JavaWeb-08 (JavaWeb-Servlet基础&java web之request/respone)

时间：2015-04-01 09:38:12 阅读：187 评论：0 收藏：0 [点我收藏+]

标签：javaweb

JavaWeb-08 JavaWeb-Servlet基础&java web之request/respone

JavaWeb-Servlet基础

一、ServletConfig对象

在Servlet的配置文件中，可以使用一个或多个<init-param>标签为servlet配置一些初始化参数。

实验1：day0800servletConfig

工程架构：

技术分享

工程下的web.xml文件内容

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name></display-name>
  <servlet>
    <servlet-name>ServletConfig1</servlet-name>
    <servlet-class>com.heima.servletConfig.ServletConfig1</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletConfig2</servlet-name>
    <servlet-class>com.heima.servletConfig.ServletConfig2</servlet-class>
    <init-param>
        <param-name>姓名</param-name>
        <param-value>张无忌</param-value>
    </init-param>
    <init-param>
        <param-name>年龄</param-name>
        <param-value>20</param-value>
    </init-param>
    <init-param>
        <param-name>性别</param-name>
        <param-value>男</param-value>
    </init-param>
  </servlet>


  <servlet-mapping>
    <servlet-name>ServletConfig1</servlet-name>
    <url-pattern>/servlet/ServletConfig1</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletConfig2</servlet-name>
    <url-pattern>/servlet/ServletConfig2</url-pattern>
  </servlet-mapping>    
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

ServletConfig1.java

import java.io.IOException;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示获取ServletConfig对象
/**
 * 方法一：采用init方法获取
 * 方法二：采用getServletConfig()方法获取
 * @author Administrator
 *
 */
public class ServletConfig1 extends HttpServlet {

    private ServletConfig config ;

    @Override
    public void init(ServletConfig config) throws ServletException {
        this.config = config ;
        super.init(config) ;
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        ServletConfig config1  = getServletConfig() ;

        System.out.println(config == config1);
    }

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

}

在配置完服务器后，在浏览器输入http://localhost:8080/day0800servletConfig/servlet/ServletConfig1

输出结果：

true，证明config和 config1 是同一个对象

当servlet配置了初始化参数后，web容器在创建servlet实例对象时，会自动将这些初始化参数封装到ServletConfig对象中，并在调用servlet的init方法时，将ServletConfig对象传递给servlet。进而，程序员通过ServletConfig对象就可以得到当前servlet的初始化参数信息。

ServletConfig2.java

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示获取配置信息
public class ServletConfig2 extends HttpServlet {

    private ServletConfig  config ;

    @Override
    public void init(ServletConfig config) throws ServletException {
        this.config = config ;
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        //演示获取单个配置信息
        //String name = config.getInitParameter("姓名") ;
        //System.out.println(name );

        //演示获取所有的配置参数
        Enumeration<String> enu = config.getInitParameterNames() ;
        while(enu.hasMoreElements()){
            String key = enu.nextElement() ;
            System.out.println(key+ ":" + config.getInitParameter(key));
        }

    }

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

}

技术分享

二、ServletContext对象

WEB容器在启动时，它会为每个WEB应用程序都创建一个对应的ServletContext对象，它代表当前web应用。

ServletConfig对象中维护了ServletContext对象的引用，开发人员在编写servlet时，可以通过ServletConfig.getServletContext方法获得ServletContext对象。

实验2：/day0801servletContext

工程架构如下：

技术分享

工程中的web.xml文件内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name></display-name>
  <servlet>
    <servlet-name>ServletContext1</servlet-name>
    <servlet-class>com.heima.servletcontext.ServletContext1</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletContext2</servlet-name>
    <servlet-class>one.ServletContext2</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletContext3</servlet-name>
    <servlet-class>one.ServletContext3</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletContext4</servlet-name>
    <servlet-class>two.ServletContext4</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletContext5</servlet-name>
    <servlet-class>three.ServletContext5</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletContext6</servlet-name>
    <servlet-class>three.ServletContext6</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletContext7</servlet-name>
    <servlet-class>four.ServletContext7</servlet-class>
  </servlet>

  <context-param>
       <param-name>name</param-name>
       <param-value>东西方不败</param-value>
  </context-param>

  <context-param>
        <param-name>sex</param-name>
        <param-value>人妖</param-value>
  </context-param>


