Java中超大文件读写

如果文件过大不能一次加载，就可以利用缓冲区：

File file = new File(filepath);
BufferedInputStream fis = new BufferedInputStream(new FileInputStream(file));
BufferedReader reader = new BufferedReader(new InputStreamReader(fis,"utf-8"),10*1024*1024);// 用10M的缓冲读取文本文件  

String line = "";
while((line = reader.readLine()) != null){
   //TODO: write your business
}

还可以用RandomAccessFile类读取，进行分段批操作：

String path = "你要读的文件的路径";
        RandomAccessFile br = new RandomAccessFile(path, "rw");
        String str = null, app = null;
        int i = 0;
        while ((str = br.readLine()) != null) {
            i++;
            app = app + str;
            if (i >= 100) {// 假设读取100行
                i = 0;
                // 这里你先对这100行操作，然后继续读
                app = null;
            }
        }
        br.close();