Read文件
代码语言：javascript
复制@Test
public void readFileLinesToJson() {
FileUtils.readFileLinesToJson("/mappings/doctorinfo_mapping.json");
}
/**
* 读取resource文件下的mapping
* @param filePath
* @return
*/
public static StringBuffer readFileLinesToJson(String filePath) {
StringBuffer stringBuffer = new StringBuffer();
try {
ClassPathResource classPathResource = new ClassPathResource(filePath);
InputStream inputStream = classPathResource.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
String temp;
while (null != (temp = bufferedReader.readLine())) {
stringBuffer.append(temp);
}
bufferedReader.close();
inputStream.close();
} catch (Exception e) {
log.debug(e.getMessage());
}
return stringBuffer;
}
代码语言：javascript
复制Java 8逐行读取文件:在此示例中，我将按行读取文件内容并在控制台打印输出。
Path filePath = Paths.get("c:/temp", "data.txt");
//try-with-resources语法,不用手动的编码关闭流
try (Stream<String> lines = Files.lines( filePath ))
{
lines.forEach(System.out::println);
}
catch (IOException e)
{
e.printStackTrace();//只是测试用例，生产环境下不要这样做异常处理
}
代码语言：javascript
复制Java8读取文件,过滤行:我们将文件内容读取为Stream。然后，我们将过滤其中包含单词"password"的所有行。
Path filePath = Paths.get("c:/temp", "data.txt");
try (Stream<String> lines = Files.lines(filePath)){
List<String> filteredLines = lines
.filter(s -> s.contains("password"))
.collect(Collectors.toList());
filteredLines.forEach(System.out::println);
} catch (IOException e) {
e.printStackTrace();//只是测试用例，生产环境下不要这样做异常处理
}
代码语言：javascript
复制Java7使用FileReader读取文件:
public static void main(String[] args) {
// 启动第一个线程
new Thread(() -> {
doSomeThing("/Users/Documents/projects/logs/articleId.txt");
}).start();
}
private static void doSomeThing(String filenamePath) {
try {
FileReader fr = new FileReader(filenamePath);
BufferedReader bf = new BufferedReader(fr);
String str;
while ((str = bf.readLine()) != null) {
log.info("文章:{}", str);
}
bf.close();
fr.close();
} catch (Exception e) {
e.printStackTrace();
}
return;
}
代码语言：javascript
复制Java7读取CSV文件：
public class ReadFileCsvUtils {
private static final String fileNamePath = "/Users/Downloads/Data/faculty.csv";
public static void main(String[] args) {
readCsvFile(fileNamePath);
}
public static void readCsvFile(String fileNamePath) {
try {
// 换成你的文件名
BufferedReader reader = new BufferedReader(new FileReader(fileNamePath));
reader.readLine();//第一行信息，为标题信息，不用,如果需要，注释掉
String line = null;
while ((line = reader.readLine()) != null) {
// CSV格式文件为逗号分隔符文件，这里根据逗号切分
String[] item = line.split(",");
System.out.println(new Gson().toJson(item));
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
Write文件
代码语言：javascript
复制Java7写TXT文件：
// FileWriter的第二个参数代表是否追加
BufferedWriter writer = new BufferedWriter(new FileWriter(targetFile, true));
// 字符串中使用换行：rn
writer.write(ss);
writer.newLine();
writer.close();
代码语言：javascript
复制Java7写CSV文件：
public void writeCsvFile(String fileNamePath) {
List<String> data = new ArrayList();
try {
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(fileNamePath, true));
bufferedWriter.write("第一列, 第二列, 第三列, 第四列");
for (int i = 0; i < data.size(); i ) {
bufferedWriter.write(data.get(i));
bufferedWriter.newLine();
}
bufferedWriter.flush();
bufferedWriter.close();
} catch (Exception e) {
log.error("error:" e.getMessage());
}
}
Cut文件
代码语言：javascript
复制public class CutFileUtils {
/**
* 按指定大小切割文件
* @param args
*/
public static void main(String[] args) {
//调用cutFile()函数 传人参数分别为 （原大文件，切割后存放的小文件的路径，切割规定的内存大小）
cutFile("/Users/Documents/projects/logs/searchmanager/Data/logs/service/SearchManager.2020-11-18-1.log",
"/Users/Documents/projects/logs/searchmanager/", 1024 * 1024 * 1000);
}
/**
* @param src 需要切割的文件
* @param endsrc 切割后文件的存放路径
* @param num 每个文件的大小
*/
public static void cutFile(String src, String endsrc, int num) {
FileInputStream fis = null;
File file = null;
try {
fis = new FileInputStream(src);
file = new File(src);
//创建规定大小的byte数组
byte[] b = new byte[num];
int len = 0;
//name为以后的小文件命名做准备
int name = 1;
//遍历将大文件读入byte数组中，当byte数组读满后写入对应的小文件中
while ((len = fis.read(b)) != -1) {
//分别找到原大文件的文件名和文件类型，为下面的小文件命名做准备
String name2 = file.getName();
int lastIndexOf = name2.lastIndexOf(".");
String substring = name2.substring(0, lastIndexOf);
String substring2 = name2.substring(lastIndexOf, name2.length());
FileOutputStream fos = new FileOutputStream(endsrc "/" substring "-" name substring2);
//将byte数组写入对应的小文件中
fos.write(b, 0, len);
//结束资源 fos.close();
name ;
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (fis != null) {
//结束资源
fis.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