  <servlet-mapping>
    <servlet-name>ServletContext1</servlet-name>
    <url-pattern>/servlet/ServletContext1</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletContext2</servlet-name>
    <url-pattern>/servlet/ServletContext2</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletContext3</servlet-name>
    <url-pattern>/servlet/ServletContext3</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletContext4</servlet-name>
    <url-pattern>/servlet/ServletContext4</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletContext5</servlet-name>
    <url-pattern>/servlet/ServletContext5</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletContext6</servlet-name>
    <url-pattern>/servlet/ServletContext6</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletContext7</servlet-name>
    <url-pattern>/servlet/ServletContext7</url-pattern>
  </servlet-mapping>    
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

ServletContext1.java

import java.io.IOException;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示获取servletContext对象的方法
/**
 * 方法一： 采用ServletConfig对象获取
 * 方法二： 采用getServletContext()方法
 * 方法二： 采用request.getSession().getServletContext() 获取
 * @author Administrator
 *
 */
public class ServletContext1 extends HttpServlet {

    private ServletContext sc ;

    @Override
    public void init(ServletConfig config) throws ServletException {
        sc = config.getServletContext() ;
    }
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        //方式二
    //  sc = getServletContext() ;
        ServletContext sc1 = request.getSession().getServletContext() ;
        System.out.println(sc == sc1);
    }

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

}

在浏览器里输入：http://localhost:8080/day0801servletContext/servlet/ServletContext1，

得出结果：true，证明sc和sc1是同一个对象。

由于一个WEB应用中的所有Servlet共享同一个ServletContext对象，因此Servlet对象之间可以通过ServletContext对象来实现通讯。ServletContext对象通常也被称之为context域对象。

技术分享

三、ServletContext应用

多个Servlet通过ServletContext对象实现数据共享。

ServletContext2.java

import java.io.IOException;

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

//演示在servletContext对象共享数据
public class ServletContext2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        ServletContext sc = getServletContext();
        sc.setAttribute("name", "东方不败");
        System.out.println("数据存储完毕");
    }

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

}

ServletContext3.java

import java.io.IOException;

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

//从servletContext中拿取数据
public class ServletContext3 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        ServletContext sc = getServletContext();

        String name = (String) sc.getAttribute("name");
        System.out.println(name);
    }

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

}

当在浏览器中输入 http://localhost:8080/day0801servletContext/servlet/ServletContext2后观察服务器的结果是：数据存储完毕。然后再在浏览器中输入 http://localhost:8080/day0801servletContext/servlet/ServletContext3，

结果为：东方不败。测试成功。

获取WEB应用的初始化参数。

ServletContext4.java

import java.io.IOException;
import java.util.Enumeration;

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

//演示获取全局配置参数
public class ServletContext4 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        ServletContext sc = getServletContext();
        // 演示获取单个配置参数
        // String name = sc.getInitParameter("name") ;
        // System.out.println(name);

        // 演示拿取多个配置参数
        Enumeration<String> enu = sc.getInitParameterNames();
        while (enu.hasMoreElements()) {
            String key = enu.nextElement();
            System.out.println(key + " :" + sc.getInitParameter(key));
        }
    }

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

}

在浏览器输入：http://localhost:8080/day0801servletContext/servlet/ServletContext4，服务器结果为： sex :人妖 name :东西方不败测试成功。

实现Servlet的转发。

ServletContext5.java

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

//演示请求转发
public class ServletContext5 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        // 获取全局对象
        ServletContext sc = getServletContext();
        // 获取请求转发器
        RequestDispatcher rd = sc
                .getRequestDispatcher("/servlet/ServletContext6");
        /**
         * URL的写法： 1. 客户端跳转: 由浏览器跳转 ：超链,重定向 : 一定要加工程路径 2. 服务器跳转 ： 由服务器发出来的跳转 :
         * 请求转发 : 不要加工程路径
         */
        // 转发
        rd.forward(request, response);

    }

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

}

ServletContext6.java

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 ServletContext6 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        response.getWriter().write("我喜欢芙蓉姐姐");
    }

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

}

当在浏览器中输入 http://localhost:8080/day0801servletContext/servlet/ServletContext5后观察结果是：

技术分享

利用ServletContext对象读取资源文件。

.properties文件（属性文件）

得到文件路径(ServletContext.getRealPath(),ServletContext.getReaourceAsStream())

在工程构架中的Properties文件内容如下：

技术分享

ServletContext7.java

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Properties;
import java.util.ResourceBundle;

