java 文件读入流问题处理

java 输出流写入

在使用 mysql 的 select * from a into outfile 'E:\\a.csv' character set utf8, 如果字段中有换行，会被转义成 \\n,Tab 转义为 \\t，无法正常处理数据文件，使用 java 处理该文件，有一个现象，写入文件尾会出现’\u0000’乱码，乱码数量取决于定义的 buff 大小

try(
	BufferedReader br = 
			new BufferedReader(
				new InputStreamReader(
					new FileInputStream(filePath), "utf-8"),1024*1024*100);
	BufferedWriter bw = 
			new BufferedWriter (
				new OutputStreamReader(
					new FileOutputStream(tofilePath), "utf-8"),1024*1024*100);
){
	bw.write("");
	char[] buff = new char[10249*1024*10];
	//逐行读取会读取行错误
	while(br.read(buff)!=-1){
		String str = new String(buff);
		//正则替换所有\r
		str = str.replaceAll("\\r","");
		//正则替换\\n 
		str = str.replaceAll("\\\\\\n","");
		bw.append(str);
	}
}catch(IOException e){}
...

对代码进行修改，去掉文件尾乱码

try(
	BufferedReader br = 
			new BufferedReader(
				new InputStreamReader(
					new FileInputStream(filePath), "utf-8"),1024*1024*100);
	BufferedWriter bw = 
			new BufferedWriter (
				new OutputStreamReader(
					new FileOutputStream(tofilePath), "utf-8"),1024*1024*100);
){
	bw.write("");
	int N = 10249*1024*10;
	char[] buff = new char[N];
	int len = 0;
	//逐行读取会读取行错误
	while((len=br.read(buff))!=-1){
		String str = new String(buff,0,len);
		//正则替换所有\r
		str = str.replaceAll("\\r","");
		//正则替换\\n 
		str = str.replaceAll("\\\\\\n","");
		bw.append(str);
		len = 0;
	}
}catch(IOException e){}
...