java Guava工具集学习（强大）

import java.util.Iterator;
import java.util.List;
import java.util.Map;

import com.google.common.base.Joiner;
import com.google.common.base.Predicate;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;

/**
 * Guava工具类
 * 
 * @author 
 * @time 2017年9月5日上午9:39:22
 */
public class GuavaUtils {
	private GuavaUtils() {
	}

	/**
	 * 用分割符把相应字符串隔开
	 * 
	 * @param separator
	 *            =>|
	 * @param objects
	 *            =>1,2,3
	 * @return 1|2|3
	 */
	public static String joinString(String separator, Object... objects) {
		Joiner joiner1 = Joiner.on(separator).skipNulls();
		return joiner1.appendTo(new StringBuilder(""), objects).toString();
	}

	/**
	 * 将map转换成string
	 * 
	 * @param map
	 * @return
	 */
	@SuppressWarnings("all")
	public static String mapToString(Map map) {
		return Joiner.on(";").withKeyValueSeparator("=").join(map);
	}

	/**
	 * 将字符串转换成List集合
	 * 
	 * @param separator
	 * @param str
	 * @return
	 */
	public static List<String> getListByStr(String separator, String str) {
		Splitter sp = Splitter.on(separator).trimResults();
		return sp.splitToList(str);
	}
	
	/**
	 * 判断集合中是否存在该元素
	 * @param list
	 * @param element
	 * @return
	 */
	public static boolean isListContainsObject(List<? extends Object> list,Object element){
		return Iterables.contains(list, element);
	}
	

	public static void main(String[] args) throws Exception {
		System.out.println(GuavaUtils.joinString("|", "1", "2", "3"));
		Map<String, String> testMap = Maps.newLinkedHashMap();
		testMap.put("Cookies", "12332");
		testMap.put("Content-Length", "30000");
		testMap.put("Date", "2016.12.16");
		testMap.put("Mime", "text/html");
		System.out.println(mapToString(testMap));

		// 分割符为|，并去掉得到元素的前后空白
		String str = "hello | world | your | Name ";
		List<String> ss = getListByStr("|", str);
		for (String it : ss) {
			System.out.println(it);
		}

		// 判断是否空
		System.out.println(Strings.isNullOrEmpty(""));

//		Preconditions.checkArgument(false, "你错了");

		Person person1 = new Person(30);
		Person person2 = new Person(32);
		Person person3 = new Person(33);
		Person person4 = new Person(34);
		List<Person> personList = Lists.newArrayList(person1, person2, person3,person4);
		// 过滤年龄大于等于32的person
		Iterable<Person> personsFilteredByAge = FluentIterable.from(personList).filter(new Predicate<Person>() {
			@Override
			public boolean apply(Person input) {
				return input.getAge() > 31;
			}
		});
		// Iterable有一个iterator方法，集合类都有一个Iterator方法
		for (Iterator<Person> it = personsFilteredByAge.iterator(); it.hasNext();) {
			System.out.println(it.next());
		}
		
		System.out.println(Iterables.contains(personsFilteredByAge, person2));
		
		System.out.println(isListContainsObject(personList, person3));
	}
}

class Person {

	private int age;

	public Person(int age) {
		super();
		this.age = age;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

}