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

//演示获取不同路径下的资源
/**
 * 第一种：采用servletContext获取资源 第二种：采用ResourceBundle类获取 : 不能拿取web环境下的资源
 * 第三种：采用类加载器加载资源 :不能拿取web环境下的资源
 * 
 * 比较： 第一种方式获取任意资源，任意路径. 第二种方式 只能获取properties类型的资源,web环境下的资源拿不到
 * 第三种方式拿取任意资源,不能拿取web环境下的资源
 */
public class ServletContext7 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        ServletContext sc = getServletContext();

        try {
            // test11(sc) ;
            // test12(sc) ;
            // test13(sc) ;
            // test21() ;
            // test22() ;
            // test31() ;
            // test32() ;
            test33();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

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

    // 方式一： 用servletContext对象获取p2的内容
    public void test11(ServletContext sc) throws Exception {
        // 拿到p2文件的路径
        String path = sc.getRealPath("/WEB-INF/classes/p2.properties");
        System.out.println(path);
        // 创建一个输入字节流对象
        FileInputStream fis = new FileInputStream(path);
        // 加载文件
        Properties pro = new Properties();
        pro.load(fis);
        // 获取内容
        System.out.println(pro.getProperty("k1"));
    }

    // 方式一： 用servletContext对象获取p1的内容
    public void test12(ServletContext sc) throws Exception {
        // 拿到p2文件的路径
        String path = sc.getRealPath("/WEB-INF/classes/four/p1.properties");
        System.out.println(path);
        // 创建一个输入字节流对象
        FileInputStream fis = new FileInputStream(path);
        // 加载文件
        Properties pro = new Properties();
        pro.load(fis);
        // 获取内容
        System.out.println(pro.getProperty("k1"));
    }

    // 方式一： 用servletContext对象获取p3的内容
    public void test13(ServletContext sc) throws Exception {
        // 拿到p2文件的路径
        String path = sc.getRealPath("/WEB-INF/p3.properties");
        System.out.println(path);
        // 创建一个输入字节流对象
        FileInputStream fis = new FileInputStream(path);
        // 加载文件
        Properties pro = new Properties();
        pro.load(fis);
        // 获取内容
        System.out.println(pro.getProperty("k1"));
    }

    // 方式二： 对象获取p2的内容
    public void test21() {
        // 获取resourceBundle对象
        ResourceBundle rb = ResourceBundle.getBundle("p2"); // 默认的路径是src,对应服务器上的路径是classes
        System.out.println(rb.getString("k1"));
    }

    // 方式二： 对象获取p1的内容
    public void test22() {
        // 获取resourceBundle对象
        ResourceBundle rb = ResourceBundle.getBundle("four.p1"); // 默认的路径是src,对应服务器上的路径是classes
        System.out.println(rb.getString("k1"));
    }

    // 方法三：采用类加载器获取p2的内容
    public void test31() throws Exception {
        // ServletContext7.class
        // this.getClass() ;
        // class.forName("four.ServletContext7") ;

        InputStream is = ServletContext7.class.getClassLoader()
                .getResourceAsStream("p2.properties"); // 默认的路径是src,对应服务器上的路径是classes
        // 加载文件
        Properties pro = new Properties();
        pro.load(is);
        // 获取内容
        System.out.println(pro.getProperty("k1"));
    }

    // 方法三：采用类加载器获取p1的内容
    public void test32() throws Exception {
        // ServletContext7.class
        // this.getClass() ;
        // class.forName("four.ServletContext7") ;

        InputStream is = ServletContext7.class.getClassLoader()
                .getResourceAsStream("four/p1.properties"); // 默认的路径是src,对应服务器上的路径是classes
        // 加载文件
        Properties pro = new Properties();
        pro.load(is);
        // 获取内容
        System.out.println(pro.getProperty("k1"));
    }

    // 方法三：采用类加载器获取p1的内容
    public void test33() throws Exception {
        // ServletContext7.class
        // this.getClass() ;
        // class.forName("four.ServletContext7") ;

        URL url = ServletContext7.class.getClassLoader().getResource(
                "four/p1.properties");// 默认的路径是src,对应服务器上的路径是classes
        String path = url.getPath();

        InputStream is = new FileInputStream(path);
        // 加载文件
        Properties pro = new Properties();
        pro.load(is);
        // 获取内容
        System.out.println(pro.getProperty("k1"));
    }

