数据库连接池工具---DbUtils

package cn.hncu.c3p0;

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

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

//我们的这个包装，只是为了把c3p0池做成让每个线程(客户端)获得的是同一个连接，方便做b/s框架下的事务
public class C3p0Pool {
private static DataSource pool;
private static ThreadLocal<Connection> t=new ThreadLocal<Connection>();
static {
pool=new ComboPooledDataSource();
}

public static DataSource getDataSource(){
return pool;
}

public static Connection getConnection() throws SQLException{
Connection con=t.get();
if (con==null){
con=pool.getConnection();
t.set(con);
}
return con;
}
}

package cn.hncu.dbutils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ext.ExtQueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.junit.Test;

import cn.hncu.c3p0.C3p0Pool;

public class DbutilsDemo {
@Test//原来不使用dbUtils工具的数据库查询代码实现
public void jdbcQuery() throws Exception{
List<Stud> list=new ArrayList<Stud>();
Connection con=C3p0Pool.getConnection();
String sql="select * from stud";
Statement st=con.createStatement();
ResultSet rs=st.executeQuery(sql);
while (rs.next()){
Stud stud=new Stud();
stud.setId(rs.getString("id"));
stud.setName(rs.getString("name"));
stud.setAge(rs.getInt("age"));
list.add(stud);
}
System.out.println(list);
}

@Test//使用dbUtils工具的数据库查询代码实现
public void dbutilsQuery() throws Exception{
QueryRunner run=new QueryRunner(C3p0Pool.getDataSource());
String sql="select * from stud";
List<Stud> stud=run.query(sql, new BeanListHandler<Stud>(Stud.class));
System.out.println(stud);
}
@Test
public void dbutilsQuery2() throws Exception{
QueryRunner run=new QueryRunner(C3p0Pool.getDataSource());
String sql="select * from stud";
List<Map<String, Object>> stud=run.query(sql, new MapListHandler());
System.out.println(stud);
}

////DbUtils工具的使用演示: 增删改--用update(),  查--用query()方法
/*
CREATE TABLE person(
id VARCHAR(30) PRIMARY KEY,
NAME VARCHAR(30),
address VARCHAR(30),
age INT
);
*/
@Test
public void save() throws Exception{
QueryRunner run=new QueryRunner(C3p0Pool.getDataSource());
//Statement方式
//run.update("insert into dbutilsperson(id,name,address,age) values('A001','Jack','湖南长沙',22)");
//PrepareStatement方式
run.update("insert into dbutilsperson(id,name,address,age) values(?,?,?,?)", "A002","Tom","中国西安",24);//如果参数个数或类型 与 “?”号不匹配，会出异常
}
@Test
public void saveTx() throws Exception{
QueryRunner run=new QueryRunner(C3p0Pool.getDataSource());
Connection con=C3p0Pool.getConnection();
try {
con.setAutoCommit(false);
//※注意，实现事务功能时，要传入con对象，且多条语句共处一个事务时，要传入同一个con对象。但如果不实现事务功能，可以不传入con对象
run.update(con, "insert into dbutilsperson(id,name,address,age) values(?,?,?,?)","A003","Tom","浙江杭州",24);
run.update(con, "insert into dbutilsperson(id,name,address,age) values(?,?,?,?)","A003","Tom","浙江杭州",24);
} catch (Exception e) {
con.rollback();
System.out.println("事务回滚了");
} finally {
con.setAutoCommit(true);
con.close();
}
}

//下面演示一下查询的结果集封装功能
@Test//封装成BeanList
public void query1() throws Exception{
QueryRunner run=new QueryRunner(C3p0Pool.getDataSource());
//封装成BeanList: 如果值对象中的属性名和表中的字段名不一致，那么该属性的值返回的是null----解决:采用别名，但是最好不要这样做，在取名字的时候我们就应该要两边保持一致，不要这样子自己坑自己
//List<Person> persons=run.query("select * from dbutilsperson", new BeanListHandler<Person>(Person.class));//没有采用别名，addr属性为null
List<Person> persons=run.query("select id,name,address addr,age from dbutilsperson", new BeanListHandler<Person>(Person.class));//用属性名 当  字段别名

