Apache Commons Pool试用小记
本文共 7804 字，大约阅读时间需要 26 分钟。
相比众多牛人的自己连接池，Apache的Pool就是牛中的大牛了，这里小试一把。
环境：
commons-pool-1.5.3-bin.zip
jdk1.5
一、基本String对象测试
import org.apache.commons.pool.impl.GenericKeyedObjectPool;
import org.apache.commons.pool.BaseKeyedPoolableObjectFactory;
/** * Created by IntelliJ IDEA. * * @author leizhimin 2009-10-27 17:46:18 */
public class Test {
public static void main(String[] args) throws Exception {
//创建一个对象池
GenericKeyedObjectPool pool = new GenericKeyedObjectPool( new BaseKeyedPoolableObjectFactory() {
@Override
public Object makeObject(Object o) throws Exception {
return o;
}
});
//添加对象到池，重复的不会重复入池
pool.addObject( "a");
pool.addObject( "a");
pool.addObject( "b");
pool.addObject( "x");
//清除最早的对象
pool.clearOldest();
//获取并输出对象
System.out.println(pool.borrowObject( "a"));
System.out.println(pool.borrowObject( "b"));
System.out.println(pool.borrowObject( "c"));
System.out.println(pool.borrowObject( "c"));
System.out.println(pool.borrowObject( "a"));
//输出池状态
System.out.println(pool.getMaxIdle());
System.out.println(pool.getMaxActive());
}
}
import org.apache.commons.pool.BaseKeyedPoolableObjectFactory;
/** * Created by IntelliJ IDEA. * * @author leizhimin 2009-10-27 17:46:18 */
public class Test {
public static void main(String[] args) throws Exception {
//创建一个对象池
GenericKeyedObjectPool pool = new GenericKeyedObjectPool( new BaseKeyedPoolableObjectFactory() {
@Override
public Object makeObject(Object o) throws Exception {
return o;
}
});
//添加对象到池，重复的不会重复入池
pool.addObject( "a");
pool.addObject( "a");
pool.addObject( "b");
pool.addObject( "x");
//清除最早的对象
pool.clearOldest();
//获取并输出对象
System.out.println(pool.borrowObject( "a"));
System.out.println(pool.borrowObject( "b"));
System.out.println(pool.borrowObject( "c"));
System.out.println(pool.borrowObject( "c"));
System.out.println(pool.borrowObject( "a"));
//输出池状态
System.out.println(pool.getMaxIdle());
System.out.println(pool.getMaxActive());
}
}
输出结果：
a
b
c
c
a
8
8
Process finished with exit code 0
b
c
c
a
8
8
Process finished with exit code 0
当运行到清除最早对象一行，内存状态如下：
初略看看，Apache Commons pool功能还很强大，DBCP数据库连接池就用了它，还可以对其进行参数配置。
二、自定义复杂对象测试
import org.apache.commons.pool.impl.GenericKeyedObjectPool;
import org.apache.commons.pool.BaseKeyedPoolableObjectFactory;
/** * Created by IntelliJ IDEA. * * @author leizhimin 2009-10-27 17:46:18 */
public class Test {
public static void main(String[] args) throws Exception {
//创建一个对象池
GenericKeyedObjectPool pool = new GenericKeyedObjectPool( new BaseKeyedPoolableObjectFactory() {
@Override
public Object makeObject(Object o) throws Exception {
if (o != null && o instanceof User)
return o;
else
return null;
}
});
//添加对象到池，重复的不会重复入池
pool.addObject( "a");
pool.addObject( "b");
pool.addObject( "x");
pool.addObject( null);
pool.addObject( null);
pool.addObject( null);
pool.addObject( new User( "zhangsan", "123"));
pool.addObject( new User( "lisi", "112"));
pool.addObject( new User( "lisi", "112", 32));
pool.addObject( new User( "lisi", "112", 32, "一个烂人！"));
//清除最早的对象
pool.clearOldest();
//获取并输出对象
User u1 = new User( "lisi", "112", 32, "一个烂人！");
System.out.println(pool.borrowObject(u1));
pool.returnObject(u1,u1);
//获取并输出对象
User u2 = new User( "lisi", "112", 32, "一个烂人！");
System.out.println(pool.borrowObject(u2));
pool.returnObject(u2,u2);
//获取并输出对象
User u3 = new User( "lisi", "112", 32);
System.out.println(pool.borrowObject(u3));
pool.returnObject(u3,u3);
//获取并输出对象
User u4 = new User( "lisi", "112");
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject( new User( "lisi", "112")));
// System.out.println(pool.borrowObject(new User("lisi", "112")));
//输出池状态
System.out.println(pool.getMaxIdle());
System.out.println(pool.getMaxActive());
pool.clearOldest();
pool.close();
}
}
class User {
private String name;
private String pswd;
private int age;
private String reamark;
User() {
}
User(String name, String pswd) {
this.name = name;
this.pswd = pswd;
}
User(String name, String pswd, int age) {
this.name = name;
this.pswd = pswd;
this.age = age;
}
User(String name, String pswd, int age, String reamark) {
this.name = name;
this.pswd = pswd;
this.age = age;
this.reamark = reamark;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPswd() {
