[转] servlet 连接池代码 (三) _链接池 servle-优快云博客

此博客展示了TestServlet类的代码，该类继承自HttpServlet。在service方法中，通过DBConnectionManager获取数据库连接，执行SQL查询语句“select * from user”，并将查询结果输出到页面。若无法获取连接则给出提示，最后释放连接资源。

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/*
* TestServlet.java
* Created on 2005-1-29
*/
package servlet;

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import db.DBConnectionManager;

/**
* @author Yewberry
*/
public class TestServlet extends HttpServlet {

private DBConnectionManager connMgr;

public void init(ServletConfig conf)
throws ServletException {
super.init(conf);
connMgr = DBConnectionManager.getInstance();
}

public void service(HttpServletRequest req,
HttpServletResponse res) throws IOException {

res.setContentType("text/html; charset=GBK");
res.setHeader("Content-Language", "zh");

  String sql = "select * from user";
PrintWriter out = res.getWriter();
Connection con = connMgr.getConnection("testDB");

if (con == null) {
  out.println("不能获取数据库连接.");
  //out.println("Can't get DB connection!");
  return;
}
ResultSet rs = null;
ResultSetMetaData md = null;
Statement stmt = null;
try {
  stmt = con.createStatement();
  rs = stmt.executeQuery(sql);
  md = rs.getMetaData();
  out.println("<H3>软件列表</H3>");
  while (rs.next()) {
   for (int i = 1; i <= md.getColumnCount(); i++) {
    out.print(rs.getString(i) + ", ");
   }
   out.println("<br>");
  }
  stmt.close();
  rs.close();
} catch (SQLException e) {
  e.printStackTrace(out);
}
connMgr.freeConnection("testDB", con);
}