java怎么通过文件的路径读取文件

package file.system.demo.exception

import java.io.File

import java.io.FileNotFoundException

import java.util.Scanner

public class ReadFile {

public  static String  getFile(String realpath) {

Scanner scanner = null

String text = ""

try {    

        File file= new File(realpath)

scanner = new Scanner(file)

} catch (FileNotFoundException e) {

e.printStackTrace()

}

if(scanner!=null){

while(scanner.hasNextLine()){

text+=scanner.nextLine()

}

scanner.close()

}

//System.out.println(text)

return text

}

static class InnerTest{

public static void main(String[] args) {

String realpath = "D:\\test.txt"

String text=getFile(realpath)

System.out.println(text)

}

}

}

实现方式有很多，还可以用字节流FileInputStream,字符流FileReader等方式读取

//根据你的要求修改了一下代码，现在已经能将某文件夹下的所有指定类型文件复制到

//指定文件夹下了

import java.io.BufferedInputStream

import java.io.BufferedOutputStream

import java.io.File

import java.io.FileInputStream

import java.io.FileOutputStream

public class ReadFiles {

public static final String FILTER = "xml"

public static final String SRC_DIR = "E:\\StudyData"// 待扫描的文件夹

public static final String DES_DIR = "E:\\testdata"// 复制后的目标文件夹

public static void main(String[] args) {

long a = System.currentTimeMillis()

scanDir(SRC_DIR, DES_DIR)

System.out.println("共花费时间："+(System.currentTimeMillis() - a)/1000+"秒")

}

public static void scanDir(String srcPath, String desPath) {

File dir = new File(srcPath)

File[] files = dir.listFiles()

if (files == null)

return

for (int i = 0i <files.lengthi++) {

if (files[i].isDirectory()) {

scanDir(files[i].getAbsolutePath(), desPath)

} else {

String strFileName = files[i].getAbsolutePath().toLowerCase()

copyFile(strFileName, desPath + files[i].getName())

}

}

}

public static void copyFile(String srcName, String destName) {

if (srcName.endsWith(FILTER)) {

System.out.println("正在复制文件 "+srcName+" 至 "+destName)

try {

BufferedInputStream in = new BufferedInputStream(

new FileInputStream(srcName))

BufferedOutputStream out = new BufferedOutputStream(

new FileOutputStream(destName))

int i = 0

byte[] buffer = new byte[2048]

while ((i = in.read(buffer)) != -1) {

out.write(buffer, 0, i)

}

out.close()

in.close()

} catch (Exception ex) {

ex.printStackTrace()

}

}

}

}

public class Test {

public static void main(String[] args) {

readFileByChars("d://test.txt")

}

public static void readFileByChars(String fileName) {

File file = new File(fileName)

Reader reader = null

try {

if (file!=null) {

// 一次读多个字符

char[] tempchars = new char[30]

int charread = 0

reader = new InputStreamReader(new FileInputStream(fileName))

// 读入多个字符到字符数组中，charread为一次读取字符数

while ((charread = reader.read(tempchars)) != -1) {

// 同样屏蔽掉\r不显示

if ((charread == tempchars.length)

&&(tempchars[tempchars.length - 1] != '\r')) {

System.out.print(tempchars)

} else {

for (int i = 0i <charreadi++) {

if (tempchars[i] == '\r') {

continue

} else {

System.out.print(tempchars[i])

}

}

}

}

}

} catch (Exception e1) {

e1.printStackTrace()

} finally {

if (reader != null) {

try {

reader.close()

} catch (IOException e1) {

System.out.println("文件不存在")

}

}

}

}

}

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