public static String fileReader(File file) throws IOException {

        String contants;
        FileReader fr =new FileReader(file);
        BufferedReader br =new BufferedReader(fr);
        //
        contants=br.readLine();
        while (br.ready()){
            contants=contants+br.readLine();
        }
        fr.close();
        br.close();
        return contants;
    }

java——文件读取内容方法