數據庫連接池:
數據庫連接池的作用是可以幫組我們連接數據庫。
1.自定義連接池
package com.itheima.uitl;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JDBCUtil {
static String driverClass = null;
static String url = null;
static String name = null;
static String password= null;
static{
try {
//1. 創建一個屬性配置對象
Properties properties = new Properties();
InputStream is = new FileInputStream("jdbc.properties");
//使用類加載器,去讀取src底下的資源文件。 後面在servlet
// InputStream is = JDBCUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");
//導入輸入流。
properties.load(is);
//讀取屬性
driverClass = properties.getProperty("driverClass");
url = properties.getProperty("url");
name = properties.getProperty("name");
password = properties.getProperty("password");
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 獲取連接對象
* @return
*/
public static Connection getConn(){
Connection conn = null;
try {
Class.forName(driverClass);
//靜態代碼塊 ---> 類加載了,就執行。 java.sql.DriverManager.registerDriver(new Driver());
//DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//DriverManager.getConnection("jdbc:mysql://localhost/test?user=monty&password=greatsqldb");
//2. 建立連接 參數一: 協議 + 訪問的數據庫 , 參數二: 用戶名 , 參數三: 密碼。
conn = DriverManager.getConnection(url, name, password);
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
/**
* 釋放資源
* @param conn
* @param st
* @param rs
*/
public static void release(Connection conn , Statement st , ResultSet rs){
closeRs(rs);
closeSt(st);
closeConn(conn);
}
public static void release(Connection conn , Statement st){
closeSt(st);
closeConn(conn);
}
private static void closeRs(ResultSet rs){
try {
if(rs != null){
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
rs = null;
}
}
private static void closeSt(Statement st){
try {
if(st != null){
st.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
st = null;
}
}
private static void closeConn(Connection conn){
try {
if(conn != null){
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
conn = null;
}
}
}
package com.itheima.uitl;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;
import javax.sql.DataSource;
/**
* 這是一個數據庫連接池
* 一開始先往池子裏面放10個連接
*
* 1. 開始創建10個連接。
*
* 2. 來的程序通過getConnection獲取連接
*
* 3. 用完之後,使用addBack 歸還連接。
*
* 4. 擴容。
*
*
* 問題:
*
* 1. sun公司針對數據庫連接池定義的一套規範。
*
* 1. 需要額外記住 addBack方法
*
* 2. 單例。
*
* 3. 無法面向接口編程。
*
* UserDao dao = new UserDaoImpl();
* dao.insert();
*
*
* DataSource dataSource = new MyDataSource();
*
* 因爲接口裏面沒有定義addBack方法。
*
* 4. 怎麼解決?
*
*/
public class MyDataSource implements DataSource {
List <Connection> list = new ArrayList<Connection>();
public MyDataSource() {
for (int i = 0; i < 10; i++) {
Connection conn = JDBCUtil.getConn();
list.add(conn);
}
}
// 該連接池對外公佈的獲取連接的方法
@Override
public Connection getConnection() throws SQLException {
//來拿連接的時候,先看看,池子裏面還有沒有。
if(list.size() == 0 ){
for (int i = 0; i < 5; i++) {
Connection conn = JDBCUtil.getConn();
list.add(conn);
}
}
//remove(0) ---> 移除第一個。 移除的是集合中的第一個。 移除的是開始的那個元素
Connection conn = list.remove(0);
return conn;
}
/**
* 用完之後,記得歸還。
* @param conn
*/
public void addBack(Connection conn){
list.add(conn);
}
//----------------------------
@Override
public PrintWriter getLogWriter() throws SQLException {
// TODO Auto-generated method stub
return null;
}
@Override
public void setLogWriter(PrintWriter out) throws SQLException {
// TODO Auto-generated method stub
}
@Override
public void setLoginTimeout(int seconds) throws SQLException {
// TODO Auto-generated method stub
}
@Override
public int getLoginTimeout() throws SQLException {
// TODO Auto-generated method stub
return 0;
}
@Override
public Logger getParentLogger() throws SQLFeatureNotSupportedException {
// TODO Auto-generated method stub
return null;
}
@Override
public <T> T unwrap(Class<T> iface) throws SQLException {
// TODO Auto-generated method stub
return null;
}
@Override
public boolean isWrapperFor(Class<?> iface) throws SQLException {
// TODO Auto-generated method stub
return false;
}
@Override
public Connection getConnection(String username, String password) throws SQLException {
// TODO Auto-generated method stub
return null;
}
}
package com.itheima.uitl;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;
import javax.sql.DataSource;
/**
* 這是一個數據庫連接池
* 一開始先往池子裏面放10個連接
*
* 1. 開始創建10個連接。
*
* 2. 來的程序通過getConnection獲取連接
*
* 3. 用完之後,使用addBack 歸還連接。
*
* 4. 擴容。
*
*
* 問題:
*
* 1. sun公司針對數據庫連接池定義的一套規範。
*
* 1. 需要額外記住 addBack方法
*
* 2. 單例。
*
* 3. 無法面向接口編程。
*
* UserDao dao = new UserDaoImpl();
* dao.insert();
*
*
* DataSource dataSource = new MyDataSource();
*
* 因爲接口裏面沒有定義addBack方法。
*
* 4. 怎麼解決?
