我一个项目中用到的，里面的方法不是太通用，但是可以从里面找到一些有用的代码，以后慢慢添补更新：
FileUtil.xml
1 package com.novel.util; 2 3 import java.io.File; 4 import java.io.FileInputStream; 5 import java.io.FileOutputStream; 6 import java.io.IOException; 7 import java.io.InputStream; 8 import java.io.InputStreamReader; 9 10 /** 11 * @author cy 12 * 13 * @date 2015年7月24日 上午8:38:38 14 * 15 * @Description 关于文件的一些工具 16 */ 17 public class FileUtils { 18 /** 19 * 将文件中所有内容读取到字符串中 20 * 21 * @param filePath 22 * 文件路径 23 * @return 文件内容 24 */ 25 public static String getStringFromFile(String filePath) { 26 File file = new File(filePath) ; 27 if(!file.exists()){ 28 return "" ; 29 } 30 /** 31 * 处理文件读取乱码问题 : 32 * 只要判定两种常见的编码就可以了：GBK和UTF-8。由于中文Windows默认的编码是GBK，所以一般只要判定UTF-8编码格式。 33 *对于UTF-8编码格式的文本文件，其前3个字节的值就是-17、-69、-65 34 */ 35 try{ 36 byte[] firstThreeByte = new byte[3] ; 37 InputStream in = new FileInputStream(file) ; 38 in.read(firstThreeByte) ; 39 in.close() ; 40 String encoding = "" ; 41 if(firstThreeByte[0] == -17 && firstThreeByte[1] == -16 && firstThreeByte[2] == -65){ 42 encoding = "utf-8" ; 43 }else{ 44 encoding = "gbk" ; 45 } 46 InputStreamReader read = new InputStreamReader(new FileInputStream(file),encoding); 47 Long filelength = file.length() / 2 ; // 该方法获取的是文件字节长度， 48 //而我要创建的是char数组，char占两个字节， 49 //byte一个字节，所以除以2表示的是该文件的字符长度 50 char[] filecontent = new char[filelength.intValue()] ; 51 read.read(filecontent) ; 52 return new String(filecontent) ; 53 }catch(Exception e ){ 54 e.printStackTrace(); 55 return "" ; 56 } 57 } 58 59 /** 60 * 将字符串写入文件 61 * 62 * @param content 63 * 字符串内容 64 * @param filePath 65 * 文件路径 66 * @throws IOException 67 */ 68 public static void writeStringToFile(String content, String filePath) 69 throws IOException { 70 71 File file = new File(filePath); 72 if (!file.exists()) { 73 file.createNewFile(); 74 } 75 FileOutputStream out = new FileOutputStream(file); 76 out.write(content.getBytes()); 77 out.close(); 78 } 79 /** 80 * 删除指定的文件 81 * @param filePath文件路径 82 */ 83 public static void deleteFile(String filePath ) { 84 File file = new File(filePath) ; 85 if(file.exists()){ 86 file.delete() ; 87 } 88 } 89 }
XmlUtil.java
1 package com.novel.util; 2 3 import java.io.File; 4 import java.io.IOException; 5 import java.util.ArrayList; 6 import java.util.HashMap; 7 import java.util.List; 8 import java.util.Map; 9 10 import javax.xml.parsers.DocumentBuilder; 11 import javax.xml.parsers.DocumentBuilderFactory; 12 import javax.xml.parsers.ParserConfigurationException; 13 import javax.xml.transform.OutputKeys; 14 import javax.xml.transform.Transformer; 15 import javax.xml.transform.TransformerConfigurationException; 16 import javax.xml.transform.TransformerException; 17 import javax.xml.transform.TransformerFactory; 18 import javax.xml.transform.TransformerFactoryConfigurationError; 19 import javax.xml.transform.dom.DOMSource; 20 import javax.xml.transform.stream.StreamResult; 21 22 import org.w3c.dom.Document; 23 import org.w3c.dom.Element; 24 import org.w3c.dom.Node; 25 import org.w3c.dom.NodeList; 26 import org.w3c.dom.Text; 27 import org.xml.sax.SAXException; 28 29 import com.novel.entity.Novel; 30 import com.novel.entity.User; 31 32 /** 33 * @author cy 34 * 35 * @date 2015年7月23日 下午3:19:06 36 * 37 * @Description 关于xml的操作 38 */ 39 public class XmlUtil { 40 /** 41 * 目标xml为 config/users.xml 42 * 43 * @param user 44 * 将要被写入xml的User对象 45 * @return 是否成功 46 */ 47 public static boolean writeUserToXml(User user) { 48 try { 49 Document doc = getDocumentFromXml("config/users.xml"); 50 Element newUserElement = doc.createElement("user"); 51 Element newUsernameElement = doc.createElement("name"); 52 Text nameTextNode = doc.createTextNode("nameValue"); 53 nameTextNode.setNodeValue(user.getName()); 54 newUsernameElement.appendChild(nameTextNode); 55 Element newUserPwdElement = doc.createElement("pwd"); 56 Text pwdTextNode = doc.createTextNode("pwdValue"); 57 pwdTextNode.setNodeValue(user.getName()); 58 newUserPwdElement.appendChild(pwdTextNode); 59 newUserElement.appendChild(newUsernameElement); 60 