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  • ServletInputStream的重复读取(多次读取)(转)

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    在使用Servlet进行Web开发的时候,有时候为了增加必要的业务处理而又不想修改现有的程序,往往采用Filter。这样在各个Filter中可能都要读取ServletInputStream流的内容,而ServletInputStream却只能读一次,这时候必须备份HttpServleRequest。

    
    class BufferedServletInputStream extends ServletInputStream {
    	private ByteArrayInputStream inputStream;
    	public BufferedServletInputStream(byte[] buffer) {
    		this.inputStream = new ByteArrayInputStream( buffer );
    	}
    	@Override
    	public int available() throws IOException {
    		return inputStream.available();
    	}
    	@Override
    	public int read() throws IOException {
    		return inputStream.read();
    	}
    	@Override
    	public int read(byte[] b, int off, int len) throws IOException {
    		return inputStream.read( b, off, len );
    	}
    }
    
    class BufferedServletRequestWrapper extends HttpServletRequestWrapper {
    	private byte[] buffer;
    	public BufferedServletRequestWrapper(HttpServletRequest request) throws IOException {
    		super( request );
    		InputStream is = request.getInputStream();
    		ByteArrayOutputStream baos = new ByteArrayOutputStream();
    		byte buff[] = new byte[ 1024 ];
    		int read;
    		while( ( read = is.read( buff ) ) > 0 ) {
    			baos.write( buff, 0, read );
    		}
    		this.buffer = baos.toByteArray();
    	}
    	@Override
    	public ServletInputStream getInputStream() throws IOException {
    		return new BufferedServletInputStream( this.buffer );
    	}
    }
    
    

    在Filter的doFilter()或者Servlet的doPost()中,

    
    //备份HttpServletRequest
    HttpServletRequest httpRequest = (HttpServletRequest)request;
    httpRequest = new BufferedServletRequestWrapper( httpRequest );
    //使用流
    InputStream is = request.getInputStream();
    //其他业务逻辑
    //将request 传到下一个Filter
    chain.doFilter(request, response);
    
    
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  • 原文地址:https://www.cnblogs.com/jiangxinnju/p/5709378.html
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