在java中實現圖片的上傳，並且顯示圖片到頁面的功能分爲以下幾步：
1、上傳圖片代碼（此處是讀取圖片，轉換爲流，寫入數據庫中保存）
FileInputStream fis = new FileInputStream("d:/test/2.jpg");
//此處是mysql數據庫驅動
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://192.168.67.19/xkxtbeta";
//配置鏈接字符串，用戶名和密碼
Connection connection = DriverManager.getConnection(url, "root", "123");
//sql語句的生成採用參數注入的方式，且img字段的類型是BLOB類型
String sql = "insert into image (id,img) values(?,?)";
PreparedStatement statement = connection.prepareStatement(sql);
statement.setInt(1, 2);
statement.setBinaryStream(2, fis);
statement.execute();
connection.close();2、從數據庫中讀取圖片的二進制流，寫入response中，代碼如下：
@RequestMapping(value = "showimg.do", method = RequestMethod.GET)
public void showImg(HttpServletRequest request,
HttpServletResponse response, ModelMap map) throws Exception {
Integer id = Integer.valueOf(request.getParameter("id"));
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://192.168.67.19/xkxtbeta";
Connection conn = DriverManager.getConnection(url, "root", "typ");
String sql = "select img from image where id="+id;
Statement sm = conn.createStatement();
ResultSet rs = sm.executeQuery(sql);
byte[] b = null;
if (rs.next()) {
b = rs.getBytes(1);
}
OutputStream os = response.getOutputStream();
os.write(b);
conn.close();
}3、jsp頁面代碼，在jsp頁面上面輸出
此處是img的src訪問第二步定義的showimg.do即可
<!DOCTYPE html>
<html>
<head>
<script src="resources/js/jquery.js"></script>
<script type="text/javascript">
</script>
</head>
<body>
<div>
<input type="text"/>
<img src="showimg.do?id=1"></img>
<img src="showimg.do?id=2" style="width:60px;height:60px"></img>
<input type="button" value="submit" />
</div>
</body>
</html>
