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laogao598599 写道匿名内部类不一定是局部内部类,还 ...
匿名内部类访问外部类中的局部变量必须是final属性 -
laogao598599:
匿名内部类不一定是局部内部类,还可以作为成员变量
匿名内部类访问外部类中的局部变量必须是final属性 -
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把主键定义为自动增长标识符类型
使用Jakarta Commons Pool可以根据需要快速的实现自己的对象池,只需要实现PoolableObjectFactory或者KeyedPoolableObjectFactory接口。KeyedPoolableObjectFactory和PoolableObjectFactory的不同之处在于KeyedPoolableObjectFactory的每个方法都比PoolableObjectFactory多了一个Object key的参数,使用这个参数可以使得对象池中的每个对象都有所不同。
PoolableObjectFactory定义了五个方法(摘至Jakarta Commons Pool API文档):
makeObject is called whenever a new instance is needed.
activateObject is invoked on every instance before it is returned from the pool.
passivateObject is invoked on every instance when it is returned to the pool.
destroyObject is invoked on every instance when it is being "dropped" from the pool (whether due to the response from validateObject, or for reasons specific to the pool implementation.)
validateObject is invoked in an implementation-specific fashion to determine if an instance is still valid to be returned by the pool. It will only be invoked on an "activated" instance.
例子
import java.net.SocketAddress;
import java.nio.channels.SocketChannel;
import org.apache.commons.pool.KeyedPoolableObjectFactory;
/**
* <p>Title: </p>
*
* <p>Description: </p>
*
* <p>Copyright: Copyright (c) 2005</p>
*
* <p>Company: </p>
*
* @author George Hill
* @version 1.0
*/
public class SocketPoolableObjectFactory implements KeyedPoolableObjectFactory {
/**
* 创建新的对象
* @param key Object 创建对象需要用到的参数
* @return Object SocketChannel实例
* @throws Exception
*/
public Object makeObject(Object key) throws Exception {
SocketAddress address = (SocketAddress) key;
// 创建SocketChannel
SocketChannel channel = SocketChannel.open(address);
return channel;
}
/**
* 销毁对象
* @param key Object 创建对象时的参数
* @param obj Object 需要销毁的对象
* @throws Exception
*/
public void destroyObject(Object key, Object obj) throws Exception {
SocketChannel channel = (SocketChannel) obj;
if (channel != null)
channel.close();
channel = null;
}
/**
* 检验对象是否有效
* @param key Object 创建对象时的参数
* @param obj Object 需要进行检验的对象
* @return boolean 有效返回true,无效返回false
*/
public boolean validateObject(Object key, Object obj) {
SocketChannel channel = (SocketChannel) obj;
if (channel != null && channel.isOpen() && channel.isConnected())
return true;
return false;
}
/**
* 将对象激活,这里不需要做任何工作
* @param key Object
* @param obj Object
* @throws Exception
*/
public void activateObject(Object key, Object obj) throws Exception {
}
/**
* 将对象挂起,这里不需要做任何工作
* @param key Object
* @param obj Object
* @throws Exception
*/
public void passivateObject(Object key, Object obj) throws Exception {
}
}
测试
import java.io.IOException;
import java.net.*;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.*;
import org.apache.commons.pool.*;
import org.apache.commons.pool.impl.*;
public class TestThread implements Runnable {
// 线程名称
private String name;
// 对象池
private KeyedObjectPool pool;
// 连接的网络地址
private InetSocketAddress address;
public TestThread(String name, KeyedObjectPool pool,
InetSocketAddress address) {
this.name = name;
this.pool = pool;
this.address = address;
}
public void run() {
System.out.println(name + ": Client Start");
SocketChannel channel = null;
try {
channel = (SocketChannel) pool.borrowObject(address);
}
catch (Exception ex) {
ex.printStackTrace();
}
// 从对象池中借出对象成功
if (channel != null) {
System.out.println(name + ": Borrow Channel successfully!");
try {
channel.configureBlocking(false);
// 创建Selector
Selector selector = Selector.open();
// 向Selector注册我们需要的READ事件
SelectionKey skey = channel.register(selector, SelectionKey.OP_READ);
boolean stop = false;
int n = 0;
int read = 0;
ByteBuffer buffer = ByteBuffer.allocate(1024);
System.out.println("Client Start");
// 轮询
while (!stop) {
// 获取Selector返回的时间值
n = selector.select();
