编辑：我根据我的原始建议（如下）修改了我的示例代码以使用InheritableThreadLocal，我发现它更简单，所以添加更新的代码。
这是更新后的 ThreadLocalManager：
package inheritableThreadLocal;
public class ThreadLocalManager {
public static final InheritableThreadLocal<String> accountUsername = new InheritableThreadLocal<String>();
public static final InheritableThreadLocal<String> accountPassword = new InheritableThreadLocal<String>();
public static final InheritableThreadLocal<Long> accountId = new InheritableThreadLocal<Long>();
}
我还更新了Runner（见下文），但现在它的唯一目的是打印变量的值：
package inheritableThreadLocal;
public class Runner implements Runnable{
@Override
public void run() {
System.out.println("Inside Runner's run");
System.out.println(ThreadLocalManager.accountId.get());
System.out.println(ThreadLocalManager.accountUsername.get());
System.out.println(ThreadLocalManager.accountPassword.get());
}
}
终于更新了包含main方法的类：
package inheritableThreadLocal;
public class ThreadLocalMain {
public static void main(String[] args) {
System.out.println("At start of main");
System.out.println(ThreadLocalManager.accountId.get());
System.out.println(ThreadLocalManager.accountUsername.get());
System.out.println(ThreadLocalManager.accountPassword.get());
Thread t1 = new Thread(new Runnable(){
@Override
public void run() {
ThreadLocalManager.accountId.set(new Long(12345));
ThreadLocalManager.accountUsername.set("user1");
ThreadLocalManager.accountPassword.set("pass1");
System.out.println("In t1 run");
System.out.println(ThreadLocalManager.accountId.get());
System.out.println(ThreadLocalManager.accountUsername.get());
System.out.println(ThreadLocalManager.accountPassword.get());
Thread t2 = new Thread(new Runner());
t2.start();
}
});
t1.start();
}
}
原建议：
因此，您可以使用 Runnable 对象创建新的 Thread 对象。如果您这样做，您可以创建实现Runnable 的自定义对象，并且可以保存ThreadLocal 变量的值，直到新的Thread 启动。一旦新的Thread 启动（即调用run 方法），这些自定义Runnable 对象就会设置ThreadLocal 变量。
这是一个我为此创建的主类：
package threadLocal;
public class ThreadLocalMain {
public static void main(String[] args) {
System.out.println("At start of main");
System.out.println(ThreadLocalManager.accountId.get());
System.out.println(ThreadLocalManager.accountUsername.get());
System.out.println(ThreadLocalManager.accountPassword.get());
Thread t1 = new Thread(new Runnable(){
@Override
public void run() {
ThreadLocalManager.accountId.set(new Long(12345));
ThreadLocalManager.accountUsername.set("user1");
ThreadLocalManager.accountPassword.set("pass1");
System.out.println("In t1 run");
System.out.println(ThreadLocalManager.accountId.get());
System.out.println(ThreadLocalManager.accountUsername.get());
System.out.println(ThreadLocalManager.accountPassword.get());
Thread t2 = new Thread(new Runner(ThreadLocalManager.accountUsername.get(),
ThreadLocalManager.accountPassword.get(),
ThreadLocalManager.accountId.get()));
t2.start();
}
});
t1.start();
}
}
为了完整起见，这里是我使用的 ThreadLocalManager：
package threadLocal;
public class ThreadLocalManager {
public static final ThreadLocal<String> accountUsername = new ThreadLocal<String>();
public static final ThreadLocal<String> accountPassword = new ThreadLocal<String>();
public static final ThreadLocal<Long> accountId = new ThreadLocal<Long>();
}
最后，这是我创建的自定义Runnable：
package threadLocal;
public class Runner implements Runnable{
private String userName, password;
private long acctId;
public Runner(String user, String pword, long accountId){
System.out.println("In Runner constructor");
System.out.println(ThreadLocalManager.accountId.get());
System.out.println(ThreadLocalManager.accountUsername.get());
System.out.println(ThreadLocalManager.accountPassword.get());
userName = user;
password = pword;
acctId = accountId;
}
@Override
public void run() {
System.out.println("Inside Runner's run");
System.out.println(ThreadLocalManager.accountId.get());
System.out.println(ThreadLocalManager.accountUsername.get());
System.out.println(ThreadLocalManager.accountPassword.get());
ThreadLocalManager.accountId.set(acctId);
ThreadLocalManager.accountUsername.set(userName);
ThreadLocalManager.accountPassword.set(password);
System.out.println("Inside Runner's run - after setting");
System.out.println(ThreadLocalManager.accountId.get());
System.out.println(ThreadLocalManager.accountUsername.get());
System.out.println(ThreadLocalManager.accountPassword.get());
}
}
此代码将ThreadLocal 变量的值传递给Runner 实例，然后Runner 实例用于创建一个新的Thread（如果您运行代码，您将看到它没有值首先是ThreadLocal 变量）。然后Runner 设置ThreadLocal 变量，您可以从控制台输出中看到它们与 t1 的匹配。
希望这会有所帮助！