Java資料介面編寫簡單例子,Java Json解析,服務端介面輸出Json資料,客戶端通過HTTP獲取介面Json資料
阿新 • • 發佈:2019-02-10
實現效果
實現原因
目前主流的CS結構,資料都是通過RESTful風格介面形式呈現,不管是桌面級應用程式還是手機端,介面是我們獲取資料的大多數選擇,主流資料介面呈現形式主要是Json和Xml,後者目前基本漸行漸遠。Json的輕量級和可讀型成為了大多數公司及個人開發者的第一選擇。 主流公司在編寫資料介面時大多通過框架實現,如RESTEasy、Retrofit等,在這裡通過簡單的java web程式碼寫一個簡單的介面專案例子供大家參考,後附專案原始碼。實現步驟
在Eclipse中新建專案JsonTest專案,專案結構如下,
此處主要用到的類只有幾個,其他類為Json測試用類,此處可以忽略。
在lib下匯入或在maven中引用gson-2.6.2.jar包和servlet-api.jar包。
gson此處用於將持久化物件解析為Json,或將Json序列化為物件。
servlet-api用於servlet相關類建立及API運用。
關於gson,是Google開源專案下的一個Java Json解析工具包,具體使用及詳細資訊可以看這篇文章:Gson簡要使用
步驟一:新建測試用Model類
新建新聞測試類News,主要用於資料模型測試顯示,Json轉換測試等,程式碼如下:新建分頁測試類NewTotal,主要用於Json分頁顯示,程式碼如下:import java.util.Date; public class News { private int nId; // 新聞ID private String title; // 新聞標題 private String content; // 新聞內容 private String date; // 新聞釋出日期 private String url; //新聞地址 private Date nDate; // 新聞日期,Date型別 public News(int nId, String title, String content, String date, String url) { this.nId = nId; this.title = title; this.content = content; this.date = date; this.url = url; } public News() { } public News(int nId, String title, String content, Date nDate, String url) { this.nId = nId; this.title = title; this.content = content; this.nDate = nDate; this.url = url; } public String getUrl() { return url; } public void setUrl(String url) { this.url = url; } public Date getnDate() { return nDate; } public void setnDate(Date nDate) { this.nDate = nDate; } public int getnId() { return nId; } public void setnId(int nId) { this.nId = nId; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getContent() { return content; } public void setContent(String content) { this.content = content; } public String getDate() { return date; } public void setDate(String date) { this.date = date; } }
import java.util.List; public class NewTotal { private int total; //新聞數量 private List<News> rows; //新聞列表 public NewTotal() { } public NewTotal(int total, List<News> rows) { this.total = total; this.rows = rows; } public int getTotal() { return total; } public void setTotal(int total) { this.total = total; } public List<News> getRows() { return rows; } public void setRows(List<News> rows) { this.rows = rows; } }
步驟二:新增測試用Action和JSP介面
新建JsonServlet,繼承自HttpServlet,具體程式碼詳解已經在程式碼中註釋:
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.google.gson.Gson;
import com.test.model.NewTotal;
import com.test.model.News;
public class JsonServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 建立多個新聞類,模擬從資料庫獲取資料,可將此處改為用JDBC從資料庫讀取資料
News new1 = new News(110, "日本地震", "日本福田發生了7級地震", "2016-5-16 10:22:20",
"http://world.huanqiu.com/exclusive/2016-05/8974294.html");
News new2 = new News(111, "Apple庫克第八次訪華", "近日庫克第八次訪華,與滴滴高層會談", "2016-5-16 10:22:20",
"http://mobile.163.com/16/0523/09/BNO7SG2B001168BQ.html");
News new3 = new News(113, "Google I/O大會開幕", "Google開發者大會即將舉辦,是否推出Android7.0?", "2016-5-16 10:22:20",
"http://www.ithome.com/html/android/227647.htm");
News new4 = new News(114, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20",
"http://news.mydrivers.com/1/484/484072.htm");
News new5 = new News(115, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new6 = new News(116, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new7 = new News(117, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new8 = new News(118, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new9 = new News(119, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new10 = new News(120, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new11 = new News(121, "獲取新資料!!!!!!", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new12 = new News(122, "獲取新資料!!!!!!", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new13 = new News(123, "獲取新資料!!!!!!", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new14 = new News(124, "獲取新資料!!!!!!", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new15 = new News(125, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new16 = new News(126, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new17 = new News(127, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new18 = new News(128, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new19 = new News(129, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
News new20 = new News(130, "格力營收下滑400億", "格里營收下滑400億,董明珠說我活得好的很", "2016-5-16 10:22:20", "www.baidu.com");
String page = req.getParameter("page");
// 將資料新增到陣列
List<News> newslist = new ArrayList<News>();
if (page == null || page.equals("0")) {
newslist.add(new1);
newslist.add(new2);
newslist.add(new3);
newslist.add(new4);
newslist.add(new5);
newslist.add(new6);
newslist.add(new7);
newslist.add(new8);
newslist.add(new9);
newslist.add(new10);
}
else {
newslist.add(new11);
newslist.add(new12);
newslist.add(new13);
newslist.add(new14);
newslist.add(new15);
newslist.add(new16);
newslist.add(new17);
newslist.add(new18);
newslist.add(new19);
newslist.add(new20);
}
// 將資料封裝到新聞總計類
NewTotal nt = new NewTotal(newslist.size(), newslist);
// 呼叫GSON jar工具包封裝好的toJson方法,可直接生成JSON字串
Gson gson = new Gson();
String json = gson.toJson(nt);
// 輸出到介面
System.out.println(json);
resp.setContentType("text/plain");
resp.setCharacterEncoding("gb2312");
PrintWriter out = new PrintWriter(resp.getOutputStream());
out.print(json);
out.flush();
// 更多Json轉換使用請看JsonTest類
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
}
修改專案index.jsp頁面如下:
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>Test Json</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<form action="getJson" method="get">
<input type="submit" value="點選獲取新聞JSON資料"/>
</form>
</body>
</html>
在專案中配置web.xml,註冊JsonServlet對映,配置如下:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>JsonTest</display-name>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>JsonServlet</servlet-name>
<servlet-class>com.test.json.JsonServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>JsonServlet</servlet-name>
<url-pattern>/getJson</url-pattern>
</servlet-mapping>
</web-app>
步驟三:新增專案到Tomcat容器,執行伺服器
執行伺服器,在位址列輸入地址:http://localhost:8080/JsonTest/getJson?page=0,效果如圖:其他關於JSON解析的也可以看我釋出的原始碼中的JsonTest類,獲取原始碼:JavaJson解析