📄 getusers.java
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package com.v512.guestbook;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class GetUsers extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String url = "jdbc:postgresql://localhost:5432/postgres";
String username = "postgres";
String password = "123456";
String sql = "select * from users";
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\">最近注册用户列表</a><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();
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
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>用户名</td><td>" + rs.getString("username") + "</td></tr>");
out.println("</table><br>");
}
}
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