Java 新手如何使用Spring MVC RestAPI 的加密？
如今，REST API 可用很多。由于cryptocurrencies是时下的热门话题，总是需要对不同的cryptocurrencies进行比较，并得到不同币种对应的价值。作为示例，我们将 REST API 调用作为
https://min-api.cryptocompare.com/data/price?fsym=LTC&tsyms=BTC,USD,EUR,INR这里 fym 代表我们需要当前价格的货币 tsyms 代表另一种货币，其中美元、欧元和印度卢比是货币符号，我们得到相应货币的价格值。
输出为 JSON 格式：
让我们看看一些货币及其符号
货币 | 符号 |
Bitcoin | BTC |
Ethereum | ETH |
Litecoin | LTC |
Zcash | ZEC |
Iota | MIOTA |
好的，现在让我们开始准备 Spring MVC 项目并以我们想要的方式呈现 JSON 响应。
执行
项目结构：
这是一个maven驱动的项目
pom.xml
<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.cryptocurrencycompare.cryptocurrencycompare_Rest_API</groupId>
<artifactId>cryptocurrencycompare_Rest_API</artifactId>
<packaging>war</packaging>
<version>0.0.1-SNAPSHOT</version>
<name>cryptocurrencycomparator</name>
<url>http://maven.apache.org</url>
<properties>
<failOnMissingWebXml>false</failOnMissingWebXml>
<spring-version>5.1.0.RELEASE</spring-version>
</properties>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring-version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring-version}</version>
</dependency>
<!-- JSTL Dependency -->
<dependency>
<groupId>javax.servlet.jsp.jstl</groupId>
<artifactId>javax.servlet.jsp.jstl-api</artifactId>
<version>1.2.1</version>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>
<!-- Servlet Dependency -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
<!-- JSP Dependency -->
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>javax.servlet.jsp-api</artifactId>
<version>2.3.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.6</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.5</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>CryptoCompareDetails</finalName>
<sourceDirectory>src/main/java</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<!-- This should be added to overcome Could not initialize
class org.apache.maven.plugin.war.util.WebappStructureSerializer -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>3.3.2</version>
</plugin>
</plugins>
</build>
</project>
让我们从调用页面开始，即 JSP 页面，我们可以在其中提供 from 货币和 to 货币
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Cryptocurrency</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js"></script>
<style type="text/css">
.main-form, .profile-area {
width: 500px;
}
.main-form {
margin: 50px auto 0px;
}
.profile-area {
margin: 10px auto;
}
.main-form section, .profile-area section {
margin-bottom: 15px;
background: #df5b47;
box-shadow: 0px 2px 2px rgba(0, 0, 0, 0.3);
}
.main-form section {
padding: 30px;
}
.profile-area section {
padding: 30px 30px 30px;
}
.profile-area section > div {
text-align: center;
}
.main-form h3 {
margin: 0 0 15px;
}
.form-control, .btn {
min-height: 38px;
border-radius: 2px;
}
.btn {
font-size: 15px;
font-weight: bold;
font-family: verdana;
}
.hideElement {
display: none;
}
</style>
</head>
<body>
<div class="main-form" id="main-form">
<section>
<h5 class="text-center">Enter a Cryptocurrency that need to be compared </h5>
<div class="form-group">
<input id="fsym" type="text" class="form-control" placeholder="Enter a Cryptocurrency that need to be compared..." required="required">
</div>
<h5 class="text-center">Enter a comparison Cryptocurrency </h5>
<div class="form-group">
<input id="tsyms" type="text" class="form-control" placeholder="Enter a comparison Cryptocurrency ..." required="required">
</div>
<div class="form-group">
<button onclick="loadData()" class="btn btn-primary btn-block">Compare Cryptocurrencies</button>
</div>
</section>
</div>
<div class="profile-area hideElement" id="profile-area">
<section>
<div id="loader" class="hideElement">
<div class="spinner-border" role="status">
<span class="sr-only">Loading...</span>
</div>
</div>
<div id="profile" class="hideElement">
<br><br>
<p><strong>USD : <span id="USD"></span></strong></p>
<p><strong>EUR : <span id="EUR"></span></strong></p>
<p><strong>INR : <span id="INR"></span></strong></p>
</div>
</section>
</div>
</body>
<script>
function loadData() {
document.getElementById("profile-area").classList.remove("hideElement");
document.getElementById("loader").classList.remove("hideElement");
document.getElementById("profile").classList.add("hideElement");
var fsym = document.getElementById("fsym").value;
var tsyms = document.getElementById("tsyms").value;
if(fsym != "" && fsym != null && tsyms != "" && tsyms != null) {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
var jsonResponse = JSON.parse(this.responseText);
document.getElementById("USD").innerHTML = jsonResponse.USD;
document.getElementById("EUR").innerHTML = jsonResponse.EUR;
document.getElementById("INR").innerHTML = jsonResponse.INR;
document.getElementById("loader").classList.add("hideElement");
document.getElementById("profile").classList.remove("hideElement");
}
};
xhttp.open("GET", "getCryptocurrencyComparisonDetailsByName?fsym=" + fsym + "&tsyms=" + tsyms, true);
xhttp.send();
console.log("done");
} else {
console.log("Enter from and to cryptocurrency...")
