Apache commons 工具包应用
Apache Commons 是一个非常有用的工具包，解决各种实际的通用问题，你会发现它们正是你冥思苦想所需要的东西。它们不是绝世武功，但确是个随手可用的擒手，Commons一出，问题手到擒来。常用的有：
commons-lang
commons-collections
commons-io
commons-beanutils
，下面是一个全面的简述表：
组件
说明BeanUtilsCommons-BeanUtils 提供对 Java 反射和自省API的包装BetwixtBetwixt提供将 JavaBean 映射至 XML 文档，以及相反映射的服务.Chain
Chain 提供实现组织复杂的处理流程的“责任链模式”.
CLI
CLI 提供针对命令行参数，选项，选项组，强制选项等的简单API.
Codec
Codec 包含一些通用的编码解码算法。包括一些语音编码器， Hex, Base64, 以及URL encoder.
Collections
Commons-Collections 提供一个类包来扩展和增加标准的 Java Collection框架
Configuration
Commons-Configuration 工具对各种各式的配置和参考文件提供读取帮助.
Daemon
一种 unix-daemon-like java 代码的替代机制
DBCP
Commons-DBCP 提供数据库连接池服务
DbUtils
DbUtils 是一个 JDBC helper 类库，完成数据库任务的简单的资源清除代码.
Digester
Commons-Digester 是一个 XML-Java对象的映射工具，用于解析 XML配置文件.
Discovery
Commons-Discovery 提供工具来定位资源 (包括类) ，通过使用各种模式来映射服务/引用名称和资源名称.EL
Commons-EL 提供在JSP2.0规范中定义的EL表达式的解释器.
FileUpload
FileUpload 使得在你可以在应用和Servlet中容易的加入强大和高性能的文件上传能力.
HttpClient
Commons-HttpClient 提供了可以工作于HTTP协议客户端的一个框架.
IO
IO 是一个 I/O 工具集.
Jelly
Jelly是一个基于 XML 的脚本和处理引擎。 Jelly 借鉴了 JSP 定指标签，Velocity, Cocoon和Xdoclet中的脚本引擎的许多优点。Jelly 可以用在命令行， Ant 或者 Servlet之中.Jexl
Jexl是一个表达式语言，通过借鉴来自于Velocity的经验扩展了JSTL定义的表达式语言.JXPath
Commons-JXPath 提供了使用Xpath语法操纵符合Java类命名规范的 JavaBeans的工具。也支持 maps, DOM 和其他对象模型.Lang
Commons-Lang 提供了许多许多通用的工具类集，提供了一些java.lang中类的扩展功能.
Latka
Commons-Latka 是一个HTTP 功能测试包，用于自动化的QA,验收和衰减测试.
Launcher
Launcher 组件是一个交叉平台的Java 应用载入器。 Commons-launcher 消除了需要批处理或者Shell脚本来载入Java 类。.原始的 Java 类来自于Jakarta Tomcat 4.0 项目.
Logging
Commons-Logging 是一个各种 logging API实现的包裹类.
Math
Math 是一个轻量的，自包含的数学和统计组件，解决了许多非常通用但没有及时出现在Java标准语言中的实践问题.
Modeler
Commons-Modeler 提供了建模兼容JMX规范的 Mbean的机制.
