使用dbcp构建数据库连接池

数据库连接池

首先，写个连接池类

public class MysqlConnection {
private static DataSource dataSource;

private static String Driver = "";
private static String Url = "";
private static String UserName = "";
private static String Password = "";

private static int InitialSize = 1;//初始化连接池大小
private static int MaxIdle = 10;//最大空闲连接
private static int MinIdle = 1;//最小空闲连接
private static int MaxActive = 20;//最大连接
private static int MaxWait = 6000;//等待时间

private static final String MySQLConnectMessagePath = "dbcp.properties";
private static Properties properties = new Properties();

public MysqlConnection() throws URISyntaxException, IOException{
InitializeDataSource();
}

/**
* 初始化数据池连接
* @throws IOException */
private void InitializeDataSource() throws URISyntaxException, IOException {
getProperties();
Driver = properties.getProperty("Driver");
Url = properties.getProperty("Url");
UserName = properties.getProperty("UserName");
Password = properties.getProperty("Password");
InitialSize = Integer.parseInt(properties.getProperty("InitialSize"));
MaxIdle = Integer.parseInt(properties.getProperty("MaxIdle"));
MinIdle = Integer.parseInt(properties.getProperty("MinIdle"));
MaxActive = Integer.parseInt(properties.getProperty("MaxActive"));
MaxWait = Integer.parseInt(properties.getProperty("MaxWait"));
BasicDataSource bs = new BasicDataSource();
bs.setDriverClassName(Driver);
bs.setUrl(Url);
bs.setUsername(UserName);
bs.setPassword(Password);
bs.setInitialSize(InitialSize);
bs.setMaxIdle(MaxIdle);
bs.setMinIdle(MinIdle);
bs.setMaxActive(MaxActive);
bs.setMaxWait(MaxWait);
dataSource = bs;
}

/**
* 读取配置文件
* @throws IOException */
private void getProperties() throws URISyntaxException, IOException {
String path = this.getClass().getClassLoader().getResource("").toURI().getPath();
FileInputStream fs = new FileInputStream(new File(path+MySQLConnectMessagePath));
try {
properties.load(fs);
} catch (IOException e) {
e.printStackTrace();
}finally{
fs.close();
}
}

/**
* 该函数只在多个DAO类下有用，DAO类初始化可以直接实例化本类，但多个DAO会造成无法连接。这就意味着，你可以在自启动的Servlet中初始化连接池，然后其他DAO类直接调用该函数，避免连接冲突*/
public static DataSource getDataSource() {
return dataSource;
}

/**
* 此方法可以不要*/
public static void setDataSource(DataSource dataSource) {
MysqlConnection.dataSource = dataSource;
}

/**
* 获取数据库连接(释放可直接调用Connection.close()方法)
* @return Connection*/
public Connection getConnection(){
Connection conn = null;
try{
conn = dataSource.getConnection();
}catch(Exception e){
e.printStackTrace();
}
return conn;
}
}

配置dbcp.properties,放在src目录下

#必须根据自己情况配置
Driver = com.mysql.jdbc.Driver
Url = jdbc:mysql://example.com/database_name
UserName = name
Password = password
#可根据自己情况配置
InitialSize = 10
MinIdle = 10
MaxIdle = 10
MaxActive = 200
MaxWait = 1000

初始化连接池

//代码手写的。。
public class DAO(){
private static MysqlConnection mysqlconnetion = null;

public DAO(){
try{
mysqlconnetion = new MysqlConnetion();
}catch(Exception e){
e.printStackTrace();
}
}

//后面直接写方法
//public void method(){}
//public *** method(){}
//示例：
public boolean execute(String sql){
Connection conn = mysqlconnetion.getConnection();
Statement st = null;
boolean flag = false;
try {
st = conn.createStatement();
st.execute(sql);
flag = true;
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
st.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return flag;
}
}

//创建一个DatabaseConnectionServlet，加个注释@WebServlet(loadOnStartup=1,urlPatterns="/DatabaseConnectionServlet")
//loadOnStartup是必须的。。一定不要忘了
//然后servlet构造函数可以这么写
public DatabaseConnectionServlet() {
try {
MysqlConnection mysqlConnection = new MysqlConnection();
System.out.println("数据库连接池初始化完成");
} catch (URISyntaxException | IOException e) {
e.printStackTrace();
}
}

//DAO类可以这么写
public class DAO {
private static DataSource dataSource = null;

/**
* 构造函数，获取连接*/
public DAO(){
dataSource = MysqlConnection.getDataSource();//servlet已经初始化好了
}

/**
* 获取连接*/
public Connection getConnection(){
Connection conn = null;
try{
conn = dataSource.getConnection();
}catch(Exception e){
e.printStackTrace();
}
return conn;
}

/**
* 无参数
* 如果执行语句不抛出异常返回值就是true
* @return boolean*/
public boolean execute(String sql){
Connection conn = getConnection();
Statement st = null;
boolean flag = false;
try {
st = conn.createStatement();
st.execute(sql);
flag = true;
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
st.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return flag;
}

最后，可以写个语句测试一波，这里不赘述了。。