关于ThreadLocal的使用

定义上下文

public class ThreadContext<T> {


    private static final ThreadLocal<ThreadContext<?>> LOCAL = new ThreadLocal<>();
    private ThreadContext(){}

    public static <T> ThreadContext<T> init(){
        ThreadContext<T> context = new ThreadContext<>();
        LOCAL.set(context);
        return context;
    }

    public static <T> ThreadContext<T> get(){
        return (ThreadContext<T>) LOCAL.get();
    }

    public static void fill(UserInfo userInfo){
        ThreadContext<UserInfo> context = ThreadContext.get();
        context.setAddress(userInfo.getAddress());
        context.setUserId(userInfo.getUserId());
        context.setUserName(context.getUserName());
    }


    public static ThreadContext<?> set(ThreadContext<?> context){
        ThreadContext<?> backup = get();
        LOCAL.set(context);
        return backup;
    }
    public static void clear(){
        LOCAL.remove();
    }

    private String userName;
    private Long userId;
    private String address;


    public Long getUserId() {
        return userId;
    }

    public String getUserName() {
        return userName;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

定义用户信息

public class UserInfo {

    private String userName;
    private Long userId;
    private String address;


    public Long getUserId() {
        return userId;
    }

    public String getUserName() {
        return userName;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }
}

定义注解用于切面

@Inherited
@Retention(
        RetentionPolicy.RUNTIME
)
@Target({ElementType.METHOD})
public @interface ThreadScene {

    String userName();
    String address();
    long userId();
}

定义切面

@Aspect
@Component
public class TreadSceneAspect {
    @Around("@annotation(scene)")
    public Object around(ProceedingJoinPoint joinPoint,ThreadScene scene) throws Throwable{
        ThreadContext<Object> originContext = ThreadContext.get();
        ThreadContext<Object> context = originContext;
        if(context == null){
            context = ThreadContext.init();
        }
        String userName = context.getUserName();
        Long userId = context.getUserId();
        String address =context.getAddress();
        try{
            context.setUserName(scene.userName());
            context.setUserId(scene.userId());
            context.setAddress(scene.address());
            return joinPoint.proceed();
        }finally {
            if(originContext == null){
                ThreadContext.clear();
            }else {
                context.setAddress(address);
                context.setUserId(userId);
                context.setUserName(userName);
            }
        }
    }
}