n******1
发帖数: 3756 | 1 我在网上看到这两段代码，一个写，一个读，但是好像是有问题的.我看写是没问题的
，我把queue打出来，输入的都有，但是reader的读行为非常奇怪，如果文件有内容，
可以读出来，但是重新写入的有时候能读一部分，比如writer写入abcde,可能read到ab
出来，但大部分时间都是null,尝试自己加过在writer加入sleep，wait什么都没用
Writer.java
import java.io.BufferedWriter;
import java.io.Console;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.logging.Level;
import java.util.logging.Logger;
public class Writer {
private final BlockingDeque queue;
private final String filename;
public static void main(String[] args) throws Exception {
final Console console = System.console();
final Writer writer = new Writer("pipe");
writer.init();
while(true) {
String readLine = console.readLine();
writer.write(new StringBuffer(readLine));
}
}
public Writer(final String filename){
this.queue = new LinkedBlockingDeque();
this.filename = filename;
}
public void write(StringBuffer buf) {
queue.add(buf);
}
public void init() {
ExecutorService single = Executors.newSingleThreadExecutor();
Runnable runnable = new Runnable() {
public void run() {
while(true) {
PrintWriter w = null;
try {
String toString = queue.take().toString();
w = new PrintWriter(new BufferedWriter(new
FileWriter(filename)), true);
w.println(toString);
} catch (Exception ex) {
Logger.getLogger(Writer.class.getName()).log(Level.
SEVERE, null, ex);
}
}
}
};
single.submit(runnable);
}
}
Reader.java
public class Reader {
private final BufferedReader br;
public Reader(final String filename) throws FileNotFoundException {
br = new BufferedReader(new FileReader(filename));
}
public String readLine() throws IOException {
return br.readLine();
}
public void close() {
try {
br.close();
} catch (IOException ex) {
Logger.getLogger(Reader.class.getName()).log(Level.SEVERE, null,
ex);
}
}
public static void main(String[] args) throws FileNotFoundException {
Reader reader = new Reader("pipe");
while(true) {
try {
String readLine = reader.readLine();
System.out.println("readLine = " + readLine);
} catch (IOException ex) {
reader.close();
break;
}
}
}
} | g*****g
发帖数: 34805 | 2 You probably should flush on writer. | n******1
发帖数: 3756 | 3 我知道了，一个比较低级的错误，
w = new PrintWriter(new BufferedWriter(new FileWriter(filename,true)), true
);
这里FileWriter需要加set append = true, 原来的true只是让PrintWriter auto
flush
我开始以为filereader是不是读的太快了，就算遇到空行也会往下读，实际上应该不会
，如果在print之前判断是否null，这样程序就演示的挺好了
谢谢了
【在 g*****g 的大作中提到】
: You probably should flush on writer.
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