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feilong is a suite of core and expanded libraries that include utility classes, http, excel,cvs, io classes, and much much more.
/*
* Copyright (C) 2008 feilong
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.feilong.core.net;
import static com.feilong.tools.slf4j.Slf4jUtil.format;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.UncheckedIOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.feilong.core.Validate;
/**
* {@link URL} 工具类.
*
* URL组成部分:
*
*
*
* 
*
*
*
* URL 的长度上限
*
*
*
*
* URL 的最大长度是多少？W3C 的 HTTP 协议 并没有限定; 然而经过试验,不同浏览器和 Web 服务器有不同的约定:
*
*
*
* - IE 长度上限是 2083 字节,其中纯路径部分不能超过 2048 字节.
* - Firefox 地址栏中超过 65536 字符后就不再显示.
* - Safari 测试到 80000 字符还工作得好好的.
* - Opera 测试到 190000 字符还工作得好好的.
*
*
*
* Web 服务器:
*
*
*
* - Apache Web 服务器在接收到大约 4000 字符长的 URL 时候产生 "413 Entity Too Large" 错误.
* - IIS 默认接收的最大 URL 是 16384 字符.
*
*
*
* @author feilong
* @since 1.2.1
*/
public final class URLUtil{
/** The Constant log. */
private static final Logger LOGGER = LoggerFactory.getLogger(URLUtil.class);
/** Don't let anyone instantiate this class. */
private URLUtil(){
//AssertionError不是必须的. 但它可以避免不小心在类的内部调用构造器. 保证该类在任何情况下都不会被实例化.
//see 《Effective Java》 2nd
throw new AssertionError("No " + getClass().getName() + " instances for you!");
}
//---------------------------------------------------------------
/**
* 将字符串 spec 转成 {@link URL}.
*
* 该方法特点:
*
*
* - 处理 check exception,转成 uncheck exception
* - 如果使用new URL 出现异常,会尝试使用 {@link #toFileURL(String)}
*
*
*
* 注意:
*
*
*
*
* 如果直接调用 {@link URL#URL(String)} 方法,如果是文件路径, 比如
*
*
*
*
* String spec = "C:/Users/feilong/feilong/train/新员工/warmReminder/20160704141057.html";
*
* URL newURL = new URL(spec);
*
*
* 会抛出异常,
*
*
* Caused by: java.net.MalformedURLException: unknown protocol: c
* at java.net.URL.{@code }(URL.java:593)
* at java.net.URL.{@code }(URL.java:483)
* at java.net.URL.{@code }(URL.java:432)
* ... 24 more
*
*
* 此时 ,你需要修改成
*
*
*
* String spec = "file://C:/Users/feilong/feilong/train/新员工/warmReminder/20160704141057.html";
*
* URL newURL = new URL(spec);
*
*
* 也就是说,此方法必须要有协议支持 (file URI scheme),如果你是文件需要转成 url的话,建议直接调用 {@link #toFileURL(String)}
*
*
* @param spec
* the String to parse as a URL.
* @return 如果 spec 是null,抛出 {@link NullPointerException}
* 如果 spec 是blank,抛出 {@link IllegalArgumentException}
* @see java.net.URL#URL(String)
* @see "org.apache.cxf.common.util.StringUtils#getURL(String)"
* @see "org.springframework.util.ResourceUtils#getURL(String)"
* @see File_URI_scheme
* @see "org.apache.xml.resolver.readers.TextCatalogReader#readCatalog(Catalog, String)"
* @see Creating a URL
* @since 1.8.0
*/
public static URL toURL(String spec){
Validate.notBlank(spec, "spec can't be blank!");
//---------------------------------------------------------------
try{
return new URL(spec);
}catch (Exception e){
// no URL -> treat as file path
LOGGER.trace("[new URL(\"{}\")] exception,cause by :[{}],will try call [toFileURL(\"{}\")]", spec, e.getMessage(), spec);
return toFileURL(spec);
}
}
//---------------------------------------------------------------
/**
* 将字符串路径 filePath 转成{@link URL}.
*
* 示例:
*
*
*
*
*
* String spec = "C:\\Users\\feilong\\feilong\\train\\新员工\\warmReminder\\20160704141057.html";
*
* URL newURL = toFileURL(spec);
*
*
*
*
* Using Java 7 你还可以使用:
*
*
* Paths#get(string).toUri().toURL();
*
*
* However, you probably want to get a URI.
* Eg, a URI begins with file:/// but a URL with file:/ (at least, that's what toString produces).
*
*
* 参见
* pass-a-local-file-in-to-url-in-java
*
*
*
* @param filePath
* 字符串路径
* @return the url
* @see java.io.File#toURI()
* @see java.net.URI#toURL()
* @see "org.apache.commons.io.FileUtils#toURLs(File[])"
* @since 1.8.0 change Access Modifiers
*/
private static URL toFileURL(String filePath){
try{
return new File(filePath).toURI().toURL();// file.toURL() 已经过时,它不会自动转义 URL 中的非法字符
}catch (Exception e){
throw new URIParseException(format("filePath:[{}]", filePath), e);
}
}
//---------------------------------------------------------------
/**
* 将 {@link URL}转成 {@link URI}.
*
* @param url
* the url
* @return 如果 url 是null,返回null
* @see "org.springframework.util.ResourceUtils#toURI(URL)"
* @see java.net.URL#toURI()
* @since 1.2.2
* @since 1.8.7 如果 null==url,返回null
*/
public static URI toURI(URL url){
if (null == url){
return null;
}
//---------------------------------------------------------------
try{
return url.toURI();
}catch (URISyntaxException e){
throw new URIParseException(format("input url:[{}]", url), e);
}
}
/**
* 打开当前url的连接,并且读取返回 InputStream.
*
*
* 这个方法是以下方法的简写
*
*
*
* url.openConnection().getInputStream()
*
*
* @param url
* the url
* @return 如果 url 是null,返回 null
* @see java.net.URL#openStream()
* @since 1.9.2
*/
public static InputStream openStream(URL url){
try{
return url == null ? null : url.openStream();
}catch (IOException e){
throw new UncheckedIOException(format("openStream url:[{}]", url), e);
}
}
//---------------------------------------------------------------
/**
* 获取联合url,通过在指定的上下文中对给定的 spec 进行解析创建 URL,新的 URL 从给定的上下文 URL 和 spec 参数创建.
*
*
* 网站地址拼接,请使用这个method
*
*
* 示例:
*
*
*
*
*
* URL url = new URL("http://www.exiaoshuo.com/jinyiyexing/");
* URIUtil.getUnionUrl(url, "/jinyiyexing/1173348/") = http://www.exiaoshuo.com/jinyiyexing/1173348/
*
*
*
*
* @param context
* 要解析规范的上下文
* @param spec
* the String to parse as a URL.
* @return 如果 spec 是null,抛出 {@link NullPointerException}
* 如果 spec 是blank,抛出 {@link IllegalArgumentException}
* @since 1.4.0
*/
public static String getUnionUrl(URL context,String spec){
Validate.notBlank(spec, "spec can't be null!");
//---------------------------------------------------------------
try{
return new URL(context, spec).toString();
}catch (Exception e){
String message = format("context:[{}],spec:[{}]", context, spec);
throw new URIParseException(message, e);
}
}
}