连接池增强close方法的原理

Posted 2020-10-22

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import java.io.PrintWriter;
import java.sql.Array;
import java.sql.Blob;
import java.sql.CallableStatement;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.NClob;
import java.sql.PreparedStatement;
import java.sql.SQLClientInfoException;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.sql.SQLWarning;
import java.sql.SQLXML;
import java.sql.Savepoint;
import java.sql.Statement;
import java.sql.Struct;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;
import java.util.logging.Logger;

import javax.sql.DataSource;

import org.junit.Test;

public class test {br/>@Test
public void test(){
Connection connection = null;
PreparedStatement prepareStatement = null;
try {
DataSource dataSource = new MyDataSource();
connection = dataSource.getConnection();
String sql ="insert into product values (null,?,?,?)";
prepareStatement = connection.prepareStatement(sql);
prepareStatement.setString(1, "柠檬");
prepareStatement.setDouble(2, 10.00);
prepareStatement.setObject(3, new Date());
int executeUpdate = prepareStatement.executeUpdate();
if(executeUpdate!=0){
System.out.println("插入成功");
}else{
System.out.println("插入失败");
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
if(prepareStatement!=null){
prepareStatement.close();
}
if(connection!=null){
connection.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}

}
class MyDataSource implements DataSource{
List<Connection> list = new ArrayList<Connection>();
public MyDataSource() {//我的链接池一初始化就有5个链接
for (int i = 0; i < 5; i++) {
try {
Class.forName("com.mysql.jdbc.Driver");
Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","root");
list.add(connection);
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
}

    }
}
/**
 * 获得增强后的链接
 */
@Override
public Connection getConnection() throws SQLException {
    Connection connection = list.remove(0);
    ConnectionWrapper connectionWrapper = new ConnectionWrapper(connection, list);
    return connectionWrapper;
}
@Override
public PrintWriter getLogWriter() throws SQLException {
    return null;
}

@Override
public void setLogWriter(PrintWriter out) throws SQLException {
}

@Override
public void setLoginTimeout(int seconds) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public int getLoginTimeout() throws SQLException {
    // TODO Auto-generated method stub
    return 0;
}

@Override
public Logger getParentLogger() throws SQLFeatureNotSupportedException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public <T> T unwrap(Class<T> iface) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public boolean isWrapperFor(Class<?> iface) throws SQLException {
    // TODO Auto-generated method stub
    return false;
}

@Override
public Connection getConnection(String username, String password) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

}
/*

增强的类
缺点：被增强类中如果有多个方法，增强类中需要多次调用

@author WangShuang
*/
class ConnectionWrapper implements Connection{
private Connection con;
private List<Connection> list;

public ConnectionWrapper(Connection con,List<Connection> list) {
    this.con=con;
    this.list=list;
}
@Override
public void close() throws SQLException {
    list.add(con);
}
@Override
public <T> T unwrap(Class<T> iface) throws SQLException {
    return con.unwrap(iface);
}

@Override
public boolean isWrapperFor(Class<?> iface) throws SQLException {
    return con.isWrapperFor(iface);
}

@Override
public Statement createStatement() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public PreparedStatement prepareStatement(String sql) throws SQLException {
    return con.prepareStatement(sql);
}

@Override
public CallableStatement prepareCall(String sql) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public String nativeSQL(String sql) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void setAutoCommit(boolean autoCommit) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public boolean getAutoCommit() throws SQLException {
    // TODO Auto-generated method stub
    return false;
}

@Override
public void commit() throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public void rollback() throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public boolean isClosed() throws SQLException {
    // TODO Auto-generated method stub
    return false;
}

@Override
public DatabaseMetaData getMetaData() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void setReadOnly(boolean readOnly) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public boolean isReadOnly() throws SQLException {
    // TODO Auto-generated method stub
    return false;
}

@Override
public void setCatalog(String catalog) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public String getCatalog() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void setTransactionIsolation(int level) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public int getTransactionIsolation() throws SQLException {
    // TODO Auto-generated method stub
    return 0;
}

@Override
public SQLWarning getWarnings() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void clearWarnings() throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency)
        throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency)
        throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public Map<String, Class<?>> getTypeMap() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void setTypeMap(Map<String, Class<?>> map) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public void setHoldability(int holdability) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public int getHoldability() throws SQLException {
    // TODO Auto-generated method stub
    return 0;
}

@Override
public Savepoint setSavepoint() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public Savepoint setSavepoint(String name) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void rollback(Savepoint savepoint) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public void releaseSavepoint(Savepoint savepoint) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability)
        throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency,
        int resultSetHoldability) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency,
        int resultSetHoldability) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public Clob createClob() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public Blob createBlob() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public NClob createNClob() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public SQLXML createSQLXML() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public boolean isValid(int timeout) throws SQLException {
    // TODO Auto-generated method stub
    return false;
}

@Override
public void setClientInfo(String name, String value) throws SQLClientInfoException {
    // TODO Auto-generated method stub

}

@Override
public void setClientInfo(Properties properties) throws SQLClientInfoException {
    // TODO Auto-generated method stub

}

@Override
public String getClientInfo(String name) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public Properties getClientInfo() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public Array createArrayOf(String typeName, Object[] elements) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public Struct createStruct(String typeName, Object[] attributes) throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void setSchema(String schema) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public String getSchema() throws SQLException {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void abort(Executor executor) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {
    // TODO Auto-generated method stub

}

@Override
public int getNetworkTimeout() throws SQLException {
    // TODO Auto-generated method stub
    return 0;
}

}

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