Apache Commons 工具类介绍及简单使用

2019-12-24 15:50:40 浏览数 (1)

Apache Commons 工具类大家都有用过,但是可能缺乏系统学习,只用到了一小部分功能,无法发挥极限的价值,肥朝用大白话说就是,一颗好白菜都让猪给拱了! 代码过多,手机观看效果不佳,建议收藏后在电脑上静悄悄地看。因内容健康,可大胆转发,即使未满十八岁,在没有家长陪同下也一样可以观看!

1、BeanUtils

提供了对于JavaBean进行各种操作, 比如对象,属性复制等等。

代码语言:javascript复制
//1、 克隆对象  
//  新创建一个普通Java Bean,用来作为被克隆的对象  

    public class Person {  
    private String name = "";  
    private String email = "";  

    private int age;  
    //省略 set,get方法  
    }  

//  再创建一个Test类,其中在main方法中代码如下:
    import java.lang.reflect.InvocationTargetException;  
    import java.util.HashMap;  
    import java.util.Map;  
    import org.apache.commons.beanutils.BeanUtils;  
    import org.apache.commons.beanutils.ConvertUtils;  
    public class Test {  

    /** 

    * @param args 

    */  
    public static void main(String[] args) {  
    Person person = new Person();  
    person.setName("tom");  
    person.setAge(21);  
    try {  
            //克隆  
        Person person2 =  (Person)BeanUtils.cloneBean(person);  
        System.out.println(person2.getName() ">>" person2.getAge());  
    } catch (IllegalAccessException e) {  
        e.printStackTrace();  
    } catch (InstantiationException e) {  
        e.printStackTrace();  
    } catch (InvocationTargetException e) {  
        e.printStackTrace();  
    } catch (NoSuchMethodException e) {  
        e.printStackTrace();  

    }  

    }  

    }  

//  原理也是通过Java的反射机制来做的。
//  2、 将一个Map对象转化为一个Bean  
//  这个Map对象的key必须与Bean的属性相对应。
    Map map = new HashMap();  
    map.put("name","tom");  
    map.put("email","tom@");  
    map.put("age","21");  
    //将map转化为一个Person对象  
    Person person = new Person();  
    BeanUtils.populate(person,map);  
//  通过上面的一行代码,此时person的属性就已经具有了上面所赋的值了。
//  将一个Bean转化为一个Map对象了,如下:
    Map map = BeanUtils.describe(person)

2.Betwixt

XML与Java对象之间相互转换。

代码语言:javascript复制
//1、 将JavaBean转为XML内容  
// 新创建一个Person类  
public class Person{  
    private String name;  
    private int age;  
    /** Need to allow bean to be created via reflection */  
    public PersonBean() {  
    }  
    public PersonBean(String name, int age) {  
        this.name = name;  
        this.age = age;  
    }  
    //省略set, get方法  
    public String toString() {  
        return "PersonBean[name='"   name   "',age='"   age   "']";  
    }  
}  

