java.util.logging.Logger 和 log4j

Question

我正在尝试从这里编译代码： http://www.brackeen.com/javagamebook/#download （第 6 章）并且遇到了麻烦。 我不明白java.util.logging.Logger和 log4j 如何一起工作，但这似乎是问题所在。 我得到的错误都在log.error()或log.warn()方法调用上。

这是来自 NetBeans 的 output：

init:
deps-clean:
Deleting directory C:\JB\NetBeansProjects\WRServer\build
Deleting directory C:\JB\NetBeansProjects\WRServer\dist
clean:
init:
deps-jar:
Created dir: C:\JB\NetBeansProjects\WRServer\build\classes
Compiling 23 source files to C:\JB\NetBeansProjects\WRServer\build\classes
C:\JB\NetBeansProjects\WRServer\src\com\hypefiend\javagamebook\server\GameServer.java:110: cannot find symbol
symbol  : method error(java.lang.String,java.lang.Exception)
location: class java.util.logging.Logger
            log.error("error initializing ServerSocket", e);
               ^
C:\JB\NetBeansProjects\WRServer\src\com\hypefiend\javagamebook\server\GameServer.java:152: cannot find symbol
symbol  : method warn(java.lang.String)
location: class java.util.logging.Logger
                log.warn("error during serverSocket select(): " + ioe.getMessage());
                   ^
C:\JB\NetBeansProjects\WRServer\src\com\hypefiend\javagamebook\server\GameServer.java:155: cannot find symbol
symbol  : method error(java.lang.String,java.lang.Exception)
location: class java.util.logging.Logger
                log.error("exception in run()", e);
                   ^
C:\JB\NetBeansProjects\WRServer\src\com\hypefiend\javagamebook\server\GameServer.java:187: cannot find symbol
symbol  : method error(java.lang.String)
location: class java.util.logging.Logger
            log.error("no gamecontroller for gameNameHash: " + gameNameHash);
               ^
C:\JB\NetBeansProjects\WRServer\src\com\hypefiend\javagamebook\server\GameServer.java:203: cannot find symbol
symbol  : method error(java.lang.String)
location: class java.util.logging.Logger
            log.error("error getting GameController directory");
               ^
C:\JB\NetBeansProjects\WRServer\src\com\hypefiend\javagamebook\server\GameServer.java:223: cannot find symbol
symbol  : method warn(java.lang.String)
location: class java.util.logging.Logger
                    log.warn("class file does not extend GameController: " + file);
                       ^
C:\JB\NetBeansProjects\WRServer\src\com\hypefiend\javagamebook\server\GameServer.java:238: cannot find symbol
symbol  : method error(java.lang.String,java.lang.Exception)
location: class java.util.logging.Logger
                log.error("Error instantiating GameController from file: " + file, e);
                   ^
Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
7 errors
BUILD FAILED (total time: 0 seconds)

这是直接来自书中的代码。 我还没有尝试编辑它。

package com.hypefiend.javagamebook.server;

import com.hypefiend.javagamebook.common.*;
import com.hypefiend.javagamebook.server.controller.*;

import java.nio.channels.*;
import java.util.*;
import java.net.*;
import java.io.*;
import java.util.logging.Logger;
import org.apache.log4j.*;

/**
 * GameServer.java
 *
 * The heart of the framework, GameServer accepts
 * incoming client connections and hands them off to 
 * the SelectAndRead class.
 * GameServer also keeps track of the connected players
 * and the GameControllers.
 *
 * @author <a href="mailto:bret@hypefiend.com">bret barker</a>
 * @version 1.0
 */
public class GameServer extends Thread {
/** log4j Logger */
private Logger log = Logger.getLogger("GameServer");

/** ServerSocketChannel for accepting client connections */
private ServerSocketChannel sSockChan;

/** selector for multiplexing ServerSocketChannels */
private Selector selector;

/** GameControllers keyed by GameName */
private Hashtable gameControllers;

