好久没有动过JavaEE了, 现在从最基础的开始写写总结.?

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在JSP页面中动态显示图片.

后台servlet中生成图片, 或者是读取某一个图片, 传到前台JSP中显示是很常见的需求.

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下面开始:

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一.?

? ? ?JSP中显示图片的主要代码就是:

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<img src="http://localhost:8080/imgShow/ImageShowServlet" />

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? ? 其中"imgShow"是项目名称, "ImageShowServlet"是url-pattern.?

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二.?

? ? ?web.xml的配置:

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<?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>imgShow</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>ImageShowServlet</display-name>
    <servlet-name>ImageShowServlet</servlet-name>
    <servlet-class>com.mashupeye.sevlet.ImageShowServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ImageShowServlet</servlet-name>
    <url-pattern>/ImageShowServlet</url-pattern>
  </servlet-mapping>
</web-app>

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三.

? ? 创建的servlet:

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    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int width=300, height=100;
        BufferedImage image = createImgage(width, height);
        //ByteArrayOutputStream bao=new ByteArrayOutputStream();
        //ImageIO.write(image, Util.JPG, bao);

        Util.showImage(response, image, Util.JPG, true);
        Util.showImage(response, bao.toByteArray(), true);
        //Util.showImage(response, "d:\\aaa.png", true);
    }

    /**
     * 生成图片
     * 
     * @param width 图片宽度
     * @param height 图片高度
     * @return
     */
    private BufferedImage createImgage(int width, int height) {
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics g = image.getGraphics();
        //以下填充背景颜色
        g.setColor(Color.lightGray);
        g.fillRect(0, 0, width, height);
        //以下设置前景色
        g.setColor(Color.blue);
        g.drawString("Http://www.mashupeye.com",10,20);
        g.drawString("Author:Keiven[mashupeye@gmail.com]",10,40);
        g.drawLine(10,50,290,50);
        g.drawString("Image Show",10,70);
        g.dispose();
        return image;
    }

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Util类:

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public class Util {

    public static final String JPG = "jpg";
    public static final String PNG = "png";
    public static final String BMP = "bmp";
    public static final String GIF = "gif";

    /**
     * 在servlet中调用该方法, jsp页面中img标签的src指向该servlet, 则会显示图片
     * 
     * @param response
     * @param path
     * @param isResponseClose
     */
    public static void showImage(HttpServletResponse response,
                                 String path,
                                 boolean isResponseClose) {
        try {
            ServletOutputStream outStream = response.getOutputStream();// 得到向客户端输出二进制数据的对象
            FileInputStream fis = new FileInputStream(path); // 以byte流的方式打开文件
            // 读数据
            byte data[] = new byte[1000];
            while (fis.read(data) > 0) {
                outS