使用Apache Bindy的isOrdered属性无法生成CSV文件

I see you're running into an issue where enabling isOrdered=true on your @CsvRecord annotation breaks CSV generation entirely, even though you need it to reorder columns. Let's break down the potential issues and fix them step by step.

Your Current Code #

TestModel Class

@CsvRecord(separator=",", generateHeaderColumns=true, isOrdered=true)
public class TestModel implements Serializable{
    @DataField(pos=1, position=2) 
    String value1;
    @DataField(pos=2, position=1) 
    String value2;
    
    // Getters and Setters
    // Constructor
}

TestProcessor Class

public class TestProcessor {
    public List<TestModel> process(){
        List<TestModel> list=new ArrayList<>();
        list.add(new TestModel("Value1","Value2"));
        list.add(new TestModel("Value3","Value4"); // Missing closing parenthesis here!
        return list;
    }
}

TestRouteBuilder Class

public class TestRouteBuilder extends RouteBuilder{
    @Override
    public void configure(){
        BindyCsvDataFormat bindy=new BindyCsvDataFormat(com.example.TestModel.class);
        from("timer:ping?period=1m")
            .to("bean:testProcessor?method=process")
            .marshal(bindy)
            .to("file://C://CSV//messages?fileName=Test.csv");
    }
}

Key Issues to Fix #

1. Syntax Error in TestProcessor
   First, there's an obvious syntax mistake in your TestProcessor code: the second list.add() call is missing a closing parenthesis. This would cause a compilation error, preventing your route from running at all. Fix that line to:

   list.add(new TestModel("Value3","Value4"));
   

2. Conflicting pos and position Annotations
   In Bindy's @DataField annotation, pos is just an alias for position—you don't need to specify both. Using both can create ambiguity, especially when isOrdered=true is enabled (which tells Bindy to sort columns by the position value).

   When isOrdered=true, Bindy relies solely on the position attribute to determine column order. Having both pos and position set to different values for the same field can confuse the sorting logic, leading to unexpected behavior or failures.

Fixed TestModel Class #

Update your TestModel to use only the position attribute to define column order:

@CsvRecord(separator=",", generateHeaderColumns=true, isOrdered=true)
public class TestModel implements Serializable{
    @DataField(position=2) // This will be the second column in the CSV
    String value1;
    @DataField(position=1) // This will be the first column in the CSV
    String value2;
    
    // Ensure you have a constructor that accepts value1 and value2
    public TestModel(String value1, String value2) {
        this.value1 = value1;
        this.value2 = value2;
    }
    
    // Getters and Setters
}

Additional Checks #

• Verify Bindy Version: If you're using an older version of Apache Camel (pre-2.20), there were some bugs related to isOrdered=true with header generation. Ensure you're on a recent, stable version of Camel.
• Check Logs for Errors: If the issue persists after fixing the above, look at your Camel application logs. Bindy will throw clear exceptions if there's a problem with the annotation configuration (e.g., missing position values when isOrdered=true).
• File Permissions: Ensure the C://CSV//messages directory exists and your application has write permissions to it. Sometimes missing directories or permissions can cause silent failures in file output.

With these fixes, your CSV should generate correctly with columns ordered as value2, value1 (since value2 has position=1 and value1 has position=2).

内容的提问来源于stack exchange，提问作者JavaDeveloper