*
*/
public class MyDataSource implements DataSource {
List <Connection> list = new ArrayList<Connection>();
public MyDataSource() {
for (int i = 0; i < 10; i++) {
Connection conn = JDBCUtil.getConn();
list.add(conn);
}
}
// 該連接池對外公佈的獲取連接的方法
@Override
public Connection getConnection() throws SQLException {
//來拿連接的時候,先看看,池子裏面還有沒有。
if(list.size() == 0 ){
for (int i = 0; i < 5; i++) {
Connection conn = JDBCUtil.getConn();
list.add(conn);
}
}
//remove(0) ---> 移除第一個。 移除的是集合中的第一個。 移除的是開始的那個元素
Connection conn = list.remove(0);
return conn;
}
/**
* 用完之後,記得歸還。
* @param conn
*/
public void addBack(Connection conn){
list.add(conn);
}
//----------------------------
@Override
public PrintWriter getLogWriter() throws SQLException {
// TODO Auto-generated method stub
return null;
}
@Override
public void setLogWriter(PrintWriter out) throws SQLException {
// TODO Auto-generated method stub
}
@Override
public void setLoginTimeout(int seconds) throws SQLException {
// TODO Auto-generated method stub
}
@Override
public int getLoginTimeout() throws SQLException {
// TODO Auto-generated method stub
return 0;
}
@Override
public Logger getParentLogger() throws SQLFeatureNotSupportedException {
// TODO Auto-generated method stub
return null;
}
@Override
public <T> T unwrap(Class<T> iface) throws SQLException {
// TODO Auto-generated method stub
return null;
}
@Override
public boolean isWrapperFor(Class<?> iface) throws SQLException {
// TODO Auto-generated method stub
return false;
}
@Override
public Connection getConnection(String username, String password) throws SQLException {
// TODO Auto-generated method stub
return null;
}
}
2使用C3P0
可以使用配置文件,也可以不使用配置文件
不使用配置文件:
package com.itheima.uitl;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JDBCUtil {
static String driverClass = null;
static String url = null;
static String name = null;
static String password= null;
static{
try {
//1. 創建一個屬性配置對象
Properties properties = new Properties();
InputStream is = new FileInputStream("jdbc.properties");
//使用類加載器,去讀取src底下的資源文件。 後面在servlet
// InputStream is = JDBCUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");
//導入輸入流。
properties.load(is);
//讀取屬性
driverClass = properties.getProperty("driverClass");
url = properties.getProperty("url");
name = properties.getProperty("name");
password = properties.getProperty("password");
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 獲取連接對象
* @return
*/
public static Connection getConn(){
Connection conn = null;
try {
Class.forName(driverClass);
//靜態代碼塊 ---> 類加載了,就執行。 java.sql.DriverManager.registerDriver(new Driver());
//DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//DriverManager.getConnection("jdbc:mysql://localhost/test?user=monty&password=greatsqldb");
//2. 建立連接 參數一: 協議 + 訪問的數據庫 , 參數二: 用戶名 , 參數三: 密碼。
conn = DriverManager.getConnection(url, name, password);
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
/**
* 釋放資源
* @param conn
* @param st
* @param rs
*/
public static void release(Connection conn , Statement st , ResultSet rs){
closeRs(rs);
closeSt(st);
closeConn(conn);
}
public static void release(Connection conn , Statement st){
closeSt(st);
closeConn(conn);
}
private static void closeRs(ResultSet rs){
try {
if(rs != null){
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
rs = null;
}
}
private static void closeSt(Statement st){
try {
if(st != null){
st.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
st = null;
}
}
private static void closeConn(Connection conn){
try {
if(conn != null){
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
conn = null;
}
}
}
