jsonschema如何表示常量

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数据小香 2024-10-24 09:52:48

文章标签 jsonschema如何表示常量 json java web.xml spring 文章分类 机器学习人工智能

JSON(JavaScriptObject Notation)是一种轻量级的数据交换格式。简单地说，JSON可以将JavaScript对象中表示的一组数据转换为字符串，然后就可以在函数之间轻松地传递这个字符串，或者在异步应用程序中将字符串从Web客户机传递给服务器端程序。这个字符串看起来有点儿古怪，但是JavaScript很容易解释它，而且JSON可以表示比"名称/值对"更复杂的结构。例如，可以表示数组和复杂的对象，而不仅仅是键和值的简单列表。

下面举几个简单的实例来介绍Json，因为JSON是javascript的原生格式，因此不需要任何特殊的API包或工具包。

实例一：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
<script type="text/javascript">

	function testJson(){
		var user = 
		{
			"name":"tom",
			"age":11,
			"info":{"tel":"lf","cellphone":"1223"},
			"address":
				[
			    	{"city":"lf","postcode":"111"},
			    	{"city":"bj","postcode":"222"},
				]
		}
			
		alert(user.name);
		alert(user.info.cellphone);
		alert(user.address[1].postcode);		
	}
</script>
</head>
<body>
	<input type="button" value="TestJson" οnclick="testJson()">
</body>
</html>

可直接运行测试。

实例二：

下面这个实例是前后台如何交互的实例，首先把环境搭起来，创建一个Maven项目json_test，具体创建过程不再赘余，pom.xml文件：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.tgb</groupId>
  <artifactId>json_test</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>json_test Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.0</version>
      <scope>test</scope>
    </dependency>
	<dependency>
		<groupId>commons-lang</groupId>
		<artifactId>commons-lang</artifactId>
		<version>2.4</version>
	</dependency>
	 <dependency>
		<groupId>commons-beanutils</groupId>
		<artifactId>commons-beanutils</artifactId>
		<version>1.7.0</version>
	</dependency>  
	<dependency>
		<groupId>commons-collections</groupId>
		<artifactId>commons-collections</artifactId>
		<version>3.2</version>
	</dependency>	
	<dependency>
		<groupId>commons-logging</groupId>
		<artifactId>commons-logging</artifactId>
		<version>1.1.1</version>
	</dependency>
	<dependency>
		<groupId>net.sf.ezmorph</groupId>
		<artifactId>ezmorph</artifactId>
		<version>1.0.6</version>
	</dependency>
	<dependency>
        <groupId>net.sf.json-lib</groupId>
        <artifactId>json-lib</artifactId>
        <version>2.4</version>
        <classifier>jdk15</classifier>
    </dependency>
	<dependency>
		<groupId>org.springframework</groupId>
		<artifactId>spring-webmvc</artifactId>
		<version>3.0.4.RELEASE</version>
	</dependency>
                
  </dependencies>
  <build>
    <finalName>json_test</finalName>
  </build>
</project>

Web.xml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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>json_test</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  
  <servlet>
  	<servlet-name>springMVC</servlet-name>
  	<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  	<load-on-startup>1</load-on-startup>
  </servlet>
  
  <servlet-mapping>
  	<servlet-name>springMVC</servlet-name>
  	<url-pattern>/</url-pattern>
  </servlet-mapping>
</web-app>

SpringMVC的配置文件和web.xml文件在同一个目录下，springMVC-servlet.xml：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xsi:schemaLocation="http://www.springframework.org/schema/beans 
	http://www.springframework.org/schema/beans/spring-beans.xsd
	http://www.springframework.org/schema/context
	http://www.springframework.org/schema/context/spring-context-3.0.xsd
	http://www.springframework.org/schema/mvc
	http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
	
