一、DBCP:Apache推出的 DataBase Connection Pool
使用步骤：1>复制jar文件到工程目录下 commons-dbcp-1.4.jar
2>添加属性资源文件dbconfig.properties
3>编写数据源，对DBCP进行封装
public class DBCPUtils {
//dbcp内部有一个数据源
//数据源又被成为连接池
private static DataSource dataSource = null;
static{
Properties properties = new Properties();
try {
//静态代码块，类加载器classloader它加载类文件时，就会运行类的静态代码块
//利用类加载器，将加载一个资源文件dbcpconfig.properties文
//把资源文件的键值放入到properties中
properties.load(DBCPUtils.class.getClassLoader().getResourceAsStream("dbcpconfig.properties"));
//使用工厂创建一个数据源
dataSource = BasicDataSourceFactory.createDataSource(properties);
} catch (Exception e) {
e.printStackTrace();
}
}
//连接方法
public static Connection getConnection(){
try {
return dataSource.getConnection();
} catch (SQLException e) {
throw new RuntimeException("服务器繁忙，请稍后再试");
}
}
//关流
public static void closeAll(PreparedStatement ps,Connection conn) {
if(ps!=null) {
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(conn!=null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
//关流
public static void closeAll(ResultSet rs,PreparedStatement ps,Connection conn) {
if(rs!=null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(ps!=null) {
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(conn!=null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
//测试类
public class Test {
public static void main(String[] args) {
Connection conn = null;
conn = DBCPUtils.getConnection();
PreparedStatement ps = null;
ResultSet rs=null;
String sql="select * from tb_user where id =?";
try {
ps= conn.prepareStatement(sql);
ps.setInt(1, 1);
rs=ps.executeQuery();
if(rs.next()){
System.out.println(rs.getString("username"));
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
DBCPUtils.closeAll(rs, ps, conn);
}
}
}
二、C3P0：源于开元社区
区别：配置文件类型不一样
dbcp:properties
c3p0:xml
//对C3P0进行封装
public class C3P0Utils {
//连接池对象
private static DataSource dataSource = new ComboPooledDataSource();
//不用写静态代码块
public static Connection getConnection(){
try {
return dataSource.getConnection();
} catch (SQLException e) {
throw new RuntimeException("服务器繁忙，请稍后再试");
}
}
//封装一个访问内部连接池的方法，为后期使用dbutils时方便使用
public static DataSource getDataSource(){
return dataSource;
}
public static void closeAll(PreparedStatement ps,Connection conn) {
if(ps!=null) {
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(conn!=null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
public static void closeAll(ResultSet rs,PreparedStatement ps,Connection conn) {
if(rs!=null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
closeAll(ps,conn);
}
}
//测试类
public class Test {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs=null;
//获取数据源
conn = C3P0Utils.getConnection();
String sql="select * from tb_user where id =?";
try {
ps= conn.prepareStatement(sql);
ps.setInt(1, 1);
rs=ps.executeQuery();
if(rs.next()){
System.out.println(rs.getString("username"));
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
C3P0Utils.closeAll(rs, ps, conn);
}
}
}
三、DBUtils数据库操作工具集
DBUtils也是Apache出品，用于操作数据库的增删查改
一般来说DBUtils要配合一款数据库连接池使用，使用c3p0做叙述
1>运行sql语句需要用到QueryRunner对象
2>方法中有query方法和update方法
3>查询结果用ResultSetBandler来实现
这里的C3P0使用二中的C3P0Utils
//测试类DBUtils
public class TestDBUtils {
public static void main(String[] args) throws Exception {
test();
}
public static void test() throws Exception{
//创建dbutils例子
//创建queryrunner对象，参数是一个数据源
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql="select * from user";
//1
//queryrunner的query方法的第二个参数resultsethander对象需要一个泛型
//这个泛型就是resultsethander返回值得类型
//resultsethander的handle方法的返回值会交给queryrunner的query方法，作为返回值返回
/*String result = qr.query(sql,new ResultSetHandler<String>(){
@Override
public String handle(ResultSet rs) throws SQLException {
if(rs.next()){
return rs.getString("password");
}else{
return null;
}
}
});
System.out.println(result);*/
//2
//User user =qr.query(sql, new UserResultSetHandle());
//System.out.println(user);
//3
//User user = qr.query(sql,new BeanResultSetHandle<User>(User.class));
