📄 getmessagesservlet.java
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package com.v512.guestbook;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class GetMessagesServlet extends HttpServlet {
private static final long serialVersionUID = 5964428201228635704L;
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String url = "jdbc:postgresql://localhost:5432/postgres";
String username = "postgres";
String password = "123456";
String sql = "select * from guestbook order by id desc";
Connection conn = null;
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head><title>display messages</title></head>");
out.println("<body>");
out.println("<a href=\"" + request.getContextPath() + "/addMessage.htm\">添加新的留言内容</a><br>");
out.println("留言内容<br><br>");
try {
Class.forName("org.postgresql.Driver");
conn = DriverManager.getConnection(url, username, password);
PreparedStatement pstmt = conn.prepareStatement(sql);
ResultSet rs = pstmt.executeQuery();
while (rs.next()) {
this.printRow(out, rs);
}
rs.close();
pstmt.close();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
out.println(" </body>");
out.println("</html>");
out.flush();
out.close();
}
private void printRow(PrintWriter out, ResultSet rs) throws SQLException {
out.println("<table width=\"600\" border=\"1\" style=\"table-layout:fixed;word-break:break-all\">");
out.println("<tr><td width=\"50\">编号</td>");
out.println("<td width=\"550\">" + rs.getInt("id") + "</td></tr>");
out.println("<tr><td>姓名</td><td>" + rs.getString("name") + "</td></tr>");
out.println("<tr><td>电话</td><td>" + StringUtil.chanageNull(rs.getString("phone"), "没填") + "</td></tr>");
out.println("<tr><td>email</td><td>" + StringUtil.chanageNull(rs.getString("email"), "没填") + "</td></tr>");
out.println("<tr><td valign=\"top\">主题</td><td>" + rs.getString("title") + " </td></tr>");
out.println("<tr><td valign=\"top\">内容</td>");
out.println("<td>" + StringUtil.chanageNull(rs.getString("content"), "没填") + "</td></tr>");
out.println("<tr><td>时间</td><td>" + rs.getString("time") + " </td></tr>");
out.println("</table><br>");
}
}
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