newUserElement.appendChild(newUserPwdElement); 61 Element usersElement = (Element) doc.getElementsByTagName("users") 62 .item(0); 63 usersElement.appendChild(newUserElement); 64 65 writeDocumentToFile(doc, "config/users.xml"); 66 return true; 67 } catch (Exception e) { 68 e.printStackTrace(); 69 return false; 70 } 71 } 72 73 /** 74 * 75 * @param doc 76 * XML中的Document对象 77 * @param filePath 78 * 输出的文件路径 79 * @throws TransformerFactoryConfigurationError 80 * @throws TransformerConfigurationException 81 * @throws TransformerException 82 */ 83 private static void writeDocumentToFile(Document doc, String filePath) 84 throws TransformerFactoryConfigurationError, 85 TransformerConfigurationException, TransformerException { 86 // 写入到硬盘 87 TransformerFactory tFactory = TransformerFactory.newInstance(); 88 Transformer transformer = tFactory.newTransformer(); 89 /** 编码 */ 90 transformer.setOutputProperty(OutputKeys.ENCODING, "utf-8"); 91 DOMSource source = new DOMSource(doc); 92 StreamResult result = new StreamResult(new File(filePath)); 93 transformer.transform(source, result); 94 } 95 96 /** 97 * 加载config/users.xml中用户信息到对象中 98 * 99 * @return 加载后的对象 100 */ 101 public static Map<String, User> initUser() { 102 InitUser.users = new HashMap<String, User>(); 103 try { 104 Document doc = getDocumentFromXml("config/users.xml"); 105 NodeList usersNodeList = doc.getElementsByTagName("user"); 106 for (int i = 0; i < usersNodeList.getLength(); i++) { 107 Element userElement = (Element) usersNodeList.item(i); 108 String userName = ((Element) (userElement 109 .getElementsByTagName("name").item(0))).getFirstChild() 110 .getNodeValue(); 111 String passwd = ((Element) (userElement 112 .getElementsByTagName("pwd").item(0))).getFirstChild() 113 .getNodeValue(); 114 InitUser.users.put(userName, new User(userName, passwd)); 115 } 116 } catch (Exception e) { 117 e.printStackTrace(); 118 } finally { 119 return InitUser.users; 120 } 121 } 122 123 /** 124 * 从xml中获取服务器运行的端口 125 * 126 * @return server.xml文件中的端口号 127 */ 128 public static int getServerPort() { 129 try { 130 Document doc = getDocumentFromXml("config/server.xml"); 131 int serverPort = Integer.parseInt(doc 132 .getElementsByTagName("server-port").item(0) 133 .getFirstChild().getNodeValue()); 134 return serverPort; 135 } catch (Exception e) { 136 e.printStackTrace(); 137 return 0; 138 } 139 } 140 141 /** 142 * 143 * @param xmlPath 144 * xml文件的位置 145 * @return 这个xml文件相应的Document对象 146 * @throws SAXException 147 * @throws IOException 148 * @throws ParserConfigurationException 149 */ 150 public static Document getDocumentFromXml(String xmlPath) 151 throws SAXException, IOException, ParserConfigurationException { 152 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); 153 DocumentBuilder builder = factory.newDocumentBuilder(); 154 Document doc = builder.parse(xmlPath); 155 return doc; 156 } 157 158 /** 159 * 读取xml中小说的信息到List中 160 * 161 * @param novelId 162 * 小说id 163 * @return 小说列表 164 * @throws ParserConfigurationException 165 * @throws IOException 166 * @throws SAXException 167 */ 168 public static List<Novel> getNovelListFromXml(String filePath) throws SAXException, IOException, ParserConfigurationException { 169 List<Novel> novelList = new ArrayList<Novel>(); 170 Document doc = getDocumentFromXml(filePath); 171 NodeList novels = doc.getElementsByTagName("novel"); 172 for (int i = 0; i < novels.getLength(); i++) { 173 Element novel = ((Element) novels.item(i)); 174 int id = Integer.parseInt(novel.getElementsByTagName("id").item(0) 175 .getFirstChild().getNodeValue()); 176 String name = novel.getElementsByTagName("name").item(0) 177 .getFirstChild().getNodeValue(); 178 String author = novel.getElementsByTagName("author").item(0) 179 .getFirstChild().getNodeValue(); 180 String category = novel.getElementsByTagName("category").item(0) 181 .getFirstChild().getNodeValue(); 182 String description = novel.getElementsByTagName("description") 183 .item(0).getFirstChild().getNodeValue(); 184 185 Novel oneNovel = new Novel(id, category, name, author, description); 