1 import java.io.BufferedReader;
2 import java.io.File;
3 import java.io.FileNotFoundException;
4 import java.io.FileReader;
5 import java.io.FileWriter;
6 import java.io.IOException;
7 import java.io.LineNumberReader;
8 import java.text.SimpleDateFormat;
9 import java.util.Date;
10
11 /**
12 * 这是一个与日志读写有关的类，定义了一些通用的方法
13 *
14 * @author Devon
15 *
16 */
17 public class LogReaderWriter {
18
19 public static int getTotalLines(String fileName) throws IOException {
20 FileReader in = new FileReader(fileName);
21 LineNumberReader reader = new LineNumberReader(in);
22 String strLine = reader.readLine();
23 int totalLines = 0;
24 while (strLine != null) {
25 totalLines++;
26 strLine = reader.readLine();
27 }
28 reader.close();
29 in.close();
30 return totalLines;
31 }
32
33 public static void readForPage(String filePath, int pageNo, int pageSize) throws IOException {
34 File file = new File(filePath);
35 FileReader in = new FileReader(file);
36 LineNumberReader reader = new LineNumberReader(in);
37 String s = "";
38 /*if (lineNumber <= 0 || lineNumber > getTotalLines(sourceFile)) {
39 System.out.println("不在文件的行数范围(1至总行数)之内。");
40 System.exit(0);
41 } */
42 int startRow = (pageNo - 1) * pageSize + 1;
43 int endRow = pageNo * pageSize;
44 int lines = 0;
45 System.out.println("startRow:" + startRow);
46 System.out.println("endRow:" + endRow);
47 while (s != null) {
48 lines++;
49 s = reader.readLine();
50 if (lines >= startRow && lines <= endRow) {
51 System.out.println("line:" + lines + ":" + s);
52 }
53 }
54 reader.close();
55 in.close();
56 }
57
58 /**
59 *
60 * @param filePath 文件路径的字符串表示形式
61 * @param KeyWords 查找包含某个关键字的信息：非null为带关键字查询；null为全文显示
62 * @return 当文件存在时，返回字符串；当文件不存在时，返回null
63 */
64 public static String readFromFile(String filePath, String KeyWords) {
65 StringBuffer stringBuffer = null;
66 File file = new File(filePath);
67 if (file.exists()) {
68 stringBuffer = new StringBuffer();
69 FileReader fileReader = null;
70 BufferedReader bufferedReader = null;
71 String temp;
72 try {
73 fileReader = new FileReader(file);
74 bufferedReader = new BufferedReader(fileReader);
75 while ((temp = bufferedReader.readLine()) != null) {
76 if (KeyWords == null) {
77 stringBuffer.append(temp).append("\n");
78 } else {
79 if (temp.contains(KeyWords)) {
80 stringBuffer.append(temp).append("\n");
81 }
82 }
83 }
84 } catch (FileNotFoundException e) {
85 //e.printStackTrace();
86 } catch (IOException e) {
87 //e.printStackTrace();
88 } finally {
89 try {
90 if (fileReader != null) {
91 fileReader.close();
92 }
93 } catch (IOException e) {
94 //e.printStackTrace();
95 }
96 try {
97 if (bufferedReader != null) {
98 bufferedReader.close();
99 }
100 } catch (IOException e) {
101 //e.printStackTrace();
102 }
103 }
104 }
105 if (stringBuffer == null) {
106 return null;
107 } else {
108 return stringBuffer.toString();
109 }
110
111 }
112
113 /**
114 * 将指定字符串写入文件。如果给定的文件路径不存在，将新建文件后写入。
115 *
116 * @param log 要写入文件的字符串
117 * @param filePath 文件路径的字符串表示形式，目录的层次分隔可以是“/”也可以是“\\”
118 * @param isAppend true：追加到文件的末尾；false：以覆盖原文件的方式写入
119 * @return 文件是否写入成功
120 */
121 public static boolean writeIntoFile(String log, String filePath, boolean isAppend) {
122 boolean isSuccess = true;
123 File file = new File(filePath);
124 if (!file.exists()) {
125 createNewFile(filePath);
126 }
127 //将logs写入文件
128 FileWriter fileWriter = null;
129 try {
130 fileWriter = new FileWriter(file, isAppend);
131 fileWriter.write(log + "\n");
132 fileWriter.flush();
133 } catch (IOException e) {
134 isSuccess = false;
135 //e.printStackTrace();
136 } finally {
137 try {
138 if (fileWriter != null) {
139 fileWriter.close();
140 }
141 } catch (IOException e) {
142 //e.printStackTrace();
143 }
144 }
145
146 return isSuccess;
147 }
148
149 /**
150 * 创建文件，如果该文件已存在将不再创建（即不起任何作用）
151 *
152 * @param filePath 要创建文件的路径的字符串表示形式，目录的层次分隔可以是“/”也可以是“\\”
153 * @return 创建成功将返回true；创建不成功则返回false
154 */
155 public static boolean createNewFile(String filePath) {
156 boolean isSuccess;
157 //创建文件
158 File file = new File(filePath);
159 try {
160 isSuccess = file.createNewFile();
161 } catch (IOException e) {
162 isSuccess = false;
163 }
164 return isSuccess;
165 }
166
167 public static void main(String[] args) {
168 String filename = "b.txt";
169
170 String str;
171 for (int i = 0; i < 100; i++) {
172 str = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(new Date()) + " - 插入数据" + i;
173 writeIntoFile(str, filename, true);
174 }
175
176 try {
177 long time = System.currentTimeMillis();
178 int count = getTotalLines(filename);
179 System.out.println(System.currentTimeMillis() - time);
180
181 System.out.println("当前文件总行数: " + count);
182 readForPage(filename, 10, 10);
183 } catch (IOException ex) {
184 ex.printStackTrace();
185 }
186 }
187 }