Net
Net 是一个网络工具集，基于 NetComponents 代码，包括 FTP 客户端等等.Pool
Commons-Pool 提供了通用对象池接口，一个用于创建模块化对象池的工具包，以及通常的对象池实现.Primitives
Commons-Primitives提供了一个更小，更快和更易使用的对Java基本类型的支持。当前主要是针对基本类型的 collection.Validator
The commons-validator提供了一个简单的，可扩展的框架来在一个XML文件中定义校验器 (校验方法)和校验规则。支持校验规则的和错误消息的国际化.详细信息位于：http://jakarta.apache.org/commons/index.html
以及Jakarta Commons:巧用类和组件
一.一、commons.lang包方法集锦
import java.util.Iterator;
import java.util.Map;
import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.ClassUtils;
import org.apache.commons.lang.RandomStringUtils;
import org.apache.commons.lang.StringEscapeUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.math.NumberUtils;
/**
?* commons-lang-2.4.jar 包常用方法集锦
?*
?*/
public class CommonsLang {
?? ?public static void main(String[] args) {
?? ???? String[] test = { "33", "ddffd" };
?? ???? String[] test1 = { "ddffd", "33" };
?? ???? // 1.判断两个数据是否相等
?? ???? System.out.println(ArrayUtils.isEquals(test, test1));
?? ???? // 2.{33,ddffd} 将数组内容以{,}形式输出．
?? ???? System.out.println(ArrayUtils.toString(test));
?? ???? Map map = ArrayUtils.toMap(new String[][] { { "RED", "#FF0000" },
?? ???? ??? ??? { "GREEN", "#00FF00" }, { "BLUE", "#0000FF" } });
?? ???? // 3.toMap 一个数组，但每个元素 Each element of the array
?? ???? // must be either a {@link java.util.Map.Entry} or an Array,
?? ???? // 方式一 下面是遍历map的方式，取得其keySet.iterator();
?? ???? Iterator it = map.keySet().iterator();
?? ???? while (it.hasNext()) {
?? ???? ??? String key = (String) it.next();
?? ???? ??? // it.next()只包含key
?? ???? ??? System.out.println("key:" + key + "value:" + map.get(key));
?? ???? }
?? ???? // 方式二,取得其entrySet()集合,
?? ???? Iterator it1 = map.entrySet().iterator();
?? ???? while (it.hasNext()) {
?? ???? ??? Map.Entry entry = (Map.Entry) it1.next();
?? ???? ??? // it1.next()中包含key和value
?? ???? ??? System.out.println("key :" + entry.getKey() + "value :"
?? ???? ??? ??? ??? + entry.getValue());
?? ???? }
?? ???? // 4.取得类名
?? ???? System.out.println(ClassUtils.getShortClassName(CommonsLang.class));
?? ???? // 取得其包名
?? ???? System.out.println(ClassUtils.getPackageName(CommonsLang.class));
?? ???? // 5.NumberUtils
?? ???? System.out.println(NumberUtils.stringToInt("6"));
?? ???? System.out.println(NumberUtils.stringToInt("7", 10));
?? ???? // 6.五位的随机字母和数字
?? ???? System.out.println(RandomStringUtils.randomAlphanumeric(5));
?? ???? // 7.StringEscapeUtils
?? ???? System.out.println(StringEscapeUtils.escapeHtml("<html>"));
?? ???? // 输出结果为<html>
?? ???? System.out.println(StringEscapeUtils.escapeJava("String"));
?? ???? // 8.StringUtils,判断是否是空格字符
?? ???? System.out.println(StringUtils.isBlank(" "));
?? ???? // 将数组中的内容以,分隔
?? ???? System.out.println(StringUtils.join(test, ","));
?? ???? // 在右边加下字符,使之总长度为6
?? ???? System.out.println(StringUtils.rightPad("abc", 6, 'T'));
?? ???? // 首字母大写
?? ???? System.out.println(StringUtils.capitalize("abc"));
?? ???? // Deletes all whitespaces from a String 删除所有空格
?? ???? System.out.println(StringUtils.deleteWhitespace(" ab c "));
?? ???? // 判断是否包含这个字符
?? ???? System.out.println(StringUtils.contains("abc", "ba"));
?? ???? // 表示左边两个字符
?? ???? System.out.println(StringUtils.left("abc", 2));
?? ???? System.out.println(StringUtils.right("abcd", 3));
?? ?}
}
?
