From ce62b5e792d12ba1da631e0969a0957243e03cbe Mon Sep 17 00:00:00 2001
From: Looly <loolly@gmail.com>
Date: Sun, 27 Feb 2022 00:08:59 +0800
Subject: [PATCH] add methods

---
 CHANGELOG.md                                  |  4 +-
 .../cn/hutool/core/stream/CollectorUtil.java  |  1 -
 .../java/cn/hutool/core/text/StrJoiner.java   | 64 +++++++++++++++----
 .../cn/hutool/core/text/StrJoinerTest.java    | 21 ++++++
 4 files changed, 75 insertions(+), 15 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index fb291f8a1..d8d57d7c4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,7 @@
 # 🚀Changelog
 
 -------------------------------------------------------------------------------------------------------------
-# 5.7.22 (2022-02-26)
+# 5.7.22 (2022-02-27)
 
 ### 🐣新特性
 * 【poi    】     ExcelUtil.readBySax增加对POI-5.2.0的兼容性（issue#I4TJF4@gitee）
@@ -16,6 +16,8 @@
 * 【http   】     增加HttpGlobalConfig.setDecodeUrl（issue#I4U8YQ@Gitee）
 * 【core   】     增加Base58（pr#2162@Github）
 * 【core   】     增加AntPathMatcher（issue#I4T7K5@Gitee）
+* 【core   】     StrJoiner修改toString策略，调用不再修改Appendable
+* 【core   】     StrJoiner增加length和merge方法
 
 ### 🐞Bug修复
 * 【cache  】     修复ReentrantCache.toString方法线程不安全问题（issue#2140@Github）
diff --git a/hutool-core/src/main/java/cn/hutool/core/stream/CollectorUtil.java b/hutool-core/src/main/java/cn/hutool/core/stream/CollectorUtil.java
index e41e9b84f..5d9c9d87a 100644
--- a/hutool-core/src/main/java/cn/hutool/core/stream/CollectorUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/stream/CollectorUtil.java
@@ -14,7 +14,6 @@ import java.util.function.BiConsumer;
 import java.util.function.BinaryOperator;
 import java.util.function.Function;
 import java.util.function.Supplier;
-import java.util.function.UnaryOperator;
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
 
diff --git a/hutool-core/src/main/java/cn/hutool/core/text/StrJoiner.java b/hutool-core/src/main/java/cn/hutool/core/text/StrJoiner.java
index bfebd8703..e2a8a5387 100644
--- a/hutool-core/src/main/java/cn/hutool/core/text/StrJoiner.java
+++ b/hutool-core/src/main/java/cn/hutool/core/text/StrJoiner.java
@@ -12,7 +12,14 @@ import java.util.Iterator;
 import java.util.function.Function;
 
 /**
- * 字符串连接器（拼接器），通过给定的字符串和多个元素，拼接为一个字符串
+ * 字符串连接器（拼接器），通过给定的字符串和多个元素，拼接为一个字符串<br>
+ * 相较于{@link java.util.StringJoiner}提供更加灵活的配置，包括：
+ * <ul>
+ *     <li>支持任意Appendable接口实现</li>
+ *     <li>支持每个元素单独wrap</li>
+ *     <li>支持自定义null的处理逻辑</li>
+ *     <li>支持自定义默认结果</li>
+ * </ul>
  *
  * @author looly
  * @since 5.7.2
@@ -282,6 +289,11 @@ public class StrJoiner implements Appendable, Serializable {
 
 	@Override
 	public StrJoiner append(CharSequence csq) {
+		return append(csq, 0, csq.length());
+	}
+
+	@Override
+	public StrJoiner append(CharSequence csq, int startInclude, int endExclude) {
 		if (null == csq) {
 			switch (this.nullMode) {
 				case IGNORE:
@@ -298,7 +310,7 @@ public class StrJoiner implements Appendable, Serializable {
 			if (wrapElement && StrUtil.isNotEmpty(this.prefix)) {
 				appendable.append(prefix);
 			}
-			appendable.append(csq);
+			appendable.append(csq, startInclude, endExclude);
 			if (wrapElement && StrUtil.isNotEmpty(this.suffix)) {
 				appendable.append(suffix);
 			}
@@ -308,29 +320,55 @@ public class StrJoiner implements Appendable, Serializable {
 		return this;
 	}
 
-	@Override
-	public StrJoiner append(CharSequence csq, int startInclude, int endExclude) {
-		return append(StrUtil.sub(csq, startInclude, endExclude));
-	}
-
 	@Override
 	public StrJoiner append(char c) {
 		return append(String.valueOf(c));
 	}
 
+	/**
+	 * 合并一个StrJoiner 到当前的StrJoiner<br>
+	 * 合并规则为，在尾部直接追加，当存在{@link #prefix}时，如果{@link #wrapElement}为{@code false}，则去除之。
+	 *
+	 * @param strJoiner 其他的StrJoiner
+	 * @return this
+	 * @since 5.7.22
+	 */
+	public StrJoiner merge(StrJoiner strJoiner){
+		if(null != strJoiner && null != strJoiner.appendable){
+			final String otherStr = strJoiner.toString();
+			if(strJoiner.wrapElement){
+				this.append(otherStr);
+			}else{
+				this.append(otherStr, this.prefix.length(), otherStr.length());
+			}
+		}
+		return this;
+	}
+
+	/**
+	 * 长度<br>
+	 * 长度计算方式为prefix + suffix + content<br>
+	 * 此方法结果与toString().length()一致。
+	 *
+	 * @return 长度，如果结果为{@code null}，返回-1
+	 * @since 5.7.22
+	 */
+	public int length() {
+		return (this.appendable != null ? this.appendable.toString().length() + suffix.length() :
+				null == this.emptyResult ? -1 : emptyResult.length());
+	}
+
 	@Override
 	public String toString() {
 		if (null == this.appendable) {
 			return emptyResult;
 		}
+
+		String result = this.appendable.toString();
 		if (false == wrapElement && StrUtil.isNotEmpty(this.suffix)) {
-			try {
-				this.appendable.append(this.suffix);
-			} catch (IOException e) {
-				throw new IORuntimeException(e);
-			}
+			result += this.suffix;
 		}
-		return this.appendable.toString();
+		return result;
 	}
 
 	/**
diff --git a/hutool-core/src/test/java/cn/hutool/core/text/StrJoinerTest.java b/hutool-core/src/test/java/cn/hutool/core/text/StrJoinerTest.java
index 2ce2eee8c..f9a2d4c30 100644
--- a/hutool-core/src/test/java/cn/hutool/core/text/StrJoinerTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/text/StrJoinerTest.java
@@ -78,4 +78,25 @@ public class StrJoinerTest {
 				.append("3");
 		Assert.assertEquals("[1],[2],[3]", append.toString());
 	}
+
+	@Test
+	public void lengthTest(){
+		StrJoiner joiner = StrJoiner.of(",", "[", "]");
+		Assert.assertEquals(joiner.toString().length(), joiner.length());
+
+		joiner.append("123");
+		Assert.assertEquals(joiner.toString().length(), joiner.length());
+	}
+
+	@Test
+	public void mergeTest(){
+		StrJoiner joiner1 = StrJoiner.of(",", "[", "]");
+		joiner1.append("123");
+		StrJoiner joiner2 = StrJoiner.of(",", "[", "]");
+		joiner1.append("456");
+		joiner1.append("789");
+
+		final StrJoiner merge = joiner1.merge(joiner2);
+		Assert.assertEquals("[123,456,789]", merge.toString());
+	}
 }