//再创建一个WriteApp类:
import java.io.StringWriter;  
import org.apache.commons.betwixt.io.BeanWriter;  
public class WriteApp {  
/** 
* 创建一个例子Bean,并将它转化为XML. 
*/  
public static final void main(String [] args) throws Exception {  
    // 先创建一个StringWriter,我们将把它写入为一个字符串         
    StringWriter outputWriter = new StringWriter();  
    // Betwixt在这里仅仅是将Bean写入为一个片断  
    // 所以如果要想完整的XML内容,我们应该写入头格式  
    outputWriter.write(“<?xml version=’1.0′ encoding=’UTF-8′ ?>n”);  
    // 创建一个BeanWriter,其将写入到我们预备的stream中  
    BeanWriter beanWriter = new BeanWriter(outputWriter);  
    // 配置betwixt  
    // 更多详情请参考java docs 或最新的文档  
    beanWriter.getXMLIntrospector().getConfiguration().setAttributesForPrimitives(false);  
    beanWriter.getBindingConfiguration().setMapIDs(false);  
    beanWriter.enablePrettyPrint();  
    // 如果这个地方不传入XML的根节点名,Betwixt将自己猜测是什么  
    // 但是让我们将例子Bean名作为根节点吧  
    beanWriter.write(“person”, new PersonBean(“John Smith”, 21));  
    //输出结果  
    System.out.println(outputWriter.toString());  
    // Betwixt写的是片断而不是一个文档,所以不要自动的关闭掉writers或者streams,  
    //但这里仅仅是一个例子,不会做更多事情,所以可以关掉  
    outputWriter.close();  
    }  
}  
//2、 将XML转化为JavaBean  
import java.io.StringReader;  
import org.apache.commons.betwixt.io.BeanReader;  
public class ReadApp {  
public static final void main(String args[]) throws Exception{  
    // 先创建一个XML,由于这里仅是作为例子,所以我们硬编码了一段XML内容  
    StringReader xmlReader = new StringReader(  
    "<?xml version=’1.0′ encoding=’UTF-8′ ?> <person><age>25</age><name>James Smith</name></person>");  
    //创建BeanReader  
    BeanReader beanReader  = new BeanReader();  
    //配置reader  
    beanReader.getXMLIntrospector().getConfiguration().setAttributesForPrimitives(false);  
    beanReader.getBindingConfiguration().setMapIDs(false);  
    //注册beans,以便betwixt知道XML将要被转化为一个什么Bean  
    beanReader.registerBeanClass("person", PersonBean.class);  
    //现在我们对XML进行解析  
    PersonBean person = (PersonBean) beanReader.parse(xmlReader);  
    //输出结果  
    System.out.println(person);  
    }  
}

3.Codec

提供了一些公共的编解码实现,比如Base64, Hex, MD5,Phonetic and URLs等等。

代码语言:javascript复制
//Base64编解码  
private static String encodeTest(String str){  
    Base64 base64 = new Base64();  
    try {  
        str = base64.encodeToString(str.getBytes("UTF-8"));  
    } catch (UnsupportedEncodingException e) {  
        e.printStackTrace();  
    }  
        System.out.println("Base64 编码后:" str);  
    return str;  
}  

private static void decodeTest(String str){  
    Base64 base64 = new Base64();  
    //str = Arrays.toString(Base64.decodeBase64(str));  
    str = new String(Base64.decodeBase64(str));  
    System.out.println("Base64 解码后:" str);  
}

4.Collections

对java.util的扩展封装,处理数据还是挺灵活的。

org.apache.commons.collections – Commons Collections自定义的一组公用的接口和工具类

org.apache.commons.collections.bag – 实现Bag接口的一组类

org.apache.commons.collections.bidimap – 实现BidiMap系列接口的一组类

org.apache.commons.collections.buffer – 实现Buffer接口的一组类

org.apache.commons.collections.collection – 实现java.util.Collection接口的一组类

org.apache.commons.collections.comparators – 实现java.util.Comparator接口的一组类

org.apache.commons.collections.functors – Commons Collections自定义的一组功能类

org.apache.commons.collections.iterators – 实现java.util.Iterator接口的一组类

org.apache.commons.collections.keyvalue – 实现集合和键/值映射相关的一组类

org.apache.commons.collections.list – 实现java.util.List接口的一组类

org.apache.commons.collections.map – 实现Map系列接口的一组类

org.apache.commons.collections.set – 实现Set系列接口的一组类

代码语言:javascript复制
/** 
* 得到集合里按顺序存放的key之后的某一Key 
*/  
OrderedMap map = new LinkedMap();  
map.put("FIVE", "5");  
map.put("SIX", "6");  
map.put("SEVEN", "7");  
map.firstKey(); // returns "FIVE"  
map.nextKey("FIVE"); // returns "SIX"  
map.nextKey("SIX"); // returns "SEVEN"   

/** 
* 通过key得到value 
* 通过value得到key 
* 将map里的key和value对调 
*/  

BidiMap bidi = new TreeBidiMap();  
bidi.put("SIX", "6");  
bidi.get("SIX");  // returns "6"  
bidi.getKey("6");  // returns "SIX"  
//       bidi.removeValue("6");  // removes the mapping  
BidiMap inverse = bidi.inverseBidiMap();  // returns a map with keys and values swapped  
System.out.println(inverse);  

