DBUtils的综合应用--DBUtils连接池管理工具对连接池的管理

1.首先在Tomcat的conf/context.xml中作如下配置。
<Resource name="jdbc/mysqlds"
   auth="Container"
   type="javax.sql.DataSource"
   maxActive="100"
   maxIdle="30"
   maxWait="10000"
   username="root"
   password="jakeyouxiang"
   driverClassName="com.mysql.jdbc.Driver"
   url="jdbc:mysql://127.0.0.1/blog"/>
</Context>
2.在配置中引入mysql-connector-java-5.1.11-bin.jar和commons-dbutils-1.3.jar
3.创建一个得到连接的类DBHelper.java
package com.jxau;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;
import org.apache.commons.dbutils.QueryRunner;
public class DBHelper {
 public static QueryRunner getQueryRunner(){
  DataSource ds=null;
  try{
   Context context=new InitialContext();
   ds=(DataSource)context.lookup("java:/comp/env/jdbc/mysqlds");
  }catch(Exception e){
   e.printStackTrace();
   System.out.println("加载数据库出错！！！");
  }
  QueryRunner qr=new QueryRunner(ds);
  return qr;
 }
}

4.在应用程序中调用DBHelper.java来操作数据库，如：
package com.jxau;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.dbutils.QueryRunner;
import com.jxau.*;
public class CateGoryServlet extends HttpServlet {
 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  response.setContentType("text/html");
  request.setCharacterEncoding("UTF-8");
  
  String method=request.getParameter("method");
  
  
  if(method.equals("add")){
   this.add(request, response);
  }else if(method.equals("delete")){
   this.delete(request,response);
  }
  
 }
 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  this.doGet(request, response);
 }
 
 public void delete(HttpServletRequest request,HttpServletResponse response)
   throws ServletException,IOException{
  
 }
 
 public void add(HttpServletRequest request,HttpServletResponse response)
   throws ServletException,IOException{
  response.setCharacterEncoding("UTF-8");
  String name=request.getParameter("name");
  String level=request.getParameter("level");
  String sql="insert into category(name,level) values(?,?)";
  String params[]={name,level};
  
  QueryRunner qr=DBHelper.getQueryRunner();
  
  int result=0;
  String message="";
  try {
   result=qr.update(sql, params);
  } catch (SQLException e) {
   e.printStackTrace();
  }
  
  if(result==1){
   message="博客添加分类成功";
  }else{
   message="博客添加分类失败";
  }
  
  request.setAttribute("message", message);
  request.getRequestDispatcher("/add.jsp").forward(request, response);
 }
}
 
5.查询的时候一般用以下的方式，它更体现了面向对象的思想。
List<Blog> list=(List<Blog>)qr.query(sql, new BeanListHandler(Blog.class));
   Blog blog=(Blog)list.get(0);