Spring Boot整合模板引擎freemarker以及servlet
阿新 • • 發佈：2018-12-24
上回分享了第一個spring boot程式之後，相信大家對spring boot已經有了初步的認識，這次分享下在springboot中使用servlet和模板引擎freemarker
一 依賴的引入
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>二 編寫配置檔案application.properties
預設情況下springboot會去src/main/resources/templates下面找模板頁面檔案，也可以根據需要進行修改spring.freemarker.allow-request-override=false spring.freemarker.cache=false spring.freemarker.check-template-location=true spring.freemarker.charset=UTF-8 spring.freemarker.content-type=text/html spring.freemarker.expose-request-attributes=false spring.freemarker.expose-session-attributes=false spring.freemarker.expose-spring-macro-helpers=false #spring.freemarker.prefix= #spring.freemarker.request-context-attribute= #spring.freemarker.settings.*= #spring.freemarker.suffix=.ftl #spring.freemarker.template-loader-path=classpath:/templates/ #comma-separated list #spring.freemarker.view-names= # whitelist of view names that can be resolved
三 編寫測試用的controller和模板檔案
package com.debug; import java.util.ArrayList; import java.util.Date; import java.util.List; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @Controller public class FMController { @RequestMapping("/useFm") public String useFm(HttpServletRequest req,HttpServletResponse res) { String name=req.getParameter("name"); req.setAttribute("name", name); return "/useFm"; } }
<!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"> <title>fm測試</title> </head> <body > <div id="fixed_body"> ${name} </div> </body> </html>
執行效果如下：
spring boot也提供了一個自己的模板引擎，因為我開發使用freemarker較多所以就用它來寫例子，大家可以選擇其他的如velocity等
四 在springboot中使用servlet
有時可能由於歷史遺留問題老專案中存在很多servlet如驗證碼、檔案上傳等,重新寫費時費力，這種情況下就可以保留原先的，使用註解就可以解決
1 改裝之前的servlet
package com.debug.servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
@WebServlet(urlPatterns="/imageCode.do",name="ImageCodeServlet")
public class ImageCodeServlet extends HttpServlet{
private static final long serialVersionUID = 1L;
private static int WIDTH = 100;
private static int HEIGHT = 44;
public char[] generateCheckCode() {
// 定義驗證碼的字元表
String chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char[] rands = new char[4];
for (int i = 0; i < 4; i++) {
int rand = (int) (Math.random() * 36);
rands[i] = chars.charAt(rand);
}
return rands;
}
public void drawRands(Graphics g, char[] rands) {
g.setColor(Color.DARK_GRAY);
g.setFont(new Font(null, Font.ITALIC | Font.BOLD, 25));
// 在不同的高度上輸出驗證碼的每個字元
g.drawString("" + rands[0], 1, 30);
g.drawString("" + rands[1], 25, 35);
g.drawString("" + rands[2], 45, 29);
g.drawString("" + rands[3], 65, 25);
}
public void drawBackground(Graphics g) {
// 畫背景
g.setColor(new Color(0xDCDCDC));
g.fillRect(0, 0, WIDTH, HEIGHT);
// 隨機產生120個干擾點
for (int i = 0; i < 120; i++) {
int x = (int) (Math.random() * WIDTH);
int y = (int) (Math.random() * HEIGHT);
int red = (int) (Math.random() * 255);
int green = (int) (Math.random() * 255);
int blue = (int) (Math.random() * 255);
g.setColor(new Color(red, green, blue));
g.drawOval(x, y, 1, 0);
}
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
HttpSession session = request.getSession();
response.setContentType("image/jpeg");
ServletOutputStream sos = response.getOutputStream();
// 設定瀏覽器不快取此圖片
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// 建立記憶體影象並獲得其圖形上下文
BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
// 產生隨機的驗證碼
char[] rands = generateCheckCode();
// 產生影象
drawBackground(g);
drawRands(g, rands);
// 結束影象的繪製過程,完成影象
g.dispose();
// 將影象輸出到客戶端
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ImageIO.write(image, "JPEG", bos);
byte[] buf = bos.toByteArray();
response.setContentLength(buf.length);
sos.write(buf);
bos.close();
sos.close();
// 將當前驗證碼存入到session中
session.setAttribute("checkCode", new String(rands));
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
就使用註解@WebServlet就行，區別不是很大
2 註冊servlet
在App.java加註解@ServletComponentScan即可，如下所示
package com.debug;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
/**
* Hello world!
*
*/
@SpringBootApplication
@ServletComponentScan
public class App
{
public static void main( String[] args )
{
System.out.println( "Hello World!" );
SpringApplication.run(App.class, args);
}
}
下回打算接著分享spring boot整合mybatis，初學者部落格可能寫的不好，隨意看看有問題寫評論給我