import java.io.*; public class BufferedStreamExample { public static void main(String[] args) { // 测试文件路径 String source = "large_data.bin"; String destination = "copy.bin"; try { long startTime = System.currentTimeMillis(); // 使用缓冲流复制文件 try (BufferedInputStream bis = new BufferedInputStream(new FileInputStream(source)); BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(destination))) { byte[] buffer = new byte[4096]; // 4KB缓冲区 int bytesRead; while ((bytesRead = bis.read(buffer)) != -1) { bos.write(buffer, 0, bytesRead); } // 手动刷新缓冲区确保数据写入 bos.flush(); } long endTime = System.currentTimeMillis(); System.out.println("使用缓冲流复制耗时: " + (endTime - startTime) + "ms"); } catch (IOException e) { e.printStackTrace(); } } }

import java.io.*; import java.nio.charset.*; public class ConversionStreamExample { public static void main(String[] args) { // 写入UTF-8编码的文件 try (OutputStreamWriter writer = new OutputStreamWriter( new FileOutputStream("utf8_file.txt"), StandardCharsets.UTF_8)) { writer.write("你好，世界！"); writer.write("\n"); writer.write("Hello, World! "); } catch (IOException e) { e.printStackTrace(); } // 读取GBK编码的文件 try (InputStreamReader reader = new InputStreamReader( new FileInputStream("gbk_file.txt"), "GBK")) { char[] buffer = new char[1024]; int charsRead; while ((charsRead = reader.read(buffer)) != -1) { System.out.print(new String(buffer, 0, charsRead)); } } catch (IOException | UnsupportedEncodingException e) { System.err.println("处理文件出错: " + e.getMessage()); } } }

import java.io.*; public class PrintStreamExample { public static void main(String[] args) { // 创建格式化的日志文件 try (PrintWriter writer = new PrintWriter( new BufferedWriter( new OutputStreamWriter( new FileOutputStream("application.log"), StandardCharsets.UTF_8)))) { // 设置自动刷新（每次println后自动flush） writer = new PrintWriter(writer, true); // 写入不同格式的数据 writer.println("====== 应用启动日志 ======"); writer.printf("启动时间: %tF %tT%n", System.currentTimeMillis(), System.currentTimeMillis()); writer.println("系统属性:"); System.getProperties().list(writer); // 打印所有系统属性 writer.printf("可用内存: %.2f MB%n", Runtime.getRuntime().freeMemory() / (1024.0 * 1024)); // 检查错误 if (writer.checkError()) { System.err.println("写入日志时发生错误"); } } catch (IOException e) { e.printStackTrace(); } // System.out重定向到文件 try (PrintStream fileOut = new PrintStream("console_output.txt")) { // 保存原始System.out PrintStream originalOut = System.out; // 重定向标准输出 System.setOut(fileOut); // 这些输出将写入文件 System.out.println("这是重定向的输出"); System.out.println(3.1415926); System.out.printf("%2d月优惠活动开始！%n", 8); // 恢复原始System.out System.setOut(originalOut); System.out.println("输出已恢复"); } catch (IOException e) { e.printStackTrace(); } } }

import java.io.*; import java.nio.charset.*; public class EncodingConverter { /** * 转换文件编码格式 * @param sourceFile 源文件路径 * @param srcEncoding 源文件编码 * @param targetFile 目标文件路径 * @param targetEncoding 目标编码 * @param useBuffer 是否使用缓冲 */ public static void convertEncoding(String sourceFile, String srcEncoding, String targetFile, String targetEncoding, boolean useBuffer) throws IOException { try (Reader reader = createReader(sourceFile, srcEncoding, useBuffer); Writer writer = createWriter(targetFile, targetEncoding, useBuffer)) { char[] buffer = new char[8192]; // 8K字符缓冲区 int charsRead; while ((charsRead = reader.read(buffer)) != -1) { writer.write(buffer, 0, charsRead); } // 确保所有内容写出 writer.flush(); } } private static Reader createReader(String file, String encoding, boolean useBuffer) throws IOException { InputStream is = new FileInputStream(file); Reader reader = new InputStreamReader(is, Charset.forName(encoding)); if (useBuffer) { reader = new BufferedReader(reader, 81920); // 80KB缓冲 } return reader; } private static Writer createWriter(String file, String encoding, boolean useBuffer) throws IOException { OutputStream os = new FileOutputStream(file); Writer writer = new OutputStreamWriter(os, Charset.forName(encoding)); if (useBuffer) { writer = new BufferedWriter(writer, 81920); // 80KB缓冲 } return writer; } public static void main(String[] args) { try { // 将GBK文件转换为UTF-8，使用缓冲 convertEncoding("source_gbk.txt", "GBK", "target_utf8.txt", "UTF-8", true); System.out.println("文件转换完成!"); } catch (IOException e) { System.err.println("转换失败: " + e.getMessage()); } } }