/** 
 * 得到两个集合中相同的元素 
 */  
List<String> list1 = new ArrayList<String>();  
list1.add("1");  
list1.add("2");  
list1.add("3");  
List<String> list2 = new ArrayList<String>();  
list2.add("2");  
list2.add("3");  
list2.add("5");  
Collection c = CollectionUtils.retainAll(list1, list2);  
System.out.println(c);

5.Compress

commons compress中的打包、压缩类库。

代码语言:javascript复制
//创建压缩对象  
ZipArchiveEntry entry = new ZipArchiveEntry("CompressTest");  
//要压缩的文件  
File f=new File("e:\test.pdf");  
FileInputStream fis=new FileInputStream(f);  
//输出的对象 压缩的文件  
ZipArchiveOutputStream zipOutput=new ZipArchiveOutputStream(new File("e:\test.zip"));    
zipOutput.putArchiveEntry(entry);  
int i=0,j;  
while((j=fis.read()) != -1)  
{   
zipOutput.write(j);  
i  ;  
System.out.println(i);  
}  
zipOutput.closeArchiveEntry();  
zipOutput.close();  
fis.close();

6.Configuration

用来帮助处理配置文件的,支持很多种存储方式。

  1. Properties files
  2. XML documents
  3. Property list files (.plist)
  4. JNDI
  5. JDBC Datasource
  6. System properties
  7. Applet parameters
  8. Servlet parameters
代码语言:javascript复制
//举一个Properties的简单例子  
# usergui.properties  
colors.background = #FFFFFF  
colors.foreground = #000080  
window.width = 500  
window.height = 300  

PropertiesConfiguration config = new PropertiesConfiguration("usergui.properties");  
config.setProperty("colors.background", "#000000);  
config.save();  

config.save("usergui.backup.properties);//save a copy  
Integer integer = config.getInteger("window.width");  

7.DBCP

(Database Connection Pool)是一个依赖Jakarta commons-pool对象池机制的数据库连接池,Tomcat的数据源使用的就是DBCP。

代码语言:javascript复制
import javax.sql.DataSource;  
import java.sql.Connection;  
import java.sql.Statement;  
import java.sql.ResultSet;  
import java.sql.SQLException;  

import org.apache.commons.pool.ObjectPool;  
import org.apache.commons.pool.impl.GenericObjectPool;  
import org.apache.commons.dbcp.ConnectionFactory;  
import org.apache.commons.dbcp.PoolingDataSource;  
import org.apache.commons.dbcp.PoolableConnectionFactory;  
import org.apache.commons.dbcp.DriverManagerConnectionFactory;  
//官方示例  
public class PoolingDataSources {  

    public static void main(String[] args) {  
        System.out.println("加载jdbc驱动");  
        try {  
        Class.forName("oracle.jdbc.driver.OracleDriver");  
        } catch (ClassNotFoundException e) {  
        e.printStackTrace();  
        }  
        System.out.println("Done.");  
        //  
        System.out.println("设置数据源");  
        DataSource dataSource = setupDataSource("jdbc:oracle:thin:@localhost:1521:test");  
        System.out.println("Done.");  

        //  
        Connection conn = null;  
        Statement stmt = null;  
        ResultSet rset = null;  

        try {  
        System.out.println("Creating connection.");  
        conn = dataSource.getConnection();  
        System.out.println("Creating statement.");  
        stmt = conn.createStatement();  
        System.out.println("Executing statement.");  
        rset = stmt.executeQuery("select * from person");  
        System.out.println("Results:");  
        int numcols = rset.getMetaData().getColumnCount();  
        while(rset.next()) {  
        for(int i=0;i<=numcols;i  ) {  
        System.out.print("t"   rset.getString(i));  
        }  
        System.out.println("");  
        }  
        } catch(SQLException e) {  
        e.printStackTrace();  
        } finally {  
        try { if (rset != null) rset.close(); } catch(Exception e) { }  
        try { if (stmt != null) stmt.close(); } catch(Exception e) { }  
        try { if (conn != null) conn.close(); } catch(Exception e) { }  
        }  
        }  

    public static DataSource setupDataSource(String connectURI) {  
        //设置连接地址  
        ConnectionFactory connectionFactory = new DriverManagerConnectionFactory(  
                connectURI, null);  

