JavaWeb--Request&Response1

Map<String,String[]> getParameterMap()：获取所有参数Map集合
String[] getParameterValues(String name)：根据名称获取参数值(数组)
String getParameter(String name)：根据名称获取参数值(单个值)

解决中文乱码(POST)：req.setCharacterEncoding("UTF-8");
乱码原因：Tomcat进行URL解码，默认字符集ISO-8859-1
URL编码：将字符串按照编码方式转为二进制；每个字节转为2个16进制数并在前面加%
URL编码实现：URLEncoder.encode(str,"utf-8");
URL解码实现：URLDecoder.decode(s,"ISO-8859-1");
解决中文乱码(GET)：
@Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");//设置字符输入流编码
        //获取username
        String username = req.getParameter("username");
        //对乱码数据进行编码转为字节数组
        byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);
        //字节数组解码
        username = new String(bytes,StandardCharsets.UTF_8);
        //username = new String(username.getBytes(StandardCharsets.ISO_8859_1),StandardCharsets.UTF_8);
    }
Tomcat8.0后，已将GET请求乱码问题解决，设置默认解码方式为UTF-8