}

request&response

一、简介

Web服务器收到客户端的http请求，会针对每一次请求，分别创建一个用于代表请求的request对象、和代表响应的response对象。

request和response对象即然代表请求和响应，那我们要获取客户机提交过来的数据，只需要找request对象就行了。要向容器输出数据，只需要找response对象就行了。

HttpServletResponse：HttpServletResponse对象代表服务器的响应。这个对象中封装了向客户端发送数据、发送响应头，发送响应状态码的方法。

二、response常见应用：

1、向客户端输出中文数据:

用OutputStream(字节流)发送数据：

a、response.getOutputStream().write(“中国”.getBytes());//以默认编码发送数据

b、response.getOutputStream().write("中国".getBytes("UTF-8"));//以UTF-8编码发送数据，浏览器(默认用GB2312)会出现乱码

画图描述出现该问题的原因。

技术分享

解决办法：

a. 通过更改浏览器的编码方式：IE/”查看”/”编码”/”UTF-8”(不可取)

b. 通过设置响应头告知客户端编码方式：response.setHeader(“Content-type”, “text/html;charset=UTF-8”);//告知浏览器数据类型及编码

c. 通过meta标签模拟请求头:out.write("<meta http-equiv=‘Content-Type‘ content=‘text/html; charset=utf-8‘ />".getBytes());

d. 通过以下方法：response.setContentType("text/html;charset=UTF-8");

总结：程序以什么编码输出，就需要告知客户端以什么编码显示。

用PrintWriter(字符流)发送数据：

示例：response.getWriter().write(“中国” );有没有乱码？

原因：以默认编码发送数据 ISO-8859-1（没有中国二字编码），此时会发生乱码

解决办法：

setCharacterEncoding(“UTF-8”);//更改编码为UTF-8
response.setHead(“Context-type”,”text/html;charset=UTF-8”);//告诉客户端编码方式
注意：不要忘记告诉客户端的编码方式。
由于经常改动编码，response提供了一种更简单的方式
response. setContentType(“text/html;charset=UTF-8”);其作用相当于以上两条代码。

实验：/day0802httpServletResponse

工程架构如图：

技术分享

工程中的web.xml文档内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
  <display-name></display-name>
  <servlet>
    <servlet-name>ServletResponse1</servlet-name>
    <servlet-class>com.heima.response.ServletResponse1</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletResponse2</servlet-name>
    <servlet-class>com.heima.response.ServletResponse2</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletResponse3</servlet-name>
    <servlet-class>com.heima.response.ServletResponse3</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletResponse4</servlet-name>
    <servlet-class>com.heima.response.ServletResponse4</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletResponse5</servlet-name>
    <servlet-class>com.heima.response.ServletResponse5</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletResponse6</servlet-name>
    <servlet-class>com.heima.response.ServletResponse6</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletResponse7</servlet-name>
    <servlet-class>com.heima.response.ServletResponse7</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ServletResponse1</servlet-name>
    <url-pattern>/servlet/ServletResponse1</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletResponse2</servlet-name>
    <url-pattern>/servlet/ServletResponse2</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletResponse3</servlet-name>
    <url-pattern>/servlet/ServletResponse3</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletResponse4</servlet-name>
    <url-pattern>/servlet/ServletResponse4</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletResponse5</servlet-name>
    <url-pattern>/servlet/ServletResponse5</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletResponse6</servlet-name>
    <url-pattern>/servlet/ServletResponse6</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletResponse7</servlet-name>
    <url-pattern>/servlet/ServletResponse7</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

ServletResponse1.java

import java.io.IOException;
import java.io.UnsupportedEncodingException;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示中文乱码的解决
public class ServletResponse1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
//      Test1(response);
        test2(response);
    }
   //字节流输出中文
    private void Test1(HttpServletResponse response) throws IOException,
            UnsupportedEncodingException {
        //演示字节流输出中文
        ServletOutputStream sos = response.getOutputStream() ;


