一、通过字符流输出
方式1（建议）
response.setCharacterEncoding("UTF-8");//设置response码表，控制response向浏览器写数据 response.setHeader("Content-type","text/html;charset=UTF-8");//控制浏览器打开的码表 PrintWriter out = response.getWriter();//得到输出字符流 out.print("中国");//输出字符方式2（建议）
response.setContentType("text/html;charset=UTF-8");//直接控制全程码表 PrintWriter out = response.getWriter();//得到输出字符流 out.print("中国");//输出字符方式3
//使用<meta>标签模拟控制码表 response.setCharacterEncoding("UTF-8");//设置response码表，控制response向浏览器写数据 PrintWriter out = response.getWriter();//得到输出字符流 out.write("<meta http-equiv='content-type' content='text/html;charset=UTF-8'>"); out.print("中国");//输出字符
二、通过字节流输出字符串
方式1（不建议使用）
//不控制码表，直接输出 OutPutStream out = response.getOutputStream();获取字节流 out.write("中国".getBytes());//输出字节流，默认gb2312方式2（建议）
response.setHeader("Content-type","text/html;charset=UTF-8");//控制浏览器打开的码表 OutputStream out = response.getOutputStream();获取字节流 out.write("中国".getBytes("UTF-8"));//输出字节流,转换为UTF-8方式3
//使用<meta>标签模拟控制码表 OutPutStream out = response.getOutputStream();//获取字节流 out.write("<meta http-equiv='content-type' content='text/html;charset=UTF-8'>".getBytes()); out.write("中国".getBytes("UTF-8"));//输出字节流,转换为UTF-8三、输出图片
BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);//创建图片 OutputStream outputStream = response.getOutputStream();//获取输出字节流 ImageIO.write(image, "jpg", outputStream);//输出图片四、文件下载
import java.io.FileInputStream; import java.io.IOException; import java.net.URLEncoder; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/ResponseDemo7") public class Test_Image extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //通过路径将图片以流的形式得到 //通过相对路径得到绝对路径 String path = this.getServletContext().getRealPath("Images/a1.jpg"); //有了路径可以得到输入流（图片，要用字节输出流） FileInputStream fis = new FileInputStream(path); //使用绝对路径将图片用输入流变成一个流 fis（图片） //用response创建一个输出流 ServletOutputStream outputStream = response.getOutputStream(); /*我们要将图片下载下来 */ //得到要下载的文件名 String fileName = path.substring(path.lastIndexOf("\\")+1); System.out.println(fileName); //设置文件的编码 fileName = URLEncoder.encode(fileName,"UTF-8"); //告知客户端要下载文件 response.setHeader("content-disposition", "attachment;filename="+URLEncoder.encode(fileName,"UTF-8"));//编码 response.setHeader("content-type", "image/jpeg"); //执行fileOutputStream的输出操作 int len = 1; byte[] b = new byte[1024]; while((len=fis.read(b))!=-1){ outputStream.write(b, 0, len); } outputStream.close(); fis.close(); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doGet(request, response); } }（进入博客查看HttpServletRequest基础知识）
