在Java中解析JSON數(shù)據(jù)代碼示例及說明
例子解析以下JSON數(shù)據(jù)
{"code":0,
"msg":"成功",
"data":
[{
"host":"1068222.com",
"port":"",
"m_token":"490e20e70e7de5f21a24b14c12a393f6",
"category":"sd",
"sub_category":"M1049",
"flyback_date":"2025-02-17",
"versions":["0.4.2"],
"req_times":["2025-02-15 02:58:20"],
"create_time":"2025-02-18 06:58:20",
"update_time":"2025-02-18 06:58:20"}]
}以下以 Gson 庫為例,展示如何解析這段 JSON 數(shù)據(jù):
首先,需要在項(xiàng)目中引入 Gson 庫的依賴。如果使用 Maven 項(xiàng)目,可以在pom.xml文件中添加以下依賴:
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.9</version>
</dependency>接下來,定義對(duì)應(yīng)的 Java 類來映射 JSON 數(shù)據(jù)結(jié)構(gòu):
import java.util.List;
public class ResponseData {
private int code;
private String msg;
private List<DataItem> data;
public int getCode() {
return code;
}
public void setCode(int code) {
this.code = code;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
public List<DataItem> getData() {
return data;
}
public void setData(List<DataItem> data) {
this.data = data;
}
public static class DataItem {
private String host;
private String port;
private String m_token;
private String category;
private String sub_category;
private String flyback_date;
private List<String> versions;
private List<String> req_times;
private String create_time;
private String update_time;
public String getHost() {
return host;
}
public void setHost(String host) {
this.host = host;
}
public String getPort() {
return port;
}
public void setPort(String port) {
this.port = port;
}
public String getM_token() {
return m_token;
}
public void setM_token(String m_token) {
this.m_token = m_token;
}
public String getCategory() {
return category;
}
public void setCategory(String category) {
this.category = category;
}
public String getSub_category() {
return sub_category;
}
public void setSub_category(String sub_category) {
this.sub_category = sub_category;
}
public String getFlyback_date() {
return flyback_date;
}
public void setFlyback_date(String flyback_date) {
this.flyback_date = flyback_date;
}
public List<String> getVersions() {
return versions;
}
public void setVersions(List<String> versions) {
this.versions = versions;
}
public List<String> getReq_times() {
return req_times;
}
public void setReq_times(List<String> req_times) {
this.req_times = req_times;
}
public String getCreate_time() {
return create_time;
}
public void setCreate_time(String create_time) {
this.create_time = create_time;
}
public String getUpdate_time() {
return update_time;
}
public void setUpdate_time(String update_time) {
this.update_time = update_time;
}
}
}然后,使用 Gson 庫解析 JSON 數(shù)據(jù):
import com.google.gson.Gson;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
class ResponseData {
private int code;
private String msg;
private List<DataItem> data;
public int getCode() {
return code;
}
public void setCode(int code) {
this.code = code;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
public List<DataItem> getData() {
return data;
}
public void setData(List<DataItem> data) {
this.data = data;
}
static class DataItem {
private String host;
private String port;
private String m_token;
private String category;
private String sub_category;
private String flyback_date;
private List<String> versions;
private List<String> req_times;
private String create_time;
private String update_time;
public String getHost() {
return host;
}
public void setHost(String host) {
this.host = host;
}
public String getPort() {
return port;
}
public void setPort(String port) {
this.port = port;
}
public String getM_token() {
return m_token;
}