186 novelList.add(oneNovel); 187 } 188 return novelList ; 189 } 190 /** 191 * 将Novel信息写入到config/novelsInfo.xml中并且将小说内容写入到novel文件夹下 192 * @param novel 小说对象 193 * @return 是否写入成功 194 * TODO：确定原子操作 195 */ 196 public static boolean writeNovelToFile(Novel novel ) { 197 /** 198 * 先将小说内容写入到novel文件夹下，再将小说信息写入到config/novelsInfo.xml中 199 */ 200 try{ 201 FileUtils.writeStringToFile(novel.getContent(), "novel/" + novel.getName() + ".txt"); 202 XmlUtil.writeNovelInfoToXml(novel) ; 203 return true ; 204 }catch(Exception e ){ 205 /** 206 * 如果写入小说到文件中出现问题，要将已经写入的信息删除 207 * 这段代码应该很少执行到 ~~~~ 208 * 209 */ 210 System.out.println("小说写入文件失败，正在回滚~~"); 211 FileUtils.deleteFile("novel/" + novel.getName() + ".txt") ; 212 XmlUtil.deleteNovelInfoFromXml(novel) ; 213 e.printStackTrace(); 214 return false ; 215 } 216 } 217 218 /** 219 * 从config/novelsInfo.xml中删除与novel对象相对应的的novel标签，根据ID号判断是否相同 220 * 221 * @param novel 222 * 小说对象 223 */ 224 public static void deleteNovelInfoFromXml(Novel novel) { 225 try { 226 Document doc = getDocumentFromXml("config/novelsInfo.xml"); 227 Element novelsElement = (Element) doc 228 .getElementsByTagName("novels").item(0); 229 NodeList novelElements = novelsElement 230 .getElementsByTagName("novel"); 231 232 Node deleteElement = null; 233 for (int i = 0; i < novelElements.getLength(); i++) { 234 String id = ((Element) novelElements.item(i)) 235 .getElementsByTagName("id").item(0).getFirstChild() 236 .getNodeValue(); 237 if (id.equals(String.valueOf(novel.getId()))) { 238 deleteElement = novelElements.item(i); 239 break; 240 } 241 } 242 novelsElement.removeChild(deleteElement); 243 writeDocumentToFile(doc, "config/novlesInfo.xml"); 244 } catch (Exception e) { 245 e.printStackTrace(); 246 } 247 } 248 /** 249 * 将小说信息写入到config/novelsInfo.xml文件中 250 * @param novel小说对象 251 */ 252 public static void writeNovelInfoToXml(Novel novel){ 253 Document doc = null ; 254 try { 255 doc = getDocumentFromXml("config/novelsInfo.xml"); 256 } catch (Exception e) { 257 e.printStackTrace(); 258 return ; 259 } 260 Element novelDocument = (Element)doc.createElement("novel") ; 261 // id 262 Element novelIdDocument = (Element)doc.createElement("id") ; 263 Text novelIdTextNode = doc.createTextNode("idValue") ; 264 novelIdTextNode.setNodeValue(String.valueOf(novel.getId())); 265 novelIdDocument.appendChild(novelIdTextNode); 266 // name 267 Element novelNameDocument = (Element)doc.createElement("name") ; 268 Text novelNameTextNode = doc.createTextNode("nameValue") ; 269 novelNameTextNode.setNodeValue(String.valueOf(novel.getName())); 270 novelNameDocument.appendChild(novelNameTextNode); 271 // author 272 Element novelAuthorDocument = (Element)doc.createElement("author") ; 273 Text novelAuthorTextNode = doc.createTextNode("authorValue") ; 274 novelAuthorTextNode.setNodeValue(String.valueOf(novel.getAuthor())); 275 novelAuthorDocument.appendChild(novelAuthorTextNode); 276 // category 277 Element novelCategoryDocument = (Element)doc.createElement("category") ; 278 Text novelCategoryTextNode = doc.createTextNode("categoryValue") ; 279 novelCategoryTextNode.setNodeValue(String.valueOf(novel.getCategory())); 280 novelCategoryDocument.appendChild(novelCategoryTextNode); 281 // description 282 Element novelDescriptionDocument = (Element)doc.createElement("description") ; 283 Text novelDescriptionTextNode = doc.createTextNode("descriptionValue") ; 284 novelDescriptionTextNode.setNodeValue(String.valueOf(novel.getDescription())); 285 novelDescriptionDocument.appendChild(novelDescriptionTextNode); 286 287 novelDocument.appendChild(novelIdDocument) ; 288 novelDocument.appendChild(novelNameDocument) ; 289 novelDocument.appendChild(novelAuthorDocument) ; 290 novelDocument.appendChild(novelCategoryDocument) ; 291 novelDocument.appendChild(novelDescriptionDocument) ; 292 doc.getElementsByTagName("novels").item(0).appendChild(novelDocument) ; 293 // 写到文件中 294 try { 295 writeDocumentToFile(doc, "config/novelsInfo.xml"); 296 } catch (Exception e) { 297 e.printStackTrace(); 298 } 299 } 300 }