java读取resource下的文件

1.假设有如下结构的代码

（1）、main方法里复制resource下的文件

import org.apache.commons.io.FileUtils;
import java.io.*;
public class App {
public static void main(String[] args) throws Exception {
//从resources下读取diff2html.min.css为输入流
InputStream inputStream = App.class.getClassLoader().getResourceAsStream("diff2html.min.css");
//利用Apache Commons IO库把输入流写入到D:\myExcel\jsAndCss\diff2html.min.css ，如果文件不存在会自动创建
FileUtils.copyInputStreamToFile(inputStream, new File("D:\\myExcel\\jsAndCss\\diff2html.min.css"));
}
}


可以把代码和resource目录打成一个jar包也同样适用。运行jar包的时候就会把jar包里resource下的diff2html.min.css文件复制到D:\myExcel\jsAndCss\diff2html.min.css

（2）、main方法里读取resource下的文件

import java.io.*;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
public class App {
public static void main(String[] args) throws Exception {
List<String> list = new ArrayList<>();
//从resources下读取diff2html.min.css为输入流
InputStream inputStream = App.class.getClassLoader().getResourceAsStream("diff2html.min.css");
BufferedInputStream buf = new BufferedInputStream(inputStream);
int len = 0;
byte[] bys = new byte[1024];
while ((len = buf.read(bys)) != -1) {
//diff2html.min.css里每一行的内容添加到list里
String row = new String(bys, 0, len, StandardCharsets.UTF_8);
System.out.println(row);
list.add(row);
}
inputStream.close();
buf.close();
}
}


2.假设有如下结构的代码

import com.haitangxt.utils.ReadSource;
public class App {
public static void main(String[] args) throws Exception {
ReadSource readSource = new ReadSource();
readSource.copyfile("D:\\myExcel\\jsAndCss");
}
}


import org.apache.commons.io.FileUtils;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
public class ReadSource {
public void copyfile(String jsCssPath) {
try {
//从resources下的test/diff2html.min.css读取为输入流
InputStream inputStream = ReadSource.class.getClassLoader().getResourceAsStream("test/diff2html.min.css");
//利用Apache Commons IO库把输入流写入到D:\myExcel\jsAndCss\diff2html.min.css ，如果文件不存在会自动创建
FileUtils.copyInputStreamToFile(inputStream, new File(jsCssPath + "\\diff2html.min.css"));
} catch (IOException e) {
e.printStackTrace();
}
}
}

二、对于springboot项目读取resource下的资源文件


@Component
public class WorldAddressUtils {
public JSONObject getAllCountrys() {
try (
//读取文件为字节流
InputStream file = this.getClass().getResourceAsStream("/resourcesfile/worldAddress.txt");
//字节流转化为字符流，以UTF-8读取防止中文乱码
InputStreamReader in = new InputStreamReader(file, "UTF-8");
//加入到缓存
BufferedReader buf = new BufferedReader(in);
) {
String str = "";
while ((str = buf.readLine()) != null) {
System.out.println(str);
}
}catch (IOException e) {
e.printStackTrace();
}
}
}