一.二、commons.lang包方法集锦
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Calendar;
import java.util.Date;
import java.util.Iterator;
import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.CharSet;
import org.apache.commons.lang.CharSetUtils;
import org.apache.commons.lang.ClassUtils;
import org.apache.commons.lang.ObjectUtils;
import org.apache.commons.lang.RandomStringUtils;
import org.apache.commons.lang.SerializationUtils;
import org.apache.commons.lang.StringEscapeUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.SystemUtils;
import org.apache.commons.lang.builder.EqualsBuilder;
import org.apache.commons.lang.builder.HashCodeBuilder;
import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;
import org.apache.commons.lang.math.NumberUtils;
import org.apache.commons.lang.time.DateFormatUtils;
import org.apache.commons.lang.time.DateUtils;
import org.apache.commons.lang.time.StopWatch;
public class LangDemo {
??? public void charSetDemo() {
??? ??? System.out.println("**CharSetDemo**");
??? ??? CharSet charSet = CharSet.getInstance("aeiou");
??? ??? String demoStr = "The quick brown fox jumps over the lazy dog.";
??? ??? int count = 0;
??? ??? for (int i = 0, len = demoStr.length(); i < len; i++) {
??? ??? ??? if (charSet.contains(demoStr.charAt(i))) {
??? ??? ??? ??? count++;
??? ??? ??? }
??? ??? }
??? ??? System.out.println("count: " + count);
??? }
??? public void charSetUtilsDemo() {
??? ??? System.out.println("**CharSetUtilsDemo**");
??? ??? System.out.println("计算字符串中包含某字符数.");
??? ??? System.out.println(CharSetUtils.count(
??? ??? ??? ??? "The quick brown fox jumps over the lazy dog.", "aeiou"));
??? ??? System.out.println("删除字符串中某字符.");
??? ??? System.out.println(CharSetUtils.delete(
??? ??? ??? ??? "The quick brown fox jumps over the lazy dog.", "aeiou"));
??? ??? System.out.println("保留字符串中某字符.");
??? ??? System.out.println(CharSetUtils.keep(
??? ??? ??? ??? "The quick brown fox jumps over the lazy dog.", "aeiou"));
??? ??? System.out.println("合并重复的字符.");
??? ??? System.out.println(CharSetUtils.squeeze("a? bbbbbb???? c dd", "b d"));
??? }
??? public void objectUtilsDemo() {
??? ??? System.out.println("**ObjectUtilsDemo**");
??? ??? System.out.println("Object为null时，默认打印某字符.");
??? ??? Object obj = null;
??? ??? System.out.println(ObjectUtils.defaultIfNull(obj, "空"));
??? ??? System.out.println("验证两个引用是否指向的Object是否相等,取决于Object的equals()方法.");
??? ??? Object a = new Object();
??? ??? Object b = a;
??? ??? Object c = new Object();
??? ??? System.out.println(ObjectUtils.equals(a, b));
??? ??? System.out.println(ObjectUtils.equals(a, c));
??? ??? System.out.println("用父类Object的toString()方法返回对象信息.");
??? ??? Date date = new Date();
??? ??? System.out.println(ObjectUtils.identityToString(date));
??? ??? System.out.println(date);
??? ??? System.out.println("返回类本身的toString()方法结果,对象为null时，返回0长度字符串.");
??? ??? System.out.println(ObjectUtils.toString(date));
??? ??? System.out.println(ObjectUtils.toString(null));
??? ??? System.out.println(date);
??? }
??? public void serializationUtilsDemo() {
??? ??? System.out.println("*SerializationUtils**");
??? ??? Date date = new Date();
??? ??? byte[] bytes = SerializationUtils.serialize(date);
??? ??? System.out.println(ArrayUtils.toString(bytes));
??? ??? System.out.println(date);
??? ??? Date reDate = (Date) SerializationUtils.deserialize(bytes);
??? ??? System.out.println(reDate);
??? ??? System.out.println(ObjectUtils.equals(date, reDate));
??? ??? System.out.println(date == reDate);
??? ??? FileOutputStream fos = null;
??? ??? FileInputStream fis = null;
??? ??? try {
??? ??? ??? fos = new FileOutputStream(new File("d:/test.txt"));
