jasperreport生成pdf_jasperreport 导出excel_jasperreport json(48)

expression be evaluated immediately, when generating the current report section.

It is the evaluationTime attribute we are talking about. It can have one of the following values:

_ Immediate evaluation: The text field expression is evaluated when filling the current band

(evaluationTime="Now").

_ End of report evaluation: The text field expression is evaluated when reaching the end of the

report (evaluationTime="Report").

_ End of page evaluation: The text field expression is evaluated when reaching the end of the current

page (evaluationTime="Page").

_ End of column evaluation: The text field expression is evaluated when reaching the end of the

current column (evaluationTime="Column").

_ End of group evaluation: The text field expression is evaluated when the group specified by the

evaluationGroup attribute changes (evaluationTime="Group").

The default value for this attribute is "Now", as already mentioned. In the example presented above,

you could easily specify evaluationTime="Page" for the text field placed in the page header

section, so that it displays the value of the sum variable only when reaching the end of the current page.

The only restriction you should be aware of, when deciding to avoid the immediate

evaluation of the text field expression, is that in such cases, the text field will never stretch

in order to acquire all its content.

This is because the text element height is calculated when the report section is generated and

even the engine will come back later with the text content of the text field, the element

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