java.lang.Object
- org.springframework.batch.item.support.SingleItemPeekableItemReader<T>

所有已实现的接口:
ItemReader<T>, ItemStream, ItemStreamReader<T>, PeekableItemReader<T>
```
public class SingleItemPeekableItemReader<T>
extends java.lang.Object
implements ItemStreamReader<T>, PeekableItemReader<T>
```
A PeekableItemReader that allows the user to peek one item ahead. Repeated calls to peek() will return the same item, and this will be the next item returned from read().
Intentionally not thread-safe: it wouldn't be possible to honour the peek in multiple threads because only one of the threads that peeked would get that item in the next call to read.
作者:
Dave Syer

构造器概要
构造器
构造器说明
SingleItemPeekableItemReader()

方法概要

所有方法实例方法具体方法
修饰符和类型	方法	说明
`void`	`close()`	If the delegate is an `ItemStream`, just pass the call on, otherwise reset the peek cache.
`void`	`open(ExecutionContext executionContext)`	If the delegate is an `ItemStream`, just pass the call on, otherwise reset the peek cache.
`T`	`peek()`	Peek at the next item, ensuring that if the delegate is an `ItemStream` the state is stored for the next call to `update(ExecutionContext)`.
`T`	`read()`	Get the next item from the delegate (whether or not it has already been peeked at).
`void`	`setDelegate(ItemReader<T> delegate)`	The item reader to use as a delegate.
`void`	`update(ExecutionContext executionContext)`	If there is a cached peek, then retrieve the execution context state from that point.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 构造器详细资料
  - SingleItemPeekableItemReader
```
public SingleItemPeekableItemReader()
```
- 方法详细资料
  - setDelegate
```
public void setDelegate(ItemReader<T> delegate)
```
    The item reader to use as a delegate. Items are read from the delegate and passed to the caller in read().
    参数:
    delegate - the delegate to set
  - read
```
public T read()
       throws java.lang.Exception,
              UnexpectedInputException,
              ParseException
```
    Get the next item from the delegate (whether or not it has already been peeked at).
    指定者:
    read 在接口中 ItemReader<T>
    返回:
    T the item to be processed or null if the data source is exhausted
    抛出:
    ParseException - if there is a problem parsing the current record (but the next one may still be valid)
    NonTransientResourceException - if there is a fatal exception in the underlying resource. After throwing this exception implementations should endeavour to return null from subsequent calls to read.
    UnexpectedInputException - if there is an uncategorised problem with the input data. Assume potentially transient, so subsequent calls to read might succeed.
    java.lang.Exception - if an there is a non-specific error.
    另请参阅:
    ItemReader.read()
  - peek
```
public T peek()
       throws java.lang.Exception,
              UnexpectedInputException,
              ParseException
```
    Peek at the next item, ensuring that if the delegate is an ItemStream the state is stored for the next call to update(ExecutionContext).
    指定者:
    peek 在接口中 PeekableItemReader<T>
    返回:
    the next item (or null if there is none).
    抛出:
    java.lang.Exception - if there is a problem
    UnexpectedInputException
    ParseException
    另请参阅:
    PeekableItemReader.peek()
  - close
```
public void close()
           throws ItemStreamException
```
    If the delegate is an ItemStream, just pass the call on, otherwise reset the peek cache.
    指定者:
    close 在接口中 ItemStream
    抛出:
    ItemStreamException - if there is a problem
    另请参阅:
    ItemStream.close()
  - open
```
public void open(ExecutionContext executionContext)
          throws ItemStreamException
```
    If the delegate is an ItemStream, just pass the call on, otherwise reset the peek cache.
    指定者:
    open 在接口中 ItemStream
    参数:
    executionContext - the current context
    抛出:
    ItemStreamException - if there is a problem
    另请参阅:
    ItemStream.open(ExecutionContext)
  - update
```
public void update(ExecutionContext executionContext)
            throws ItemStreamException
```
    If there is a cached peek, then retrieve the execution context state from that point. If there is no peek cached, then call directly to the delegate.
    指定者:
    update 在接口中 ItemStream
    参数:
    executionContext - the current context
    抛出:
    ItemStreamException - if there is a problem
    另请参阅:
    ItemStream.update(ExecutionContext)

类 SingleItemPeekableItemReader<T>

构造器概要

方法概要

从类继承的方法 java.lang.Object

构造器详细资料

SingleItemPeekableItemReader

方法详细资料

setDelegate

read

peek

close

open

update