package syn;
//不能改动此Test类
public class Test extends Thread{
private TestDo testDo;
private String key;
private String value;
public Test(String key,String key2,String value){
this.testDo = TestDo.getInstance();
/*常量"1"和"1"是同一个对象，下面这行代码就是要用"1"+""的方式产生新的对象，
以实现内容没有改变，仍然相等（都还为"1"），但对象却不再是同一个的效果*/
this.key = key+key2;
this.value = value;
}
public static void main(String[] args) throws InterruptedException{
Test a = new Test("1","","1");
Test b = new Test("1","","2");
Test c = new Test("3","","3");
Test d = new Test("4","","4");
System.out.println("begin:"+(System.currentTimeMillis()/1000));
a.start();
b.start();
c.start();
d.start();
}
public void run(){
testDo.doSome(key, value);
}
}
class TestDo {
private TestDo() {}
private static TestDo _instance = new TestDo();
public static TestDo getInstance() {
return _instance;
}
public void doSome(Object key, String value) {
// 以大括号内的是需要局部同步的代码，不能改动!
{
try {
Thread.sleep(1000);
System.out.println(key+":"+value + ":"
+ (System.currentTimeMillis() / 1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
改完后：
//不能改动此Test类
public class Test3 extends Thread {
private TestDo2 testDo2;
private String key;
private String value;
public Test3(String key, String key2, String value) {
this.testDo2 = TestDo2.getInstance();
/*常量"1"和"1"是同一个对象，下面这行代码就是要用"1"+""的方式产生新的对象，
以实现内容没有改变，仍然相等（都还为"1"），但对象却不再是同一个的效果*/
this.key = key + key2;
this.value = value;
}
public static void main(String[] args) throws InterruptedException {
Test3 a = new Test3("1", "", "1");
Test3 b = new Test3("1", "", "2");
Test3 c = new Test3("3", "", "3");
Test3 d = new Test3("4", "", "4");
System.out.println("begin:" + (System.currentTimeMillis() / 1000));
a.start();
b.start();
c.start();
d.start();
}
public void run() {
testDo2.doSome(key, value);
}
}
class TestDo2 {
private TestDo2() {
}
private static TestDo2 _instance = new TestDo2();
public static TestDo2 getInstance() {
return _instance;
}
private CopyOnWriteArrayList<Object> list = new CopyOnWriteArrayList<>();
public void doSome(Object key, String value) {
Object o = key;
if (!list.contains(key)) {
list.add(o);
} else {
for (Iterator iterator = list.iterator(); iterator.hasNext(); ) {
Object oo = iterator.next();
if (oo.equals(o)) {
o = oo;
}
}
}
// 以大括号内的是需要局部同步的代码，不能改动!
synchronized (o) {
try {
Thread.sleep(1000);
System.out.println(key + ":" + value + ":"
+ (System.currentTimeMillis() / 1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
如有疑问，请发邮件：[email protected]
github:??https://github.com/wangrui0/