jsp页面显示二进制图片

 

1. DAO层

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

/**
 * @Title: getAlfterImgById
 * @deprecated: 根据图像id查找二进制图像
 * @param imageId
 *            图像id
 * @return byte[]
 * @throws Exception
 * @author 
 * @date 2014-11-5
 */
@Override
public Blob getAlfterImgById(String imageId) throws Exception {

	Connection conn = null;
	PreparedStatement ps = null;
	ResultSet rs = null;

	try {
		// TODO 获取java.sql.Connection
		conn = ...;
		
		// ALFTER_IMG 在数据库中的类型为 BLOB, IMAGE_ID 为主键
		String sql = "SELECT ALFTER_IMG FROM HW_IMAGE WHERE IMAGE_ID = ?";

		ps = conn.prepareStatement(sql);

		ps.setString(1, imageId);

		rs = ps.executeQuery();

		if (rs.next()) {// 根据主键查询,只会返回一个结果
			return rs.getBlob("ALFTER_IMG");
		}

	} catch (Exception e) {
		log.error("get alfterImg by imageId fail:" + e.getMessage(), e);
		throw e;
	} finally {
		// TODO close ResultSet
		// TODO close PreparedStatement
		// TODO close/release Connection
	}

	return null;
}

 

2. service 层

service方法省略，无非调用dao层方法。

 

3. controller/action 层

本例使用的是 spring 3.2.4.RELEASE，同样也适用于 Struts2、Servlet。

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import javax.servlet.http.HttpServletResponse;
import java.io.InputStream;
import java.io.OutputStream;
/**
 * @Title: displayAlfterImg
 * @deprecated: 显示分析后的二进制图片
 * @return String
 * @author 
 * @date 2014-11-5
 */
@RequestMapping("/displayAlfterImg")
public String displayAlfterImg(@RequestParam("imageId") String imageId,
		HttpServletResponse resp) {

	InputStream is = null;
	OutputStream os = null;

	try {
		// 调用service层方法
		Blob blob = hwImageService.getAlfterImgById(imageId);

		log.info("get alfterImgBy Id,the result is:" + blob);

		if (null != blob) {

			is = blob.getBinaryStream();

			resp.setContentType("image/jpeg");

			os = resp.getOutputStream();

			int num = (int) blob.length();

			byte buf[] = new byte[num];

			while ((num = is.read(buf)) != -1) {
				os.write(buf);
			}
		}

	} catch (Exception e) {
		log.error("display alfterImg fail:" + e.getMessage(), e);
	} finally {
		IOUtils.closeStream(is, os);
	}

	return null;
}

 

4. jsp

jsp上直接使用 <img>标签

<img width="333" height="249" 
	src="${ctx}/hw/image/displayAlfterImg?imageId=${reportVO.imageId }"/>