Suspend和Resume：
Suspend和Resume使用方法：
以下例子证明了线程确实被暂停了，而且还可以恢复成运行状态。
public class SuspendResumeThread extends Thread{
private long i = 0;
public long getI() {
return i;
}
public void setI(long i) {
this.i = i;
}
@Override
public void run() {
while(true){
i++;
}
}
}
public class ThreadRunMain {
public static void main(String[] args) {
testSuspendResumeThread();
}
public static void testSuspendResumeThread(){
try {
SuspendResumeThread srt = new SuspendResumeThread();
srt.start();
Thread.sleep(5000);
srt.suspend();
System.out.println("A= " + System.currentTimeMillis() + " i=" + srt.getI());
Thread.sleep(5000);
System.out.println("A= " + System.currentTimeMillis() + " i=" + srt.getI());
srt.resume();
Thread.sleep(5000);
srt.suspend();
System.out.println("A= " + System.currentTimeMillis() + " i=" + srt.getI());
Thread.sleep(5000);
System.out.println("A= " + System.currentTimeMillis() + " i=" + srt.getI());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}运行结果：
Suspend和Resume缺点1-独占：
public class SuspendResumeObject {
synchronized public void printString(){
System.out.println("begin");
if(Thread.currentThread().getName().equals("a")){
System.out.println("a thread will suspend.");
Thread.currentThread().suspend();
}
System.out.println("SuspendResumeObject end");
}
}
public class ThreadRunMain {
public static void main(String[] args) {
testSuspendResumeObject();
}
public static void testSuspendResumeObject(){
try {
final SuspendResumeObject object = new SuspendResumeObject();
Thread t = new Thread(){
@Override
public void run() {
object.printString();
}
};
t.setName("a");
t.start();
Thread.sleep(1000);
Thread t2 = new Thread(){
@Override
public void run() {
System.out.println("Thread 2 start, but can't enter printString()");
System.out.println("Because of printString() is blocked by thread a");
object.printString();
System.out.println("Thread 2 complete");
}
};
t2.start();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}运行结果：
public class SuspendResumePrintStreamIssue extends Thread{
private long i = 0;
@Override
public void run() {
while (true){
// try {
i++;
// Thread.sleep(1);
System.out.println(i);
// } catch (InterruptedException e) {
// e.printStackTrace();
// }
}
}
}
public class ThreadRunMain {
public static void main(String[] args) {
testSuspendResumePrintStreamIssue();
}
public static void testSuspendResumePrintStreamIssue(){
try {
SuspendResumePrintStreamIssue srpsi = new SuspendResumePrintStreamIssue();
srpsi.start();
Thread.sleep(1000);
srpsi.suspend();
System.out.println("Main end.");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}运行结果：
同样是独占，当程序运行到PrintStream对象println()方法内部停止时，同步锁未被释放。这导致main()方法中的System.out.println("Main end.");不能被执行。
Suspend和Resume缺点2-数据不一致：
public class SuspendResumeDataIssue {
private String userName = "1";
private String password = "11";
synchronized public void setValue(String u, String p){
this.userName = u;
if(Thread.currentThread().getName().equals("a")){
System.out.println("Thread a suspend.");
Thread.currentThread().suspend();
}
this.password = p;
}
public void printUserNamePassword(){
System.out.println(userName + " " + password);
}
}
public class ThreadRunMain {
public static void main(String[] args) {
testSuspendResumeDataIssue();
}
public static void testSuspendResumeDataIssue(){
try {
SuspendResumeDataIssue srdi = new SuspendResumeDataIssue();
Thread t1 = new Thread(){
@Override
public void run() {
srdi.setValue("a", "aa");
}
};
t1.setName("a");
t1.start();
Thread.sleep(500);
Thread t2 = new Thread(){
@Override
public void run() {
srdi.printUserNamePassword();
}
};
t2.start();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}运行结果：