package com.itheima.c3p0;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import org.apache.commons.dbcp.BasicDataSource;
import org.junit.Test;
import com.itheima.uitl.JDBCUtil;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class C3P0Demo {
@Test
public void testC3P0 (){
Connection conn = null;
PreparedStatement ps = null;
try {
//1. 創建datasource
// ComboPooledDataSource dataSource = new ComboPooledDataSource("oracle");
//默認會找 xml 中的 default-config 分支。
ComboPooledDataSource dataSource = new ComboPooledDataSource();
System.out.println(dataSource.hashCode() );
ComboPooledDataSource dataSource2 = new ComboPooledDataSource();
System.out.println(dataSource2.hashCode()+"-------");
//2. 設置連接數據的信息
dataSource.setDriverClass("com.mysql.jdbc.Driver");
//忘記了---> 去以前的代碼 ---> jdbc的文檔
dataSource.setJdbcUrl("jdbc:mysql://localhost/bank");
dataSource.setUser("root");
dataSource.setPassword("root");
//2. 得到連接對象
conn = dataSource.getConnection();
String sql = "insert into account values(null , ? , ?)";
ps = conn.prepareStatement(sql);
ps.setString(1, "admi234n");
ps.setInt(2, 103200);
ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
}finally {
JDBCUtil.release(conn, ps);
}
}
}
使用配置文件:
<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
<!-- default-config 默認的配置, -->
<default-config>
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://localhost/bank</property>
<property name="user">root</property>
<property name="password">root</property>
<property name="initialPoolSize">10</property>
<property name="maxIdleTime">30</property>
<property name="maxPoolSize">100</property>
<property name="minPoolSize">10</property>
<property name="maxStatements">200</property>
</default-config>
<!-- This app is massive! -->
<named-config name="oracle">
<property name="acquireIncrement">50</property>
<property name="initialPoolSize">100</property>
<property name="minPoolSize">50</property>
<property name="maxPoolSize">1000</property>
<!-- intergalactoApp adopts a different approach to configuring statement caching -->
<property name="maxStatements">0</property>
<property name="maxStatementsPerConnection">5</property>
<!-- he's important, but there's only one of him -->
<user-overrides user="master-of-the-universe">
<property name="acquireIncrement">1</property>
<property name="initialPoolSize">1</property>
<property name="minPoolSize">1</property>
<property name="maxPoolSize">5</property>
<property name="maxStatementsPerConnection">50</property>
</user-overrides>
</named-config>
</c3p0-config>
package com.itheima.c3p0;
import java.sql.Connection;
import java.sql.PreparedStatement;
import org.junit.Test;
import com.itheima.uitl.JDBCUtil;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class C3P0Demo02 {
@Test
public void testC3P0(){
Connection conn = null;
PreparedStatement ps = null;
try {
//就new了一個對象。
ComboPooledDataSource dataSource = new ComboPooledDataSource();
//2. 得到連接對象
conn = dataSource.getConnection();
String sql = "insert into account values(null , ? , ?)";
ps = conn.prepareStatement(sql);
ps.setString(1, "wangwu2");
ps.setInt(2, 2600);
ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
}finally {
JDBCUtil.release(conn, ps);
}
}
}
3.使用DBCP
也是可以使用配置文件和不使用配置文件:
不使用配置文件文件:
package com.itheima.uitl;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JDBCUtil {
static String driverClass = null;
static String url = null;
static String name = null;
static String password= null;
static{
try {
//1. 創建一個屬性配置對象
Properties properties = new Properties();
InputStream is = new FileInputStream("jdbc.properties");
//使用類加載器,去讀取src底下的資源文件。 後面在servlet
// InputStream is = JDBCUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");
//導入輸入流。
