java.lang.Object
- org.springframework.batch.item.ItemStreamSupport
- - org.springframework.batch.item.support.AbstractItemStreamItemReader<T>
  - - org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader<T>
    - - org.springframework.batch.item.data.AbstractPaginatedDataItemReader<T>
      - org.springframework.batch.item.data.MongoItemReader<T>

所有已实现的接口:
ItemReader<T>, ItemStream, ItemStreamReader<T>, org.springframework.beans.factory.InitializingBean
```
public class MongoItemReader<T>
extends AbstractPaginatedDataItemReader<T>
implements org.springframework.beans.factory.InitializingBean
```
Restartable ItemReader that reads documents from MongoDB via a paging technique.
If you set JSON String query setQuery(String) then it executes the JSON to retrieve the requested documents.
If you set Query object setQuery(Query) then it executes the Query to retrieve the requested documents.
The query is executed using paged requests specified in the AbstractPaginatedDataItemReader.setPageSize(int). Additional pages are requested as needed to provide data when the AbstractItemCountingItemStreamItemReader.read() method is called.
The JSON String query provided supports parameter substitution via ?<index> placeholders where the <index> indicates the index of the parameterValue to substitute.
The implementation is thread-safe between calls to AbstractItemCountingItemStreamItemReader.open(ExecutionContext), but remember to use saveState=false if used in a multi-threaded client (no restart available).
作者:
Michael Minella, Takaaki Iida

字段概要
- 从类继承的字段 org.springframework.batch.item.data.AbstractPaginatedDataItemReader
  page, pageSize, results

构造器概要
构造器
构造器说明
MongoItemReader()

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`	`afterPropertiesSet()`	Checks mandatory properties
`protected java.util.Iterator<T>`	`doPageRead()`	Method this `ItemStreamReader` delegates to for the actual work of reading a page.
`void`	`setCollection(java.lang.String collection)`
`void`	`setFields(java.lang.String fields)`	JSON defining the fields to be returned from the matching documents by MongoDB.
`void`	`setHint(java.lang.String hint)`	JSON String telling MongoDB what index to use.
`void`	`setParameterValues(java.util.List<java.lang.Object> parameterValues)`	`List` of values to be substituted in for each of the parameters in the query.
`void`	`setQuery(java.lang.String queryString)`	A JSON formatted MongoDB query.
`void`	`setQuery(org.springframework.data.mongodb.core.query.Query query)`	A Mongo Query to be used.
`void`	`setSort(java.util.Map<java.lang.String,org.springframework.data.domain.Sort.Direction> sorts)`	`Map` of property names/`Sort.Direction` values to sort the input by.
`void`	`setTargetType(java.lang.Class<? extends T> type)`	The type of object to be returned for each `AbstractItemCountingItemStreamItemReader.read()` call.
`void`	`setTemplate(org.springframework.data.mongodb.core.MongoOperations template)`	Used to perform operations against the MongoDB instance.

从类继承的方法 org.springframework.batch.item.data.AbstractPaginatedDataItemReader
doClose, doOpen, doRead, jumpToItem, setPageSize

从类继承的方法 org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader
close, getCurrentItemCount, isSaveState, open, read, setCurrentItemCount, setMaxItemCount, setSaveState, update

从类继承的方法 org.springframework.batch.item.ItemStreamSupport
getExecutionContextKey, setExecutionContextName, setName

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
  - MongoItemReader
```
public MongoItemReader()
```
- 方法详细资料
  - setQuery
```
public void setQuery(org.springframework.data.mongodb.core.query.Query query)
```
    A Mongo Query to be used.
    参数:
    query - Mongo Query to be used.
  - setTemplate
```
public void setTemplate(org.springframework.data.mongodb.core.MongoOperations template)
```
    Used to perform operations against the MongoDB instance. Also handles the mapping of documents to objects.
    参数:
    template - the MongoOperations instance to use
    另请参阅:
    MongoOperations
  - setQuery
```
public void setQuery(java.lang.String queryString)
```
    A JSON formatted MongoDB query. Parameterization of the provided query is allowed via ?<index> placeholders where the <index> indicates the index of the parameterValue to substitute.
    参数:
    queryString - JSON formatted Mongo query
  - setTargetType
```
public void setTargetType(java.lang.Class<? extends T> type)
```
    The type of object to be returned for each AbstractItemCountingItemStreamItemReader.read() call.
    参数:
    type - the type of object to return
  - setParameterValues
```
public void setParameterValues(java.util.List<java.lang.Object> parameterValues)
```
    List of values to be substituted in for each of the parameters in the query.
    参数:
    parameterValues - values
  - setFields
```
public void setFields(java.lang.String fields)
```
    JSON defining the fields to be returned from the matching documents by MongoDB.
    参数:
    fields - JSON string that identifies the fields to sort by.
  - setSort
```
public void setSort(java.util.Map<java.lang.String,org.springframework.data.domain.Sort.Direction> sorts)
```
    Map of property names/Sort.Direction values to sort the input by.
    参数:
    sorts - map of properties and direction to sort each.
  - setCollection
```
public void setCollection(java.lang.String collection)
```
    参数:
    collection - Mongo collection to be queried.
  - setHint
```
public void setHint(java.lang.String hint)
```
    JSON String telling MongoDB what index to use.
    参数:
    hint - string indicating what index to use.
  - doPageRead
```
protected java.util.Iterator<T> doPageRead()
```
    从类复制的说明: AbstractPaginatedDataItemReader
    Method this ItemStreamReader delegates to for the actual work of reading a page. Each time this method is called, the resulting Iterator should contain the items read within the next page.
    
    If the Iterator is empty or null when it is returned, this ItemReader will assume that the input has been exhausted.
    指定者:
    doPageRead 在类中 AbstractPaginatedDataItemReader<T>
    返回:
    an Iterator containing the items within a page.
  - afterPropertiesSet
```
public void afterPropertiesSet()
                        throws java.lang.Exception
```
    Checks mandatory properties
    指定者:
    afterPropertiesSet 在接口中 org.springframework.beans.factory.InitializingBean
    抛出:
    java.lang.Exception
    另请参阅:
    InitializingBean.afterPropertiesSet()

类 MongoItemReader<T>

字段概要

从类继承的字段 org.springframework.batch.item.data.AbstractPaginatedDataItemReader

构造器概要

方法概要

从类继承的方法 org.springframework.batch.item.data.AbstractPaginatedDataItemReader

从类继承的方法 org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader

从类继承的方法 org.springframework.batch.item.ItemStreamSupport

从类继承的方法 java.lang.Object

构造器详细资料

MongoItemReader

方法详细资料

setQuery

setTemplate

setQuery

setTargetType

setParameterValues

setFields

setSort

setCollection

setHint

doPageRead

afterPropertiesSet