public void setM_token(String m_token) {
this.m_token = m_token;
}
public String getCategory() {
return category;
}
public void setCategory(String category) {
this.category = category;
}
public String getSub_category() {
return sub_category;
}
public void setSub_category(String sub_category) {
this.sub_category = sub_category;
}
public String getFlyback_date() {
return flyback_date;
}
public void setFlyback_date(String flyback_date) {
this.flyback_date = flyback_date;
}
public List<String> getVersions() {
return versions;
}
public void setVersions(List<String> versions) {
this.versions = versions;
}
public List<String> getReq_times() {
return req_times;
}
public void setReq_times(List<String> req_times) {
this.req_times = req_times;
}
public String getCreate_time() {
return create_time;
}
public void setCreate_time(String create_time) {
this.create_time = create_time;
}
public String getUpdate_time() {
return update_time;
}
public void setUpdate_time(String update_time) {
this.update_time = update_time;
}
}
}
public class JsonParsingExample {
public static void main(String[] args) {
String json = "{\"code\":0,\"msg\":\"成功\",\"data\":[{\"host\":\"1068222.com\",\"port\":\"\",\"m_token\":\"490e20e70e7de5f21a24b14c12a393f6\",\"category\":\"sd\",\"sub_category\":\"M1049\",\"flyback_date\":\"2025-02-17\",\"versions\":[\"0.4.2\"],\"req_times\":[\"2025-02-15 02:58:20\"],\"create_time\":\"2025-02-18 06:58:20\",\"update_time\":\"2025-02-18 06:58:20\"}]}";
Gson gson = new Gson();
ResponseData response = gson.fromJson(json, ResponseData.class);
System.out.println("Code: " + response.getCode());
System.out.println("Message: " + response.getMsg());
for (ResponseData.DataItem item : response.getData()) {
System.out.println("Host: " + item.getHost());
System.out.println("Port: " + item.getPort());
System.out.println("m_token: " + item.getM_token());
System.out.println("Category: " + item.getCategory());
System.out.println("Sub Category: " + item.getSub_category());
System.out.println("Flyback Date: " + item.getFlyback_date());
System.out.println("Versions: " + item.getVersions());
System.out.println("Req Times: " + item.getReq_times());
System.out.println("Create Time: " + item.getCreate_time());
System.out.println("Update Time: " + item.getUpdate_time());
if (!item.getReq_times().isEmpty()) {
String firstReqTime = item.getReq_times().get(0);
try {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = sdf.parse(firstReqTime);
long timestamp = date.getTime();
System.out.println("First Req Time Timestamp: " + timestamp);
} catch (ParseException e) {
System.err.println("Failed to parse date: " + firstReqTime);
e.printStackTrace();
}
}
}
}
}以上代碼首先定義了與 JSON 數(shù)據(jù)結(jié)構(gòu)對(duì)應(yīng)的 Java 類,然后使用 Gson 庫將 JSON 字符串解析為 Java 對(duì)象,并打印出解析后的數(shù)據(jù)。如果使用 Jackson 庫,解析過程會(huì)有所不同,但原理類似。
將解析出的 req_times 列表中的第一個(gè)時(shí)間字符串轉(zhuǎn)換為時(shí)間戳。在 Java 中,可以使用 SimpleDateFormat 類來解析日期時(shí)間字符串,并將其轉(zhuǎn)換為 Date 對(duì)象,然后通過 Date 對(duì)象的 getTime() 方法獲取對(duì)應(yīng)的時(shí)間戳。
代碼說明:
- 日期格式化:使用
SimpleDateFormat類,其構(gòu)造函數(shù)傳入"yyyy-MM-dd HH:mm:ss"作為日期時(shí)間的格式模板,該模板與 JSON 數(shù)據(jù)中的日期時(shí)間字符串格式相匹配。 - 解析日期字符串:調(diào)用
SimpleDateFormat對(duì)象的parse()方法將日期時(shí)間字符串解析為Date對(duì)象。 - 獲取時(shí)間戳:通過
Date對(duì)象的getTime()方法獲取對(duì)應(yīng)的時(shí)間戳(從 1970 年 1 月 1 日 00:00:00 UTC 到該日期的毫秒數(shù))。 - 異常處理:使用
try-catch塊捕獲ParseException異常,當(dāng)日期時(shí)間字符串格式不符合模板時(shí),會(huì)拋出該異常,捕獲后打印錯(cuò)誤信息并輸出堆棧跟蹤。
運(yùn)行上述代碼,在輸出 Req Times 信息后,會(huì)額外輸出第一個(gè)請(qǐng)求時(shí)間對(duì)應(yīng)的時(shí)間戳。
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