properties.load(is);
//讀取屬性
driverClass = properties.getProperty("driverClass");
url = properties.getProperty("url");
name = properties.getProperty("name");
password = properties.getProperty("password");
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 獲取連接對象
* @return
*/
public static Connection getConn(){
Connection conn = null;
try {
Class.forName(driverClass);
//靜態代碼塊 ---> 類加載了,就執行。 java.sql.DriverManager.registerDriver(new Driver());
//DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//DriverManager.getConnection("jdbc:mysql://localhost/test?user=monty&password=greatsqldb");
//2. 建立連接 參數一: 協議 + 訪問的數據庫 , 參數二: 用戶名 , 參數三: 密碼。
conn = DriverManager.getConnection(url, name, password);
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
/**
* 釋放資源
* @param conn
* @param st
* @param rs
*/
public static void release(Connection conn , Statement st , ResultSet rs){
closeRs(rs);
closeSt(st);
closeConn(conn);
}
public static void release(Connection conn , Statement st){
closeSt(st);
closeConn(conn);
}
private static void closeRs(ResultSet rs){
try {
if(rs != null){
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
rs = null;
}
}
private static void closeSt(Statement st){
try {
if(st != null){
st.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
st = null;
}
}
private static void closeConn(Connection conn){
try {
if(conn != null){
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
conn = null;
}
}
}
package com.itheima.dbcp;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import org.apache.commons.dbcp.BasicDataSource;
import org.junit.Test;
import com.itheima.uitl.JDBCUtil;
public class DBCPDemo {
@Test
public void testDBCP01(){
Connection conn = null;
PreparedStatement ps = null;
try {
//1. 構建數據源對象
BasicDataSource dataSource = new BasicDataSource();
//連的是什麼類型的數據庫, 訪問的是哪個數據庫 , 用戶名, 密碼。。
// jdbc:mysql://localhost/bank 主協議:子協議 ://本地/數據庫
dataSource.setDriverClassName("com.mysql.jdbc.Driver");
dataSource.setUrl("jdbc:mysql://localhost/bank");
dataSource.setUsername("root");
dataSource.setPassword("root");
//2. 得到連接對象
conn = dataSource.getConnection();
String sql = "insert into account values(null , ? , ?)";
ps = conn.prepareStatement(sql);
ps.setString(1, "admin");
ps.setInt(2, 1000);
ps.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}finally {
JDBCUtil.release(conn, ps);
}
}
}
使用配置文件:
#連接設置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/bank
username=root
password=root
#<!-- 初始化連接 -->
initialSize=10
#最大連接數量
maxActive=50
#<!-- 最大空閒連接 -->
maxIdle=20
#<!-- 最小空閒連接 -->
minIdle=5
#<!-- 超時等待時間以毫秒爲單位 6000毫秒/1000等於60秒 -->
maxWait=60000
#JDBC驅動建立連接時附帶的連接屬性屬性的格式必須爲這樣:[屬性名=property;]
#注意:"user" 與 "password" 兩個屬性會被明確地傳遞,因此這裏不需要包含他們。
connectionProperties=useUnicode=true;characterEncoding=gbk
#指定由連接池所創建的連接的自動提交(auto-commit)狀態。
defaultAutoCommit=true
#driver default 指定由連接池所創建的連接的事務級別(TransactionIsolation)。
#可用值爲下列之一:(詳情可見javadoc。)NONE,READ_UNCOMMITTED, READ_COMMITTED, REPEATABLE_READ, SERIALIZABLE
defaultTransactionIsolation=READ_UNCOMMITTED
package com.itheima.dbcp;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.Properties;
import java.util.ResourceBundle;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;
import org.junit.Test;
import com.itheima.uitl.JDBCUtil;
public class DBCPDemo02 {
@Test
public void testDBCP02(){
Connection conn = null;
PreparedStatement ps = null;
try {
BasicDataSourceFactory factory = new BasicDataSourceFactory();
Properties properties = new Properties();
// InputStream is = new FileInputStream("src//dbcpconfig.properties");
InputStream is = getClass().getClassLoader().getResourceAsStream("dbcpconfig.properties");
properties.load(is);
