JDBC自定义连接池
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2022-03-28 16:28:55
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Conn ......
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<connection> pool; public connectionpool(connection connection, linkedlist<connection> 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 resultsetconcurrency) throws sqlexception { return null; } @override public map<string, class<?>> gettypemap() throws sqlexception { return null; } @override public void settypemap(map<string, class<?>> 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> t unwrap(class<t> 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<connection> pool = new linkedlist<connection>(); //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> t unwrap(class<t> 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(?,?)"; //3.必须在自定义的connection类中重写preparestatement(sql)方法 pstmt = conn.preparestatement(sql); pstmt.setstring(1, "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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