        // 创建连接工厂  
        PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(  
                connectionFactory);  

        //获取GenericObjectPool 连接的实例  
        ObjectPool connectionPool = new GenericObjectPool(  
                poolableConnectionFactory);  

        // 创建 PoolingDriver  
        PoolingDataSource dataSource = new PoolingDataSource(connectionPool);  

        return dataSource;  
    }  
}

8.DbUtils

Apache组织提供的一个资源JDBC工具类库,它是对JDBC的简单封装,对传统操作数据库的类进行二次封装,可以把结果集转化成List。,同时也不影响程序的性能。

DbUtils类:启动类

ResultSetHandler接口:转换类型接口

MapListHandler类:实现类,把记录转化成List

BeanListHandler类:实现类,把记录转化成List,使记录为JavaBean类型的对象

Qrery Runner类:执行SQL语句的类

代码语言:javascript复制
import org.apache.commons.dbutils.DbUtils;  
import org.apache.commons.dbutils.QueryRunner;  
import org.apache.commons.dbutils.handlers.BeanListHandler;  
import java.sql.Connection;  
import java.sql.DriverManager;  
import java.sql.SQLException;  
import java.util.List;  
//转换成list  
public class BeanLists {  
    public static void main(String[] args) {  
        Connection conn = null;  
        String url = "jdbc:mysql://localhost:3306/ptest";  
        String jdbcDriver = "com.mysql.jdbc.Driver";  
        String user = "root";  
        String password = "ptest";  

        DbUtils.loadDriver(jdbcDriver);  
        try {  
            conn = DriverManager.getConnection(url, user, password);  
            QueryRunner qr = new QueryRunner();  
            List results = (List) qr.query(conn, "select id,name from person", new BeanListHandler(Person.class));  
            for (int i = 0; i < results.size(); i  ) {  
                Person p = (Person) results.get(i);  
                System.out.println("id:"   p.getId()   ",name:"   p.getName());  
            }  
        } catch (SQLException e) {  
            e.printStackTrace();  
        } finally {  
            DbUtils.closeQuietly(conn);  
        }  
    }  
}  

public class Person{  
    private Integer id;  
    private String name;  

   //省略set, get方法  
}  

import org.apache.commons.dbutils.DbUtils;  
import org.apache.commons.dbutils.QueryRunner;  
import org.apache.commons.dbutils.handlers.MapListHandler;  

import java.sql.Connection;  
import java.sql.DriverManager;  
import java.sql.SQLException;  

import java.util.List;  
import java.util.Map;  
//转换成map  
public class MapLists {  
    public static void main(String[] args) {  
        Connection conn = null;  
        String url = "jdbc:mysql://localhost:3306/ptest";  
        String jdbcDriver = "com.mysql.jdbc.Driver";  
        String user = "root";  
        String password = "ptest";  

        DbUtils.loadDriver(jdbcDriver);  
        try {  
            conn = DriverManager.getConnection(url, user, password);  
            QueryRunner qr = new QueryRunner();  
            List results = (List) qr.query(conn, "select id,name from person", new MapListHandler());  
            for (int i = 0; i < results.size(); i  ) {  
                Map map = (Map) results.get(i);  
                System.out.println("id:"   map.get("id")   ",name:"   map.get("name"));  
            }  
        } catch (SQLException e) {  
            e.printStackTrace();  
        } finally {  
            DbUtils.closeQuietly(conn);  
        }  
    }  
}