//System.out.println(user);
//4
Map<String,Object> map = qr.query(sql, new MapHander());
System.out.println(map);
}
static class UserResultSetHandle implements ResultSetHandler<User>{
@Override
public User handle(ResultSet rs) throws SQLException {
if(rs.next()){
User user = new User();
user.setId(rs.getInt("id"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
return user;
}
return null;
}
}
static class BeanResultSetHandle<T> implements ResultSetHandler<T>{
private Class<T> clazz = null;
public BeanResultSetHandle(Class<T> clazz){
this.clazz = clazz;
}
@Override
public T handle(ResultSet rs) throws SQLException {
try {
if(rs.next()){
T object = clazz.newInstance();
Field [] fields =clazz.getDeclaredFields();
for (int i = 0; i < fields.length; i++) {
fields[i].setAccessible(true);
fields[i].set(object, rs.getObject(fields[i].getName()));
}
return object;
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
static class MapHander implements ResultSetHandler<Map<String,Object>> {
@Override
public Map<String, Object> handle(ResultSet rs) throws SQLException {
if(rs.next()){
Map<String,Object> map =new HashMap<String,Object>();
for (int i = 0; i < rs.getMetaData().getColumnCount(); i++) {
String key= rs.getMetaData().getColumnName(i+1);
Object value =rs.getObject(i+1);
map.put(key, value);
}
return map;
}
return null;
}
}
}
将要查询的数据进行封装，不再一一实现
public class TestResultSetHander {
//1、Arrayhander,适合取一条记录
public static void test1() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql= "select id,username,password from user where id=? and username=?";
Object [] arr=qr.query(sql, new ArrayHandler(), 2,"李四");
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i]+",");
}
}
//2、ArrayListHander，适合取出多条记录
//每一条记录都是Object[],再将Object存入list中
public static void test2() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql="select * from user";
List<Object[]> list =qr.query(sql, new ArrayListHandler());
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
for (int j = 0; j < list.get(i).length; j++) {
System.out.print(list.get(i)[j]+",");
}
System.out.println();
}
}
//3、columnListHander取一列数据
public static void test3() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql="select * from user";
//ColumnListHander构造方法可以传入一个int值，如果不传入，默认是1
//这个值表示的是结果集列的序号，列的序号从1开始，
List<Object> list = qr.query(sql, new ColumnListHandler(2));
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
}
//4、MapHander取一条记录，将记录放入Map集合中
public static void test4() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql= "select * from user where id =? ";
Map<String, Object> map =qr.query(sql, new MapHandler(),2);
System.out.println(map);
for (Map.Entry<String,Object> m: map.entrySet()) {
System.out.println(m.getKey()+"--"+m.getValue());
}
}
//5、keyedhander
//取出一个查询集合，返回一个map的map，每一条记录封装到map中，每一字段又在map里面的map中
//Map<Object,Map<String,Object>>
public static void test5() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql= "select * from user";
Map<Object,Map<String,Object>> map =qr.query(sql, new KeyedHandler(3));
for (Map.Entry<Object,Map<String,Object>> m: map.entrySet()) {
System.out.print(m.getKey()+":");
for(Map.Entry<String, Object> mm:m.getValue().entrySet()){
System.out.print(mm.getKey()+":"+mm.getValue());
}
System.out.println();
System.out.println("-----");
}
}
//6、MapListHandler
//List<Map<String,Object>>
//每一行都是一个Map,再讲Map放入List中
public static void test6() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql= "select * from user";
List<Map<String,Object>> list =qr.query(sql, new MapListHandler());
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
for(Map.Entry<String,Object> m :list.get(i).entrySet()){
System.out.println(m.getKey()+"--"+m.getValue());
}
System.out.println("------");
}
}
//7、scalarhandler取单行单列，***加强记忆
//比如：比如说求count()*
public static void test7() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
//String sql = "select count(*),count(*)+1,count(*)+2,count(*)+3,count(*)+4 from user ";