??? ??? ??? fis = new FileInputStream(new File("d:/test.txt"));
??? ??? ??? SerializationUtils.serialize(date, fos);
??? ??? ??? Date reDate2 = (Date) SerializationUtils.deserialize(fis);
??? ??? ??? System.out.println(date.equals(reDate2));
??? ??? } catch (FileNotFoundException e) {
??? ??? ??? e.printStackTrace();
??? ??? } finally {
??? ??? ??? try {
??? ??? ??? ??? fos.close();
??? ??? ??? ??? fis.close();
??? ??? ??? } catch (IOException e) {
??? ??? ??? ??? e.printStackTrace();
??? ??? ??? }
??? ??? }
??? }
??? public void randomStringUtilsDemo() {
??? ??? System.out.println("**RandomStringUtilsDemo**");
??? ??? System.out.println("生成指定长度的随机字符串,好像没什么用.");
??? ??? System.out.println(RandomStringUtils.random(500));
??? ??? System.out.println("在指定字符串中生成长度为n的随机字符串.");
??? ??? System.out.println(RandomStringUtils.random(5, "abcdefghijk"));
??? ??? System.out.println("指定从字符或数字中生成随机字符串.");
??? ??? System.out.println(RandomStringUtils.random(5, true, false));
??? ??? System.out.println(RandomStringUtils.random(5, false, true));
??? }
??? public void stringUtilsDemo() {
??? ??? System.out.println("**StringUtilsDemo**");
??? ??? System.out.println("将字符串重复n次，将文字按某宽度居中，将字符串数组用某字符串连接.");
??? ??? String[] header = new String[3];
??? ??? header[0] = StringUtils.repeat("*", 50);
??? ??? header[1] = StringUtils.center("? StringUtilsDemo? ", 50, "^O^");
??? ??? header[2] = header[0];
??? ??? String head = StringUtils.join(header, "/n");
??? ??? System.out.println(head);
??? ??? System.out.println("缩短到某长度,用...结尾.");
??? ??? System.out.println(StringUtils.abbreviate(
??? ??? ??? ??? "The quick brown fox jumps over the lazy dog.", 10));
??? ??? System.out.println(StringUtils.abbreviate(
??? ??? ??? ??? "The quick brown fox jumps over the lazy dog.", 15, 10));
??? ??? System.out.println("返回两字符串不同处索引号.");
??? ??? System.out.println(StringUtils.indexOfDifference("aaabc", "aaacc"));
??? ??? System.out.println("返回两字符串不同处开始至结束.");
??? ??? System.out.println(StringUtils.difference("aaabcde", "aaaccde"));
??? ??? System.out.println("截去字符串为以指定字符串结尾的部分.");
??? ??? System.out.println(StringUtils.chomp("aaabcde", "de"));
??? ??? System.out.println("检查一字符串是否为另一字符串的子集.");
??? ??? System.out.println(StringUtils.containsOnly("aad", "aadd"));
??? ??? System.out.println("检查一字符串是否不是另一字符串的子集.");
??? ??? System.out.println(StringUtils.containsNone("defg", "aadd"));
??? ??? System.out.println("检查一字符串是否包含另一字符串.");
??? ??? System.out.println(StringUtils.contains("defg", "ef"));
??? ??? System.out.println(StringUtils.containsOnly("ef", "defg"));
??? ??? System.out.println("返回可以处理null的toString().");
??? ??? System.out.println(StringUtils.defaultString("aaaa"));
??? ??? System.out.println("?" + StringUtils.defaultString(null) + "!");
??? ??? System.out.println("去除字符中的空格.");
??? ??? System.out.println(StringUtils.deleteWhitespace("aa? bb? cc"));
??? ??? System.out.println("判断是否是某类字符.");
??? ??? System.out.println(StringUtils.isAlpha("ab"));
??? ??? System.out.println(StringUtils.isAlphanumeric("12"));
??? ??? System.out.println(StringUtils.isBlank(""));
??? ??? System.out.println(StringUtils.isNumeric("123"));
??? }
??? public void systemUtilsDemo() {
??? ??? System.out.println(genHeader("SystemUtilsDemo"));
??? ??? System.out.println("获得系统文件分隔符.");
??? ??? System.out.println(SystemUtils.FILE_SEPARATOR);
??? ??? System.out.println("获得源文件编码.");
??? ??? System.out.println(SystemUtils.FILE_ENCODING);
??? ??? System.out.println("获得ext目录.");
??? ??? System.out.println(SystemUtils.JAVA_EXT_DIRS);
??? ??? System.out.println("获得java版本.");
??? ??? System.out.println(SystemUtils.JAVA_VM_VERSION);
