PerThreadValue (Tapestry API - 5.7.2)乐学网一站式学习平台

```
public interface PerThreadValue<T>
```
Provides access to per-thread (and, by extension, per-request) data, managed by the PerthreadManager. A PerThreadValue stores a particular type of information.

Since:

5.2.0

See Also:

PerthreadManager.createValue()

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`exists()`	Is a value stored (even null)?
`T`	`get()`	Reads the current per-thread value, or returns null if no value has been stored.
`T`	`get(T defaultValue)`	Gets the current per-thread value if it exists (even if null), or the defaultValue if no value has been stored.
`T`	`set(T newValue)`	Sets the current per-thread value, then returns that value.

- Method Detail
  - exists
```
boolean exists()
```
    Is a value stored (even null)?
  - get
```
T get()
```
    Reads the current per-thread value, or returns null if no value has been stored.
  - get
```
T get(T defaultValue)
```
    Gets the current per-thread value if it exists (even if null), or the defaultValue if no value has been stored.
  - set
```
T set(T newValue)
```
    Sets the current per-thread value, then returns that value.