java读取文件java 读写文件

import java.io.Bufferedreader;import java.io.BufferedWriter;import java.io.file;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import org.apache.commons.io.FileUtils; /** * 文件工具类 */public class FileUtil { /** * 创建文件（文件存在，则删除） * * @param fileName * @return */ public static File makeNewFile(String fileName) { try { File file = new File(fileName); if (file.exists()) { //文件存在，删除 file.delete(); } else { //文件不存在，先创建路径 String filePath = fileName.substring(0, fileName.lastIndexOf(System.getProperty("file.separator"))); file = new File(filePath); if (!file.exists()) { file.mkdirs(); } } //创建文件 file = new File(fileName); if (!file.exists()) { file.createNewFile(); } return file; } catch (Exception e) { e.printStackTrace(); return null; } } /** * 创建文件（文件存在，则删除） * * @param fileName * @param content * @return */ public static int makeNewFile(String fileName, String content) { try { File file = new File(fileName); if (file.exists()) { //文件存在，删除 file.delete(); } else { //文件不存在，先创建路径 String filePath = fileName.substring(0, fileName.lastIndexOf(System.getProperty("file.separator"))); file = new File(filePath); if (!file.exists()) { file.mkdirs(); } } //创建文件 file = new File(fileName); if (!file.exists()) { file.createNewFile(); } FileUtils.writeStringToFile(file, content, "UTF-8"); return 0; } catch (Exception e) { e.printStackTrace(); return -1; } } /** * 文件追加内容 * * @param fileName * @param content * @return */ public static int fileAppend(String fileName, String content) { BufferedWriter writer = null; try { //创建路径 String filePath = fileName.substring(0, fileName.lastIndexOf(System.getProperty("file.separator"))); File file = new File(filePath); if (!file.exists()) { file.mkdirs(); } //创建文件 file = new File(fileName); if (!file.exists()) { file.createNewFile(); } //追加日志 writer = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(file, true), "UTF-8")); if (file.length() != 0) {//空文件 writer.write("\r\n"); } writer.write(content); } catch (IOException e) { e.printStackTrace(); return -1; } finally { if (writer != null) { try { writer.close(); } catch (IOException ex) { ex.printStackTrace(); } } } return 0; } /** * 文件追加内容 * * @param fileName * @param content * @return */ public static int fileAppendGBK(String fileName, String content) { BufferedWriter writer = null; try { //创建路径 String filePath = fileName.substring(0, fileName.lastIndexOf(System.getProperty("file.separator"))); File file = new File(filePath); if (!file.exists()) { file.mkdirs(); } //创建文件 file = new File(fileName); if (!file.exists()) { file.createNewFile(); } //追加日志 writer = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(file, true), "GBK")); if (file.length() != 0) {//空文件 writer.write("\r\n"); } writer.write(content); } catch (IOException e) { e.printStackTrace(); return -1; } finally { if (writer != null) { try { writer.close(); } catch (IOException ex) { ex.printStackTrace(); } } } return 0; } /** * 把串内容写到文件指定行上，如果插入行与该行内容相同则覆盖，不同则插入到该行<br> * 如果插入行号<=0，则在文件最后追加一行 * * @param fileName 文件名称，全路径 * @param content 插入的行内容 * @param insertLineNum 要插入到文件的行号 * @return */ public static int insertAssignedLineWithCompare(String fileName, String content, int insertLineNum) { BufferedWriter writer = null; BufferedReader reader = null; try { // 创建路径 String filePath = fileName.substring(0, fileName.lastIndexOf(System .getProperty("file.separator"))); File file = new File(filePath); if (!file.exists()) { file.mkdirs(); } file = new File(fileName); if (!file.exists()) { // 文件不存在，新建文件，直接写入内容为一行 file.createNewFile(); writer = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(file, true), "UTF-8")); writer.write(content); } else { // 文件已存在 if (insertLineNum <= 0) { // 把内容追加到文件最后 writer = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(file, true), "UTF-8")); if (file.length() != 0) {// 非空文件 writer.write("\r\n");//换行 } writer.write(content); } else { // 把内容插入到指定行 reader = new BufferedReader(new InputStreamReader( new FileInputStream(file), "UTF-8")); StringBuilder front = new StringBuilder();// 第insertLineNum行前面的内容 StringBuilder back = new StringBuilder();// 第insertLineNum行后面的内容 String insertLineStr = "";// 第insertLineNum行的内容 String currentLineStr = reader.readLine();// 每一行内容 int currentLineNum = 0;// 当前行号 while (currentLineStr != null && !"".equals(currentLineStr)) { currentLineNum++; if (currentLineNum < insertLineNum) { front.append(currentLineStr).append("\r\n"); } else if (currentLineNum == insertLineNum) { insertLineStr = currentLineStr; } else { back.append(currentLineStr).append("\r\n"); } currentLineStr = reader.readLine(); } //currentLineNum目前为文件更大行号 if (currentLineNum < insertLineNum) { // 写入行号大于文件更大行号，把内容追加到文件最后 front.append(content); } else { // 把内容追加到文件指定行 if (content.indexOf(insertLineStr) < 0) { // 没有插入过此行，插入 front.append(content).append("\r\n").append(insertLineStr); if (back.toString() != null && !"".equals(back.toString())) { front.append("\r\n").append(back.substring(0, back.lastIndexOf("\r\n"))); } } else { // 插入过此行，覆盖 front.append(content); if (back.toString() != null && !"".equals(back.toString())) { front.append("\r\n").append(back.substring(0, back.lastIndexOf("\r\n"))); } } } // 重新创建文件 try { reader.close(); } catch (IOException ex) { ex.printStackTrace(); return -1; } file.delete(); file.createNewFile(); writer = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(file, true), "UTF-8")); writer.write(front.toString()); } } } catch (Exception e) { e.printStackTrace(); return -2; } finally { if (writer != null) { try { writer.close(); } catch (IOException ex) { ex.printStackTrace(); } } } return 0; } /** * 获取文件 * * @param filePath * @return */ public static File getFile(String filePath) { try { File file = new File(filePath); if (!file.exists()) { file.getParentFile().mkdirs(); file.createNewFile(); } return file; } catch (Exception ex) { ex.printStackTrace(); return null; } } /** * 读取文件内容 * * @param file * @return */ public static String getFileContent(File file) { StringBuilder fileContent = new StringBuilder(); try { if (file.isFile() && file.exists()) { InputStreamReader read = new InputStreamReader(new FileInputStream(file), "UTF-8"); BufferedReader reader = new BufferedReader(read); String line; while ((line = reader.readLine()) != null) { fileContent.append(line); } read.close(); } } catch (Exception ex) { ex.printStackTrace(); } return fileContent.toString(); } }