        //方法一：告诉用户自己选择编码(不靠谱)
        //方法二：通知浏览器采用哪个码表
        //response.setHeader("Content-Type", "text/html;charset=UTF-8") ;
        //方式三：输出字符串
        //sos.write("<meta http-equiv=‘content-type‘ content=‘text/html; charset=UTF-8‘>".getBytes()) ;
        //方法四：通知服务器用的编码，同时告诉浏览器用的码表
        //response.setCharacterEncoding("UTF-8") ;
        //response.setHeader("Content-Type", "text/html;charset=UTF-8") ;
        //方法五: (推荐)
        response.setContentType("text/html;charset=UTF-8") ;  //此句话有两个作用： 1.告诉服务器发送数据的的时候的编码
                                                                //               2. 通知浏览器解码的时候所用的码表


        sos.write("林志玲3".getBytes("UTF-8")) ;
    }
    //演示字符流输出中文
    public void test2(HttpServletResponse response){
            response.setContentType("text/html;charset=UTF-8") ;
        try {
            response.getWriter().write("陈冠希") ;
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

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

}

在浏览器输入http://localhost:8080/day0802httpServletResponse/servlet/ServletResponse1

结果：

技术分享

2、演示中文文件名的下载：

ServletResponse2.java

import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示中文文件名的下载
public class ServletResponse2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");

        //拿到图片的绝对路径
        String path = getServletContext().getRealPath("/WEB-INF/classes/美女.jpg") ;

        //创建一个输入流
        FileInputStream fis = new FileInputStream(path) ;

        //创建一个输出流
        ServletOutputStream sos = response.getOutputStream() ;

        //截取中文文件名
        String filename = path.substring(path.lastIndexOf("\\") + 1) ;

        //通知浏览器以下载的方式打开
        response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename,"UTF-8")) ;
        //通知浏览器文件名的MIME类型
        response.setHeader("Content-Type", "application/octet-stream") ;

        //输送数据
        byte[] bs = new byte[1024] ;
        int b = 0 ;
        while((b = fis.read(bs)) != -1){
            sos.write(bs,0,b) ;
        }   
        fis.close() ;

    }

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

}

在浏览器中输入：http://localhost:8080/day0802httpServletResponse/servlet/ServletResponse2

结果如图：

技术分享

3、验证码实验

a. 输出随机图片(CAPTCHA图像):Completely Automated Public Turing Test to Tell Computers and Humans Apart (全自动区分计算机和人类的测试) 


b. 相关主要类(JDK 查看API)
    BufferedImage:内存图像
    Graphics：画笔
    ImageIO：输出图像
    放在html页面上<img src/>
    注意：浏览器默认会缓存图片

    控制客户端不要缓存：
    response.addHeader("Pragma", "no-cache"); 
    response.setHeader("Cache-Control", "no-cache"); 
    response.setHeader("Expires", "0");

c. js刷新图片

MyHtml.html

<!DOCTYPE html>
<html>
  <head>
    <title>MyHtml.html</title>

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">

    <!--<link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/./styles.css">-->

  </head>
    <script type="text/javascript">

        function changeImage(){
            //拿到图片对象
            var image = document.getElementById("img") ;
            //设置src属性
            image.src = "/day08_02_httpServletResponse/servlet/ServletResponse3?t=" +new Date() ;
        }
    </script>
  <body>
     <form action="" method="post">
        <table border =1 >
            <tr>
                <td><br><br>    姓名：</td>
                <td><input type = "text" name = "username"></td>
            </tr>
            <tr>
                <td>密码：</td>
                <td><input type = "password" name = "pass"></td>
            </tr>
            <tr>
                <td>请输入验证码：</td>
                <td><input type = "text" name = "code">&nbsp;&nbsp;<img src = "/day08_02_httpServletResponse/servlet/ServletResponse3" id = "img"> <a href = "javascript:changeImage()">看不清楚，换一张</a></td>
            </tr>
        </table>
     </form>
  </body>
</html>

ServletResponse3.java

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示验证码的生成
public class ServletResponse3 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //设置图片的宽度，高度
        int width = 120 ;
        int height = 30 ;
        //创建图片
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB) ;
        //拿到图片的画笔
        Graphics g = image.getGraphics() ;

        //设置边框的颜色
        g.setColor(Color.RED) ;
        //将图片画出来
        g.drawRect(0, 0, width, height) ;

        //填充一下背景
        g.setColor(Color.yellow) ;
        //填充背景
        g.fillRect(1, 1, width-2, height-2) ;



        //画4个数字
        Random r = new Random() ;
        g.setColor(Color.red) ;
        g.setFont(new Font("幼圆", Font.BOLD + Font.ITALIC, 18)) ;
//      for (int i = 0; i < 4; i++) {
//          g.drawString(r.nextInt(10) + "", 20 + i*20, 20) ;
//      }