??? ??? System.out.println("获得java厂商.");
??? ??? System.out.println(SystemUtils.JAVA_VENDOR);
??? }
??? public void classUtilsDemo() {
??? ??? System.out.println(genHeader("ClassUtilsDemo"));
??? ??? System.out.println("获取类实现的所有接口.");
??? ??? System.out.println(ClassUtils.getAllInterfaces(Date.class));
??? ??? System.out.println("获取类所有父类.");
??? ??? System.out.println(ClassUtils.getAllSuperclasses(Date.class));
??? ??? System.out.println("获取简单类名.");
??? ??? System.out.println(ClassUtils.getShortClassName(Date.class));
??? ??? System.out.println("获取包名.");
??? ??? System.out.println(ClassUtils.getPackageName(Date.class));
??? ??? System.out.println("判断是否可以转型.");
??? ??? System.out.println(ClassUtils.isAssignable(Date.class, Object.class));
??? ??? System.out.println(ClassUtils.isAssignable(Object.class, Date.class));
??? }
??? public void stringEscapeUtilsDemo() {
??? ??? System.out.println(genHeader("StringEcsapeUtils"));
??? ??? System.out.println("转换特殊字符.");
??? ??? System.out.println("html:" + StringEscapeUtils.escapeHtml(""));
??? ??? System.out.println("html:" + StringEscapeUtils.unescapeHtml("<p>"));
??? }
??? private final class BuildDemo {
??? ??? String name;
??? ??? int age;
??? ??? public BuildDemo(String name, int age) {
??? ??? ??? this.name = name;
??? ??? ??? this.age = age;
??? ??? }
??? ??? public String toString() {
??? ??? ??? ToStringBuilder tsb = new ToStringBuilder(this,
??? ??? ??? ??? ??? ToStringStyle.MULTI_LINE_STYLE);
??? ??? ??? tsb.append("Name", name);
??? ??? ??? tsb.append("Age", age);
??? ??? ??? return tsb.toString();
??? ??? }
??? ??? public int hashCode() {
??? ??? ??? HashCodeBuilder hcb = new HashCodeBuilder();
??? ??? ??? hcb.append(name);
??? ??? ??? hcb.append(age);
??? ??? ??? return hcb.hashCode();
??? ??? }
??? ??? public boolean equals(Object obj) {
??? ??? ??? if (!(obj instanceof BuildDemo)) {
??? ??? ??? ??? return false;
??? ??? ??? }
??? ??? ??? BuildDemo bd = (BuildDemo) obj;
??? ??? ??? EqualsBuilder eb = new EqualsBuilder();
??? ??? ??? eb.append(name, bd.name);
??? ??? ??? eb.append(age, bd.age);
??? ??? ??? return eb.isEquals();
??? ??? }
??? }
??? public void builderDemo() {
??? ??? System.out.println(genHeader("BuilderDemo"));
??? ??? BuildDemo obj1 = new BuildDemo("a", 1);
??? ??? BuildDemo obj2 = new BuildDemo("b", 2);
??? ??? BuildDemo obj3 = new BuildDemo("a", 1);
??? ??? System.out.println("toString()");
??? ??? System.out.println(obj1);
??? ??? System.out.println(obj2);
??? ??? System.out.println(obj3);
??? ??? System.out.println("hashCode()");
??? ??? System.out.println(obj1.hashCode());
??? ??? System.out.println(obj2.hashCode());
??? ??? System.out.println(obj3.hashCode());
??? ??? System.out.println("equals()");
??? ??? System.out.println(obj1.equals(obj2));
??? ??? System.out.println(obj1.equals(obj3));
??? }
??? public void numberUtils() {
??? ??? System.out.println(genHeader("NumberUtils"));
??? ??? System.out.println("字符串转为数字(不知道有什么用).");
??? ??? System.out.println(NumberUtils.stringToInt("ba", 33));
??? ??? System.out.println("从数组中选出最大值.");
??? ??? System.out.println(NumberUtils.max(new int[] { 1, 2, 3, 4 }));
??? ??? System.out.println("判断字符串是否全是整数.");
??? ??? System.out.println(NumberUtils.isDigits("123.1"));
??? ??? System.out.println("判断字符串是否是有效数字.");
??? ??? System.out.println(NumberUtils.isNumber("0123.1"));
??? }
??? public void dateFormatUtilsDemo() {
??? ??? System.out.println(genHeader("DateFormatUtilsDemo"));
??? ??? System.out.println("格式化日期输出.");
??? ??? System.out.println(DateFormatUtils.format(System.currentTimeMillis(),
??? ??? ??? ??? "yyyy-MM-dd HH:mm:ss"));
??? ??? System.out.println("秒表.");
