瞎j8封装第二版之数据库连接池
2024-10-10 23:57:07
写得很蛋疼，本来想支持多线程的，奈何对多线程和连接池理解着实太菜；
所以，起码是能拿到连接了。。。
但是还是不太懂这个连接池
我也是半抄别人的，以后再搞一搞这个吧。
先是配置文件 理想是很丰满的，奈何现实。。。
jdbc.driver=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&useSSL=true jdbc.username=root jdbc.password=yck940522 #最小连接数 jdbc.minSize= #最大连接数 jdbc.maxSize= #初始化连接数 jdbc.initSize= #重试次数 jdbc.tryTimes= #延迟时间 jdbc.delay= jdbc.maxActiveSize= jdbc.timeOut= jdbc.check = true jdbc.checkTime =
配了那么多参数，很多都没用上。。唉，还是太菜；
package jdbc;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
public class DataBase {
private static String username;
private static String password;
private static String url;
private static String driver;
private static Integer minSize;
private static Integer maxSize;
private static Integer initSize;
private static Integer maxActiveSize;
private static Integer tryTimes;
private static Long delay;
private static Long timeOut;
private static Boolean checked;
private static Long checkTime;
private static DataBase instance;
private DataBase(){
InputStream in = DataBase.class.getClassLoader().getResourceAsStream("jdbc.properties");
Properties p = new Properties();
try {
p.load(in);
username = p.getProperty("jdbc.username");
password = p.getProperty("jdbc.password");
url = p.getProperty("jdbc.url");
driver = p.getProperty("jdbc.driver");
minSize = Integer.valueOf(p.getProperty("jdbc.minSize","3"));
maxSize = Integer.valueOf(p.getProperty("jdbc.maxSize","20"));
initSize = Integer.valueOf(p.getProperty("jdbc.initSize","5"));
maxActiveSize = Integer.valueOf(p.getProperty("jdbc.maxActiveSize","100"));
tryTimes =Integer.valueOf(p.getProperty("jdbc.tryTimes","2"));
delay = Long.valueOf(p.getProperty("jdbc.delay","1000"));
timeOut = Long.valueOf(p.getProperty("jdbc.timeOut","1200000"));
checked = Boolean.valueOf(p.getProperty("jdbc.check","false"));
checkTime = Long.valueOf(p.getProperty("jdbc.checkTime","30000"));
} catch (IOException e) {
e.printStackTrace();
}finally {
if(in != null){
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public static DataBase getInstance(){
if(instance == null){
synchronized (DataBase.class){
if(instance == null){
instance = new DataBase();
}
}
}
return instance;
}
public String getUsername() {
return username;
}
public String getPassword() {
return password;
}
public String getUrl() {
return url;
}
public String getDriver() {
return driver;
}
public Integer getMinSize() {
return minSize;
}
public Integer getMaxSize() {
return maxSize;
}
public Integer getInitSize() {
return initSize;
}
public Integer getMaxActiveSize() {
return maxActiveSize;
}
public Integer getTryTimes() {
return tryTimes;
}
public Long getDelay() {
return delay;
}
public Long getTimeOut() {
return timeOut;
}
public Boolean getChecked() {
return checked;
}
public Long getCheckTime() {
return checkTime;
}
}
对单例也不太懂，瞎写，有经验的大佬指正一下啊
package jdbc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;
import java.util.Vector;
import java.util.concurrent.atomic.AtomicInteger;
public class ConnectionPool{
private static final Long lazyTime = 30000L;
private DataBase dataBase;
private AtomicInteger totalSize = new AtomicInteger(0);
private List<Connection> freeConnections = new Vector<Connection>();
private ThreadLocal<Connection> threadLocal = new ThreadLocal<Connection>();
private static ConnectionPool instance;
private ConnectionPool(){
this.dataBase = DataBase.getInstance();
init();
}
public static ConnectionPool getInstance(){
if(instance == null){
synchronized (ConnectionPool.class){
if(instance == null){
instance = new ConnectionPool();
}
}
}
return instance;
}
private void init(){
try {
Class.forName(dataBase.getDriver());
for(int i=0;i<dataBase.getInitSize();i++){
Connection connection = createConnection();
freeConnections.add(connection);
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
private synchronized Connection createConnection(){
try {
Class.forName(dataBase.getDriver());
Connection conn= DriverManager.getConnection(dataBase.getUrl(),dataBase.getUsername(),dataBase.getPassword());
totalSize.incrementAndGet();
return conn;
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
return null;
}
private synchronized Connection getConnection() {
Connection conn= null;
try {
if(totalSize.get() < dataBase.getMaxSize()){
if(freeConnections.size()>0){
conn = freeConnections.get(0);
if(conn != null){
threadLocal.set(conn);
}
freeConnections.remove(0);
}else {
conn = createConnection();
}
}else {
wait(dataBase.getDelay());
conn = getConnection();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
return conn;
}
private boolean isValid(Connection conn){
try {
if(conn == null || conn.isClosed()){
return false;
}
} catch (SQLException e) {
e.printStackTrace();
}
return true;
}
public synchronized Connection getCurrentConnection() {
Connection conn = threadLocal.get();
if(!isValid(conn)){
return getConnection();
}
return conn;
}
public void checkPool() {
if(dataBase.getChecked()){
new Timer().schedule(new TimerTask() {
@Override
public void run() {
System.out.println("空线池连接数："+freeConnections.size());
System.out.println("总的连接数："+totalSize.get());
}
}, lazyTime, dataBase.getCheckTime());
}
}
}
这个连接池我就不做什么说明了。。。自己只能理解最简单的。。。简单的说就是先初始化一部分连接放在一个list里，要用的时候就去取，如果没有超过上限也不用close了。。但是我一直没搞明白怎么去判断它空闲了多长时间然后close掉。。。所以很多也没实现。
大王让我写代码
2017-12-30
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