return pswd;
}
public void setPswd(String pswd) {
this.pswd = pswd;
}
public int getAge() {
return age;
}
public void setAge( int age) {
this.age = age;
}
public String getReamark() {
return reamark;
}
public void setReamark(String reamark) {
this.reamark = reamark;
}
@Override
public boolean equals(Object o) {
if ( this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
User user = (User) o;
if (!name.equals(user.name)) return false;
if (!pswd.equals(user.pswd)) return false;
return true;
}
@Override
public int hashCode() {
int result = name.hashCode();
result = 31 * result + pswd.hashCode();
return result;
}
@Override
public String toString() {
return "User{" +
"name='" + name + '\'' +
", pswd='" + pswd + '\'' +
", age=" + age +
", reamark='" + reamark + '\'' +
'}';
}
}
import org.apache.commons.pool.BaseKeyedPoolableObjectFactory;
/** * Created by IntelliJ IDEA. * * @author leizhimin 2009-10-27 17:46:18 */
public class Test {
public static void main(String[] args) throws Exception {
//创建一个对象池
GenericKeyedObjectPool pool = new GenericKeyedObjectPool( new BaseKeyedPoolableObjectFactory() {
@Override
public Object makeObject(Object o) throws Exception {
if (o != null && o instanceof User)
return o;
else
return null;
}
});
//添加对象到池，重复的不会重复入池
pool.addObject( "a");
pool.addObject( "b");
pool.addObject( "x");
pool.addObject( null);
pool.addObject( null);
pool.addObject( null);
pool.addObject( new User( "zhangsan", "123"));
pool.addObject( new User( "lisi", "112"));
pool.addObject( new User( "lisi", "112", 32));
pool.addObject( new User( "lisi", "112", 32, "一个烂人！"));
//清除最早的对象
pool.clearOldest();
//获取并输出对象
User u1 = new User( "lisi", "112", 32, "一个烂人！");
System.out.println(pool.borrowObject(u1));
pool.returnObject(u1,u1);
//获取并输出对象
User u2 = new User( "lisi", "112", 32, "一个烂人！");
System.out.println(pool.borrowObject(u2));
pool.returnObject(u2,u2);
//获取并输出对象
User u3 = new User( "lisi", "112", 32);
System.out.println(pool.borrowObject(u3));
pool.returnObject(u3,u3);
//获取并输出对象
User u4 = new User( "lisi", "112");
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject(u4));
pool.returnObject(u4,u4);
System.out.println(pool.borrowObject( new User( "lisi", "112")));
// System.out.println(pool.borrowObject(new User("lisi", "112")));
//输出池状态
System.out.println(pool.getMaxIdle());
System.out.println(pool.getMaxActive());
pool.clearOldest();
pool.close();
}
}
class User {
private String name;
private String pswd;
private int age;
private String reamark;
User() {
}
User(String name, String pswd) {
this.name = name;
this.pswd = pswd;
}
User(String name, String pswd, int age) {
this.name = name;
this.pswd = pswd;
this.age = age;
}
User(String name, String pswd, int age, String reamark) {
this.name = name;
this.pswd = pswd;
this.age = age;
this.reamark = reamark;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPswd() {
return pswd;
}
public void setPswd(String pswd) {
this.pswd = pswd;
}
public int getAge() {
return age;
}
public void setAge( int age) {
this.age = age;
}
public String getReamark() {
return reamark;
}
public void setReamark(String reamark) {
this.reamark = reamark;
}
@Override
public boolean equals(Object o) {
if ( this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
User user = (User) o;
if (!name.equals(user.name)) return false;
if (!pswd.equals(user.pswd)) return false;
return true;
}
@Override
public int hashCode() {
int result = name.hashCode();
result = 31 * result + pswd.hashCode();
return result;
}
@Override
public String toString() {
return "User{" +
"name='" + name + '\'' +
", pswd='" + pswd + '\'' +
", age=" + age +
", reamark='" + reamark + '\'' +
'}';
}
}
测试结果：
User{name='lisi', pswd='112', age=32, reamark=' null'}
User{name='lisi', pswd='112', age=32, reamark='一个烂人！'}
User{name='lisi', pswd='112', age=32, reamark='一个烂人！'}
User{name='lisi', pswd='112', age=32, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
8
8
Process finished with exit code 0
User{name='lisi', pswd='112', age=32, reamark='一个烂人！'}
User{name='lisi', pswd='112', age=32, reamark='一个烂人！'}
User{name='lisi', pswd='112', age=32, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
User{name='lisi', pswd='112', age=0, reamark=' null'}
