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

在工作的过程中，如果写业务的话。那么就是拼工具箱里工具了。Guava对于很多JDK 1.7的人来说是不错的一个工具，而且很好用说的几个都是基础的功能

Guava
一．Strings
1．Strings.padEnd方法
//padEnd普全右
		String a="12345";
		String b=Strings.padEnd(a, 10, 'x');
		System.out.println(b);
 
结果为：12345xxxxx
2．Strings.padStart方法
//padStart 普全左
		String a="12345";
		String b=Strings.padStart(a, 10, 'x');
		System.out.println(b);
		结果为：xxxxx12345
 
 
 
3．Strings.isNullOrEmpty 方法
//Strings.isNullOrEmpty 校验空值
		String a="";
		boolean b=Strings.isNullOrEmpty(a);
		System.out.println(b);
结果为：true
 
4．Strings.nullToEmpty  方法
	//Strings.nullToEmpty  如果为null 转为""
		String a=null;
		String b=Strings.nullToEmpty(a);
		System.out.println(b);
		结果为：
 
 
5．Strings.emptyToNull  方法
	//Strings.emptyToNull  如果为"" 转为null
		String a="";
		String b=Strings.emptyToNull(a);
		System.out.println(b);
		结果为：null
 
 
 
 
 
6．Strings.repeat  方法
	//Strings.repeat  重复字符串
		String a="123";
		String b=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
		String a="abcdsfsfs";
		String b="abc3sfsd";
		String c=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
		String a="faaxyz";
		String b="fwefxyz";
		String c=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
Joiner joiner =  Joiner.on(",");
		List<String> list =new ArrayList<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
Joiner joiner =  Joiner.on(",");
		List<String> list =new ArrayList<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 
Joiner joiner =  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
 
	Joiner joiner =  Joiner.on(",");
		List<String> list =new ArrayList<String>();
		list.add("xiaoming");
		list.add("xiaohong");
		list.add("wangsan"); 
		StringBuilder builder=new StringBuilder("标题");
		System.out.println(joiner.appendTo(builder,list));
结果：标题xiaoming,xiaohong,wangsan
 
5.跳过null值连接
		Joiner joiner =  Joiner.on(",").skipNulls();
		List<String> list =new ArrayList<String>();
		list.add("xiaoming");
		list.add(null);
		list.add("wangsan"); 
		StringBuilder builder=new StringBuilder("标题");
		System.out.println(joiner.appendTo(builder,list));
6.替换null值进行连接
	Joiner joiner =  Joiner.on(",").useForNull("123");//替换null为123
		List<String> list =new ArrayList<String>();
		list.add("xiaoming");
		list.add(null);
		list.add("wangsan"); 
		StringBuilder builder=new StringBuilder("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 
	Splitter splitter =Splitter.on(",");
		String str="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
 
		Splitter splitter =Splitter.on(",").omitEmptyStrings();
		String str="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
Splitter splitter =Splitter.on(",").omitEmptyStrings().trimResults();
		String str="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
 
		Escaper htmlEscaper =HtmlEscapers.htmlEscaper();
		System.out.println(htmlEscaper.escape("<a>你好</a>"));
		
结果：<a>你好</a>