String sql = "select count(*) from user";
Object object =qr.query(sql, new ScalarHandler());
//******当查询count()的时候，返回的是一个long型
//当转为integer和int时会报classcastexception
//拿到的object，只能换成long
//Long转为long为拆箱
//long转为int为基本数据的类型转换,造成精度损失
//Long转为Integer类转化异常
System.out.println(object);
}
//8、beanhander
public static void test8() throws SQLException{
QueryRunner qr = new QueryRunner();
String sql = "select * from user where id = ?";
User user = qr.query(sql, new BeanHandler<User>(User.class),3);
System.out.println(user);
}
public static void main(String[] args) throws SQLException {
test1();
}
//增删改
public static void testInsert() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql = "insert into user values(?,?,?)";
int rs =qr.update(sql,4,"maliu","12345");
if(rs>0){
System.out.println("数据添加成功");
}
}
public static void testUpdate() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql = "update user set password =? where id=?";
int rs =qr.update(sql,"maliu",4);
if(rs>0){
System.out.println("数据修改成功");
}
}
public static void testDelete() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql = "delete from user where id =?";
int rs =qr.update(sql,4);
if(rs>0){
System.out.println("数据删除成功");
}
}
}
User实体类
public class User {
private int id ;
private String username;
private String password;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return "User [id=" + id + ", username=" + username + ", password=" + password + "]";
}
}
c3p0-config.xml 配置文件，存放在src目录下
<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
<default-config>
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8</property>
<property name="user">root</property>
<property name="password">dang</property>
<property name="checkoutTimeout">30000</property>
<property name="idleConnectionTestPeriod">30</property>
<property name="initialPoolSize">10</property>
<property name="maxIdleTime">30</property>
<property name="maxPoolSize">100</property>
<property name="minPoolSize">10</property>
</default-config>
</c3p0-config>
//使用c3p0做1-100加的总和，每次睡眠1秒，且程序中途终止，再次运行不影响结果
public class Excise1 {
public static void main(String[] args) throws SQLException {
Object arr[]= task();
int id =(int)arr[0]+1;
int sum=(int)arr[1];
for (int i=id;i <=100; i++) {
sum+=i;
update(i,sum);
System.out.println(i+"------"+sum);
}
}
//作业
public static Object [] task() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql ="select * from tb_task";
Object arr [] =qr.query(sql, new ArrayHandler());
return arr;
}
public static void update(int i,int sum) throws SQLException{
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql ="update tb_task set id=?,sum=?";
int r =qr.update(sql,i,sum);
}
}
//自己实现ResultSetHandler，查询所有的数据并存入list中返回
public class Excise2 {
public static void main(String[] args) {
try {
test();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void test() throws SQLException{
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
String sql="select * from user";
List<User> list =(List) qr.query(sql, new BeanListHandler<User>(User.class));
for (Object object : list) {
System.out.println(object);
}
}
static class BeanListHandler<T> implements ResultSetHandler<List<T>>{
private Class <T> cls= null;
public BeanListHandler(Class<T> clazz) {
this.cls = clazz;
}
@Override
public List<T> handle(ResultSet rs) {
List<T> list = new ArrayList<T>();
Field [] fields =cls.getDeclaredFields();
try {
for(;rs.next();){
//创建由此类对象表示的类的新实例。 该类被实例化为一个具有空参数列表的new表达式。 如果类尚未初始化，则初始化该类。
T object = null;
try {
object = cls.newInstance();
} catch (Exception e) {
e.printStackTrace();
}
for (int i = 0; i < fields.length; i++) {
fields[i].setAccessible(true);
String colName=fields[i].getName();
try {
fields[i].set(object, rs.getObject(colName));
} catch (Exception e) {
e.printStackTrace();
}
}
list.add(object);
}
} catch (SecurityException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}
}
}