;
import com.google.gson.GsonBuilder;
class GsonUser {
    @Expose(serialize = true, deserialize = true) // 序列化和反序列化都生效
    private Integer id;
    @Expose(serialize = false) // 僅反序列化，不序列化
    private String tempField;
    // Getter和Setter省略
}
// 自定義適配器（處理日期格式）
class DateAdapter implements com.google.gson.TypeAdapter<Date> {
    private SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
    @Override
    public void write(com.google.gson.stream.JsonWriter out, Date value) throws IOException {
        out.value(sdf.format(value));
    }
    @Override
    public Date read(com.google.gson.stream.JsonReader in) throws IOException {
        try {
            return sdf.parse(in.nextString());
        } catch (ParseException e) {
            return null;
        }
    }
}
// 使用示例
Gson gson = new GsonBuilder()
        .registerTypeAdapter(Date.class, new DateAdapter()) // 注冊(cè)適配器
        .excludeFieldsWithoutExposeAnnotation() // 只序列化帶@Expose注解的字段
        .create();

import com.alibaba.fastjson.JSON;
import java.util.List;
public class FastJsonDemo {
    public static void main(String[] args) {
        String jsonStr = "{\"id\":1,\"name\":\"趙六\",\"address\":\"北京\"}";
        // JSON轉(zhuǎn)對(duì)象
        User user = JSON.parseObject(jsonStr, User.class);
        System.out.println("反序列化結(jié)果：" + user.getAddress());
        // 對(duì)象轉(zhuǎn)JSON
        String newJsonStr = JSON.toJSONString(user);
        System.out.println("序列化結(jié)果：" + newJsonStr);
        // JSON轉(zhuǎn)List
        String listJson = "[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]";
        List<User> userList = JSON.parseArray(listJson, User.class);
        System.out.println("List反序列化大?。? + userList.size());
    }
}

import com.alibaba.fastjson.serializer.SerializerFeature;
// 動(dòng)態(tài)字段解析（JSON轉(zhuǎn)Map）
String dynamicJson = "{\"id\":1,\"name\":\"孫七\(yùn)",\"score\":90.5}";
Map<String, Object> map = JSON.parseObject(dynamicJson, Map.class);
System.out.println("動(dòng)態(tài)字段score：" + map.get("score"));
// 格式化輸出（美化JSON）
User user = new User();
user.setId(2);
user.setName("周八");
String prettyJson = JSON.toJSONString(user, SerializerFeature.PrettyFormat);
System.out.println("美化后的JSON：" + prettyJson);
// 日期格式化
JSON.DEFFAULT_DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";
String dateJson = JSON.toJSONString(new Date(), SerializerFeature.WriteDateUseDateFormat);
System.out.println("日期格式化結(jié)果：" + dateJson);

import com.jayway.jsonpath.JsonPath;
import java.util.List;
public class JsonPathDemo {
    public static void main(String[] args) {
        // 復(fù)雜嵌套JSON
        String complexJson = """
            {
                "store": {
                    "book": [
                        {"title": "Java編程思想", "price": 108, "category": "編程"},
                        {"title": "深入理解Java虛擬機(jī)", "price": 89, "category": "編程"},
                        {"title": "三體", "price": 39, "category": "科幻"}
                    ],
                    "address": {
                        "city": "北京",
                        "street": "科技園路"
                    }
                }
            }
        """;
        // 1. 提取單個(gè)字段（商店城市）
        String city = JsonPath.read(complexJson, "$.store.address.city");
        System.out.println("商店城市：" + city);
        // 2. 提取數(shù)組所有元素的某個(gè)字段（所有書籍標(biāo)題）
        List<String> bookTitles = JsonPath.read(complexJson, "$.store.book[*].title");
        System.out.println("所有書籍標(biāo)題：" + bookTitles);
        // 3. 條件過(guò)濾（價(jià)格大于80的書籍）
        List<Object> expensiveBooks = JsonPath.read(complexJson, "$.store.book[?(@.price > 80)]");
        System.out.println("價(jià)格大于80的書籍：" + expensiveBooks);
        // 4. 提取數(shù)組指定索引元素（第一本書的價(jià)格）
        Double firstBookPrice = JsonPath.read(complexJson, "$.store.book[0].price");
        System.out.println("第一本書價(jià)格：" + firstBookPrice);
    }
}

import org.json.JSONArray;
import org.json.JSONObject;
public class OrgJsonDemo {
    public static void main(String[] args) {
        // 1. 解析JSON字符串
        String jsonStr = "{\"id\":1,\"name\":\"吳九\",\"hobbies\":[\"籃球\",\"讀書\"]}";
        JSONObject jsonObject = new JSONObject(jsonStr);
        // 提取字段
        String name = jsonObject.getString("name");
        JSONArray hobbies = jsonObject.getJSONArray("hobbies");
        System.out.println("姓名：" + name + "，愛(ài)好：" + hobbies.get(0));
        // 2. 構(gòu)造JSON
        JSONObject newJsonObject = new JSONObject();
        newJsonObject.put("id", 2);
        newJsonObject.put("name", "鄭十");
        newJsonObject.put("age", 30);
        // 構(gòu)造JSON數(shù)組
        JSONArray skills = new JSONArray();
        skills.put("Java");
        skills.put("MySQL");
        newJsonObject.put("skills", skills);
        System.out.println("構(gòu)造的JSON：" + newJsonObject.toString());
    }
}

import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class ManualParseDemo {
    public static void main(String[] args) {
        String jsonStr = "{\"id\":1,\"name\":\"手動(dòng)解析\",\"value\":\"test\"}";
        Map<String, String> resultMap = parseJson(jsonStr);
        System.out.println("id：" + resultMap.get("id"));
        System.out.println("name：" + resultMap.get("name"));
    }
    // 簡(jiǎn)單JSON手動(dòng)解析（僅支持字符串和數(shù)字字段）
    private static Map<String, String> parseJson(String json) {
        Map<String, String> map = new HashMap<>();
        // 正則表達(dá)式匹配 "key":"value" 或 "key":number
        Pattern pattern = Pattern.compile("\"(.*?)\":\"?(.*?)\"?(,|})");
        Matcher matcher = pattern.matcher(json.replaceAll("\\s+", "")); // 去除空格
        while (matcher.find()) {
            String key = matcher.group(1);
            String value = matcher.group(2);
            map.put(key, value);
        }
        return map;
    }
}