8
8
Process finished with exit code 0
内存状态：
这次测试得出一些有用的结论：
1、复杂对象应该实现equals() 、hashCode()方法，以便不重复入池。
2、对于非入池的目标对象，比如a、b、x字符串，目前没有有效的办法过滤掉，不让其入池，虽然在工厂方法里做了努力。
3、试图将null入池，不会成功的，但也不抛异常。
4、对于池对象，使用应该遵循“接而有还，再借不难”-----从池中获取，不用时候归池，否则当池中没有空闲可用的对象时候，程序会处于等待状态，如果没有显式的调用归还方法，则造成程序死锁。
三、使用GenericObjectPool
import org.apache.commons.pool.impl.GenericObjectPool;
import org.apache.commons.pool.BasePoolableObjectFactory;
import java.util.Random;
/** * Created by IntelliJ IDEA. * * @author leizhimin 2009-10-28 10:51:11 */
public class Test2 {
public static void main(String[] args) throws Exception {
GenericObjectPool pool = new GenericObjectPool( new BasePoolableObjectFactory() {
public Object makeObject() throws Exception {
return new Random().nextFloat();
}
});
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
Object o = pool.borrowObject();
System.out.println(o);
pool.returnObject(o);
Object o1 = pool.borrowObject();
System.out.println(o1);
Object o2 = pool.borrowObject();
System.out.println(o2);
Object o3 = pool.borrowObject();
System.out.println(o3);
Object o4 = pool.borrowObject();
System.out.println(o4);
Object o5 = pool.borrowObject();
System.out.println(o5);
Object o6 = pool.borrowObject();
System.out.println(o6);
Object o7 = pool.borrowObject();
System.out.println(o7);
Object o8 = pool.borrowObject();
System.out.println(o8);
pool.returnObject(o1);
pool.returnObject(o2);
pool.returnObject(o3);
pool.returnObject(o4);
pool.returnObject(o5);
pool.returnObject(o6);
pool.returnObject(o7);
pool.returnObject(o8);
Object o9 = pool.borrowObject();
System.out.println(o9);
pool.returnObject(o9);
Object o10 = pool.borrowObject();
System.out.println(o10);
pool.returnObject(o10);
Object o11 = pool.borrowObject();
System.out.println(o11);
pool.returnObject(o11);
Object o12 = pool.borrowObject();
System.out.println(o12);
pool.returnObject(o12);
Object o13 = pool.borrowObject();
System.out.println(o13);
pool.returnObject(o13);
}
}
import org.apache.commons.pool.BasePoolableObjectFactory;
import java.util.Random;
/** * Created by IntelliJ IDEA. * * @author leizhimin 2009-10-28 10:51:11 */
public class Test2 {
public static void main(String[] args) throws Exception {
GenericObjectPool pool = new GenericObjectPool( new BasePoolableObjectFactory() {
public Object makeObject() throws Exception {
return new Random().nextFloat();
}
});
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
pool.addObject();
Object o = pool.borrowObject();
System.out.println(o);
pool.returnObject(o);
Object o1 = pool.borrowObject();
System.out.println(o1);
Object o2 = pool.borrowObject();
System.out.println(o2);
Object o3 = pool.borrowObject();
System.out.println(o3);
Object o4 = pool.borrowObject();
System.out.println(o4);
Object o5 = pool.borrowObject();
System.out.println(o5);
Object o6 = pool.borrowObject();
System.out.println(o6);
Object o7 = pool.borrowObject();
System.out.println(o7);
Object o8 = pool.borrowObject();
System.out.println(o8);
pool.returnObject(o1);
pool.returnObject(o2);
pool.returnObject(o3);
pool.returnObject(o4);
pool.returnObject(o5);
pool.returnObject(o6);
pool.returnObject(o7);
pool.returnObject(o8);
Object o9 = pool.borrowObject();
System.out.println(o9);
pool.returnObject(o9);
Object o10 = pool.borrowObject();
System.out.println(o10);
pool.returnObject(o10);
Object o11 = pool.borrowObject();
System.out.println(o11);
pool.returnObject(o11);
Object o12 = pool.borrowObject();
System.out.println(o12);
pool.returnObject(o12);
Object o13 = pool.borrowObject();
System.out.println(o13);
pool.returnObject(o13);
}
}
输出：
0.7358789
0.7358789
0.15324193
0.7465391
0.7198403
0.7477861
0.37906575
0.049714446
0.9650687
0.9650687
0.9650687
0.9650687
0.9650687
0.9650687
Process finished with exit code 0
0.7358789
0.15324193
0.7465391
0.7198403
0.7477861
0.37906575
0.049714446
0.9650687
0.9650687
0.9650687
0.9650687
0.9650687
0.9650687
Process finished with exit code 0
从内存状态看到，这种对象池，没法将指定的对象入池，只能通过工厂生成对象入池，而且无法给工厂传递参数。
这种池适合数据库连接池等，所有的池对象拿出来都一样用。
经过上面三个例子综合测试得知，池的大小是初始化配置的，在没有显式配置指定的情况下，池大小默认为8.可以通过 来配置。
本文转自 leizhimin 51CTO博客，原文链接：http://blog.51cto.com/lavasoft/217547，如需转载请自行联系原作者
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