/** classname prefix used for dynamically loading GameControllers */
private static final String CONTROLLER_CLASS_PREFIX = 
"com.hypefiend.javagamebook.server.controller.";

/** players keyed by playerId */
private static Hashtable playersByPlayerId;

/** players keyed by sessionId */
private static Hashtable playersBySessionId;

private boolean running;
private SelectAndRead selectAndRead;
private EventWriter eventWriter;

private static long nextSessionId = 0;

/**
 * main. 
 * setup log4j and fireup the GameServer
 */
public static void main(String args[]) {
BasicConfigurator.configure();
GameServer gs = new GameServer();
gs.start();
}

/**
 * constructor, just initialize our hashtables
 */
public GameServer() {
gameControllers = new Hashtable();
playersByPlayerId = new Hashtable();
playersBySessionId = new Hashtable();
}

/**
 * init the GameServer, startup our workers, etc.
 */ 
public void init() {
log.info("GameServer initializing");

loadGameControllers();
initServerSocket();

selectAndRead = new SelectAndRead(this);
selectAndRead.start();

eventWriter = new EventWriter(this, Globals.EVENT_WRITER_WORKERS); 
}

/**
 * GameServer specific initialization, bind to the server port,
 * setup the Selector, etc.
 */
private void initServerSocket() {
try {
    // open a non-blocking server socket channel
    sSockChan = ServerSocketChannel.open();
    sSockChan.configureBlocking(false);

    // bind to localhost on designated port
    InetAddress addr = InetAddress.getLocalHost();
    log.info("binding to address: " + addr.getHostAddress());
    sSockChan.socket().bind(new InetSocketAddress(addr, Globals.PORT));

    // get a selector
    selector = Selector.open();

    // register the channel with the selector to handle accepts
    SelectionKey acceptKey = sSockChan.register(selector, SelectionKey.OP_ACCEPT);
}
catch (Exception e) {
    log.error("error initializing ServerSocket", e);
    System.exit(1);
}
}

/**
 * Here's the meat, loop over the select() call to 
 * accept socket connections and hand them off to SelectAndRead
 */
public void run() {
init();
log.info("******** GameServer running ********");
running = true;
int numReady = 0;

while (running) {
    // note, since we only have one ServerSocket to listen to,
    // we don't need a Selector here, but we set it up for 
    // later additions such as listening on another port 
    // for administrative uses.
    try {
    // blocking select, will return when we get a new connection
    selector.select();

    // fetch the keys
    Set readyKeys = selector.selectedKeys();

    // run through the keys and process
    Iterator i = readyKeys.iterator();
    while (i.hasNext()) {
        SelectionKey key = (SelectionKey) i.next();
        i.remove();

        ServerSocketChannel ssChannel = (ServerSocketChannel) key.channel();
        SocketChannel clientChannel = ssChannel.accept();

        // add to the list in SelectAndRead for processing
        selectAndRead.addNewClient(clientChannel);
        log.info("got connection from: " + clientChannel.socket().getInetAddress());
    }       
    }
    catch (IOException ioe) {
    log.warn("error during serverSocket select(): " + ioe.getMessage());
    }
    catch (Exception e) {
    log.error("exception in run()", e);
    }
}
}

/** 
 * shutdown the GameServer
 */
public void shutdown() {
selector.wakeup();
}

/**
 * Return the next available sessionId
 */
public synchronized String nextSessionId() {
return "" + nextSessionId++;
}

/**
 * finds the GameController for a given GameName
 */
public GameController getGameController(String gameName) {
return getGameControllerByHash(gameName.hashCode());
}

/**
 * finds the GameController for a given GameName hash code
 */
public GameController getGameControllerByHash(int gameNameHash) {
GameController gc = (GameController) gameControllers.get("" + gameNameHash);
if (gc == null) 
    log.error("no gamecontroller for gameNameHash: " + gameNameHash);
return gc;
}

