java 调用Ireport报错，总以为是字体问题

报错如下
net.sf.jasperreports.engine.fonts.FontUtil - Font 'net/sf/jasperreports/fonts/simsun.ttc' is not available to the JVM. For more details, see http://jasperreports.sourceforge.net/api/net/sf/jasperreports/engine/util/JRFontNotFoundException.html
WARN  n.sf.jasperreports.engine.export.PdfGlyphRenderer - Unpatched iText found, cannot use glyph rendering

总以为是字体问题，结果报表查询出来是空，就会报如下错误。