dbutils开源项目用法
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[size=large]
dbutils 开源项目用法：
项目地址：http://commons.apache.org/dbutils/
最新版本为 1.1
英文文档中这样写到：
DbUtils is a very small library of classes so it won't take long to go throughthe javadocs for each class.
The core classes/interfaces in DbUtils are QueryRunner and ResultSetHandler.
You don't need to know about any other DbUtils classes to benefit from usingthe library.
大概意思是： DbUtils 是一个非常小的类库因此你不需要花费太长的时间去研究javadocs
它的核心接口是 QueryRunner 和ResultSetHandler
你不需要关心其他DbUtils的类如何使用
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QueryRunner
构造 QueryRunner ：
QueryRunner()
QueryRunner(javax.sql.DataSource ds)
有两种方法来构造QueryRunner 一种是无参数的一种是有DataSource类型参数的构造方法这里使用DataSource来构造它使用连接池来构造它的好处就是我们无需管Connection对象的创建与关闭了后面调用QueryRunner对象的方法也无需传入Connection对象了那我们就要用到另外一个开源数据库连接池组件dbcp以下为dbcp的用法：
Java代码
public class DBUtils {
private static Properties properties;
private static DataSource dataSource;
private static Connection conn;
static {
try {
properties = new Properties();
//载入dbcp的配置文件
properties.load(DBUtils.class..getResourceAsStream("/dbcpconfig.properties"));
//创建个BasicDataSourceFactory对象用于创建连接池对象
BasicDataSourceFactory b = new BasicDataSourceFactory();
//把properties对象设置给BasicDataSourceFactory
dataSource = b.createDataSource(properties);
} catch (Exception e) {
e.printStackTrace();
}
}
public static DataSource getdataSource() {
return dataSource;
}
}
public class DBUtils {
private static Properties properties;
private static DataSource dataSource;
private static Connection conn;
static {
try {
properties = new Properties();
//载入dbcp的配置文件
properties.load(DBUtils.class..getResourceAsStream("/dbcpconfig.properties"));
//创建个BasicDataSourceFactory对象用于创建连接池对象
BasicDataSourceFactory b = new BasicDataSourceFactory();
//把properties对象设置给BasicDataSourceFactory
dataSource = b.createDataSource(properties);
} catch (Exception e) {
e.printStackTrace();
}
}
public static DataSource getdataSource() {
return dataSource;
}
}
注意：需要导入dbcp连接池的jarcommons-dbcp-1.2.1.jar 和所依赖的commons-pool-1.2.jar
commons-collections-3.1.jar
Java代码
//这样我们就可以构造个queryRunner对象了
QueryRunner queryRunner = new QueryRunner(DBUtils.getdataSource());
//这样我们就可以构造个queryRunner对象了
QueryRunner queryRunner = new QueryRunner(DBUtils.getdataSource());
QueryRunner 主要方法：
Java代码
//更新一列
queryRunner.update("update Users set username=?,password=? where id = ?", new String[]{"11","22","1"});
//删除一列
queryRunner.update("delete from Users where id =?", 1);
//更新一列
queryRunner.update("update Users setusername=?,password=? where id = ?", newString[]{"11","22","1"});
//删除一列
queryRunner.update("delete from Users where id =?", 1);
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如果要使用 QueryRunner的查询方法也就是query()方法的话那么就需要有对象来接收查询出来的ResultSet
用什么来接收呢？要用到实现ResultSetHandler接口的类
1. BeanHandler 返回个entitybean对象
Java代码
//指定返回哪个 entitybean
ResultSetHandler rsh = new BeanHandler(Users.class);
QueryRunner queryRunner = new QueryRunner(DBUtils.getdataSource());
Users users = (Users) queryRunner.query("select * from Users where id=?",2, rsh);
System.out.println(users.getUsername());
//指定返回哪个 entitybean
ResultSetHandler rsh = new BeanHandler(Users.class);
QueryRunner queryRunner = new QueryRunner(DBUtils.getdataSource());
Users users = (Users) queryRunner.query("select * from Userswhere id=?",2, rsh);
System.out.println(users.getUsername());
--------------------------------------------------------------------------------------------------------------
2. BeanListHandler 返回个List List里装的是entitybean对象
Java代码
QueryRunner queryRunner = new QueryRunner(DBUtils.getdataSource());
ResultSetHandler rsh = new BeanListHandler(Users.class);
List<Users> list = (List) queryRunner.query(
"select * from Users ", rsh);
for(Users user:list){
System.out.println(user.getUsername());
}
