Dbutils详解

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Common Dbutils是操作数据库的组件，对传统操作数据库的类进行二次封装，可以把结果集转化成List。

DBUtils包括3个包：
org.apache.commons.dbutils
org.apache.commons.dbutils.handlers
org.apache.commons.dbutils.wrappers
DBUtils封装了对JDBC的操作，简化了JDBC操作，可以少写代码。

org.apache.commons.dbutils
DbUtils 关闭链接等操作
QueryRunner 进行查询的操作

org.apache.commons.dbutils.handlers
ArrayHandler ：将ResultSet中第一行的数据转化成对象数组
ArrayListHandler将ResultSet中所有的数据转化成List，List中存放的是Object[]
BeanHandler ：将ResultSet中第一行的数据转化成类对象
BeanListHandler ：将ResultSet中所有的数据转化成List，List中存放的是类对象
ColumnListHandler ：将ResultSet中某一列的数据存成List，List中存放的是Object对象
KeyedHandler ：将ResultSet中存成映射，key为某一列对应为Map。Map中存放的是数据
MapHandler ：将ResultSet中第一行的数据存成Map映射
MapListHandler ：将ResultSet中所有的数据存成List。List中存放的是Map
ScalarHandler ：将ResultSet中一条记录的其中某一列的数据存成Object

org.apache.commons.dbutils.wrappers
SqlNullCheckedResultSet ：对ResultSet进行操作，改版里面的值
StringTrimmedResultSet ：去除ResultSet中中字段的左右空格。Trim()

主要方法：

DbUtils类：启动类

ResultSetHandler接口：转换类型接口

MapListHandler类：实现类，把记录转化成List

BeanListHandler类：实现类，把记录转化成List，使记录为JavaBean类型的对象

Qrery Runner类：执行SQL语句的类

建立三个Java文件

命名为BeanListExample.java

Guestbook.java

MapListExample.java

源码：

BeanListExample.java

Code
package com.sy;

import org.apache.commons.dbutils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.List;

public class BeanListExample {
    public static void main(String[] args) {
        Connection conn = null;
        String url = "jdbc:mysql://localhost:3306/people";
        String jdbcDriver = "com.mysql.jdbc.Driver";
        String user = "root";
        String password = "hicc";

        DbUtils.loadDriver(jdbcDriver);
        try {
            conn = DriverManager.getConnection(url, user, password);
            QueryRunner qr = new QueryRunner();
            List results = (List) qr.query(conn, "select id,name from guestbook", new BeanListHandler(Guestbook.class));
            for (int i = 0; i < results.size(); i++) {
                Guestbook gb = (Guestbook) results.get(i);
                System.out.println("id:" + gb.getId() + ",name:" + gb.getName());
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DbUtils.closeQuietly(conn);
        }
    }
}

Guestbook.java

Code
package com.sy;

public class Guestbook {
    private Integer id;
    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

MapListExample.java

Code
package com.sy;

import org.apache.commons.dbutils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.MapListHandler;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

import java.util.List;
import java.util.Map;

public class MapListExample {
    public static void main(String[] args) {
        Connection conn = null;
        String url = "jdbc:mysql://localhost:3306/people";
        String jdbcDriver = "com.mysql.jdbc.Driver";
        String user = "root";
        String password = "hicc";

        DbUtils.loadDriver(jdbcDriver);
        try {
            conn = DriverManager.getConnection(url, user, password);
            QueryRunner qr = new QueryRunner();
            List results = (List) qr.query(conn, "select id,name from guestmessage", new MapListHandler());
            for (int i = 0; i < results.size(); i++) {
                Map map = (Map) results.get(i);
                System.out.println("id:" + map.get("id") + ",name:" + map.get("name"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DbUtils.closeQuietly(conn);
        }
    }
}

使用组建好需要添加commons-dbutils-1.1.jar和mysql-connector-java-5.1.6-bin.jar两个jar包。

配置完毕！！！

//另一种方法
//使用dbutils1.0版本

import java.util.*;
import java.util.logging.*;
import java.sql.*;
import org.apache.commons.dbutils.*;
import org.apache.commons.dbutils.handlers.*;

public class TestDBUnits {

public static void main(String[]args) throws Exception {
  TestDBUnits test = new TestDBUnits();

  for(int i = 0 ; i < 1 ; i++) {
   test.testQuery1();
   test.testQuery2();
   test.testUpdate();
  }
}

public void testQuery1(){
  try {
   QueryRunner qr = new QueryRunner() ;
   ResultSetHandler rsh = new ArrayListHandler();
   String strsql = "select * from test1";
   ArrayList result = (ArrayList)qr.query(getConnection() ,strsql ,rsh);
   //System.out.print("");
  } catch(Exception ex) {
   ex.printStackTrace(System.out);
  }
}

public void testQuery2(){
  try {
   QueryRunner qr = new QueryRunner() ;
   ResultSetHandler rsh = new MapListHandler();
   String strsql = "select * from test1";
   ArrayList result = (ArrayList)qr.query(getConnection() ,strsql ,rsh);
   for(int i = 0 ; i < result.size() ; i++) {
    Map map = (Map)result.get(i);
    //System.out.println(map);
   }
   //System.out.print("");
  } catch(Exception ex) {
   ex.printStackTrace(System.out);
  }
}

public void testUpdate(){
  try {
   QueryRunner qr = new QueryRunner() ;
   ResultSetHandler rsh = new ArrayListHandler();
   String strsql = "insert test1(page ,writable ,content)values('ttt','ttt','faskldfjklasdjklfjasdklj')";
   qr.update(getConnection() ,strsql);
   //System.out.print("");
  } catch(Exception ex) {
   ex.printStackTrace(System.out);
  }
}

private  Connection getConnection() throws InstantiationException,
   IllegalAccessException, ClassNotFoundException, SQLException {

  String strDriver = "org.gjt.mm.mysql.Driver";
  String strUrl = "jdbc:mysql://localhost:3306/test";
  String strUser = "root";
  String strPass = "";

  Class.forName(strDriver).newInstance();
  return DriverManager.getConnection(strUrl, strUser, strPass);
}
}