import java.io.*; import java.nio.charset.*; public class StreamDebugger { public static void diagnoseEncodingIssue(String filePath) { System.out.println("诊断文件编码问题: " + filePath); // 尝试使用不同编码读取 String[] encodings = {"UTF-8", "GBK", "ISO-8859-1", "Windows-1252"}; for (String encoding : encodings) { System.out.println("\n尝试使用编码: " + encoding); try (BufferedReader reader = new BufferedReader( new InputStreamReader( new FileInputStream(filePath), encoding))) { char[] buffer = new char[1024]; int count; boolean hasError = false; while ((count = reader.read(buffer)) != -1) { // 显示前256字符内容 if (reader.getPosition() < 256) { System.out.println("内容预览: " + new String(buffer, 0, Math.min(count, 50))); } // 检查非法字符 for (int i = 0; i < count; i++) { if (buffer[i] == '\ufffd') { hasError = true; } } } if (hasError) { System.out.println("检测到替换字符(�)，可能编码不匹配"); } else { System.out.println("此编码没有检测到替换字符"); } } catch (IOException | UnsupportedEncodingException e) { System.err.println(encoding + " 编码测试失败: " + e.getMessage()); } } } }

import java.io.*; import java.nio.charset.*; import java.util.*; import java.util.regex.*; public class LogAnalyzer { public static void main(String[] args) { String[] logFiles = {"system.log", "app_gbk.log", "network.log"}; String output = "report.html"; // 收集所有日志条目 List entries = new ArrayList<>(); for (String file : logFiles) { try (BufferedReader reader = detectEncodingReader(file)) { entries.addAll(parseLogEntries(reader)); } catch (IOException e) { System.err.println("处理日志失败: " + file + " - " + e.getMessage()); } } // 按时间排序 Collections.sort(entries); // 生成HTML报告 try (PrintWriter writer = new PrintWriter(new BufferedWriter(new FileWriter(output)))) { generateHtmlReport(writer, entries); System.out.println("日志报告生成完成: " + output); } catch (IOException e) { e.printStackTrace(); } } // 自动检测编码创建Reader（简化版） private static BufferedReader detectEncodingReader(String file) throws IOException { // 实际项目中应使用juniversalchardet等库 String encoding = file.contains("gbk") ? "GBK" : "UTF-8"; return new BufferedReader( new InputStreamReader(new FileInputStream(file), encoding)); } // 解析日志条目（简化实现） private static List parseLogEntries(BufferedReader reader) throws IOException { List entries = new ArrayList<>(); Pattern pattern = Pattern.compile("^\\[(.+?)\\]\\s+(\\w+):\\s+(.*)"); String line; int lineNum = 1; while ((line = reader.readLine()) != null) { Matcher matcher = pattern.matcher(line); if (matcher.find()) { entries.add(new LogEntry( matcher.group(1), // 时间戳 matcher.group(2), // 级别 matcher.group(3), // 消息 lineNum, reader )); } lineNum++; } return entries; } // 生成HTML报告 private static void generateHtmlReport(PrintWriter writer, List entries) { writer.println(" "); writer.println(" "); writer.println(" "); writer.println("

系统日志分析报告

"); writer.println(" "); writer.println(" "); for (LogEntry entry : entries) { String rowClass = ""; if ("ERROR".equals(entry.level)) rowClass = "error"; else if ("WARN".equals(entry.level)) rowClass = "warn"; writer.printf(" %n", rowClass, entry.timestamp, entry.level, entry.message); } writer.println("

时间	级别	消息
%s	%s	%s

"); writer.println(" "); } static class LogEntry implements Comparable { String timestamp; String level; String message; int lineNumber; BufferedReader source; public LogEntry(String timestamp, String level, String message, int lineNumber, BufferedReader source) { this.timestamp = timestamp; this.level = level; this.message = message; this.lineNumber = lineNumber; this.source = source; } @Override public int compareTo(LogEntry o) { return timestamp.compareTo(o.timestamp); } } }