/**
 *  Dynamically loads GameControllers
 */
private void loadGameControllers() {
log.info("loading GameControllers");

// grab all class files in the same directory as GameController
String baseClass = "com/hypefiend/javagamebook/server/controller/GameController.class";
File f = new File( this.getClass( ).getClassLoader().getResource(baseClass).getPath());
File[] files = f.getParentFile().listFiles( );

if (files == null) {
    log.error("error getting GameController directory");
    return;
}

for( int i = 0; ( i < files.length); i++) {
    String file = files[i].getName( );
    if (file.indexOf( ".class") == -1)
    continue;
    if (file.equals("GameController.class"))
    continue;

    try {
    // grab the class
    String controllerClassName = CONTROLLER_CLASS_PREFIX + file.substring(0, file.indexOf(".class"));
    log.info("loading class: " + controllerClassName);

    Class cl = Class.forName(controllerClassName);

    // make sure it extends GameController
    if (!GameController.class.isAssignableFrom(cl)) {
        log.warn("class file does not extend GameController: " + file);
        continue;
    }

    // get an instance and initialize
    GameController gc = (GameController) cl.newInstance();
    String gameName = gc.getGameName();
    gc.init(this, getGameConfig(gameName));

    // add to our controllers hash
    gameControllers.put("" + gameName.hashCode(), gc);

    log.info("loaded controller for gameName: " + gameName + ", hash: " + gameName.hashCode());
    } 
    catch (Exception e) {
    log.error("Error instantiating GameController from file: " + file, e);
    }
}
}


/**
 * pass the event on to the EventWriter
 */
public void writeEvent(GameEvent e) {
eventWriter.handleEvent(e);
}

/**
 * returns the GameConfig object for the given gameName
 */
public GameConfig getGameConfig(String gameName) {
// todo: implement getGameConfig()
return null;
}

/**
 * fetches the Player for a given playerId
 */
public static Player getPlayerById( String id) {
return (Player) playersByPlayerId.get(id);
}

/**
 * fetches the Player for a given sessionId
 */
public static Player getPlayerBySessionId(String id) {
return (Player) playersBySessionId.get(id);
}

/** 
 * add a player to our lists
 */
public static void addPlayer(Player p) {
playersByPlayerId.put(p.getPlayerId(), p);
playersBySessionId.put(p.getSessionId(), p);
}

/**
 * remove a player from our lists
 */
public static void removePlayer(Player p) {
playersByPlayerId.remove(p.getPlayerId());
playersBySessionId.remove(p.getPlayerId());
}

}// GameServer

Answer 1

java.util.logging.Logger没有warn()方法（尽管它有一个warning()方法）。

但是， org.apache.log4j.Logger确实有一个名为warn()的方法。

您确定要导入正确的类吗？

Answer 2

在您的 class 中导入 java.util.logging.Logger 似乎会导致问题（编译器尝试针对该问题进行编译，尽管其目的似乎是使用 Z2E025341F0D1BACE9F141876Z9 类）。

尝试从导入中删除 java.util.logging.Logger 并重新编译。

编辑：好吧，我刚刚检查了问题中链接的页面中链接的 ZIP 文件中的原始 GameServer.java。 它不包含 java.util.logging.Logger 的任何导入。 我的猜测是：

• 您的项目的类路径中没有 log4j
• 您或您的 IDE 试图以某种方式自动组织导入。 这最终将 java.util.logging.Logger 添加到导入中，因为在项目的类路径中没有找到该名称的其他 class。

因此，首先将 log4j 添加到类路径中，然后从导入中删除 java.util.logging.Logger。

Answer 3

你能格式化你的代码吗？ Ti 会更具可读性...

您正在尝试在 java.util.logger.Logger 的实例上调用 error(String, String) 方法。 没有这样的方法。 您应该改用 Logger.log(Level.SEVERE, "mesage")，或使用 log4J Logger 的实例。 检查源文件的导入部分...