// 当传回的值大于0事,读事件发生了
if (n > 0) {
Set set = selector.selectedKeys();
Iterator it = set.iterator();
while (it.hasNext()) {
skey = (SelectionKey) it.next();
it.remove();
if (skey.isReadable()) {
SocketChannel sc = (SocketChannel) skey.channel();
while ( (read = sc.read(buffer)) != -1) {
if (read == 0) {
break;
}
buffer.flip();
byte[] array = new byte[read];
buffer.get(array);
String s = new String(array);
System.out.print(s);
buffer.clear();
if (s.indexOf("new") != -1) {
stop = true;
System.out.println();
}
}
}
}
}
}
}
catch (IOException ioe) {
ioe.printStackTrace();
}
try {
pool.returnObject(address, channel);
}
catch (Exception ex) {
ex.printStackTrace();
}
}
System.out.println(name + ": Client Stop");
}
public static void main(String[] args) throws Exception {
SocketPoolableObjectFactory factory = new SocketPoolableObjectFactory();
StackKeyedObjectPoolFactory poolFactory = new StackKeyedObjectPoolFactory(factory);
KeyedObjectPool pool = poolFactory.createPool();
// 创建连接清华BBS的线程
Thread t1 = new Thread(new TestThread("清华", pool, new InetSocketAddress("bbs.tsinghua.edu.cn", 23)));
t1.start();
// 创建连接华南理工BBS的线程
Thread t2 = new Thread(new TestThread("华南理工", pool, new InetSocketAddress("bbs.gznet.edu.cn", 23)));
t2.start();
}
}
参考
1. Jakarta Commons Pool网站:http://jakarta.apache.org/commons/pool/
2. IBM开发者的一篇很好的文章《使用Jakarta Commons Pool处理对象池化》 https://www.ibm.com/developerworks/cn/java/l-common-pool/
PoolableObjectFactory定义了五个方法(摘至Jakarta Commons Pool API文档):
makeObject is called whenever a new instance is needed.
activateObject is invoked on every instance before it is returned from the pool.
passivateObject is invoked on every instance when it is returned to the pool.
destroyObject is invoked on every instance when it is being "dropped" from the pool (whether due to the response from validateObject, or for reasons specific to the pool implementation.)
validateObject is invoked in an implementation-specific fashion to determine if an instance is still valid to be returned by the pool. It will only be invoked on an "activated" instance.
例子
import java.net.SocketAddress;
import java.nio.channels.SocketChannel;
import org.apache.commons.pool.KeyedPoolableObjectFactory;
/**
* <p>Title: </p>
*
* <p>Description: </p>
*
* <p>Copyright: Copyright (c) 2005</p>
*
* <p>Company: </p>
*
* @author George Hill
* @version 1.0
*/
public class SocketPoolableObjectFactory implements KeyedPoolableObjectFactory {
/**
* 创建新的对象
* @param key Object 创建对象需要用到的参数
* @return Object SocketChannel实例
* @throws Exception
*/
public Object makeObject(Object key) throws Exception {
SocketAddress address = (SocketAddress) key;
// 创建SocketChannel
SocketChannel channel = SocketChannel.open(address);
return channel;
}
/**
* 销毁对象
* @param key Object 创建对象时的参数
* @param obj Object 需要销毁的对象
* @throws Exception
*/
public void destroyObject(Object key, Object obj) throws Exception {
SocketChannel channel = (SocketChannel) obj;
if (channel != null)
channel.close();
channel = null;
}
/**
* 检验对象是否有效
* @param key Object 创建对象时的参数
* @param obj Object 需要进行检验的对象
* @return boolean 有效返回true,无效返回false
*/
public boolean validateObject(Object key, Object obj) {
SocketChannel channel = (SocketChannel) obj;
if (channel != null && channel.isOpen() && channel.isConnected())
return true;
return false;
}
/**
* 将对象激活,这里不需要做任何工作
* @param key Object
* @param obj Object
* @throws Exception
*/
public void activateObject(Object key, Object obj) throws Exception {
}
/**
* 将对象挂起,这里不需要做任何工作
* @param key Object
* @param obj Object
* @throws Exception
*/
public void passivateObject(Object key, Object obj) throws Exception {
}
}
测试
import java.io.IOException;
import java.net.*;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.*;
import org.apache.commons.pool.*;
import org.apache.commons.pool.impl.*;
public class TestThread implements Runnable {
// 线程名称