        //随机画30条干扰线
        g.setColor(Color.gray) ;
        for (int i = 0; i < 30; i++) {
            g.drawLine(r.nextInt(width), r.nextInt(height),r.nextInt(width), r.nextInt(height)) ;
        }

        //画中文
        g.setColor(Color.red) ;
        String s = "中国好声音深圳黑鸟训练营Ilovemoney" ;
        s = "\u4E2D\u56FD\u597D\u58F0\u97F3\u6DF1\u5733\u9ED1\u9A6C\u8BAD\u7EC3\u8425Ilovemoney" ;
        for (int i = 0; i < 4; i++) {
            g.drawString(s.charAt(r.nextInt(s.length())) + "", 20 + i*20 + r.nextInt(5), 18 + r.nextInt(5)) ;
        }

        response.setHeader("Expires", "-1") ;
        response.setHeader("Cache-Control", "no-cache") ;  //使用1.1协议
        response.setHeader("Pragma", "no-cache") ;    //使用1.0协议


        //创建imageIO对象
        ImageIO.write(image, "jpg", response.getOutputStream()) ;

    }

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

}

在浏览器中输入：http://localhost:8080/day0802httpServletResponse/MyHtml.html

输出结果：

技术分享

4、用request演示刷新

ServletResponse4.java

import java.io.IOException;
import java.util.Random;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示刷新
public class ServletResponse4 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        //定时刷新自己
        //response.setHeader("Refresh", "2") ;
        //response.getWriter().write("abcd" + new Random().nextInt()) ;

        //定时刷新到其他页面
        response.setHeader("Refresh", "2;url=/day08_02_httpServletResponse/MyHtml.html") ;
    }

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

}

在浏览器中输入：http://localhost:8080/day0802httpServletResponse/servlet/ServletResponse4

输出结果：2秒后刷新到另一个页面中：

技术分享

5、用request控制浏览器缓存时间

ServletResponse5.java

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//控制浏览器缓存时间
public class ServletResponse5 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.getOutputStream().write("大家好".getBytes()) ;
        response.setDateHeader("Expires", System.currentTimeMillis() + 10000) ;

    }

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

}

在浏览器中输入：http://localhost:8080/day0802httpServletResponse/servlet/ServletResponse5

结果：

技术分享

6、用request演示请求重定向

ServletResponse6.java

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示请求重定向
public class ServletResponse6 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //第一种方式
        //response.setStatus(302) ;
        //response.setHeader("Location", "/day08_02_httpServletResponse/servlet/ServletResponse3") ;

        //第二种方式
        response.sendRedirect("/day08_02_httpServletResponse/servlet/ServletResponse3") ;
    }

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

}

在浏览器中输入：http://localhost:8080/day0802httpServletResponse/servlet/ServletResponse6 结果页面重定向到了http://localhost:8080/day0802httpServletResponse/servlet/ServletResponse3

如图：

技术分享

重定向的流程如下：

流程1

流程2

流程3

流程4

流程5

流程6

流程7

流程8

流程9

流程10

流程11

流程12

流程13

流程14

流程15

流程16

7、response细节：

a. getOutputStream和getWriter方法分别用于得到输出二进制数据、输出文本数据的ServletOuputStream、Printwriter对象。


b. getOutputStream和getWriter这两个方法互相排斥，调用了其中的任何一个方法后，就不能再调用另一方法。  会抛异常。

c. Servlet程序向ServletOutputStream或PrintWriter对象中写入的数据将被Servlet引擎从response里面获取，Servlet引擎将这些数据当作响应消息的正文，然后再与响应状态行和各响应头组合后输出到客户端。 

d. Serlvet的service方法结束后，Servlet引擎将检查getWriter或getOutputStream方法返回的输出流对象是否已经调用过close方法，如果没有，Servlet引擎将调用close方法关闭该输出流对象。

ServletResponse7.java

package com.heima.response;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示response细节
public class ServletResponse7 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //response.getWriter().write("aaaaaaaaaaaaaaaaaaa") ;
        //response.getOutputStream().write("大s".getBytes()) ;
        response.getOutputStream().write((65+"").getBytes()) ;
    }

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

}

在浏览器中输入：http://localhost:8080/day0802httpServletResponse/servlet/ServletResponse7

结果：

技术分享

资料下载

JavaWeb-08 (JavaWeb-Servlet基础&java web之request/respone)

标签：javaweb

原文地址：http://blog.csdn.net/faith_yee/article/details/44788471

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