用处：处理数据库中事务管理器较为常用，所有的操作都是针对同一份数据。系统角度进行开发编程。
第一种方法，这种方法比较粗糙
public class ThreadScopeShareData {
private static int data = 0;
private static Map<Thread , Integer> threadData = new HashMap<Thread,Integer>();
public static void main(String[] args){
for (int i = 0; i < 2; i++) {
new Thread(new Runnable(){
public void run(){
data = new Random().nextInt();
System.out.println(Thread.currentThread().getName()
+ " has put data :"+data);
threadData.put(Thread.currentThread(),data);
new A().get();
new B().get();
}
}).start();
}
}
static class A{
public void get(){
data = threadData.get(Thread.currentThread());
System.out.println("A from "+ Thread.currentThread().getName()+" get data :"+data);
}
}
static class B{
public void get(){
data = threadData.get(Thread.currentThread());
System.out.println("B from "+ Thread.currentThread().getName()+" get data :"+data);
}
}
}
第二种方法：ThreadLocal，该类相当于一个Map
public class ThreadLocalTest {
static final ThreadLocal<Integer> x = new ThreadLocal<Integer>();
public static void main(String[] args){
for (int i = 0; i < 2; i++) {
new Thread(new Runnable(){
public void run(){
int data = new Random().nextInt()/10000000;
System.out.println(Thread.currentThread().getName()
+ " has put data :"+data);
x.set(data);
new A().get();
new B().get();
}
}).start();
}
}
static class A{
public void get(){
int data = x.get();
System.out.println("A from "+ Thread.currentThread().getName()+" get data :"+data);
}
}
static class B{
public void get(){
int data = x.get();
System.out.println("B from "+ Thread.currentThread().getName()+" get data :"+data);
}
}
}
第三种方法：操作多个数据，不单单是基本数据类型。可以整合成一个实体对象，然后往ThreadLocal中set这个对象。
public class ThreadLocalTest {
private static final ThreadLocal<Integer> x = new ThreadLocal<Integer>();
private static final ThreadLocal<MyThreadScopeData> myThreadScopeData = new ThreadLocal<MyThreadScopeData>();
public static void main(String[] args){
for (int i = 0; i < 2; i++) {
new Thread(new Runnable(){
public void run(){
int data = new Random().nextInt()/10000000;
System.out.println(Thread.currentThread().getName()
+ " has put data :"+data);
x.set(data);
MyThreadScopeData myData = new MyThreadScopeData();
myData.setName(" name "+data);
myData.setAge(data);
myThreadScopeData.set(myData);
new A().get();
new B().get();
}
}).start();
}
}
static class A{
public void get(){
int data = x.get();
System.out.println("A from "+ Thread.currentThread().getName()+" get data :"+data);
MyThreadScopeData myData = myThreadScopeData.get();
System.out.println("A from "+ Thread.currentThread().getName()+" getMydata :"+myData.getName()+","+myData.getAge());
}
}
static class B{
public void get(){
int data = x.get();
System.out.println("B from "+ Thread.currentThread().getName()+" get data :"+data);
MyThreadScopeData myData = myThreadScopeData.get();
System.out.println("B from "+ Thread.currentThread().getName()+" getMydata :"+myData.getName()+","+myData.getAge());
}
}
}
class MyThreadScopeData{
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
第四种方式：很优雅的处理办法，仿单例模式处理。ThradLocal类放到实体类的背后了，设计也交给了实体类，调用者不需要关心实体类的设计，只需要get到实体类的实例对象即可，同一线程内，任何地方调用实体类的实例对象，都是同一个实例对象，操作的数据都是同一份，也就达到了线程内数据共享的效果。该处理方法很好的体现了面向对象的思想。
strust2也是如此的设计方式。
public class ThreadLocalTest {
private static final ThreadLocal<Integer> x = new ThreadLocal<Integer>();
private static final ThreadLocal<MyThreadScopeData> myThreadScopeData = new ThreadLocal<MyThreadScopeData>();
public static void main(String[] args){
for (int i = 0; i < 2; i++) {
new Thread(new Runnable(){
public void run(){
int data = new Random().nextInt()/10000000;
System.out.println(Thread.currentThread().getName()
+ " has put data :"+data);
x.set(data);
MyThreadScopeData.getThreadInstance().setName(" name "+data);
MyThreadScopeData.getThreadInstance().setAge(data);
new A().get();
new B().get();
}
}).start();
}
}
static class A{
public void get(){
int data = x.get();
System.out.println("A from "+ Thread.currentThread().getName()+" get data :"+data);
MyThreadScopeData myData = MyThreadScopeData.getThreadInstance();
System.out.println("A from "+ Thread.currentThread().getName()+" getMydata :"+myData.getName()+","+myData.getAge());
}
}
static class B{
public void get(){
int data = x.get();
System.out.println("B from "+ Thread.currentThread().getName()+" get data :"+data);
MyThreadScopeData myData = MyThreadScopeData.getThreadInstance();
System.out.println("B from "+ Thread.currentThread().getName()+" getMydata :"+myData.getName()+","+myData.getAge());
}
}
}
class MyThreadScopeData{
private MyThreadScopeData(){};
private static ThreadLocal<MyThreadScopeData> map = new ThreadLocal<MyThreadScopeData>();
public static MyThreadScopeData getThreadInstance(){
MyThreadScopeData instance = map.get();
if(instance == null){
instance = new MyThreadScopeData();
map.set(instance);
}
return instance;
}
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
使用ThreadLocal类：
类似于一种栈机制，不同的线程在其有不同的记录，当时间一久，越积越多，提供clean（）方法供清理。当然其内部可以自动进行回收，不用担心如果自己不处理会溢出问题。线程一完成，则会自动回收对应的实例对象的引用。如果不同的ThreadLocal对象中，同一线程有记录，则当该线程处理完后，这些不同的ThreadLocal对象中的记录都会被回收，除非该线程对应的实例对象有其他的线程所关联操作。详细查询jdk文档。
提问：如何控制线程死亡状态？
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