9.Email

提供的一个开源的API,是对javamail的封装。

代码语言:javascript复制
//用commons email发送邮件  
public static void main(String args[]){  
    Email email = new SimpleEmail();  
    email.setHostName("smtp.googlemail.com");  
    email.setSmtpPort(465);  
    email.setAuthenticator(new DefaultAuthenticator("username", "password"));  
    email.setSSLOnConnect(true);  
    email.setFrom("user@gmail.com");  
    email.setSubject("TestMail");  
    email.setMsg("This is a test mail ... :-)");  
    email.addTo("foo@bar.com");  
    email.send();  
}

10.FileUpload

java web文件上传功能。

代码语言:javascript复制
//官方示例:
//* 检查请求是否含有上传文件  
// Check that we have a file upload request  
boolean isMultipart = ServletFileUpload.isMultipartContent(request);  

//现在我们得到了items的列表  

//如果你的应用近于最简单的情况,上面的处理就够了。但我们有时候还是需要更多的控制。
//下面提供了几种控制选择:
// Create a factory for disk-based file items  
DiskFileItemFactory factory = new DiskFileItemFactory();  

// Set factory constraints  
factory.setSizeThreshold(yourMaxMemorySize);  
factory.setRepository(yourTempDirectory);  

// Create a new file upload handler  
ServletFileUpload upload = new ServletFileUpload(factory);  

// 设置最大上传大小  
upload.setSizeMax(yourMaxRequestSize);  

// 解析所有请求  
List /* FileItem */ items = upload.parseRequest(request);  

// Create a factory for disk-based file items  
DiskFileItemFactory factory = new DiskFileItemFactory(  
        yourMaxMemorySize, yourTempDirectory);  

//一旦解析完成,你需要进一步处理item的列表。
// Process the uploaded items  
Iterator iter = items.iterator();  
while (iter.hasNext()) {  
    FileItem item = (FileItem) iter.next();  

    if (item.isFormField()) {  
        processFormField(item);  
    } else {  
        processUploadedFile(item);  
    }  
}  

//区分数据是否为简单的表单数据,如果是简单的数据:
// processFormField  
if (item.isFormField()) {  
    String name = item.getFieldName();  
    String value = item.getString();  
    //...省略步骤  
}  

//如果是提交的文件:
// processUploadedFile  
if (!item.isFormField()) {  
    String fieldName = item.getFieldName();  
    String fileName = item.getName();  
    String contentType = item.getContentType();  
    boolean isInMemory = item.isInMemory();  
    long sizeInBytes = item.getSize();  
    //...省略步骤  
}  

//对于这些item,我们通常要把它们写入文件,或转为一个流  
// Process a file upload  
if (writeToFile) {  
    File uploadedFile = new File(...);  
    item.write(uploadedFile);  
} else {  
    InputStream uploadedStream = item.getInputStream();  
    //...省略步骤  
    uploadedStream.close();  
}  

//或转为字节数组保存在内存中:
// Process a file upload in memory  
byte[] data = item.get();  
//...省略步骤  
//如果这个文件真的很大,你可能会希望向用户报告到底传了多少到服务端,让用户了解上传的过程  
//Create a progress listener  
ProgressListener progressListener = new ProgressListener(){  
   public void update(long pBytesRead, long pContentLength, int pItems) {  
       System.out.println("We are currently reading item "   pItems);  
       if (pContentLength == -1) {  
           System.out.println("So far, "   pBytesRead   " bytes have been read.");  
       } else {  
           System.out.println("So far, "   pBytesRead   " of "   pContentLength  
                                " bytes have been read.");  
       }  
   }  
};  
upload.setProgressListener(progressListener);

11.HttpClient

基于HttpCore实 现的一个HTTP/1.1兼容的HTTP客户端,它提供了一系列可重用的客户端身份验证、HTTP状态保持、HTTP连接管理module。

代码语言:javascript复制
//GET方法  
import java.io.IOException;  
import org.apache.commons.httpclient.*;  
import org.apache.commons.httpclient.methods.GetMethod;  
import org.apache.commons.httpclient.params.HttpMethodParams;  

