] Guava学习笔记之Joiner ，Strings，Splitter 工具实例

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Guava
一．Strings
1．Strings.padEnd方法
//padEnd普全右
Stringa="12345";
Stringb=Strings.padEnd(a,10,'x');
System.out.println(b);

结果为：12345xxxxx
2．Strings.padStart方法
//padStart普全左
Stringa="12345";
Stringb=Strings.padStart(a,10,'x');
System.out.println(b);
结果为：xxxxx12345



3．Strings.isNullOrEmpty方法
//Strings.isNullOrEmpty校验空值
Stringa="";
booleanb=Strings.isNullOrEmpty(a);
System.out.println(b);
结果为：true

4．Strings.nullToEmpty方法
//Strings.nullToEmpty如果为null转为""
Stringa=null;
Stringb=Strings.nullToEmpty(a);
System.out.println(b);
结果为：


5．Strings.emptyToNull方法
//Strings.emptyToNull如果为""转为null
Stringa="";
Stringb=Strings.emptyToNull(a);
System.out.println(b);
结果为：null





6．Strings.repeat方法
//Strings.repeat重复字符串
Stringa="123";
Stringb=Strings.repeat(a,3);
System.out.println(b);
结果为：123123123

7．Strings.commonPrefix方法
//Strings.commonPrefix获取a,b左公共部分字符串
Stringa="abcdsfsfs";
Stringb="abc3sfsd";
Stringc=Strings.commonPrefix(a,b);
System.out.println(c);
结果为：abc


8．Strings.commonSuffix方法
//Strings.commonSuffix获取a,b右公共部分字符串
Stringa="faaxyz";
Stringb="fwefxyz";
Stringc=Strings.commonSuffix(a,b);
System.out.println(c);
System.out.println(c);
结果为：xyz





















二，Joiner连接工具类

分析源码可知：该类构造方法被private修身，无法直接通过new实现
通过调用on传如分隔符来得到实例。
1．连接List列表
Joinerjoiner=Joiner.on(",");
List<String>list=newArrayList<String>();
list.add("xiaoming");
list.add("xiaohong");
list.add("wangsan");
System.out.println(joiner.join(list));
结果：xiaoming,xiaohong,wangsan

2．连接Iterator<T>列表
Joinerjoiner=Joiner.on(",");
List<String>list=newArrayList<String>();
list.add("xiaoming");
list.add("xiaohong");
list.add("wangsan");
Iterator<String>it=list.iterator();
System.out.println(joiner.join(it));
结果：xiaoming,xiaohong,wangsan

3．连接多个字符串
Joinerjoiner=Joiner.on(",");
System.out.println(joiner.join("123","345","56","43"));
结果：123,345,56,43

4.连接字符串与列表

Joinerjoiner=Joiner.on(",");
List<String>list=newArrayList<String>();
list.add("xiaoming");
list.add("xiaohong");
list.add("wangsan");
StringBuilderbuilder=newStringBuilder("标题");
System.out.println(joiner.appendTo(builder,list));
结果：标题xiaoming,xiaohong,wangsan

5.跳过null值连接
Joinerjoiner=Joiner.on(",").skipNulls();
List<String>list=newArrayList<String>();
list.add("xiaoming");
list.add(null);
list.add("wangsan");
StringBuilderbuilder=newStringBuilder("标题");
System.out.println(joiner.appendTo(builder,list));
6.替换null值进行连接
Joinerjoiner=Joiner.on(",").useForNull("123");//替换null为123
List<String>list=newArrayList<String>();
list.add("xiaoming");
list.add(null);
list.add("wangsan");
StringBuilderbuilder=newStringBuilder("标题");
System.out.println(joiner.appendTo(builder,list));
结果：标题xiaoming,123,wangsan


三．Splitter工具类
主要功能是拆分字符串为集合Map等。

通过分析源码可知，该工具类同意通过on函数传入拆分字符得到实例。

1．拆分字符串为List集合
Splittersplitter=Splitter.on(",");
Stringstr="a,b,c,d,e,f,g";
List<String>list=splitter.splitToList(str);
System.out.println(list);
结果：[a,b,c,d,e,f,g]
2.忽略空字符

Splittersplitter=Splitter.on(",").omitEmptyStrings();
Stringstr="a,b,c,d,,f,g";
List<String>list=splitter.splitToList(str);
System.out.println(list);
结果：[a,b,c,d,f,g]

3.忽略空字符且去除字符串前后空格
Splittersplitter=Splitter.on(",").omitEmptyStrings().trimResults();
Stringstr="a,b,c,d,,f,g";
List<String>list=splitter.splitToList(str);
System.out.println(list);

结果：[a,b,c,d,f,g]





HtmlEscapers工具类
将html转义如下源码所示

EscaperhtmlEscaper=HtmlEscapers.htmlEscaper();
System.out.println(htmlEscaper.escape("<a>你好</a>"));

结果：<a>你好</a>