StringBuffer同步--真的安全吗？ - 黑马程序员技术交流社区

import java.io.IOException;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class Test {
public static void main(String[] args) throws InterruptedException{
Test2 t = new Test2();
Test1 t1 = new Test1(t);
Thread d1 = new Thread(t1); Thread d2 = new Thread(t1);
Thread d3 = new Thread(t1); Thread d4 = new Thread(t1);
Thread d5 = new Thread(t1); Thread d6 = new Thread(t1);
d1.start(); d2.start(); d3.start(); d4.start(); d5.start(); d6.start();
d1.join(); d2.join(); d3.join(); d4.join(); d5.join(); d6.join();
new TPrint().me(t1.str);
//new TPrint().me(t.ap);
}
}
class Test1 implements Runnable {
StringBuffer str = new StringBuffer();
private Test2 t;
private int count = 0;
public Test1(Test2 t) {
this.t = t;
}
public void run() {
while (count++ < 100000)
try {
// t.fun();
// t.fun(str);
//t.fun1(str);
t.fun2(str);
} catch (Exception e) {
e.printStackTrace();
}
}
}
class TPrint{
public void me(StringBuffer str) {
String str1 = new String(str);
//切割验证是否顺序添加
String[] st = str1.split("abcdefghijklmnopqrstuvwxyz");
// String[] st = str1.split("0");
for (int x = 0; x < st.length; x++)
System.out.println(x + "*****\t" + st[x]);
}
}
class Test2 {
private Lock lock = new ReentrantLock();
StringBuffer ap = new StringBuffer();
char x = 'a';
int count = 0;
public void fun(StringBuffer ap) throws Exception {
method(ap);
}
public void fun1(Appendable ap) throws Exception {
method(ap);
}
public void fun2(Appendable ap) throws Exception {
lock.lock();
try {
method(ap);
} finally {
lock.unlock();
}
}
public void fun() throws Exception {
lock.lock();
try {
method(ap);
} finally {
lock.unlock();
}
}
private void method(Appendable ap) throws IOException {
//添加字符a到z
if (x > 'z') {
x = 'a';
ap.append("0");
}
ap.append(x++);
System.out.println(Thread.currentThread() + "****" + count++ + x);
}
}

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