	<context:component-scan base-package="com.tgb.json" />

	<mvc:annotation-driven />
	 
	<mvc:resources location="/js/" mapping="/js/**"/>
</beans>

上面关于SpringMVC的东西也不多讲，因为这不是要讲的重点。项目中还会用到Jquery，因此大家自行下载jquery包，放到webapp/js包下。

下面开始编写后台的代码，首先创建一个POJO类User：

package com.tgb.json;

public class User {

	private String username;
	
	private int age;

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}
}

然后创建TestJson类，在这个类中，我写了三个方法，是分别测试传递User对象、List集合和Map的。

package com.tgb.json;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class TestJson {
	
	@RequestMapping("logon.do")
	public String logon(HttpServletRequest request,HttpServletResponse response){
		return "/test/addUser";
	}
	
	//返回User对象
	@RequestMapping("/test/json1")
	public void returnUser(HttpServletRequest request,HttpServletResponse response) throws Exception{
		
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		
		User u1 = new User();
		u1.setUsername("tom1");
		u1.setAge(11);
	
		//Json返回实体
		JSONObject jsonObject = JSONObject.fromObject(u1);
		//返给ajax请求
		out.print(jsonObject);
	}
	
	//返回List
	@RequestMapping("/test/json2")
	public void returnList(HttpServletRequest request,HttpServletResponse response) throws Exception{
		
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		
		//传递List
		List<User> list = new ArrayList<User>();
		
		User u1 = new User();
		u1.setUsername("tom1");
		u1.setAge(11);
	
		User u2 = new User();
		u2.setUsername("jack");
		u2.setAge(22);
		
		list.add(u1);
		list.add(u2);
		//Json返回list
		JSONArray jsonArray = JSONArray.fromObject(list);
		//返给ajax请求
		out.print(jsonArray);
	}
	
	//返回Map
	@RequestMapping("/test/json3")
	public void returnMap(HttpServletRequest request,HttpServletResponse response) throws Exception{
		
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		
		Map<String,User> map = new HashMap<String,User>();
		
		User u1 = new User();
		u1.setUsername("tom1");
		u1.setAge(11);
	
		User u2 = new User();
		u2.setUsername("jack");
		u2.setAge(22);
		
		map.put("u1", u1);
		map.put("u2", u2);
		
		//Json返回map
		JSONObject jsonObject = JSONObject.fromObject(map);
		//返给ajax请求
		out.print(jsonObject);
	}	
}

完成了后台代码的编写，页面上就需要获取后台传过来的Json数据，并将它显示出来，创建页面testJson.jsp：

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<script type="text/javascript" src="json_test/../js/jquery-1.7.1.js"></script>
<title>Insert title here</title>
<script type="text/javascript">
	
	//获取User对象
	function getJsonObject(){
		$.ajax({
			type:"POST",
			url:"/json_test/test/json1",
			dataType:"json",
			success:function(json){
				alert(json.username);
				alert(json.age);
			},
			error:function(){
				alert("网络错误！");
			}
		});
	}
	
	//获取List对象
	function getJsonList(){
		$.ajax({
			type:"POST",
			url:"/json_test/test/json2",
			dataType:"json",
			success:function(json){
				alert(json[0].username);
				alert(json[1].age);
			},
			error:function(){
				alert("网络错误！");
			}
		});
	}	
	
	//获取Map对象
	function getJsonMap(){
		$.ajax({
			type:"POST",
			url:"/json_test/test/json3",
			dataType:"json",
			success:function(json){
				alert(json.u1.username);
				alert(json.u2.age);
			},
			error:function(){
				alert("网络错误！");
			}
		});
	}	
</script>
</head>
<body>
	<input type="button" value="获取User对象" οnclick="getJsonObject()"><br/>
	<input type="button" value="获取List" οnclick="getJsonList()"><br/>
	<input type="button" value="获取Map" οnclick="getJsonMap()">
</body>
</html>

通过以上这几个例子基本能说明Json的大致用途，他和XML的联系与区别，大家可自行查阅。

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