java一次读取文本文件所有内容

public String readToString(String fileName) {  
        String encoding = "UTF-8";  
        File file = new File(fileName);  
        Long filelength = file.length();  
        byte[] filecontent = new byte[filelength.intValue()];  
        try {  
            FileInputStream in = new FileInputStream(file);  
            in.read(filecontent);  
            return new String(filecontent, encoding);
        } catch (Exception e) {  
            e.printStackTrace();  
　　　　　　　return null;
        } finally {  
            in.close;  
        }  
    }