public class GetSample{  
    public static void main(String[] args) {  
        // 构造HttpClient的实例  
        HttpClient httpClient = new HttpClient();  
        // 创建GET方法的实例  
        GetMethod getMethod = new GetMethod("http://www.ibm.com");  
        // 使用系统提供的默认的恢复策略  
        getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,  
                new DefaultHttpMethodRetryHandler());  
        try {  
            // 执行getMethod  
            int statusCode = httpClient.executeMethod(getMethod);  
            if (statusCode != HttpStatus.SC_OK) {  
                System.err.println("Method failed: "  
                          getMethod.getStatusLine());  
            }  
            // 读取内容  
            byte[] responseBody = getMethod.getResponseBody();  
            // 处理内容  
            System.out.println(new String(responseBody));  
        } catch (HttpException e) {  
            // 发生致命的异常,可能是协议不对或者返回的内容有问题  
            System.out.println("Please check your provided http address!");  
            e.printStackTrace();  
        } catch (IOException e) {  
            // 发生网络异常  
            e.printStackTrace();  
        } finally {  
            // 释放连接  
            getMethod.releaseConnection();  
        }  
    }  
}  

//POST方法  
import java.io.IOException;  
import org.apache.commons.httpclient.*;  
import org.apache.commons.httpclient.methods.PostMethod;  
import org.apache.commons.httpclient.params.HttpMethodParams;  

public class PostSample{  
    public static void main(String[] args) {  
        // 构造HttpClient的实例  
        HttpClient httpClient = new HttpClient();  
        // 创建POST方法的实例  
        String url = "http://www.oracle.com/";  
        PostMethod postMethod = new PostMethod(url);  
        // 填入各个表单域的值  
        NameValuePair[] data = { new NameValuePair("id", "youUserName"),  
        new NameValuePair("passwd", "yourPwd") };  
        // 将表单的值放入postMethod中  
        postMethod.setRequestBody(data);  
        // 执行postMethod  
        int statusCode = httpClient.executeMethod(postMethod);  
        // HttpClient对于要求接受后继服务的请求,象POST和PUT等不能自动处理转发  
        // 301或者302  
        if (statusCode == HttpStatus.SC_MOVED_PERMANENTLY ||   
        statusCode == HttpStatus.SC_MOVED_TEMPORARILY) {  
            // 从头中取出转向的地址  
            Header locationHeader = postMethod.getResponseHeader("location");  
            String location = null;  
            if (locationHeader != null) {  
             location = locationHeader.getValue();  
             System.out.println("The page was redirected to:"   location);  
            } else {  
             System.err.println("Location field value is null.");  
            }  
            return;  
        }  
    }  
}

12.IO

对java.io的扩展 操作文件非常方便。

代码语言:javascript复制
//1.读取Stream  

//标准代码:
InputStream in = new URL( "http://jakarta.apache.org" ).openStream();  
try {  
       InputStreamReader inR = new InputStreamReader( in );  
       BufferedReader buf = new BufferedReader( inR );  
       String line;  
       while ( ( line = buf.readLine() ) != null ) {  
          System.out.println( line );  
       }  
  } finally {  
    in.close();  
  }  

//使用IOUtils  

InputStream in = new URL( "http://jakarta.apache.org" ).openStream();  
try {  
    System.out.println( IOUtils.toString( in ) );  
} finally {  
    IOUtils.closeQuietly(in);  
}  

//2.读取文件  
File file = new File("/commons/io/project.properties");  
List lines = FileUtils.readLines(file, "UTF-8");  
//3.察看剩余空间  
long freeSpace = FileSystemUtils.freeSpace("C:/");

13.Lang

主要是一些公共的工具集合,比如对字符、数组的操作等等。

代码语言:javascript复制
// 1 合并两个数组: org.apache.commons.lang. ArrayUtils  
// 有时我们需要将两个数组合并为一个数组,用ArrayUtils就非常方便,示例如下:
private static void testArr() {  
String[] s1 = new String[] { "1", "2", "3" };  
String[] s2 = new String[] { "a", "b", "c" };  
String[] s = (String[]) ArrayUtils.addAll(s1, s2);  
for (int i = 0; i < s.length; i  ) {  
    System.out.println(s[i]);  
}  
String str = ArrayUtils.toString(s);  
str = str.substring(1, str.length() - 1);  
System.out.println(str   ">>"   str.length());  

