Java 使用Struts 2在MySQL的JSP页面中查看图像

我有一个按钮来获取图像并将其放入MySQL数据库。在此之后，我希望图像将显示在同一页。我是Struts2的新手，现在不知道该怎么办

这是我的类

Registrazione.java

：

public String visualizzaimg() throws SQLException, IOException {
    Connessione();    // DB connection method
    PreparedStatement pstmt = con.prepareStatement("SELECT Immagine FROM Utenti WHERE Username = ?");
    pstmt.setString(1,username);
    ResultSet rs = pstmt.executeQuery();
    while(rs.next()){
    fin = rs.getBinaryStream("Immagine");
    byte[] b = new byte[fin.available()];
    fin.read(b);
    }
    return "success";
}

这是我的

struts.xml

文件：

<action name="visualizzaimg" class="Model.Registrazione" method="visualizzaimg">
<result name="success" type="stream">
        <param name="contentType">image/jpeg</param>
        <param name="inputName">fin</param>
        <param name="contentDisposition">attachment;filename=${fileName}</param> /* Not sure if i've understood what i have to put here.. */
        <param name="bufferSize">1024</param>
    </result>
</action>

---

关键是将url写入

标记。url应该映射一个将流数据传输到响应的操作

现在配置结果

private InputStream inputStream;

public ImputStream getInputStream(){
  return inputStream;
}

public String visualizzaimg() throws SQLException, IOException {
    Connessione();    // DB connection method
    PreparedStatement pstmt = con.prepareStatement("SELECT Immagine FROM Utenti WHERE Username = ?");
    pstmt.setString(1,username);
    ResultSet rs = pstmt.executeQuery();
    if(rs.next()){
      inputStream = rs.getBinaryStream(1);
    }
    return "success";
}

图像/jpeg

它确实有效！！但你能解释一下吗？为什么要将1放入getBinaryStream<代码>输入流=rs.getBinaryStream（1）因为方法使用类型为

int

的列索引参数。。。。您可以在页面上找到参数a从1开始计数。好的，谢谢。是否可以在同一个jsp页面中查看图像？因为当我点击“VisualizeZa”按钮时，它会打开另一个名为“VisualizeZaimg.action”的操作，该操作带有图像，它应该是另一个在结果中返回JSP的操作。

<img src="<s:url action='visualizzaimg'/>">  

private InputStream inputStream;

public ImputStream getInputStream(){
  return inputStream;
}

public String visualizzaimg() throws SQLException, IOException {
    Connessione();    // DB connection method
    PreparedStatement pstmt = con.prepareStatement("SELECT Immagine FROM Utenti WHERE Username = ?");
    pstmt.setString(1,username);
    ResultSet rs = pstmt.executeQuery();
    if(rs.next()){
      inputStream = rs.getBinaryStream(1);
    }
    return "success";
}

<result name="success" type="stream">
   <param name="contentType">image/jpeg</param>
</result>