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1: /* SelectorProvider.java 2: Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: package java.nio.channels.spi; 39: 40: import gnu.java.nio.SelectorProviderImpl; 41: 42: import java.io.IOException; 43: import java.nio.channels.Channel; 44: import java.nio.channels.DatagramChannel; 45: import java.nio.channels.Pipe; 46: import java.nio.channels.ServerSocketChannel; 47: import java.nio.channels.SocketChannel; 48: 49: import java.security.AccessController; 50: import java.security.PrivilegedAction; 51: 52: /** 53: * @author Michael Koch 54: * @since 1.4 55: */ 56: public abstract class SelectorProvider 57: { 58: private static SelectorProvider systemDefaultProvider; 59: 60: /** 61: * Initializes the selector provider. 62: * 63: * @exception SecurityException If a security manager has been installed and 64: * it denies @see RuntimePermission ("selectorProvider"). 65: */ 66: protected SelectorProvider() 67: { 68: SecurityManager sm = System.getSecurityManager(); 69: if (sm != null) 70: sm.checkPermission(new RuntimePermission("selectorProvider")); 71: } 72: 73: /** 74: * Opens a datagram channel. 75: * 76: * @return a new datagram channel object 77: * 78: * @exception IOException if an error occurs 79: */ 80: public abstract DatagramChannel openDatagramChannel() 81: throws IOException; 82: 83: /** 84: * Opens a pipe. 85: * 86: * @return a new pipe object 87: * 88: * @exception IOException if an error occurs 89: */ 90: public abstract Pipe openPipe() throws IOException; 91: 92: /** 93: * Opens a selector. 94: * 95: * @return a new selector object 96: * 97: * @exception IOException if an error occurs 98: */ 99: public abstract AbstractSelector openSelector() throws IOException; 100: 101: /** 102: * Opens a server socket channel. 103: * 104: * @return a new server socket channel object 105: * 106: * @exception IOException if an error occurs 107: */ 108: public abstract ServerSocketChannel openServerSocketChannel() 109: throws IOException; 110: 111: /** 112: * Opens a socket channel. 113: * 114: * @return a new socket channel object 115: * 116: * @exception IOException if an error occurs 117: */ 118: public abstract SocketChannel openSocketChannel() throws IOException; 119: 120: /** 121: * Returns the inherited channel of the VM. 122: * 123: * @return the inherited channel of the VM 124: * 125: * @throws IOException If an I/O error occurs 126: * @throws SecurityException If an installed security manager denies access 127: * to RuntimePermission("inheritedChannel") 128: * 129: * @since 1.5 130: */ 131: public Channel inheritedChannel() 132: throws IOException 133: { 134: SecurityManager sm = System.getSecurityManager(); 135: if (sm != null) 136: { 137: sm.checkPermission(new RuntimePermission("inheritedChannel")); 138: } 139: // Implementation note: The default implementation can't do much more 140: // than return null. If a VM can provide something more useful it should 141: // install its own SelectorProvider (maybe a subclass of this one) to 142: // return something more useful. 143: return null; 144: } 145: 146: /** 147: * Returns the system-wide default selector provider for this invocation 148: * of the Java virtual machine. 149: * 150: * @return the default selector provider 151: */ 152: public static synchronized SelectorProvider provider() 153: { 154: if (systemDefaultProvider == null) 155: { 156: String propertyValue = AccessController.doPrivileged(new PrivilegedAction<String> () { 157: public String run() 158: { 159: return System.getProperty("java.nio.channels.spi.SelectorProvider"); 160: } 161: }); 162: 163: if (propertyValue == null || propertyValue.equals("")) 164: systemDefaultProvider = new SelectorProviderImpl(); 165: else 166: { 167: try 168: { 169: systemDefaultProvider = 170: (SelectorProvider) Class.forName(propertyValue) 171: .newInstance(); 172: } 173: catch (Exception e) 174: { 175: System.err.println("Could not instantiate class: " 176: + propertyValue); 177: systemDefaultProvider = new SelectorProviderImpl(); 178: } 179: } 180: } 181: 182: return systemDefaultProvider; 183: } 184: }