The character stream of the JPG file read from the database is converted into the relevant code for displaying the picture on the page.

public void doPost(HttpServletRequest req, HttpServletResponse res)
    throws ServletException, IOException {
    ServletOutputStream out = res.getOutputStream();
    Statement dispStmt = null, setStmt = null;
    try {
        dispStmt = Con.createStatement();
        setStmt = Con.createStatement();
        setStmt.executeUpdate("set textsize 2048000");
    } catch (Exception e) {
        out.println("Create Statement error:" + e.toString() + "<br>");
    }

    String ls_sql = null;
    ls_sql = req.getParameter("ImageSQL");
    if (ls_sql == null)
        ls_sql = "";
    ls_sql = ls_sql.trim();
    if (!ls_sql.equals("")) {
        ResultSet rs = null;
        try {
            rs = dispStmt.executeQuery(ls_sql);
        } catch (Exception e) {
            System.out.println(
                "Unable to Exec Statment" + e.toString() + "<br>");
        }
        try {
            while (rs.next()) {
                try {
                    res.setContentType("image/jpeg");
                    InputStream is = rs.getBinaryStream(1);
                    int size = is.available();
                    byte[] bzp = new byte[size];
                    is.read(bzp);
                    out.write(bzp);
                } catch (Exception e) {
                    System.out.println("Wirte image error: " + e.toString());
                }
            }
            rs.close();
        } catch (Exception e) {
            System.out.println("Unable to Close Statment" + e.toString());
        }
    }
    try {
        dispStmt.close();
    } catch (Exception e) {
        System.out.println("Close Statement Error: " + e.toString());
    }
    out.close();
}

--------------------------------------------------------------------------------

再附一个：

从库中读图片显示到页面上的主要源码
 <%@ page contentType="text/html;charset=iso8859_1"%>
<%@ page import="java.sql.ResultSet"%>
<jsp:useBean id="query" class="pub.MakeDB"/>
<%
String sql = "select * from images";
ResultSet rs = query.executeQuery(sql);
rs.next();
InputStream in = rs.getBinaryStream("image");
ServletOutputStream sos = response.getOutputStream();
int len = 0;
byte[] b = new byte[1024];
response.reset();
response.setContentType("image/gif");
while((len = in.read(b)) > 0)
sos.write(b,0,len);
in.close();
sos.close();
query.cls();
%>
如果是写到文件只要把sos
定义为DataOutputStream sos = new DataOutputStream(new BufferedOutputStream(new FileOutputStream("/a.gif")));