}
}
</script>
</html>输出：
让我们提供货币的往返值
为了正确呈现 JSON 响应，我们按照控制器文件通过 Spring 执行操作。让我们看看重要文件
应用程序配置文件
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;
@Configuration
@EnableWebMvc
@ComponentScan(basePackages = { "com.cryptocurrencycompare.cryptocurrencycompare_Rest_API" })
public class AppConfig {
@Bean
public InternalResourceViewResolver resolver() {
InternalResourceViewResolver resolver = new InternalResourceViewResolver();
resolver.setViewClass(JstlView.class);
resolver.setPrefix("/");
resolver.setSuffix(".jsp");
return resolver;
}
}SpringMvcDispatcherServletInitializer.java
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
public class SpringMvcDispatcherServletInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
@Override
protected Class<?>[] getRootConfigClasses() {
return null;
}
@Override
protected Class<?>[] getServletConfigClasses() {
return new Class[] { AppConfig.class };
}
@Override
protected String[] getServletMappings() {
return new String[] { "/" };
}
}
控制器类
CryptocurrencyComparatorController.java
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.StringTokenizer;
import org.springframework.stereotype.Controller;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import com.google.gson.Gson;
import com.google.gson.JsonObject;
@Controller
public class CryptocurrencyComparatorController {
@RequestMapping("/getCryptocurrencyComparisonDetailsByName")
public @ResponseBody
JsonObject getCryptocurrencyComparatorDetails(String fsym,String tsyms) throws IOException {
JsonObject jsonObject = new JsonObject();
jsonObject = getCryptocurrencyComparatorData(fsym,tsyms);
String data = jsonObject.toString().replaceAll("^\"|\"$", "");
StringTokenizer jsonTokenizer = new StringTokenizer(data,",");
String internalData[];
String expectedCryptocurrencyOutput = null;
while (jsonTokenizer.hasMoreTokens()) {
expectedCryptocurrencyOutput = jsonTokenizer.nextToken();
internalData = StringUtils.split(expectedCryptocurrencyOutput,":");
System.out.println(internalData[0]+internalData[1]);
if (internalData[0].substring(2,internalData[0].length()-1).equalsIgnoreCase("BTC")) {
jsonObject.addProperty("BTC",internalData[1].substring(0,internalData[1].length()));
}
if (internalData[0].substring(1,internalData[0].length()-1).equalsIgnoreCase("USD")) {
jsonObject.addProperty("USD",internalData[1].substring(0,internalData[1].length()));
}
if (internalData[0].substring(1,internalData[0].length()-1).equalsIgnoreCase("EUR")) {
jsonObject.addProperty("EUR",internalData[1].substring(0,internalData[1].length()));
}
if (internalData[0].substring(1,internalData[0].length()-1).equalsIgnoreCase("INR")) {
jsonObject.addProperty("INR",internalData[1].substring(0,internalData[1].length()-1));
}
}
return jsonObject;
}
private JsonObject getCryptocurrencyComparatorData(String fromCryptocurrency,String toCryptocurrency) throws IOException {
StringBuilder responseData = new StringBuilder();
JsonObject jsonObject = null;
URL url = null;
url = new URL("https://min-api.cryptocompare.com/data/price?fsym="+fromCryptocurrency+"&tsyms="+toCryptocurrency+",USD,EUR,INR");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("GET");
con.setRequestProperty("User-Agent", "Mozilla/5.0");
int responseCode = con.getResponseCode();
System.out.println("\nSending 'GET' request to URL : " + url);
System.out.println("Response Code : " + responseCode);
try (BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()))) {
String line;
while ((line = in.readLine()) != null) {
responseData.append(line);
}
jsonObject = new Gson().fromJson(responseData.toString(), JsonObject.class);
}
System.out.println(jsonObject);
return jsonObject;
}
}
输出：
