create database mydb character set utf8;
alert database mydb character set utf8;
1.自定义连接池为了不去经常创建连接和释放对象而占用大量资源
-----JdbcTool3 -----------获得connection(通过·)和释放资源------------
public class JdbcTool3 {
private static String drive;
private static String sql;
private static String username;
private static String passord;
static {
try {
ClassLoader classLoader = JdbcTool3.class.getClassLoader();
InputStream input = classLoader.getResourceAsStream("db.properties");
Properties properties = new Properties();
properties.load(input);
drive = properties.getProperty("driver");
sql = properties.getProperty("url");
username = properties.getProperty("username");
passord = properties.getProperty("psaaword");
} catch (Exception e) {
e.printStackTrace();
}
}
public static Connection connection() {
try {
Class.forName(drive);
} catch (Exception e) {
e.printStackTrace();
}
Connection con = null;
try {
con = DriverManager.getConnection(sql, username, passord);
} catch (Exception e) {
e.printStackTrace();
}
return con;
}
public static void relese(Statement sta, Connection con, ResultSet res) {
if (res != null) {
try {
res.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (con != null) {
try {
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (sta != null) {
try {
sta.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
---------有了conn之后便是创建几个放入连接池，在使用完后同样回收到连接池---
implements 是重写接口所以需要全部覆盖
public class MyDatasource implements DataSource{
private static LinkedList pool=new LinkedList<>();
static{
Connection conn=null;
for (int i = 0; i < 5; i++) {
conn=JdbcTool3.connection();
pool.add(conn);
}
}
/**放回池中
* @param conn
*/
public static void backConnection(Connection conn) {
pool.add(conn);
}
@Override
public Connection getConnection() throws SQLException {
if (pool.size()==0) {
Connection conn=null;
for (int i = 0; i < 5; i++) {
conn=JdbcTool3.connection();
pool.add(conn);
}
}
return pool.remove(0);
}
- 修饰者设计模式：为了将.close修改成把链接放回连接池而不是释放
--------修改原本的功能重写一个类继承connection，为了修改.close方法--------
因为实例化所以同样需要重写prepareStatement方法
public class ColectionMackClose implements Connection {
private static LinkedList pool;
private static Connection con;
public ColectionMackClose(Connection con, LinkedList pool) {
this.pool = pool;
this.con = con;
}
@Override
public void close() throws SQLException {
pool.add(con);
}
@Override
public PreparedStatement prepareStatement(String sql) throws SQLException {
return con.prepareStatement(sql);
}
----------获得con之后用新的类ColectionMackClose 包装得到重写的con---------
public class MyDatasource1 implements DataSource{
private static LinkedList pool=new LinkedList<>();
static{
Connection conn=null;
for (int i = 0; i < 5; i++) {
conn=JdbcTool3.connection();
ColectionMackClose myCollection = new ColectionMackClose(conn, pool);
pool.add(myCollection);
}
}
@Override
public Connection getConnection() throws SQLException {
if (pool.size()==0) {
Connection conn=null;
for (int i = 0; i < 5; i++) {
conn=JdbcTool3.connection();
ColectionMackClose myCollection = new ColectionMackClose(conn, pool);
pool.add(myCollection);
}
}
return pool.remove(0);
}
2.c3p0连接池，使用较多
- 导包
从SourceForge 网站下载最新的版本
http://sourceforge.net/projects/c3p0/
出现找不到或无法加载主类 cn.fb.textDatasource.C3p0Text，从项目文件夹.path文件中删除多余路径
注意添加两个文件c3p0-0.9.5.2.jar和mchange-commons-java-0.2.11.jar（有时候没mchange也行，和版本有关？）
图片.png
------c3p0-config.xml名称唯一放在scr下-----
com.mysql.jdbc.Driver
jdbc:mysql:///web09
root
0616
5
20
com.mysql.jdbc.Driver
jdbc:mysql:///web09
root
0616
------c3p0会自动获取xml文件配置---使用set方法设置也行---
public class C3p0Utiles {
private static ComboPooledDataSource datasourse=new ComboPooledDataSource("text");如果没参数会自动加载default
public static ComboPooledDataSource getCombpdatasource() {
return datasourse;
}
public static Connection getCon() {
try {
return datasourse.getConnection();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
-----------text----------------
public void textadd2() {
Connection con = null;
PreparedStatement pst = null;
try {
con =C3p0Utiles.getCon();
String sql = "insert into product values(?,?,?,null)";
pst = con.prepareStatement(sql);
pst.setString(1, "p022");
pst.setString(2, "云河2");
pst.setDouble(3, 30);
int row = pst.executeUpdate();
if (row > 0) {
System.out.println("添加成功");
} else {
System.out.println("添加失败");
}
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
}finally {
JdbcTool3.relese(pst, con, null);
}
}
3.dbcp
图片.png
同样使用.properties文件，BasicDataSourceFactory创建
private static DataSource dataSource;
static {
try {
InputStream input = DbcpUtils.class.getClassLoader().getResourceAsStream("db.properties");
Properties pro = new Properties();
pro.load(input);
dataSource = BasicDataSourceFactory.createDataSource(pro);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
public static DataSource getdatasource() {
return dataSource;
}
public static Connection getconnection() {
try {
return dataSource.getConnection();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
-------------properties----放在src下-----------
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/web09?useUnicode=true&characterEncoding=utf8
username=root
psaaword=0616
4.dbutils
图片.png
MapHandler：单行处理器！把结果集转换成Map，其中列名为键！
MapListHandler：多行处理器！把结果集转换成List>；
BeanHandler：单行处理器！把结果集转换成Bean，该处理器需要Class参数，即Bean的类型；
BeanListHandler：多行处理器！把结果集转换成List；
ColumnListHandler：多行单列处理器！把结果集转换成List