??? ??? StopWatch sw = new StopWatch();
??? ??? sw.start();
??? ??? for (Iterator iterator = DateUtils.iterator(new Date(),
??? ??? ??? ??? DateUtils.RANGE_WEEK_CENTER); iterator.hasNext();) {
??? ??? ??? Calendar cal = (Calendar) iterator.next();
??? ??? ??? System.out.println(DateFormatUtils.format(cal.getTime(),
??? ??? ??? ??? ??? "yy-MM-dd HH:mm"));
??? ??? }
??? ??? sw.stop();
??? ??? System.out.println("秒表计时:" + sw.getTime());
??? }
??? private String genHeader(String head) {
??? ??? String[] header = new String[3];
??? ??? header[0] = StringUtils.repeat("*", 50);
??? ??? header[1] = StringUtils.center("? " + head + "? ", 50, "^O^");
??? ??? header[2] = header[0];
??? ??? return StringUtils.join(header, "/n");
??? }
??? /**
??? ?* @param args
??? ?*/
??? public static void main(String[] args) {
??? ??? LangDemo langDemo = new LangDemo();
??? ??? langDemo.charSetDemo();
??? ??? langDemo.charSetUtilsDemo();
??? ??? langDemo.objectUtilsDemo();
??? ??? langDemo.serializationUtilsDemo();
??? ??? langDemo.randomStringUtilsDemo();
??? ??? langDemo.stringUtilsDemo();
??? ??? langDemo.systemUtilsDemo();
??? ??? langDemo.classUtilsDemo();
??? ??? langDemo.stringEscapeUtilsDemo();
??? ??? langDemo.builderDemo();
??? ??? langDemo.numberUtils();
??? ??? langDemo.dateFormatUtilsDemo();
??? }
}
?
一.三、commons.lang包(StringUtils)方法集锦
处理文本对Java应用来说应该算是家常便饭了，在1.4出现之前，Java自身提供的API非常有限，如String、StringTokenizer、StringBuffer，操作也比较单一。无非就是查找substring、分解、合并等等。到1.4的出现可以说Java的文字处理上了一个台阶，因为它支持regular expression了。这可是个重量级而方便的东东啊，缺点是太复杂，学习起来有一定难度。相较而言，Jakarta Commons提供的StringUtils和WordUtils至今还维持着那种简洁而强大的美，使用起来也很顺手。来看一个例子：
package sean.study.jakarta.commons.lang;
import org.apache.commons.lang.StringUtils;
public class StringUtilsAndWordUtilsUsage {
public static void main(String[] args) {
// data setup
String str1 = "";
String str2 = " ";
String str3 = "\t";
String str4 = null;
String str5 = "123";
String str6 = "ABCDEFG";
String str7 = "It feels good to use Jakarta Commons.\r\n";
// check for empty strings
System.out.println("==============================");
System.out.println("Is str1 blank? " + StringUtils.isBlank(str1));
System.out.println("Is str2 blank? " + StringUtils.isBlank(str2));
System.out.println("Is str3 blank? " + StringUtils.isBlank(str3));
System.out.println("Is str4 blank? " + StringUtils.isBlank(str4));
// check for numerics
System.out.println("==============================");
System.out.println("Is str5 numeric? " + StringUtils.isNumeric(str5));
System.out.println("Is str6 numeric? " + StringUtils.isNumeric(str6));
// reverse strings / whole words
System.out.println("==============================");
System.out.println("str6: " + str6);
System.out.println("str6 reversed: " + StringUtils.reverse(str6));
System.out.println("str7: " + str7);
String str8 = StringUtils.chomp(str7);
str8 = StringUtils.reverseDelimited(str8, ' ');
System.out.println("str7 reversed whole words : \r\n" + str8);
// build header (useful to print log messages that are easy to locate)
System.out.println("==============================");
System.out.println("print header:");
String padding = StringUtils.repeat("=", 50);
String msg = StringUtils.center(" Customised Header ", 50, "%");
Object[] raw = new Object[]{padding, msg, padding};
String header = StringUtils.join(raw, "\r\n");
System.out.println(header);
}
}
输出的结果如下：
==============================
Is str1 blank? true
Is str2 blank? true
Is str3 blank? true
Is str4 blank? true
==============================
Is str5 numeric? true
Is str6 numeric? false
==============================
str6: ABCDEFG
str6 reversed: GFEDCBA
str7: It feels good to use Jakarta Commons.