private String name;
// 对象池
private KeyedObjectPool pool;
// 连接的网络地址
private InetSocketAddress address;
public TestThread(String name, KeyedObjectPool pool,
InetSocketAddress address) {
this.name = name;
this.pool = pool;
this.address = address;
}
public void run() {
System.out.println(name + ": Client Start");
SocketChannel channel = null;
try {
channel = (SocketChannel) pool.borrowObject(address);
}
catch (Exception ex) {
ex.printStackTrace();
}
// 从对象池中借出对象成功
if (channel != null) {
System.out.println(name + ": Borrow Channel successfully!");
try {
channel.configureBlocking(false);
// 创建Selector
Selector selector = Selector.open();
// 向Selector注册我们需要的READ事件
SelectionKey skey = channel.register(selector, SelectionKey.OP_READ);
boolean stop = false;
int n = 0;
int read = 0;
ByteBuffer buffer = ByteBuffer.allocate(1024);
System.out.println("Client Start");
// 轮询
while (!stop) {
// 获取Selector返回的时间值
n = selector.select();
// 当传回的值大于0事,读事件发生了
if (n > 0) {
Set set = selector.selectedKeys();
Iterator it = set.iterator();
while (it.hasNext()) {
skey = (SelectionKey) it.next();
it.remove();
if (skey.isReadable()) {
SocketChannel sc = (SocketChannel) skey.channel();
while ( (read = sc.read(buffer)) != -1) {
if (read == 0) {
break;
}
buffer.flip();
byte[] array = new byte[read];
buffer.get(array);
String s = new String(array);
System.out.print(s);
buffer.clear();
if (s.indexOf("new") != -1) {
stop = true;
System.out.println();
}
}
}
}
}
}
}
catch (IOException ioe) {
ioe.printStackTrace();
}
try {
pool.returnObject(address, channel);
}
catch (Exception ex) {
ex.printStackTrace();
}
}
System.out.println(name + ": Client Stop");
}
public static void main(String[] args) throws Exception {
SocketPoolableObjectFactory factory = new SocketPoolableObjectFactory();
StackKeyedObjectPoolFactory poolFactory = new StackKeyedObjectPoolFactory(factory);
KeyedObjectPool pool = poolFactory.createPool();
// 创建连接清华BBS的线程
Thread t1 = new Thread(new TestThread("清华", pool, new InetSocketAddress("bbs.tsinghua.edu.cn", 23)));
t1.start();
// 创建连接华南理工BBS的线程
Thread t2 = new Thread(new TestThread("华南理工", pool, new InetSocketAddress("bbs.gznet.edu.cn", 23)));
t2.start();
}
}
参考
1. Jakarta Commons Pool网站:http://jakarta.apache.org/commons/pool/
2. IBM开发者的一篇很好的文章《使用Jakarta Commons Pool处理对象池化》 https://www.ibm.com/developerworks/cn/java/l-common-pool/
发表评论
-
java.lang.ClassCircularityError
2015-07-27 00:39 1269类循环依赖错误。在初始化一个类时,若检测到类之间循环依赖则抛出 ... -
随记内容
2015-06-09 00:10 0public static CloseableHttpClie ... -
httpclient3.1使用小结
2017-08-18 00:08 640Jakarta的httpclient3.1是 ... -
POI
2014-05-21 16:08 513Apache POI是一个开源的Java读写Excel、WOR ... -
servlet与js 跳转
2014-05-15 17:19 807servlet跳转 1.request.getRequestD ... -
jdk各个版本下载地址
2014-05-12 17:40 893http://www.oracle.com/technetwo ... -
Jackson库
2014-04-20 13:17 905概述 Jackson库(http://jac ... -
生成Webservice客户端的4种方法
2014-04-09 15:39 10481.使用Axis生产客户端代码(另存为bat文件) 之前很多次 ... -
map遍历
2013-12-14 23:41 477Map<String, String> map = ... -
POI处理Excel
2013-12-14 22:44 8451.读取2003 InputStream stream ... -
常用数据库 JDBC URL 格式
2013-12-04 18:35 1089Microsoft SQL Server Microsoft ... -
公共查询接口
2013-12-04 15:19 1136http://www.webmasterhome.cn/ ht ... -
天气预报接口
2013-12-04 11:18 1357天气预报接口(中国天气网) 中国天气weather.com ... -
Java 判断文件夹、文件是否存在
2013-12-04 10:00 50591、判断文件是否存在,不存在创建文件 File file=ne ... -
多线程读写资料利器-ReentrantReadWriteLock
2013-12-03 14:49 1261多线程读写文件利器-ReentrantReadWriteLoc ... -
保持顺序的 Java Properties 类
2013-12-02 16:21 858public class OrderedProperties ... -
java中用poi处理Excel表格之读取
2013-11-18 16:24 1987http://tool.oschina.net/apidocs ... -
科大讯飞语音识别服务
2013-09-03 17:06 13431.官方地址:http://open.voicecloud.c ... -
ibatis数据库字段带下划线(_)映射与java类不一致
2013-08-24 17:00 5267ibatis数据库字段带下划线(_)与java pojo对象映 ... -
Java Timer
2013-05-28 15:07 10121)java.util.Timer. 2)ServletC ...
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