guava的基本语法整理

package com.panther.base;

import com.google.common.base.CharMatcher;
import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.base.Stopwatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.TimeUnit;

import static com.google.common.base.Preconditions.checkNotNull;

/**
* guava的一些简单应用
* 预先判断Preconditions
* Object.toStringHelper()
* Stopwatch(计时器)
* CharMatcher(字符匹配)
* String Joining 字符串连接
* String Splitting字符串分割
* Created by panther.dongdong on 2015/11/16.
*/
public class BaseTest {
private static final Logger LOGGER = LoggerFactory.getLogger(BaseTest.class.getName());

public static void main(final String[] args) {

final Stopwatch stopwatch = Stopwatch.createUnstarted().start();
LOGGER.info("原生类型判断开始");
Double b = 2.0;
setRating(b);
LOGGER.info("原生类型判断结束");
LOGGER.info("guava判断开始");
setRatingGuava(b);
LOGGER.info("guava判断结束");
LOGGER.info("guava字符匹配开始");
matchGuava();
LOGGER.info("guava字符匹配结束");
LOGGER.info("guava字符串连接接结束");
joinGuava();
LOGGER.info("guava字符串连接结束");
LOGGER.info("guava字符串分割结束");
splitGuava();
LOGGER.info("guava字符串分割结束");
LOGGER.info("Object.toStringHelper()测试开始");
LOGGER.info(new Student().toString());
LOGGER.info("Object.toStringHelper()测试结束");
long nanos = stopwatch.elapsed(TimeUnit.MILLISECONDS);
LOGGER.info("总共耗时:{}", nanos);
}

/**
* 原生类型的判断
*
* @param rating double参数
*/
public static void setRating(Double rating) {
if (rating == null) {
throw new NullPointerException();
}
LOGGER.info("r = {}", rating);
}

/**
* 使用guava后代码更整洁
*
* @param rating double参数
*/
public static void setRatingGuava(Double rating) {
Double r = checkNotNull(rating);
LOGGER.info("r = {}", r);
}

/**
* guava字符匹配
* todo see
*/
public static void matchGuava() {
String userInput = "nihao1234-1";
CharMatcher ID_MATCHER = CharMatcher.DIGIT.or(CharMatcher.is('-')).or(CharMatcher.JAVA_LOWER_CASE);
LOGGER.info(ID_MATCHER.retainFrom(userInput));
}

/**
* 字符串链接
* String Joining 字符串连接
* 可以快速地把一组字符数组连接成为用特殊符合连接的一个字符串，
* 如果这组字符中有null值的话，我们可以使用skipNulls或是useForNull来控制我们要输出的内容。
*/
public static void joinGuava() {
Joiner JOINER = Joiner.on(",").useForNull("null");
Joiner JOINER1 = Joiner.on(",").skipNulls();

String str = JOINER.join("hello", "world", null, "qiyadeng");
String str1 = JOINER1.join("hello", "world", null, "qiyadeng");

//hello,world,null,qiyadeng
LOGGER.info("str is : {}", str);
LOGGER.info("str1(不带null) is : {}", str1);
}

/**
* String Splitting字符串分割
* 有这样一组字符串”hello,,qiyadeng,com,”
* 我们用split(“,”)分割字符串,
* 得到的结果是["hello","","qiyaeng","com"]
* ，但是我们如果希望的是把空值去掉，还需要另外处理，
* 使用guava的Splitter可以简单做到。
*/

public static void splitGuava() {
Iterable<String> splitStr = Splitter.on(',').trimResults().omitEmptyStrings().split("hello,,qiyadeng,com");
for (String string : splitStr) {
LOGGER.info(string);
}
}
}

/**
* guava中的计时器
* Stopwatch stopwatch = new Stopwatch().start();
* //do something test
* for (int i = 0; i < 10000; i++) {
* }
* long nanos = stopwatch.elapsed(TimeUnit.NANOSECONDS);
* System.out.println(nanos);
*/

package com.panther.base;

import com.google.common.base.Objects;

/**
* 测试Object.toStringHelper()的pojo
* Created by panther.dongdong on 2015/11/16.
*/
public class Student {
private int id;
private String name;
private String sex;
private int age;

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public String getSex() {
return sex;
}

public void setSex(String sex) {
this.sex = sex;
}

public int getAge() {
return age;
}

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

@Override
public String toString() {
return Objects.toStringHelper(this).add("id", id)
.add("name", name)
.add("sex", sex)
.add("age", age)
.omitNullValues()
.toString();
}
}