HttpServletRequest

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1、HttpServletRequest

service方法中的request的类型是ServletRequest，而doGet/doPost方法的request的类型是HttpServletRequest，HttpServletRequest是ServletRequest的子接口，功能和方法更加强大。

request的运行流程：

这里写图片描述

1.1、通过request获得请求行

获得客户端的请求方式：
String getMethod()
获得请求的资源：
String getRequestURI() 
StringBuffer getRequestURL() 
String getContextPath() ---web应用的名称
String getQueryString() ---- get提交url地址后的参数字符串
username=zhangsan&password=123

注意：request获得客户机（客户端）的一些信息
request.getRemoteAddr() — 获得访问的客户端IP地址

html:

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <form action="/WEB15/line" method="post">
        <input type="text" name="username"><br>
        <input type="password" name="password"><br>
        <input type="submit" name="提交"><br>

    </form>
</body>
</html>

servlet:

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    //1、获得请求方式
    String method = request.getMethod();
    System.out.println("method:"+method);
    //2、获得请求的资源相关的内容
    String requestURI = request.getRequestURI();
    StringBuffer requestURL = request.getRequestURL();
    System.out.println("uri:"+requestURI);
    System.out.println("url:"+requestURL);
    //获得web应用的名称
    String contextPath = request.getContextPath();
    System.out.println("web应用："+contextPath);
    //地址后的参数的字符串
    String queryString = request.getQueryString();
    System.out.println(queryString);
    //3、获得客户机的信息---获得访问者IP地址
    String remoteAddr = request.getRemoteAddr();
    System.out.println("IP:"+remoteAddr);
}

打印结果:

method:POST
uri:/WEB15/line
url:http://localhost:8080/WEB15/line
web应用：/WEB15
null
IP:0:0:0:0:0:0:0:1

1.2、通过request获得请求头

long getDateHeader(String name)
String getHeader(String name)
Enumeration getHeaderNames()
Enumeration getHeaders(String name)
int getIntHeader(String name)
referer头的作用：执行该此访问的的来源，做防盗链

protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
    //1、获得指定的头
    String header = request.getHeader("User-Agent");
    System.out.println(header);
    //2、获得所有的头的名称
    Enumeration<String> headerNames = request.getHeaderNames();
    while(headerNames.hasMoreElements()){
        String headerName = headerNames.nextElement();
        String headerValue = request.getHeader(headerName);
        System.out.println(headerName+":"+headerValue);
    }
}

打印出结果：

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0
host:localhost:8080
user-agent:Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0
accept:text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
accept-language:zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3
accept-encoding:gzip, deflate
connection:keep-alive
upgrade-insecure-requests:1
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0
host:localhost:8080
user-agent:Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0
accept:text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
accept-language:zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3
accept-encoding:gzip, deflate
connection:keep-alive
upgrade-insecure-requests:1

连接跳转的时候，referer：

protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    //对来源的进行判断
    String header = request.getHeader("referer");
    if(header!=null&&header.startsWith("http://localhost")){
        //是从我自己的网站跳转过来的 可以看
        response.setContentType("text/html;charset=UTF-8");
        response.getWriter().write("中国确实已经拿到100块金牌....");
    }else{
        response.getWriter().write("你是盗链者，可耻！！");
    }
}

1.3、通过request获得请求体

html

<form action="/WEB15/content" method="get">
    <input type="text" name="username"><br>
    <input type="password" name="password"><br>
    <input type="checkbox" name="hobby" value="zq">足球
    <input type="checkbox" name="hobby" value="pq">排球
    <input type="checkbox" name="hobby" value="ppq">乒乓球<br>
    <input type="submit" value="提交"><br>
</form>

请求体中的内容是通过post提交的请求参数，格式是：

username=zhangsan&password=123&hobby=football&hobby=basketball

方法获得请求参数：

String getParameter(String name) 
String[] getParameterValues(String name)
Enumeration getParameterNames()
Map<String,String[]> getParameterMap()

servlet

protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    //1、获得单个表单值
    String username = request.getParameter("username");
    System.out.println(username);
    String password = request.getParameter("password");
    System.out.println(password);
    //2、获得多个表单的值
    String[] hobbys = request.getParameterValues("hobby");
    for(String hobby:hobbys){
        System.out.println(hobby);
    }
    //3、获得所有的请求参数的名称
    Enumeration<String> parameterNames = request.getParameterNames();
    while(parameterNames.hasMoreElements()){
        System.out.println(parameterNames.nextElement());
    }
    System.out.println("------------------");
    //4、获得所有的参数 参数封装到一个Map<String,String[]>
    Map<String, String[]> parameterMap = request.getParameterMap();
    for(Map.Entry<String, String[]> entry:parameterMap.entrySet()){
        System.out.println(entry.getKey());
        for(String str:entry.getValue()){
            System.out.println(str);
        }
        System.out.println("---------------------------");
    }
}

注意：get请求方式的请求参数上述的方法一样可以获得

解决post提交方式的乱码：request.setCharacterEncoding("UTF-8");
解决get提交的方式的乱码：parameter = new String(parameter.getbytes("iso8859-1"),"utf-8");

