C3P0连接池的三种实现方式
用到的jar包：
mysql-connector-java-5.1.30-bin.jar
c3p0-0.9.5.2.jar
mchange-commons-java-0.2.11.jar
直接设置参数:
C3P0Inner.java
package com.song.c3p0.db.inner;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class C3P0Inner {
private static ComboPooledDataSource ds;
//静态初始化块进行初始化
static{
try {
ds = new ComboPooledDataSource();//创建连接池实例
ds.setDriverClass("com.mysql.jdbc.Driver");//设置连接池连接数据库所需的驱动
ds.setJdbcUrl("jdbc:mysql://localhost:3306/cloudhospital");//设置连接数据库的URL
ds.setUser("root");//设置连接数据库的用户名
ds.setPassword("admin");//设置连接数据库的密码
ds.setMaxPoolSize(40);//设置连接池的最大连接数
ds.setMinPoolSize(2);//设置连接池的最小连接数
ds.setInitialPoolSize(10);//设置连接池的初始连接数
ds.setMaxStatements(100);//设置连接池的缓存Statement的最大数
} catch (Exception e) {
e.printStackTrace();
}
}
//获取与指定数据库的连接
public static ComboPooledDataSource getInstance(){
return ds;
}
//从连接池返回一个连接
public static Connection getConnection(){
Connection conn = null;
try {
conn = ds.getConnection();
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
//释放资源
public static void realeaseResource(ResultSet rs,PreparedStatement ps,Connection conn){
if(null != rs){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(null != ps){
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}C3P0InnerMain.java
package com.song.c3p0.db.inner;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class C3P0InnerMain {
public PreparedStatement setStatement(Connection conn,String sql){
PreparedStatement ps = null;
try {
ps = conn.prepareStatement(sql);
} catch (SQLException e) {
e.printStackTrace();
}
return ps;
}
public PreparedStatement setParameter(PreparedStatement ps,Object...values){
try {
if(null != values){
for(int i=1;i<=values.length;i++){
ps.setObject(i, values[i-1]);
}
}
} catch (Exception e) {
e.printStackTrace();
}
return ps;
}
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = C3P0Inner.getConnection();
C3P0InnerMain c3P0InnerMain = new C3P0InnerMain();
String sql = "SELECT * FROM tb_user WHERE ID < ? ";
ps = c3P0InnerMain.setStatement(conn, sql);
ps = c3P0InnerMain.setParameter(ps, new Object[]{20});
rs = ps.executeQuery();
while(rs.next()){
Object ob = rs.getObject(1);
Object name = rs.getObject(4);
System.out.println("ID: " + ob + ",NAME:" + name);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
//释放资源
C3P0Inner.realeaseResource(rs, ps, conn);
}
}
}
用配置文件设置参数：
1.从配置文件中逐条获取参数
config.properties
DriverClass = com.mysql.jdbc.Driver
JdbcUrl = jdbc:mysql://localhost:3306/cloudhospital
User = root
Password = admin
MaxPoolSize = 20
MinPoolSize = 2
InitialPoolSize = 5
MaxStatements = 30
MaxIdleTime = 100C3P0Properties.java
package com.song.c3p0.db.properties;
import java.sql.Connection;
import java.util.Properties;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class C3P0Properties {
private ComboPooledDataSource cpds;
private static C3P0Properties c3P0Properties;
static{
c3P0Properties = new C3P0Properties();
}
public C3P0Properties() {
try {
cpds = new ComboPooledDataSource();
//加载配置文件
Properties props = new Properties();
props.load(C3P0Properties.class.getClassLoader().getResourceAsStream("config.properties"));
cpds.setDriverClass(props.getProperty("DriverClass"));
cpds.setJdbcUrl(props.getProperty("JdbcUrl"));
cpds.setUser(props.getProperty("User"));
cpds.setPassword(props.getProperty("Password"));
cpds.setMaxPoolSize(Integer.parseInt(props.getProperty("MaxPoolSize")));
cpds.setMinPoolSize(Integer.parseInt(props.getProperty("MinPoolSize")));
cpds.setInitialPoolSize(Integer.parseInt(props.getProperty("InitialPoolSize")));
cpds.setMaxStatements(Integer.parseInt(props.getProperty("MaxStatements")));
cpds.setMaxIdleTime(Integer.parseInt(props.getProperty("MaxIdleTime")));
} catch (Exception e) {
e.printStackTrace();
}
}
public static C3P0Properties getInstance(){
return c3P0Properties;
}
public Connection getConnection(){
Connection conn = null;
try {
conn = cpds.getConnection();
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
}
C3POPropertiesMain.java
package com.song.c3p0.db.properties;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class C3POPropertiesMain {
public PreparedStatement getPrepareStatement(Connection conn,String sql){
PreparedStatement ps = null;
try {
ps = conn.prepareStatement(sql);
} catch (SQLException e) {
e.printStackTrace();
}
return ps;
}
public PreparedStatement setPrepareStatementParameter(PreparedStatement ps,Object... values){
try {
if (null != values) {
for (int i = 1; i <= values.length; i++) {
ps.setObject(i, values[i - 1]);
}
}
} catch (SQLException e) {
e.printStackTrace();
}
return ps;
}
//释放资源
public static void realeaseResource(ResultSet rs,PreparedStatement ps,Connection conn){
if(null != rs){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(null != ps){
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = C3P0Properties.getInstance().getConnection();
