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apache 工具类
Apache Commons包含了很多开源的工具,用于解决平时编程经常会遇到的问题,减少重复劳动。下面是我这几年做开发过程中自己用过的工具类做简单介绍。
组件 | 功能介绍 |
BeanUtils | 提供了对于JavaBean进行各种操作,克隆对象,属性等等. |
Betwixt | XML与Java对象之间相互转换. |
Codec | 处理常用的编码方法的工具类包 例如DES、SHA1、MD5、Base64等. |
Collections | java集合框架操作. |
Compress | java提供文件打包 压缩类库. |
Configuration | 一个java应用程序的配置管理类库. |
DBCP | 提供数据库连接池服务. |
DbUtils | 提供对jdbc 的操作封装来简化数据查询和记录读取操作. |
java发送邮件 对javamail的封装. | |
FileUpload | 提供文件上传功能. |
HttpClien | 提供HTTP客户端与服务器的各种通讯操作. 现在已改成HttpComponents |
IO | io工具的封装. |
Lang | Java基本对象方法的工具类包 如:StringUtils,ArrayUtils等等. |
Logging | 提供的是一个Java 的日志接口. |
Validator | 提供了客户端和服务器端的数据验证框架. |
1、BeanUtils
提供了对于JavaBean进行各种操作, 比如对象,属性复制等等。
- //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。
- //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。
- //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
- /**
- * 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。
- //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
- //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。
- 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
- 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。
- //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。
- //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。
- //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。
- //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。
- // 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<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(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。
- 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。
验证日期
- // 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;
- }
表达式验证
- // 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");
配置文件中使用验证
- <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>
- </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>
验证类
- 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();
- }