* 新增头的非空校验 [Issue #1765]

src/main/java/com/alibaba/excel/metadata/Head.java

@@ -3,6 +3,7 @@ package com.alibaba.excel.metadata;
 import java.util.ArrayList;
 import java.util.List;
 
+import com.alibaba.excel.exception.ExcelGenerateException;
 import com.alibaba.excel.metadata.property.ColumnWidthProperty;
 import com.alibaba.excel.metadata.property.FontProperty;
 import com.alibaba.excel.metadata.property.LoopMergeProperty;
@@ -64,9 +65,15 @@ public class Head {
         this.columnIndex = columnIndex;
         this.fieldName = fieldName;
         if (headNameList == null) {
-            headNameList = new ArrayList<String>();
+            this.headNameList = new ArrayList<>();
+        } else {
+            this.headNameList = headNameList;
+            for (String headName : headNameList) {
+                if (headName == null) {
+                    throw new ExcelGenerateException("head name can not be null.");
+                }
+            }
         }
-        this.headNameList = headNameList;
         this.forceIndex = forceIndex;
         this.forceName = forceName;
     }

src/main/java/com/alibaba/excel/util/StringUtils.java

@@ -69,7 +69,6 @@ public class StringUtils {
         return true;
     }
 
-
     /**
      * <p>Checks if a CharSequence is not empty (""), not null and not whitespace only.</p>
      *
@@ -83,9 +82,9 @@ public class StringUtils {
      * StringUtils.isNotBlank("  bob  ") = true
      * </pre>
      *
-     * @param cs  the CharSequence to check, may be null
+     * @param cs the CharSequence to check, may be null
      * @return {@code true} if the CharSequence is
-     *  not empty and not null and not whitespace only
+     * not empty and not null and not whitespace only
      * @since 2.0
      * @since 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence)
      */
@@ -93,5 +92,97 @@ public class StringUtils {
         return !isBlank(cs);
     }
 
+    /**
+     * <p>Compares two CharSequences, returning {@code true} if they represent
+     * equal sequences of characters.</p>
+     *
+     * <p>{@code null}s are handled without exceptions. Two {@code null}
+     * references are considered to be equal. The comparison is case sensitive.</p>
+     *
+     * <pre>
+     * StringUtils.equals(null, null)   = true
+     * StringUtils.equals(null, "abc")  = false
+     * StringUtils.equals("abc", null)  = false
+     * StringUtils.equals("abc", "abc") = true
+     * StringUtils.equals("abc", "ABC") = false
+     * </pre>
+     *
+     * @param cs1 the first CharSequence, may be {@code null}
+     * @param cs2 the second CharSequence, may be {@code null}
+     * @return {@code true} if the CharSequences are equal (case-sensitive), or both {@code null}
+     * @see Object#equals(Object)
+     * @since 3.0 Changed signature from equals(String, String) to equals(CharSequence, CharSequence)
+     */
+    public static boolean equals(final CharSequence cs1, final CharSequence cs2) {
+        if (cs1 == cs2) {
+            return true;
+        }
+        if (cs1 == null || cs2 == null) {
+            return false;
+        }
+        if (cs1.length() != cs2.length()) {
+            return false;
+        }
+        if (cs1 instanceof String && cs2 instanceof String) {
+            return cs1.equals(cs2);
+        }
+        return regionMatches(cs1, false, 0, cs2, 0, cs1.length());
+    }
+
+    /**
+     * Green implementation of regionMatches.
+     *
+     * @param cs         the {@code CharSequence} to be processed
+     * @param ignoreCase whether or not to be case insensitive
+     * @param thisStart  the index to start on the {@code cs} CharSequence
+     * @param substring  the {@code CharSequence} to be looked for
+     * @param start      the index to start on the {@code substring} CharSequence
+     * @param length     character length of the region
+     * @return whether the region matched
+     */
+    public static boolean regionMatches(final CharSequence cs, final boolean ignoreCase, final int thisStart,
+        final CharSequence substring, final int start, final int length) {
+        if (cs instanceof String && substring instanceof String) {
+            return ((String)cs).regionMatches(ignoreCase, thisStart, (String)substring, start, length);
+        }
+        int index1 = thisStart;
+        int index2 = start;
+        int tmpLen = length;
+
+        // Extract these first so we detect NPEs the same as the java.lang.String version
+        final int srcLen = cs.length() - thisStart;
+        final int otherLen = substring.length() - start;
+
+        // Check for invalid parameters
+        if (thisStart < 0 || start < 0 || length < 0) {
+            return false;
+        }
+
+        // Check that the regions are long enough
+        if (srcLen < length || otherLen < length) {
+            return false;
+        }
+
+        while (tmpLen-- > 0) {
+            final char c1 = cs.charAt(index1++);
+            final char c2 = substring.charAt(index2++);
+
+            if (c1 == c2) {
+                continue;
+            }
+
+            if (!ignoreCase) {
+                return false;
+            }
+
+            // The same check as in String.regionMatches():
+            if (Character.toUpperCase(c1) != Character.toUpperCase(c2)
+                && Character.toLowerCase(c1) != Character.toLowerCase(c2)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
 
 }

src/main/java/com/alibaba/excel/write/property/ExcelWriteHeadProperty.java

@@ -142,7 +142,7 @@ public class ExcelWriteHeadProperty extends ExcelHeadProperty {
                     continue;
                 }
                 alreadyRangeSet.add(i + "-" + j);
-                String headName = headNameList.get(j) == null ? "" : headNameList.get(j);
+                String headName = headNameList.get(j);
                 int lastCol = i;
                 int lastRow = j;
                 for (int k = i + 1; k < headList.size(); k++) {

src/test/java/com/alibaba/easyexcel/test/demo/Test1765/Issue1765.java

-package com.alibaba.easyexcel.test.demo.Test1765;
-
-import com.alibaba.easyexcel.test.util.TestFileUtil;
-import com.alibaba.excel.EasyExcel;
-import com.alibaba.excel.EasyExcelFactory;
-import org.junit.Assert;
-import org.junit.Test;
-
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
-import java.io.InputStream;
-import java.util.ArrayList;
-import java.util.Date;
-import java.util.List;
-
-public class Issue1765 {
-    @Test
-    public void test1765() throws FileNotFoundException {
-        String fileName = "src/test/java/com/alibaba/easyexcel/test/demo/Test1765/Data1765.xlsx";
-        EasyExcel.write(fileName).head(head()).sheet("模板").doWrite(dataList());
-    }
-
-
-    private List<List<String>> head() {
-        List<List<String>> list = new ArrayList<List<String>>();
-        List<String> head0 = new ArrayList<String>();
-        List<String> head1 = new ArrayList<String>();
-        List<String> head2 = new ArrayList<String>();
-        List<String> head3 = new ArrayList<String>();
-        head0.add("表头");
-        head1.add("日期");
-        head2.add(null);
-        head3.add("数字");
-        list.add(head0);
-        list.add(head1);
-        list.add(head2);
-        list.add(head3);
-
-        return list;
-    }
-
-    private List<List<Object>> dataList() {
-        List<List<Object>> list = new ArrayList<List<Object>>();
-        for (int i = 0; i < 5; i++) {
-            List<Object> data = new ArrayList<Object>();
-            data.add("字符串" + i);
-            data.add(new Date());
-            data.add(i * 2);
-            data.add(i * 3);
-            list.add(data);
-        }
-        return list;
-    }
-}