str7 reversed whole words :
Commons. Jakarta use to good feels It
==============================
print header:
==================================================
%%%%%%%%%%%%%%% Customised Header %%%%%%%%%%%%%%%%
==================================================
从代码中我们可以大致了解到这个StringUtils类简单而强大的处理能力，从检查空串（对null的情况处理很得体），到分割子串，到生成格式化的字符串，使用都很简洁，也很直截了当。
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一.四、commons.io包(StringUtils)方法集锦
1.文件内容拷贝：import java.io.File;import java.io.FileWriter;import java.io.IOException;import java.io.InputStream;import java.io.Writer; import org.apache.commons.io.FileUtils;import org.apache.commons.io.IOUtils; publicclass FileCopyExample { publicstaticvoid main(String[] args) { try { File src = new File( "test.dat" ); File dest = new File( "test.dat.bak" ); FileUtils.copyFile( src, dest ); } catch( IOException ioe ) { System.out.println( "Problem copying file." ); } try { File src = new File( "test.dat" ); File dir = new File( "./temp" ); FileUtils.copyFileToDirectory( src, dir ); } catch( IOException ioe ) { System.out.println( "Problem copying file to dir."); } try { String string = "Blah blah blah"; File dest = new File( "test.tmp" ); FileUtils.writeStringToFile( dest, string, "ISO-8859-1" ); } catch( IOException ioe ) { System.out.println( "Error writing out a String." ); } try { Writer writer = new FileWriter( "test.dat" ); InputStream inputStream =FileCopyExample.class. getClass().getResourceAsStream("/io/web.xml"); IOUtils.copy( inputStream, writer ); writer.close(); inputStream.close(); } catch (IOException e) { System.out.println( "Error copying data" ); } try { File src = new File( "test.txt" ); OutputStream output = new FileOutputStream(src); InputStream inputStream =FileCopyExample.class. getClass().getResourceAsStream("/io/web.xml"); IOUtils.copy( inputStream, output );// writer.close(); inputStream.close(); output.close(); } catch (IOException e) { System.out.println( "Error copying data" ); } } } 2.文件删除：File file = new File( ("io/project.properties") ); String display = FileUtils.byteCountToDisplaySize( file.length() ); System.out.println( "project.xml is " + display ); FileUtils.forceDelete(file) 3.读取取文本中的每一行：import java.io.File;import java.io.IOException;import java.util.List; import org.apache.commons.io.FileSystemUtils;import org.apache.commons.io.FileUtils; public class Test { public static void main(String[] args) throws IOException { // TODO Auto-generated method stub File file = new File((Test.class.getClass().getResource("/io/web.xml")).getFile()); List lines = FileUtils.readLines(file, "UTF-8"); for(int i=0;i<lines.size();i++) System.out.println(lines.get(i)); }}
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一.五、commons包，网上的一些参考资料
http://www.blogjava.net/coolingverse/category/26252.html
http://www.open-open.com????? open文档-->我收藏的文档中，账号junjun1986
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