DataSource dataSource = factory.createDataSource(properties);
//2. 得到連接對象
conn = dataSource.getConnection();
String sql = "insert into account values(null , ? , ?)";
ps = conn.prepareStatement(sql);
ps.setString(1, "liangchaowei22");
ps.setInt(2, 200);
ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
}finally {
JDBCUtil.release(conn, ps);
}
}
}
4.DBUtils
如果我們使用DBUtils,假設我們使用的是C3P0,那麼我們的JDBCUtils的代碼就可以改成如下代碼:
package com.itheima.uitl;
import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class JDBCUtil02 {
static ComboPooledDataSource dataSource = null;
static{
dataSource = new ComboPooledDataSource();
}
/**
* 獲取連接對象
* @return
* @throws SQLException
*/
public static Connection getConn() throws SQLException{
return dataSource.getConnection();
}
/**
* 釋放資源
* @param conn
* @param st
* @param rs
*/
public static void release(Connection conn , Statement st , ResultSet rs){
closeRs(rs);
closeSt(st);
closeConn(conn);
}
public static void release(Connection conn , Statement st){
closeSt(st);
closeConn(conn);
}
private static void closeRs(ResultSet rs){
try {
if(rs != null){
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
rs = null;
}
}
private static void closeSt(Statement st){
try {
if(st != null){
st.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
st = null;
}
}
private static void closeConn(Connection conn){
try {
if(conn != null){
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
conn = null;
}
}
}
DBUtils主要的作用是幫助我們方便的執行sql語句。
package com.itheima.domain;
public class Account {
private String name02;
private int money;
public int getMoney() {
return money;
}
public void setMoney(int money) {
this.money = money;
}
public String getName02() {
return name02;
}
public void setName02(String name02) {
this.name02 = name02;
}
@Override
public String toString() {
return "Account [name02=" + name02 + ", money=" + money + "]";
}
}
package com.itheima.dbutils;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.junit.Test;
import com.itheima.domain.Account;
import com.mchange.v2.c3p0.ComboPooledDataSource;
/*
//針對增加 、 刪除 、 修改
queryRunner.update(sql)
//針對查詢
queryRunner.query(sql, rsh);*/
public class TestDBUtils {
@Test
public void testInsert() throws SQLException, InstantiationException, IllegalAccessException{
// ComboPooledDataSource dataSource = new ComboPooledDataSource();
//dbutils 只是幫我們簡化了CRUD 的代碼, 但是連接的創建以及獲取工作。 不在他的考慮範圍
QueryRunner queryRunner = new QueryRunner(new ComboPooledDataSource());
//增加
//queryRunner.update("insert into account values (null , ? , ? )", "aa" ,1000);
//刪除
// queryRunner.update("delete from account where id = ?", 5);
//更新
//queryRunner.update("update account set money = ? where id = ?", 10000000 , 6);
//去執行查詢,查詢到的數據還是在哪個result裏面。 然後調用下面的handle方法,由用戶手動去封裝。
/*Account account = queryRunner.query("select * from account where id = ?", new ResultSetHandler<Account>(){
@Override
public Account handle(ResultSet rs) throws SQLException {
Account account = new Account();
while(rs.next()){
String name = rs.getString("name");
int money = rs.getInt("money");
account.setName(name);
account.setMoney(money);
}
return account;
}
}, 6);
System.out.println(account.toString());
*/
// 通過類的字節碼得到該類的實例
/*
Account a = new Account();
//創建一個類的實例。
Account a1= Account.class.newInstance();
*/
//查詢單個對象
Account account = queryRunner.query("select * from account where id = ?",
new BeanHandler<Account>(Account.class), 8);
System.out.println(account.toString());
/*List<Account> list = queryRunner.query("select * from account ",
new BeanListHandler<Account>(Account.class));
for (Account account : list) {
System.out.println(account.toString());
}*/
}
}