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：

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);    }}

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：

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。

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：

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：

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。

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-8response.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：

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：

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：

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：

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：

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：

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：

• 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：

资料下载