java 多线程读取大文件 java多线程写文件会冲突吗

多线程写文件是会有冲突的，会有脏数据，所以我们要给写文件的代码加上锁。

具体流程在以前代码基础上加上锁代码：

FileOutputStream fos = new FileOutputStream(file, true);
FileChannel fc = fos.getChannel();
while(true){
    try{
         lock = fc.tryLock();
     }catch (OverlappingFileLockException e){
         lock = null;
     }
     if(lock != null){
         break;
     }
}

将上面代码放到写之前就可以。

然后在finally里面

lock.release();

我的整体代码就是

public void writeToFileAppend(String fileName, String outDir, String encode, List<String> data){

        OutputStreamWriter osr = null;
        BufferedWriter bw = null;
        FileLock lock = null;
        try {
            File file = new File(outDir, fileName);
            File out = new File(outDir);
            if(!out.exists()){
                out.mkdirs();
            }
            FileOutputStream fos = new FileOutputStream(file, true);
            FileChannel fc = fos.getChannel();
            while(true){
                try{
                    lock = fc.tryLock();
                }catch (OverlappingFileLockException e){
                    lock = null;
                }
                if(lock != null){
                    break;
                }
            }
            osr = new OutputStreamWriter(fos, encode);
            bw = new BufferedWriter(osr);
            for(int i = 0;i < data.size();i++){
                bw.write(data.get(i));
                bw.newLine();
            }
            bw.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try{
                lock.release();
                osr.close();
                bw.close();
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    }