Foreword
Any language input and output streams are very important part, such as a read from the file contents, analysis, or to another output files, etc., are required file stream operation. Here a brief introduction to use reader, wirter, inputstream, outputstream of. In fact, Apache commons, which has a method IOUtils but realize convenient stream copy, interested can refer to the official documentation.
JAVA stream input and output, there are two, one is the byte stream (InPutStream, OutPutStream), one is the character stream (Reader, Writer).
Byte stream is of general application, such as we read a video, music, or text can be used in this way.
Character stream can only read text similar to this document. So what is the relationship between them? Look below at this drawing!
Substantially can see the relationships between them, we can use to implement InPutStreamReader byte character stream flowing conversion. such as
Reader reader = new InputStreamReader(new FileInputStream(fileName));OutPutStreamWriter may also be used to achieve byte character conversion flowing stream, such as
Writer writer = new OutputStreamWriter(new FileOutputStream(filePathName));Following is a brief case, file read and write files to sample!
Press OK to read the file!
1 /**
2 * 以行为单位读取文件，常用于读面向行的格式化文件
3 *
4 * @paramfileName:文件名
5 */
6 public static List<String> readFileByLines(String fileName) {
7 List<String> list = new ArrayList<String>();
8 if (fileName != null && !"".equals(fileName)) {
9 File file = new File(fileName);
10 BufferedReader reader = null;
11 try {
12 System.out.println("以行为单位读取文件内容，一次读一整行：");
13 reader = new BufferedReader(new FileReader(file));
14 String tempString = null;
15 /* 一次读入一行，直到读入null为文件结束 */
16 while ((tempString = reader.readLine()) != null) {
17 System.out.println(tempString);
18 list.add(tempString);
19 }
20 } catch (IOException e) {
21 System.out.println("读取文本文件异常" + e);
22 } finally {
23 if (reader != null) {
24 try {
25 reader.close();
26 } catch (IOException e1) {
27 System.out.println("读取文本文件异常" + e1);
28 }
29 }
30 }
31 }
32 return list;
33 }Write to the file directly overwrite the original content.
1 /**
2 * 把内容写到文件
3 *
4 * @paramfilePathName文件名
5 * @paramList<String>文件内容
6 */
7 public static boolean writerFile(String filePathName, String content) {
8 boolean flag = false;
9 OutputStreamWriter osw = null;
10 try {
11 if (filePathName != null && !"".equals(filePathName)) {
12 osw = new OutputStreamWriter(new FileOutputStream(filePathName));
13 }
14 } catch (FileNotFoundException e1) {
15 flag = false;
16 e1.printStackTrace();
17 }
18 if (osw != null) {
19 BufferedWriter bw = new BufferedWriter(osw);
20 try {
21 if (content != null && !"".equals(content)) {
22 bw.write(content);
23 flag = true;
24 }
25 } catch (IOException e) {
26 flag = false;
27 e.printStackTrace();
28 } finally {
29 try {
30 bw.close();
31 osw.close();
32 } catch (IOException e) {
33 flag = false;
34 e.printStackTrace();
35 }
36 }
37 }
38 return flag;
39 }Additional content to a file, appended to the end.
1 /**
2 * 把内容写到文件或追加到文件中
3 *
4 * @paramfilePathName文件名
5 * @paramList<String>文件内容
6 */
7 public static boolean writerFileIsAppend(String filePathName, String content) {
8 boolean flag = false;
9 OutputStreamWriter osw = null;
10 try {
11 if (filePathName != null && !"".equals(filePathName)) {
12 osw = new OutputStreamWriter(new FileOutputStream(filePathName,
13 true));
14 }
15 } catch (Exception e1) {
16 flag = false;
17 e1.printStackTrace();
18 }
19 if (osw != null) {
20 BufferedWriter bw = new BufferedWriter(osw);
21 try {
22 if (content != null && !"".equals(content)) {
23 bw.write(content);
24 flag = true;
25 }
26 } catch (IOException e) {
27 flag = false;
28 e.printStackTrace();
29 } finally {
30 try {
31 bw.close();
32 osw.close();
33 } catch (IOException e) {
34 flag = false;
35 e.printStackTrace();
36 }
37 }
38 }
39 return flag;
40 }All codes
1 package testIO;
2
3 import java.io.BufferedReader;
4 import java.io.BufferedWriter;
5 import java.io.File;
6 import java.io.FileInputStream;
7 import java.io.FileNotFoundException;
8 import java.io.FileOutputStream;
9 import java.io.FileReader;
10 import java.io.IOException;
11 import java.io.InputStream;
12 import java.io.InputStreamReader;
13 import java.io.OutputStreamWriter;
14 import java.io.Reader;
15 import java.util.ArrayList;
16 import java.util.List;
17
18 public class testIO {
19 public static void main(String[] args) {
20 readFileByBytes("C:\\Users\\Administrator\\Desktop\\新建文本文档.txt");
21 readFileByChars("C:\\Users\\Administrator\\Desktop\\新建文本文档.txt");
22 readFileByLines("C:\\Users\\Administrator\\Desktop\\新建文本文档.txt");
