本文主要是介绍java 读取文件 两例，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
1
采用InputStream is = new FileInputStream(File filePath)；等输入流的 形式，读取文件并存放在StringBuffer中。
import java.io.BufferedReader; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader;
public class Read ... {
private static String openFile(String filePath) ...{ File f = new File(filePath); String ee = new String(); System.out.println("Opening file: " + filePath); try ...{ InputStream is = new FileInputStream(f); BufferedReader reader = new BufferedReader( new InputStreamReader(is)); StringBuffer buffer = new StringBuffer(); String line; // 用来保存每行读取的内容 line = reader.readLine(); // 读取第一行 while (line != null) ...{ // 如果 line 为空说明读完了 buffer.append(line); // 将读到的内容添加到 buffer 中 buffer.append(" "); // 添加换行符 line = reader.readLine(); // 读取下一行
}// System.out.print(buffer.toString()); ee = buffer.toString(); } catch (FileNotFoundException e) ...{ e.printStackTrace(); } catch (IOException e) ...{ e.printStackTrace(); } return ee; } public static void main(String[] args)...{ System.out.print(Read.openFile("l:/fence.log")); }
} 2 采用支持对随机存取文件的读取和写入 的类 RandomAccessFile，成功读取文件第一行和最后一行。
import java.io.FileNotFoundException; import java.io.IOException; import java.io.RandomAccessFile; import java.util.ArrayList; import java.util.StringTokenizer; public class Read2222 ... { public String rea(String descAddr)...{ String result = new String(); RandomAccessFile rf = null; StringTokenizer st = new StringTokenizer(descAddr,"."); String fileLuJing = st.nextToken() + ".db"; ArrayList<String> ziFu = new ArrayList<String>();//每一行的字符串为一个元素 try ...{ rf = new RandomAccessFile(fileLuJing, "r"); long len = rf.length(); long start = rf.getFilePointer(); //System.out.println(start); long nextend = start + len - 1; String eachLine;//用于向ArrayList添加元素的代表 String lastLine;//最后一行的字符串 String firstLine = rf.readLine(); rf.seek(start); int c = -1; while (start<nextend) ...{ c = rf.read(); if (c == ' ' || c == ' ') ...{ eachLine= rf.readLine(); ziFu.add(eachLine); } rf.seek(start); start++; } rf.close(); lastLine = ziFu.get(ziFu.size()-1); /** *//*********转置*****/// System.out.println("firstLine: "+firstLine);// System.out.println("lastLine: "+lastLine); StringTokenizer nameToken = new StringTokenizer(firstLine," "); StringTokenizer valueToken = new StringTokenizer(lastLine," "); String temp; while(nameToken.hasMoreTokens() && valueToken.hasMoreTokens() ) ...{// System.out.println(result); temp = nameToken.nextToken() + " " + valueToken.nextToken() + " " ; result+= temp ; } /** *//*********转置*****/ } catch (FileNotFoundException e) ...{ e.printStackTrace(); } catch (IOException e) ...{ e.printStackTrace(); } finally ...{ try ...{ if (rf != null) rf.close(); } catch (IOException e) ...{ e.printStackTrace(); } } return result; }} 特别注意，rf.seek()定位，这条语句的地方； rf.readLine()读取定位点之后的一行，所以第一行的读取在循环之外。
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