QueryRunner queryRunner = new QueryRunner(DBUtils.getdataSource());
ResultSetHandler rsh = new BeanListHandler(Users.class);
List<Users> list = (List) queryRunner.query(
"select * from Users ", rsh);
for(Users user:list){
System.out.println(user.getUsername());
}
--------------------------------------------------------------------------------------------------------------
3. ArrayListHandler 返回List 对象 list里装的为Object数组
Java代码
QueryRunner queryRunner = new QueryRunner(DBUtils.getdataSource());
// 使用ArrayListHandler 实现类来存放结果会返回ArrayList对象
ResultSetHandler rsh = new ArrayListHandler();
//list里装的是对象数组
List<Object[]> list = (List) queryRunner.query(
"select * from Users ", rsh);
for(Object[] user:list) {
for(Object obj:user)
{
System.out.println(obj);
}
}
QueryRunner queryRunner = new QueryRunner(DBUtils.getdataSource());
// 使用ArrayListHandler 实现类来存放结果会返回ArrayList对象
ResultSetHandler rsh = new ArrayListHandler();
//list里装的是对象数组
List<Object[]> list = (List) queryRunner.query(
"select * from Users ", rsh);
for(Object[] user:list) {
for(Object obj:user)
{
System.out.println(obj);
}
}
-------------------------------------------------------------------------------------------------------------
4. ColumnListHandler 返回List 对象
注意: 构造ColumnListHandler() 对象时候如果是无参数的话
像这样 ResultSetHandler rsh= new ColumnListHandler();
查询出来的List 里放的类型为主键的类型值为主键的值;
Java代码
ResultSetHandler rsh = new ColumnListHandler();
List<Integer> list = (List) queryRunner.query( "select * from Users ", rsh);
//System.out.println(list.get(0).getClass().getSimpleName());
for(Integer in:list){
System.out.println(in);
}
ResultSetHandler rsh = new ColumnListHandler();
List<Integer> list = (List) queryRunner.query("select *from Users ", rsh);
//System.out.println(list.get(0).getClass().getSimpleName());
for(Integer in:list){
System.out.println(in);
}
构造 ColumnListHandler() 对象时候如果是有参数的话像这样 ResultSetHandler rsh = newColumnListHandler(主键值); 那么查询出来的List 里放的是就是这个主键对应的一行的记录; Java代码
ResultSetHandler rsh = new ColumnListHandler(2);
List<String> list = (List) queryRunner.query(
"select * from Users ", rsh);
for(String in:list){
System.out.println(in);
}
ResultSetHandler rsh = new ColumnListHandler(2);
List<String> list = (List) queryRunner.query("select *from Users ", rsh);
for(String in:list){
System.out.println(in);
}
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5. KeyedHandler 根据键返回Map
Java代码
ResultSetHandler rsh = new KeyedHandler();
//map里装的key为主键的值 value 为主键对应的那行记录名称和记录
Map map = (Map) queryRunner.query("select id,username,password from Users ", rsh);
//根据主键值出去那一列
// Map t = (Map) map.get(2);
System.out.println(map.get(2));
ResultSetHandler rsh = new KeyedHandler();
//map里装的key为主键的值 value 为主键对应的那行记录名称和记录
Map map = (Map)queryRunner.query("select id,username,password from Users ", rsh);
//根据主键值出去那一列
// Map t = (Map) map.get(2);
System.out.println(map.get(2));
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6. MapHandler 根据键返回Map
Java代码
QueryRunner queryRunner = new QueryRunner(DBUtils.getdataSource());
ResultSetHandler rsh = new MapHandler();
Map map = (Map) queryRunner.query("select * from Users ", rsh); System.out.println(map);
QueryRunner queryRunner = newQueryRunner(DBUtils.getdataSource());
ResultSetHandler rsh = new MapHandler();
Map map = (Map) queryRunner.query(
"select * from Users ", rsh);
System.out.println(map);
---------------------------------------------------------------------------------------------------------------
7. ScalarHandler 根据键返回第一行记录
Java代码
QueryRunner queryRunner = new QueryRunner(DBUtils.getdataSource());
// 这样就会返回第一行记录名字为username的值
ResultSetHandler rsh = new ScalarHandler("username");
//这的类型根据表里数据的类型而定如果上面
ResultSetHandler rsh = new ScalarHandler("username");
//取出来的类型为int的话那么这里也必须由int 来接收
String result = (String) queryRunner.query("select * from Users where id=99 ", rsh);
System.out.println(result);