23 writerFile("C:\\Users\\Administrator\\Desktop\\新建文本文档.txt",
24 "BufferedWriter");
25 writerFileIsAppend("C:\\Users\\Administrator\\Desktop\\新建文本文档.txt",
26 "Append");
27 }
28
29 /**
30 * 以字节为单位读取文件，常用于读二进制文件，如图片、声音、影像等文件。
31 *
32 * @paramfileName:文件的名
33 */
34 public static void readFileByBytes(String fileName) {
35 File file = new File(fileName);
36 InputStream in = null;
37 try {
38 System.out.println("以字节为单位读取文件内容，一次读多个字节：");
39 /* 一次读多个字节 */
40 byte[] tempbytes = new byte[100];
41 int byteread = 0;
42 in = new FileInputStream(file);
43 /* 读入多个字节到字节数组中，byteread为一次读入的字节数 */
44 while ((byteread = in.read(tempbytes)) != -1) {
45 for (byte b : tempbytes) {
46 System.out.println((char) b);
47 }
48 System.out.println(byteread);
49 }
50 } catch (Exception e1) {
51 System.out.println("读取文本文件异常" + e1);
52 } finally {
53 if (in != null) {
54 try {
55 in.close();
56 } catch (IOException e1) {
57 System.out.println("读取文本文件异常" + e1);
58 }
59 }
60 }
61 }
62
63 /**
64 * 以字符为单位读取文件，常用于读文本，数字等类型的文件
65 *
66 * @paramfileName:文件名
67 */
68 public static void readFileByChars(String fileName) {
69 Reader reader = null;
70 try {
71 System.out.println("以字符为单位读取文件内容，一次读多个字节：");
72 /* 一次读多个字符 */
73 char[] tempchars = new char[100];
74 int charread = 0;
75 if (fileName != null && !"".equals(fileName)) {
76 reader = new InputStreamReader(new FileInputStream(fileName));
77 /* 读入多个字符到字符数组中，charread为一次读取字符数 */
78 while ((charread = reader.read(tempchars)) != -1) {
79 for (char c : tempchars) {
80 System.out.println(c);
81 }
82 }
83 }
84 } catch (Exception e1) {
85 System.out.println("读取文本文件异常" + e1);
86 } finally {
87 if (reader != null) {
88 try {
89 reader.close();
90 } catch (IOException e1) {
91 System.out.println("读取文本文件异常" + e1);
92 }
93 }
94 }
95 }
96
97 /**
98 * 以行为单位读取文件，常用于读面向行的格式化文件
99 *
100 * @paramfileName:文件名
101 */
102 public static List<String> readFileByLines(String fileName) {
103 List<String> list = new ArrayList<String>();
104 if (fileName != null && !"".equals(fileName)) {
105 File file = new File(fileName);
106 BufferedReader reader = null;
107 try {
108 System.out.println("以行为单位读取文件内容，一次读一整行：");
109 reader = new BufferedReader(new FileReader(file));
110 String tempString = null;
111 /* 一次读入一行，直到读入null为文件结束 */
112 while ((tempString = reader.readLine()) != null) {
113 System.out.println(tempString);
114 list.add(tempString);
115 }
116 } catch (IOException e) {
117 System.out.println("读取文本文件异常" + e);
118 } finally {
119 if (reader != null) {
120 try {
121 reader.close();
122 } catch (IOException e1) {
123 System.out.println("读取文本文件异常" + e1);
124 }
125 }
126 }
127 }
128 return list;
129 }
130
131 /**
132 * 把内容写到文件
133 *
134 * @paramfilePathName文件名
135 * @paramList<String>文件内容
136 */
137 public static boolean writerFile(String filePathName, String content) {
138 boolean flag = false;
139 OutputStreamWriter osw = null;
140 try {
141 if (filePathName != null && !"".equals(filePathName)) {
142 osw = new OutputStreamWriter(new FileOutputStream(filePathName));
143 }
144 } catch (FileNotFoundException e1) {
145 flag = false;
146 e1.printStackTrace();
147 }
148 if (osw != null) {
149 BufferedWriter bw = new BufferedWriter(osw);
150 try {
151 if (content != null && !"".equals(content)) {
152 bw.write(content);
153 flag = true;
154 }
155 } catch (IOException e) {
156 flag = false;
157 e.printStackTrace();
158 } finally {
159 try {
160 bw.close();
161 osw.close();
162 } catch (IOException e) {
163 flag = false;
164 e.printStackTrace();
165 }
166 }
167 }
168 return flag;
169 }
170
171 /**
172 * 把内容写到文件或追加到文件中
173 *
174 * @paramfilePathName文件名
175 * @paramList<String>文件内容
176 */
177 public static boolean writerFileIsAppend(String filePathName, String content) {
178 boolean flag = false;
179 OutputStreamWriter osw = null;
180 try {
181 if (filePathName != null && !"".equals(filePathName)) {
182 osw = new OutputStreamWriter(new FileOutputStream(filePathName,
183 true));
184 }
185 } catch (Exception e1) {
186 flag = false;
187 e1.printStackTrace();
188 }
189 if (osw != null) {
190 BufferedWriter bw = new BufferedWriter(osw);
191 try {
192 if (content != null && !"".equals(content)) {
193 bw.write(content);
194 flag = true;
195 }
196 } catch (IOException e) {
197 flag = false;
198 e.printStackTrace();
199 } finally {
200 try {
201 bw.close();
202 osw.close();
203 } catch (IOException e) {
204 flag = false;
205 e.printStackTrace();
206 }
207 }
208 }
209 return flag;
210 }
211 }
Content Reference
http://www.2cto.com/kf/201206/136072.html
http://blog.csdn.net/liuhenghui5201/article/details/8292552
Reproduced in: https: //my.oschina.net/u/204616/blog/545438