1 java8读取文本文件
2
3
4
public
static
void java8ReadFileLines(String fileName)
throws IOException {
5 List lineList = Files.readAllLines(Paths.get(fileName), StandardCharsets.UTF_8);
6
7
for(String line:lineList){
8 System.out.println(line);
9 }
10 }
11
12
13
14 一行一行地读取文件
15
16
17
public
static
void readFileByLines(String fileName) {
18 File file =
new File(fileName);
19 BufferedReader reader =
null;
20
try {
21 reader =
new BufferedReader(
new FileReader(file));
22 String line =
null;
23
while((line=reader.readLine())!=
null ) {
24 System.out.println(line);
25 }
26 }
catch (IOException e) {
27
28 }
finally {
29
if(reader!=
null) {
30
try{
31 reader.close();
32 }
catch (IOException e) {
33 ;
34 }
35 }
36 }
37 }
38
39
40
41 一次读取多个字符
42
43
44
public
static
void readFileByMultiChars(String fileName) {
45 File file =
new File(fileName);
46
try{
47 InputStreamReader inputStreamReader =
new InputStreamReader(
new FileInputStream(file));
48
49
char[] tempChars =
new
char[30];
50
51
int readCount = 0;
52
while((readCount=inputStreamReader.read(tempChars))!=-1) {
53
if(readCount==tempChars.length) {
54 System.out.println(tempChars);
55 }
else{
56 System.out.println(Arrays.copyOf(tempChars, readCount));
57 }
58 }
59
60
61 inputStreamReader.close();
62 }
catch(Exception e) {
63 e.printStackTrace();
64 }
65 }
66
67
68
69 一个字符一个字符地读取
70
71
72
public
static
void readFileByChars(String fileName) {
73 File file =
new File(fileName);
74
try{
75 InputStreamReader inputStreamReader =
new InputStreamReader(
new FileInputStream(file));
76
77
int tempChar;
78
79
while((tempChar=inputStreamReader.read())!=-1) {
80 System.out.println((
char)tempChar);
81 }
82
83
84 inputStreamReader.close();
85 }
catch(Exception e) {
86 e.printStackTrace();
87 }
88 }
89
90
91
92 java8读取字节 超级简单
93
94
95
public
static
byte[] java8ReadBytes(String fileName)
throws IOException {
96
return Files.readAllBytes(Paths.get(fileName));
97 }
98
99
100
101 一个字节一个字节地读取
102
103
104
public
static
void readFileByOneByte(String fileName) {
105 File file =
new File(fileName);
106 InputStream inputStream =
null;
107
108
try{
109 inputStream =
new FileInputStream(file);
110
int tempByte;
111
while( (tempByte=inputStream.read())!=-1) {
112 System.out.println(tempByte);
113 }
114
115 inputStream.close();
116 }
catch (IOException e) {
117 System.out.println(e);
118 }
119
120 }
121
122
123
124 一个字节一个字节读取到ByteBuffer
125
126
127
public
static
byte[] readFileByOneByteToBuffer(String fileName) {
128
129
130 ByteBuffer byteBuffer = ByteBuffer.allocate(1024 * 1024);
131
132 File file =
new File(fileName);
133 InputStream inputStream =
null;
134
135
try{
136 inputStream =
new FileInputStream(file);
137
int tempByte;
138
while( (tempByte=inputStream.read())!=-1) {
139 byteBuffer.put((
byte)tempByte);
140 }
141
142 inputStream.close();
143 }
catch (IOException e) {
144 System.out.println(e);
145 }
146
147 byteBuffer.flip();
148 System.out.println("one limit:" + byteBuffer.limit());
149
byte[] result =
new
byte[byteBuffer.limit()];
150 byteBuffer.get(result);
151
152
return result;
153
154
155 }
156
157
158
159 多个字节进行读取
160
161
162
public
static
void readFileByMultiBytes(String fileName) {
163
164 File file =
new File(fileName);
165 InputStream inputStream =
null;
166
167
try {
168
byte[] bytes =
new
byte[50];
169
int byteRead = 0;
170 inputStream =
new FileInputStream(fileName);
171
172
while( (byteRead = inputStream.read(bytes))!=-1 ) {
173 System.out.println(byteRead);
174 }
175 }
catch(IOException e) {
176 System.out.println(e);
177 }
finally {
178
if(inputStream!=
null) {
179
try{
180 inputStream.close();
181 }
catch(IOException e){
182 System.out.println("iput stream close exception" + e);
183 }
184 }
185 }
186 }
187
188
189
190 读取多个字节到ByteBuffer
191
192
193
public
static
byte[] readFileByMultiBytesToBuffer(String fileName) {
194
195 ByteBuffer byteBuffer = ByteBuffer.allocate(1024*1024);
196 InputStream inputStream =
null;
197
198
try {
199
byte[] bytes =
new
byte[50];
200
int byteRead = 0;
201 inputStream =
new FileInputStream(fileName);
202
203
int count = 0;
204
while( (byteRead = inputStream.read(bytes))!=-1 ) {
205 byteBuffer.put(bytes, 0, byteRead);
206 count+=byteRead;
207 }
208
209 System.out.println("readCount:"+count);
210 }
catch(IOException e) {
211 System.out.println(e);
212 }
finally {
213
if(inputStream!=
null) {
214
try{
215 inputStream.close();
216 }
catch(IOException e){
217 System.out.println("iput stream close exception" + e);
218 }
219 }
220 }
221
222 byteBuffer.flip();
223 System.out.println("multi limit:" + byteBuffer.limit());
224
byte[] result =
new
byte[byteBuffer.limit()];
225 byteBuffer.get(result);
226
227
return result;
228 }
229
转载于:https://www.cnblogs.com/jym-sunshine/p/5613100.html
相关资源：java读写文件(txt)
