HttpServletResponse相关
目录
返回给客户端数据：字节流和字符流
package com.zhujunwei.httpServletResponse;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HttpServletResponse01 extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
/**
* 返回给客户端数据两种方式：字节流和字符流方式
* 一次只能执行其中的一个
*/
// byWriter(resp);
byOutputStream(resp);
//设置当前这个请求的处理状态码
// resp.setStatus(sc);
//设置一个头
// resp.setHeader(name, value);
//设置相应的类型，以及编码
// resp.setContentType(type);
}
/**
* 以字节流的方式写数据
* @param resp
* @throws IOException
*/
private void byOutputStream(HttpServletResponse resp) throws IOException {
resp.getOutputStream().write("getOutputStream().write()".getBytes());
}
/**
* 以字符流的方式写数据
* @param resp
* @throws IOException
*/
@SuppressWarnings("unused")
private void byWriter(HttpServletResponse resp) throws IOException {
resp.getWriter().write("<h1>getWriter().write()</h1><br>");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
结果：
getOutputStream().write()解决返回字节流和字符流乱码问题
package com.zhujunwei.httpServletResponse;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HttpServletResponse02 extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//字符流输出
// writerEncoding(resp);
//字节流输出
outPutStreamEncoding(resp);
}
/**
* 解决字节流输出乱码
* @param resp
* @throws IOException
* @throws UnsupportedEncodingException
*/
private void outPutStreamEncoding(HttpServletResponse resp) throws IOException, UnsupportedEncodingException {
//1、指定浏览器看这份数据使用的码表
resp.setHeader("Content-Type", "text/html; charset=UTF-8");
//2、指定输出的中文用的码表
resp.getOutputStream().write("我是最帅的。。".getBytes());
}
/**
* 解决字符流输出乱码
* @param resp
* @throws IOException
*/
@SuppressWarnings("unused")
private void writerEncoding(HttpServletResponse resp) throws IOException {
//这里写出去的文字，默认使用的是ISO-8859-1，我们可以指定写出去的时候，使用什么编码写
//1、指定输出到客户端的时候，这些文字使用UTF-8
resp.setCharacterEncoding("UTF-8");
//2、直接规定浏览器看这份数据的时候，使用什么编码看
resp.setHeader("Content-Type", "text/html; charset=UTF-8");
resp.getWriter().write("我是最帅的。。。");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
结果：
我是最帅的。。万能解决乱码
package com.zhujunwei.httpServletResponse;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HttpServletResponse03 extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//只需要设置这一行就可以不管是字节或者字符流都不会乱码
resp.setContentType("text/html; charset=UTF-8");
//字符流输出
writerEncoding(resp);
//字节流输出
// outPutStreamEncoding(resp);
}
/**
* 解决字节流输出乱码
* @param resp
* @throws IOException
* @throws UnsupportedEncodingException
*/
@SuppressWarnings("unused")
private void outPutStreamEncoding(HttpServletResponse resp) throws IOException, UnsupportedEncodingException {
resp.getOutputStream().write("我真的是最帅的。。".getBytes());
}
/**
* 解决字符流输出乱码
* @param resp
* @throws IOException
*/
private void writerEncoding(HttpServletResponse resp) throws IOException {
resp.getWriter().write("我真的是最帅的。。。");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
结果
我真的是最帅的。。。文件下载
tomcat提供的默认下载方式
Tomcat提供的有文件下在的默认Servlet，如果浏览器能打开这种文件的话会自动打开，不会弹出下载框。
我们在项目里面放置几个文件供测试使用
download.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>tomcat提供的默认下载方式</h2>
<a href="download/test.txt">test.txt</a><br>
<a href="download/m1.jpg">m1.jpg</a><br>
<a href="download/download.rar">download.rar</a><br>
<hr>
<h2>手动写下载方法</h2>
<a href="DownloadServlet?fileName=test.txt">test.txt</a><br>
<a href="DownloadServlet?fileName=m1.jpg">m1.jpg</a><br>
<a href="DownloadServlet?fileName=download.rar">download.rar</a><br>
</body>
</html>手动编写的DownloadServlet
package com.zhujunwei.download;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DownloadServlet extends HttpServlet{
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1、获取要下载的文件名字
String fileName = req.getParameter("fileName");
//2、获取这个文件在tomcat里面的绝对路径地址
String path = getServletContext().getRealPath("download/"+fileName);
//让浏览器收到这份资源的时候，以下载的方式提醒用户，而不是直接展示
resp.setHeader("Content-Disposition", "attachment; filename="+fileName);
//3、转换成输入流
InputStream is = new FileInputStream(path);
OutputStream os = resp.getOutputStream();
int len = 0 ;
byte[] buffer = new byte[1024];
while((len = is.read(buffer))!=-1) {
os.write(buffer,0,len);
}
os.close();
is.close();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
结果：
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我每一次回头，都感觉自己不够努力，所以我不再回头。
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