response的outputstream（十）

ServletOutputStream getOutputStream()

获得字节流，通过该字节流的write(byte[] bytes)可以向response缓冲区中写入字节，再由Tomcat服务器将字节内容组成Http响应返回给浏览器。

上一节展示了response.getWriter().write("字符串")，这个方法只能写字符串。如果要写字节，比如，传个图片，怎么办呢？就要靠response.getOutputStream()

我们从服务器往客户端发送一张图片。

package com.ken.content;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ByteServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// 使用response获得字节输出
		ServletOutputStream out = response.getOutputStream();

		// 获得服务器上的图片
		String realPath = this.getServletContext().getRealPath("a.jpg");
		InputStream in = new FileInputStream(realPath);

		int len = 0;
		byte[] buffer = new byte[1024];
		while ((len = in.read(buffer)) > 0) {
			out.write(buffer, 0, len);
		}

		in.close();
		out.close();
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}
}

我们看一下response

源码下载