Java不是我的主要编程语言,所以我可能会问一个明显的问题。
但是在Java中是否有一个简单的文件处理库,例如python?
例如,我只想说:
File f = Open('file.txt', 'w')
for(String line:f){
//do something with the line from file
}
谢谢!
更新:嗯,stackoverflow自动接受一个奇怪的答案。这与我放置的赏金有关-因此,如果您想查看其他答案,请向下滚动!
参考方案
我在考虑以下方面:
File f = File.open("C:/Users/File.txt");
for(String s : f){
System.out.println(s);
}
这是我的源代码:
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.Iterator;
public abstract class File implements Iterable<String>{
public final static String READ = "r";
public final static String WRITE = "w";
public static File open(String filepath) throws IOException{
return open(filepath, READ);
}
public static File open(String filepath, String mode) throws IOException{
if(mode == READ){
return new ReadableFile(filepath);
}else if(mode == WRITE){
return new WritableFile(filepath);
}
throw new IllegalArgumentException("Invalid File Write mode '" + mode + "'");
}
//common methods
public abstract void close() throws IOException;
// writer specific
public abstract void write(String s) throws IOException;
}
class WritableFile extends File{
String filepath;
Writer writer;
public WritableFile(String filepath){
this.filepath = filepath;
}
private Writer writer() throws IOException{
if(this.writer == null){
writer = new BufferedWriter(new FileWriter(this.filepath));
}
return writer;
}
public void write(String chars) throws IOException{
writer().write(chars);
}
public void close() throws IOException{
writer().close();
}
@Override
public Iterator<String> iterator() {
return null;
}
}
class ReadableFile extends File implements Iterator<String>{
private BufferedReader reader;
private String line;
private String read_ahead;
public ReadableFile(String filepath) throws IOException{
this.reader = new BufferedReader(new FileReader(filepath));
this.read_ahead = this.reader.readLine();
}
private Reader reader() throws IOException{
if(reader == null){
reader = new BufferedReader(new FileReader(filepath));
}
return reader;
}
@Override
public Iterator<String> iterator() {
return this;
}
@Override
public void close() throws IOException {
reader().close();
}
@Override
public void write(String s) throws IOException {
throw new IOException("Cannot write to a read-only file.");
}
@Override
public boolean hasNext() {
return this.read_ahead != null;
}
@Override
public String next() {
if(read_ahead == null)
line = null;
else
line = new String(this.read_ahead);
try {
read_ahead = this.reader.readLine();
} catch (IOException e) {
read_ahead = null;
reader.close()
}
return line;
}
@Override
public void remove() {
// do nothing
}
}
这是它的单元测试:
import java.io.IOException;
import org.junit.Test;
public class FileTest {
@Test
public void testFile(){
File f;
try {
f = File.open("File.java");
for(String s : f){
System.out.println(s);
}
} catch (IOException e) {
e.printStackTrace();
}
}
@Test
public void testReadAndWriteFile(){
File from;
File to;
try {
from = File.open("File.java");
to = File.open("Out.txt", "w");
for(String s : from){
to.write(s + System.getProperty("line.separator"));
}
to.close();
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
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