发表新帖
发表新帖

How to read csv lines chunked by id-column with Spring-Batch?

后端 未结
关注
1 788
隐瞒了意图╮
隐瞒了意图╮ 2020-12-04 00:31

I\'m using Spring-Batch to read a csv file, format the content and write it to a database like:

StepBuilder builder = stepBuilderFac
1条回答
  • 心在旅途
    心在旅途 (楼主)
    2020-12-04 01:07

    I did the same using a custom CompletionPolicy and a PeekableItemReader.
    The idea behind the code is to peek next item, perfrom next element read and check from value change.
    When a value change happens return true from CompletionPolicy.isComplete().

    Important: this policy must be registered as step listener!

    public class BreakKeyCompletionPolicy extends CompletionPolicySupport{
    private BreakKeyCompletionContext cc;
    private PeekableItemReader reader;
    // Strategy used to check for value break
    private BreakKeyStrategy strategy;

    public void setReader(PeekableItemReader forseeingReader){
        this.reader = forseeingReader;
    }

    @Override
    public boolean isComplete(RepeatContext context){
        return this.cc.isComplete();
    }

    @Override
    public RepeatContext start(RepeatContext context)   {
        context.setAttribute("current", null);
        this.cc = new BreakKeyCompletionContext(context);
        return cc;
    }
    /** Context contains current element ("current" property" and manage next element.
     * Null next element is treated as a key break
     */
    protected class BreakKeyCompletionContext extends RepeatContextSupport {
        public BreakKeyCompletionContext(RepeatContext context)     {
            super(context);
        }
        public boolean isComplete(){
            final Object next;
            try{
                next = reader.peek();
            }
            catch (Exception e){
                throw new NonTransientResourceException("Unable to peek", e);
            }
            if (null == next){
                return true;
            }
            return strategy.isKeyBreak(this.getAttribute("current"), next);
        }
    }

    @AfterRead
    public void afterRead(Object item){
        this.cc.setAttribute("current", item);
    }
}

    
    
             
    
                                                        
    
            
            
    
              
                
                0
              
                   
                
               讨论(0)
              
                                                  
              
              
    
                          
             
       
          
              
    
                                    
    
                         
          
                              			
        
        
        
    
          
    
            
            
    
              
              
    
            
    


                                 
              
    
            
    
                          
    

        
         
    
                
                
    
                  
                
    
                
    
                   看不清?
                
    
              
    
                                  
    
                    
   
                 
             
              
    提交回复
    
            
    
          
    
        
    
      
       
      
    
    
    
          
 
     
 
    
        
    热议问题