使用JXL生成Excel时发生java.lang.ArrayIndexOutOfBoundsException错误

错误信息如下：

......

java.lang.ArrayIndexOutOfBoundsException
        at java.lang.System.arraycopy(Native Method)
        at jxl.biff.StringHelper.getBytes(StringHelper.java:127)
        at jxl.write.biff.WriteAccessRecord.<init>(WriteAccessRecord.java:59)
        at jxl.write.biff.WritableWorkbookImpl.write(WritableWorkbookImpl.java:726) 

......

 

神奇的是，在项目中发现该现象只有在Linux环境下才发生而Window下则正常运行。

根据错误信息的提示，发现问题出在WriteAccessRecord文件里，其源代码如下所示：

package jxl.write.biff;import jxl.Workbook;import jxl.biff.StringHelper;import jxl.biff.Type;import jxl.biff.WritableRecordData;/** * The name used when Excel was installed. * When writing worksheets, it uses the value from the WorkbookSettings object, * if this is not set (null) this is hard coded as * Java Excel API + Version number */class WriteAccessRecord extends WritableRecordData{ /** * The data to output to file */ private byte[] data; // String of length 112 characters /** * The author of this workbook (ie. the Java Excel API) */ private final static String authorString = "Java Excel API"; private String userName; /** * Constructor */ public WriteAccessRecord(String userName) { super(Type.WRITEACCESS); data = new byte[112]; String astring = userName != null ? userName : authorString + " v" + Workbook.getVersion(); StringHelper.getBytes(astring, data, 0); // Pad out the record with space characters for (int i = astring.length() ; i < data.length ;i++) { data[i] = 0x20; } } /** * Gets the data for output to file * * @return the binary data */ public byte[] getData() { return data; }}

分析上诉代码发现，byte数组data的最大长度被定义为112，当被传入的参数userName达到一定长度时就会抛错。

跟踪代码WritableWorkbookImpl发现，userName实际就是WorkbookSettings类中的writeAccess字段，亦即生成Excel是的用户信息。可能在linux环境UTF8下每个汉字的字节数为3位(Windows中是2位)的缘故，出现了上诉的奇异现象。

 

解决的办法如下：

1.修改JXL源代码中WriteAccessRecord文件代码，重新设置变量data的长度，例如：data = new byte[astring.getBytes().length];

2.一般我们在读取模板文件生成新的Excel时往往使用如下代码：

import java.io.File;import jxl.Workbook;import jxl.write.WritableSheet;import jxl.write.WritableWorkbook;public class Test {public static void main(String[] args) throws Exception {Workbook wb = Workbook.getWorkbook(new File("C:/data_template.xls"));WritableWorkbook workbook = Workbook.createWorkbook(new File("C:/data_output.xls"), wb);WritableSheet sheet = workbook.getSheet(3);sheet.getSettings().setSelected(true);workbook.write();workbook.close();}}

只要在代码中强制设置变量WorkbookSettings.writeAccess的值即可，例如：

Workbook wb = Workbook.getWorkbook(new File("C:/data_template.xls"));
WorkbookSettings settings = new WorkbookSettings ();
settings.setWriteAccess(null);
WritableWorkbook workbook = Workbook.createWorkbook(new File("C:/data_output.xls"), wb, settings);

WritableSheet sheet = workbook.getSheet(3);
sheet.getSettings().setSelected(true);

workbook.write();
workbook.close();