//如果你一定要像下面这句一样不加别名的话就把Person类中的getAddr和setAddr改为getAddress和setAddress，因为QueryRunner的Query方法
//的类反射是根据数据库字段名来调用getter和setter方法的
//List<Person> persons=run.query("select id,name,address,age from dbutilsperson", new BeanListHandler<Person>(Person.class));
System.out.println(persons);
}
@Test//封装成MapList
public void query2() throws SQLException{
QueryRunner run=new QueryRunner(C3p0Pool.getDataSource());
String sql="select * from dbutilsperson";
List<Map<String, Object>> persons=run.query(sql, new MapListHandler());
System.out.println(persons);
}
@Test//封装成BeanList---查询带参数
public void query3() throws SQLException{
QueryRunner run=new QueryRunner(C3p0Pool.getDataSource());
String sql="select id,name,address addr,age from dbutilsperson where name like ? and age>?";
List<Person> persons=run.query(sql, new BeanListHandler<Person>(Person.class), "%a%", 20);//用属性名 当  字段别名
System.out.println(persons);
}

@Test//演示批处理功能
public void batch() throws SQLException{
QueryRunner run=new QueryRunner(C3p0Pool.getDataSource());
for (int i=1;i<=100;i++){
String sql="insert into dbutilsstud(id,name) values(?,?)";
String str="000"+i;
str=str.substring(str.length()-3, str.length());
String id1="A"+str;
String id2="B"+str;
String params[][]={{id1,"Jack"+i},{id2,"Rose"+i}};
run.batch(sql, params);
}
}

////////以下演示扩展包commons-dbutilss-ext.jar的功能//////////////
//注意，下面的用法要生效，必须给值对象添加注解
@Test//封装成BeanList---直接通过JavaBean的字节码查询
public void query4(){
ExtQueryRunner run=new ExtQueryRunner(C3p0Pool.getDataSource());
List<Person> persons=run.query(Person.class);
System.out.println(persons);
}

@Test//封装成BeanList---直接通过JavaBean的字节码查询
public void save3(){
ExtQueryRunner run=new ExtQueryRunner(C3p0Pool.getDataSource());
Stud stud=new Stud();
stud.setId("A06");
stud.setName("Jenney");
run.save(stud);
System.out.println(stud);
}
}

package cn.hncu.dbutils;

import org.apache.commons.dbutils.ext.Table;

@Table(value = "dbutilsperson")
public class Person {
private String id;
private String name;

//@Column(value="address")//该注解无效，反正以后开发时属性名都取成和数据库表字段名一样
//如果你一定要把这里设的和数据库里面的字段名不一样，那么请把这里的getter和setter方法后的名字设置成和数据库字段名一样的，
//这样照样能设置，因为这个扩展包里面的类反射获取getter和setter方法是根据数据库里面的字段名来设置的，我这里就设置成了和数据         //库字段名一样的，你们可以试试改成和本类的属性名一样的试试，一定无法取到值的
private String addr;

private int age;

public Person() {
super();
}

public String getId() {
return id;
}

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

public String getName() {
return name;
}

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

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public String getAddress() {
return addr;
}

public void setAddress(String addr) {
this.addr = addr;
}

@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.hashCode());
return result;
}

@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Person other = (Person) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}

@Override
public String toString() {
return id + ", " + name + ", " + addr + ", " + age;
}
}

package cn.hncu.dbutils;

import org.apache.commons.dbutils.ext.Column;
import org.apache.commons.dbutils.ext.Table;

@Table(value="dbutilsstud")
public class Stud {
@Column
private String id;
@Column
private String name;
private int age;

public Stud() {
super();
}

public String getId() {
return id;
}

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

public String getName() {
return name;
}

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

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.hashCode());
return result;
}

@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Stud other = (Stud) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}

@Override
public String toString() {
return id + ", " + name + ", "+age;
}
}