String sql = "SELECT * FROM tb_user WHERE ID < ? ";
C3POPropertiesMain c3p0Instance = new C3POPropertiesMain();
ps = c3p0Instance.getPrepareStatement(conn, sql);
c3p0Instance.setPrepareStatementParameter(ps, new Object[]{20});
rs = ps.executeQuery();
while(rs.next()){
Object obj1 = rs.getObject(1);
Object obj4 = rs.getObject(4);
System.out.println("ID: " + obj1 + ",NAME: " + obj4);
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
//释放资源
C3POPropertiesMain.realeaseResource(rs, ps, conn);
}
}
}
2.不用显式的从配置文件中获取参数
c3p0.properties
c3p0.driverClass = com.mysql.jdbc.Driver
c3p0.jdbcUrl = jdbc:mysql://localhost:3306/cloudhospital
c3p0.user = root
c3p0.password = admin
c3p0.maxPoolSize = 20
c3p0.minPoolSize = 3
c3p0.maxStatements = 30
c3p0.maxIdleTime = 150C3P0PropertiesSimplify.java
package com.song.c3p0.db.properties;
import java.sql.Connection;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class C3P0PropertiesSimplify {
private static C3P0PropertiesSimplify c3P0PropertiesSimplify;
private ComboPooledDataSource cpds;
static{
c3P0PropertiesSimplify = new C3P0PropertiesSimplify();
}
public C3P0PropertiesSimplify() {
cpds = new ComboPooledDataSource();
}
public static C3P0PropertiesSimplify getInstance(){
return c3P0PropertiesSimplify;
}
public Connection getConnection(){
Connection conn = null;
try {
conn = cpds.getConnection();
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
}
C3P0PropertiesSimplifyMain.java
package com.song.c3p0.db.properties;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class C3P0PropertiesSimplifyMain {
public PreparedStatement createStatement(Connection conn,String sql){
PreparedStatement ps = null;
try {
ps = conn.prepareStatement(sql);
} catch (SQLException e) {
e.printStackTrace();
}
return ps;
}
public PreparedStatement setParameters(PreparedStatement ps,Object...values){
try {
if(null != values){
for(int i=1;i<=values.length;i++){
ps.setObject(i, values[i-1]);
}
}
} catch (Exception e) {
e.printStackTrace();
}
return ps;
}
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = C3P0PropertiesSimplify.getInstance().getConnection();
C3P0PropertiesSimplifyMain c3p0Instance = new C3P0PropertiesSimplifyMain();
String sql = "SELECT * FROM tb_user WHERE ID < ? ";
ps = c3p0Instance.createStatement(conn, sql);
ps = c3p0Instance.setParameters(ps, new Object[]{20});
rs = ps.executeQuery();
while(rs.next()){
Object obj1 = rs.getObject(1);
Object obj4 = rs.getObject(4);
System.out.println("ID: " + obj1 + ",Name: " + obj4);
}
} catch (Exception e) {
}finally{
try {
if(null != rs){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(null != ps){
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
} catch (Exception e2) {
e2.printStackTrace();
}
}
}
}
用xml文件设置参数：
c3p0-config.xml
com.mysql.jdbc.Driver
jdbc:mysql://localhost:3306/cloudhospital
root
admin
20
3
30
150
package com.song.c3p0.db.xml;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class C3P0XmlSimplify {
private static C3P0XmlSimplify c3P0XmlSimplify;
private ComboPooledDataSource cpds;
static{
c3P0XmlSimplify = new C3P0XmlSimplify();
}
public C3P0XmlSimplify() {
cpds = new ComboPooledDataSource("myc3p0xml");
}
public static C3P0XmlSimplify getInstance(){
return c3P0XmlSimplify;
}
public Connection getConnection(){
Connection conn = null;
try {
conn = cpds.getConnection();
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
public static PreparedStatement setStatement(Connection conn, String sql){
PreparedStatement ps = null;
try {
ps = conn.prepareStatement(sql);
} catch (SQLException e) {
e.printStackTrace();
}
return ps;
}
public static PreparedStatement setSQLParameters(PreparedStatement ps,Object...values){
try {
if (null != values) {
for (int i = 1; i <= values.length; i++) {
ps.setObject(i, values[i-1]);
}
}
} catch (Exception e) {
e.printStackTrace();
}
return ps;
}
public static void releaseSources(Connection conn, PreparedStatement ps, ResultSet rs){
if(null != rs){
try {
rs.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if(null != ps){
try {
ps.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if(null != conn){
try {
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
package com.song.c3p0.db.xml;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class C3P0XmlSimplifyMain {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = C3P0XmlSimplify.getInstance().getConnection();
String sql = " SELECT * FROM tb_user WHERE ID < ? ";
ps = C3P0XmlSimplify.setStatement(conn, sql);
ps = C3P0XmlSimplify.setSQLParameters(ps, new Object[]{20});
rs = ps.executeQuery();
while(rs.next()){
Object obj1 = rs.getObject(1);
Object obj4 = rs.getObject(4);
System.out.println("ID: " + obj1 + ",Name: " + obj4);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
C3P0XmlSimplify.releaseSources(conn, ps, rs);
}
}
}