}  
//2 截取从from开始字符串  
StringUtils.substringAfter("SELECT * FROM PERSON ", "from");  
//3 判断该字符串是不是为数字(0~9)组成,如果是,返回true 但该方法不识别有小数点和 请注意。
StringUtils.isNumeric("454534"); //返回true  
//4.取得类名  
System.out.println(ClassUtils.getShortClassName(Test.class));  
//取得其包名  
System.out.println(ClassUtils.getPackageName(Test.class));  

//5.NumberUtils  
System.out.println(NumberUtils.stringToInt("6"));  
//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&lt;html&gt;  
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(NumberUtils.stringToInt("33"));

14.Logging

提供的是一个Java 的日志接口,同时兼顾轻量级和不依赖于具体的日志实现工具。

代码语言:javascript复制
import org.apache.commons.logging.Log;  
import org.apache.commons.logging.LogFactory;  

public class CommonLogTest {  
 private static Log log = LogFactory.getLog(CommonLogTest.class);  
 //日志打印  
 public static void main(String[] args) {  
     log.error("ERROR");  
     log.debug("DEBUG");  
     log.warn("WARN");  
     log.info("INFO");  
     log.trace("TRACE");  
  System.out.println(log.getClass());  
 }  
}

15.Validator

通用验证系统,该组件提供了客户端和服务器端的数据验证框架。

1.验证日期

代码语言:javascript复制
// 获取日期验证  
DateValidator validator = DateValidator.getInstance();  

// 验证/转换日期  
Date fooDate = validator.validate(fooString, "dd/MM/yyyy");  
if (fooDate == null) {  
  // 错误 不是日期  
  return;  
}

2.表达式验证

代码语言:javascript复制
// 设置参数  
boolean caseSensitive = false;  
String regex1   = "^([A-Z]*)(?:\-)([A-Z]*)*$"  
String regex2   = "^([A-Z]*)$";  
String[] regexs = new String[] {regex1, regex1};  

// 创建验证  
RegexValidator validator = new RegexValidator(regexs, caseSensitive);  

// 验证返回boolean  
boolean valid = validator.isValid("abc-def");  

// 验证返回字符串  
String result = validator.validate("abc-def");  

// 验证返回数组  
String[] groups = validator.match("abc-def");

3.配置文件中使用验证

代码语言:javascript复制
<form-validation>  
   <global>  
       <validator name="required"  
          classname="org.apache.commons.validator.TestValidator"  
          method="validateRequired"  
          methodParams="java.lang.Object, org.apache.commons.validator.Field"/>  
    </global>  
    <formset>  
    </formset>  
</form-validation>  

添加姓名验证.  

<form-validation>  
   <global>  
       <validator name="required"  
          classname="org.apache.commons.validator.TestValidator"  
          method="validateRequired"  
          methodParams="java.lang.Object, org.apache.commons.validator.Field"/>  
    </global>  
    <formset>  
       <form name="nameForm">  
          <field property="firstName" depends="required">  
             <arg0 key="nameForm.firstname.displayname"/>  
          </field>  
          <field property="lastName" depends="required">  
             <arg0 key="nameForm.lastname.displayname"/>  
          </field>  
       </form>  
    </formset>  
</form-validation>

4.验证类

代码语言:javascript复制
Excerpts from org.apache.commons.validator.RequiredNameTest  
//加载验证配置文件  
InputStream in = this.getClass().getResourceAsStream("validator-name-required.xml");  

ValidatorResources resources = new ValidatorResources(in);  
//这个是自己创建的bean 我这里省略了  
Name name = new Name();  

Validator validator = new Validator(resources, "nameForm");  
//设置参数  
validator.setParameter(Validator.BEAN_PARAM, name);  


Map results = null;  
//验证  
results = validator.validate();  

if (results.get("firstName") == null) {  
    //验证成功  
} else {  
    //有错误     int errors = ((Integer)results.get("firstName")).intValue();  
}

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