JDBC自定义连接池过程详解

JDBC自定义连接池过程详解

这篇文章主要介绍了JDBC自定义连接池过程详解,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

开发中，"获得连接"和"释放资源"是非常消耗系统资源的，为了解决此类性能问题可以采用连接池技术来共享连接Connection。

1、概述

用池来管理Connection,这样可以重复使用Connection.这样我们就不用创建Connection,用池来管理Connection对象，当使用完Connection对象后，将Connection对象归还给池，这样后续还可以从池中获取Connection对象，可以重新再利用这个连接对象啦。

java为数据库连接池提供了公共接口：javax.sql.DataSource,各个厂商需要让自己的连接池实现这个接口。

常见的连接池：DBCP,C3P0

2、自定义连接池

编写自定义连接池

1、创建连接池并实现接口javax.sql.DataSource，并使用接口中的getConnection()方法

2、提供一个集合，用于存放连接，可以采用LinkedList

3、后面程序如果需要，可以调用实现类getConnection(),并从list中获取链接。为保证当前连接只能提供给一个线程使用，所以我们需要将连接先从连接池中移除

4、当用户用完连接后，将连接归还到连接池中

3、自定义连接池采用装饰者设计模式

public class ConnectionPool implements Connection {

private Connection connection;

private LinkedList pool;

public ConnectionPool(Connection connection, LinkedList pool){

this.connection=connection;

this.pool=pool;

}

@Override

public PreparedStatement prepareStatement(String sql) throws SQLException {

return connection.prepareStatement(sql);

}

@Override

public void close() throws SQLException {

pool.add(connection);

}

@Override

public Statement createStatement() throws SQLException {

return null;

}

@Override

public CallableStatement prepareCall(String sql) throws SQLException {

return null;

}

@Override

public String nativeSQL(String sql) throws SQLException {

return null;

}

@Override

public void setAutoCommit(boolean autoCommit) throws SQLException {

}

@Override

public boolean getAutoCommit() throws SQLException {

return false;

}

@Override

public void commit() throws SQLException {

}

@Override

public void rollback() throws SQLException {

}

@Override

public boolean isClosed() throws SQLException {

return false;

}

@Override

public DatabaseMetaData getMetaData() throws SQLException {

return null;

}

@Override

public void setReadOnly(boolean readOnly) throws SQLException {

}

@Override

public boolean isReadOnly() throws SQLException {

return false;

}

@Override

public void setCatalog(String catalog) throws SQLException {

}

@Override

public String getCatalog() throws SQLException {

return null;

}

@Override

public void setTransactionIsolation(int level) throws SQLException {

}

@Override

public int getTransactionIsolation() throws SQLException {

return 0;

}

@Override

public SQLWarning getWarnings() throws SQLException {

return null;

}

@Override

public void clearWarnings() throws SQLException {

}

@Override

public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {

return null;

}

@Override

public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {

return null;

}

@Override

public CallableStatement prepareCall(String sql, int resultSetType, int rehttp://sultSetConcurrency) throws SQLException {

return null;

}

@Override

public Map> getTypeMap() throws SQLException {

return null;

}

@Override

public void setTypeMap(Map> map) throws SQLException {

}

@Override

public void setHoldability(int holdability) throws SQLException {

}

@Override

public int getHoldability() throws SQLException {

return 0;

}

@Override

public Savepoint setSavepoint() throws SQLException {

return null;

}

@Override

public Savepoint setSavepoint(String name) throws SQLException {

return null;

}

@Override

public void rollback(Savepoint savepoint) throws SQLException {

}

@Override

public void releaseSavepoint(Savepoint savepoint) throws SQLException {

}

@Override

public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {

return null;

}

@Override

public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {

return null;

}

@Override

public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {

return null;

}

@Override

public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {

return null;

}

@Override

public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {

return null;

}

@Override

public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {

return null;

}

@Override

public Clob createClob() throws SQLException {

return null;

}

@Override

public Blob createBlob() throws SQLException {

return null;

}

@Override

public NClob createNClob() throws SQLException {

return null;

}

@Override

public SQLXML createSQLXML() throws SQLException {

return null;

}

@Override

public boolean isValid(int timeout) throws SQLException {

return false;

}

@Override

public void setClientInfo(String name, String value) throws SQLClientInfoException {

}

@Override

public void setClientInfo(Properties properties) throws SQLClientInfoException {

}

@Override

public String getClientInfo(String name) throws SQLException {

return null;

}

@Override

public Properties getClientInfo() throws SQLException {

return null;

}

@Override

public Array createArrayOf(String typeName, Object[] elements) throws SQLException {

return null;

}

@Override

public Struct createStruct(String typeName, Object[] attributes) throws SQLException {

return null;

}

@Override

public void setSchema(String schema) throws SQLException {

}

@Override

public String getSchema() throws SQLException {

return null;

}

@Override

public void abort(Executor executor) throws SQLException {

}

@Override

public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {

}

@Override

public int getNetworkTimeout() throws SQLException {

return 0;

}

@Override

public T unwrap(Class iface) throws SQLException {

return null;

}

@Override

public boolean isWrapperFor(Class> iface) throws SQLException {

return false;

}

}

DataSourcePool

public class DataSourcePool implements DataSource {

//1.创建1个容器用于存储Connection对象

private static LinkedList pool = new LinkedList();

//2.创建5个连接放到容器中去

static{

for (int i = 0; i < 5; i++) {

Connection conn = JDBCUtils.getConnection();

//放入池子中connection对象已经经过改造了

ConnectionPool connectionPool = new ConnectionPool(conn, pool);

pool.add(connectionPool);

}

}

/**

* 重写获取连接的方法

*/

@Override

public Connection getConnection() throws SQLException {

Connection conn = null;

//3.使用前先判断

if(pool.size()==0){

//4.池子里面没有，我们再创建一些

for (int i = 0; i < 5; i++) {

conn = JDBCUtils.getConnection();

//放入池子中connection对象已经经过改造了

ConnectionPool connectionPool = new ConnectionPool(conn, pool);

pool.add(connectionPool);

}

}

//5.从池子里面获取一个连接对象Connection

conn = pool.remove(0);

return conn;

}

@Override

public Connection getConnection(String username, String password) throws SQLException {

return null;

}

@Override

public T unwrap(Class iface) throws SQLException {

return null;

}

@Override

public boolean isWrapperFor(Class> iface) throws SQLException {

return false;

}

@Override

public PrintWriter getLogWriter() throws SQLException {

return null;

}

@Override

public void setLogWriter(PrintWriter out) throws SQLException {

}

@Override

public void setLoginTimeout(int seconds) throws SQLException {

}

@Override

public int getLoginTimeout() throws SQLException {

return 0;

}

@Override

public Logger getParentLogger() throws SQLFeatureNotSupportedException {

return null;

}

}

测试代码如下

@Test

public void test1(){

Connection conn = null;

PreparedStatement pstmt = null;

// 1.创建自定义连接池对象

DataSource dataSource = new DataSourcePool();

try {

// 2.从池子中获取连接

conn = dataSource.getConnection();

String sql = "insert into USER values(?,?)";

/http:///3.必须在自定义的connection类中重写prepareStatement(sql)方法

pstmt = conn.prepareStatement(sql);

pstmt.setString(1http://, "李四");

pstmt.setString(2, "1234");

int rows = pstmt.executeUpdate();

System.out.println("rows:"+rows);

} catch (Exception e) {

throw new RuntimeException(e);

} finally {

JDBCUtils.relase(conn, pstmt, null);

}

}

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