A brief analysis of methods and techniques for converting Java to HTML

Java is an object-oriented programming language that is widely used in the development of various enterprise applications. HTML, on the other hand, is a markup language used to create web pages. In actual development, converting Java code into HTML pages is a very practical requirement. This article will introduce methods and techniques for converting Java to HTML.

1. Using the template engine

The template engine is a tool that processes template files and some data. Generally speaking, a template file is the skeleton of an HTML page. We only need to dynamically fill in Java data to generate the final HTML page.

Common Java template engines include Thymeleaf, FreeMarker, etc. They all provide the ability to parse templates and fill in data. We only need to prepare the data in Java, and then pass the data and template files into the template engine to easily generate HTML pages.

Example of Thymeleaf:

// 加载模板文件
ClassLoaderTemplateResolver resolver = new ClassLoaderTemplateResolver();
resolver.setTemplateMode("HTML");

// 创建模板引擎
TemplateEngine templateEngine = new TemplateEngine();
templateEngine.setTemplateResolver(resolver);

// 准备数据
Map<String, Object> data = new HashMap<>();
data.put("name", "张三");

// 渲染模板
String html = templateEngine.process("index.html", new Context(Locale.CHINA, data));

System.out.println(html);

Example of FreeMarker:

// 加载模板文件
Configuration cfg = new Configuration(Configuration.VERSION_2_3_22);
cfg.setClassForTemplateLoading(this.getClass(), "/templates/");

// 创建模板
Template template = cfg.getTemplate("index.ftl");

// 准备数据
Map<String, Object> data = new HashMap<>();
data.put("name", "张三");

// 渲染模板
Writer out = new StringWriter();
template.process(data, out);

System.out.println(out.toString());

2. Use web crawler

If we need to convert some data from Java applications Dynamically displayed on web pages can be achieved using web crawlers. A web crawler simulates a browser accessing a website and converts the acquired data into HTML pages.

The most commonly used web crawler framework in Java is Jsoup. It provides some practical methods, such as selectors, filters, etc., to easily extract data from web pages.

The following is an example of using Jsoup to crawl web pages:

// 解析网页
Document doc = Jsoup.connect("https://www.baidu.com/").get();

// 选择元素
Element input = doc.select("input[name=wd]").first();

// 修改元素
input.attr("value", "Java 转 HTML");

// 输出 HTML
System.out.println(doc.toString());

3. Using PhantomJS

PhantomJS is an interfaceless browser based on WebKit. It can easily execute JavaScript and output the execution results as HTML pages.

In Java, the most common use of PhantomJS is to use Selenium Webdriver to drive the browser. Selenium provides APIs for various programming languages, including Java. We can write Java code to start PhantomJS, then let it execute JavaScript and save the execution results as an HTML file.

Before using it, you need to download PhantomJS first.

The following is an example of using PhantomJS to generate HTML:

// 创建 WebDriver
System.setProperty("webdriver.phantomjs.driver", "/usr/local/bin/phantomjs");
WebDriver driver = new PhantomJSDriver();

// 打开网页
driver.get("https://www.baidu.com/");

// 执行 JavaScript
String script = "var body = document.body.innerHTML; return body;";
String html = (String) ((JavascriptExecutor) driver).executeScript(script);

// 输出 HTML
System.out.println(html);

Summary

There are many ways to convert Java to HTML, and you can choose the appropriate method according to actual needs. If you just need to populate a predefined HTML template with Java data, you can choose to use a template engine. If you need to extract data from a web page, you can use a web crawler framework. If you need to dynamically generate HTML files, you can use PhantomJS. Regardless of the method, data from Java applications can be easily displayed on a web page.

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