1.4、request是一个域对象
request对象也是一个存储数据的区域对象，所以也具有如下方法：

setAttribute(String name, Object o)
getAttribute(String name)
removeAttribute(String name)

注意：request域的作用范围：一次请求中

1.5、request完成请求转发

//获得请求转发器----path是转发的地址
RequestDispatcher getRequestDispatcher(String path)
//通过转发器对象转发
requestDispathcer.forward(ServletRequest request, ServletResponse response)

servlet1

protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    //想request域中存储数据
    request.setAttribute("name", "tom");

    //servlet1 将请求转发给servlet2
    RequestDispatcher dispatcher = request.getRequestDispatcher("/servlet2");
    //执行转发的方法
    dispatcher.forward(request, response);
}

servlet2

protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    //从request域中取出数据
    Object attribute = request.getAttribute("name");

    response.getWriter().write("hello haohao..."+attribute);
}

1.6、细节问题

ServletContext域与Request域的生命周期比较
ServletContext：创建：服务器启动；销毁：服务器关闭；域的作用范围：整个web应用
request：创建：访问时创建request；销毁：响应结束request销毁；域的作用范围：一次请求中

转发与重定向的区别
重定向两次请求，转发一次请求；
重定向地址栏的地址变化，转发地址不变；
重新定向可以访问外部网站转发只能访问内部资源；
转发的性能要优于重定向。

户端地址与服务器端地址的写法
客户端地址：是客户端去访问服务器的地址，服务器外部的地址，特点：写上web应用名称、直接输入地址：重定向；
服务器端地址：服务器内部资源的跳转的地址，特点：不需要写web应用的名称、转发。

2、用户注册案例

建表

CREATE TABLE `user` (
  `uid` varchar(32) NOT NULL,
  `username` varchar(20) DEFAULT NULL,
  `password` varchar(20) DEFAULT NULL,
  `name` varchar(20) DEFAULT NULL,
  `email` varchar(30) DEFAULT NULL,
  `telephone` varchar(20) DEFAULT NULL,
  `birthday` varchar(20) DEFAULT NULL,
  `sex` varchar(10) DEFAULT NULL,
  `state` int(11) DEFAULT NULL,
  `code` varchar(64) DEFAULT NULL,
  PRIMARY KEY (`uid`)
)

导入jar包和c3p0

Servlet

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.sql.SQLException;
import java.util.Map;
import java.util.UUID;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.dbutils.QueryRunner;
import com.ithiema.utils.DataSourceUtils;
public class RegisterServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //设置request的编码---只适合post方式
        request.setCharacterEncoding("UTF-8");

        //get方式乱码解决
        //String username = request.getParameter("username");//乱码
        //先用iso8859-1编码 在使用utf-8解码
        //username = new String(username.getBytes("iso8859-1"),"UTF-8");

        //1、获取数据
        //2、将散装的封装到javaBean
        //使用BeanUtils进行自动映射封装
        //BeanUtils工作原理：将map中的数据 根据key与实体的属性的对应关系封装
        //只要key的名字与实体的属性 的名字一样 就自动封装到实体中
        Map<String, String[]> properties = request.getParameterMap();
        User user = new User();
        try {
            BeanUtils.populate(user, properties);
        } catch (IllegalAccessException | InvocationTargetException e) {
            e.printStackTrace();
        }
        //现在这个位置 user对象已经封装好了
        //手动封装uid----uuid---随机不重复的字符串32位--java代码生成后是36位
        user.setUid(UUID.randomUUID().toString());

        //3、将参数传递给一个业务操作方法
        try {
            regist(user);
        } catch (SQLException e) {
            e.printStackTrace();
        }

        //4、认为注册成功跳转到登录页面
        response.sendRedirect(request.getContextPath()+"/login.jsp");
    }

    //注册的方法
    public void regist(User user) throws SQLException{
        //操作数据库
        QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
        String sql = "insert into user values(?,?,?,?,?,?,?,?,?,?)";
        runner.update(sql,user.getUid(),user.getUsername(),user.getPassword(),user.getName(),
                user.getEmail(),null,user.getBirthday(),user.getSex(),null,null);
    }

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

登陆servlet

import java.io.IOException;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import com.ithiema.register.User;
import com.ithiema.utils.DataSourceUtils;
public class LoginServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        //1、获得用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        //2、调用一个业务方法进行该用户查询
        User login = null;
        try {
            login = login(username,password);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        //3、通过user是否为null判断用户名和密码是否正确
        if(login!=null){
            //用户名和密码正确
            //登录成功 跳转到网站的首页
            response.sendRedirect(request.getContextPath());
        }else{
            //用户名或密码错误
            //跳回当前login.jsp
            //使用转发 转发到login.jsp  向request域中存储错误信息
            request.setAttribute("loginInfo", "用户名或密码错误");
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }
    }

    public User login(String username,String password) throws SQLException{
        QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
        String sql = "select * from user where username=? and password=?";
        User user = runner.query(sql, new BeanHandler<User>(User.class), username,password);
        return user;
    }

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