(Apache)使用HttpClient方式访问HTTP 有更新!

2017-09-05

    Apache使用GET方式访问HTTP
    得到访问地址 HttpGet(有参数提供参数)
    得到网络访问对象HttpClient,进行连接
    得到返回值
    如果返回值正常,返回得到的数据对象HttpEntity,得到数据流

    注意:
    GET方式在URL中传递中文参数乱码问题我解决了。
    乱码原因:不管客户端采用什么方式给中文字符编码,最终附加到URL中之前,都将在已有的编码基础上再对字符以ISO-8859-1字符集做二次编码然后再附加到URL中。

    即所有的非ASCII字符集参数在URL中最终都是ISO-8859-1编码,如果之前已经进行了一次编码,那么这就是在已有编码的基础上二次编码

    解码是编码的逆操作,只要在服务器端对客户端进行的编码再进行对应解码即可。过程如下:
    1. 在客户端对中文字符串编码,比如使用UTF-8编码
    String codeParam = URLEncoder.encode("中文字符串", "UTF-8");
    2. 把这个编码好的codeParam作为参数附加到URL地址中;
    3. 服务器端getRequestParameter()方法获得该参数(当然这个参数作为URL提交时已经又被ISO-8859-1编码了一次)
    4. 对这个参数做解码,首先要按ISO-8859-1解码一次
    byte[ ] decodeBytes = codeParam.getBytes("ISO-8859-1");
    5. 再按客户端编码模式做二次解码
    String decodeParam = new String(decodeBytes, "UTF-8");

    此时获得的decodeParam可以正确显示中文字符。
    PS:当然客户端也可以不进行一次编码,那就系统默认的中文编码,但是URL提交时,依然会对这个已经编码的字符串再用ISO-8859-1字符集做二次编码,URL中的非ASCII字符集最终都是ISO-8859-1编码的,这个无法更改。

    示例代码:

        package com.hht.apache;
    
        import java.io.BufferedReader;
        import java.io.IOException;
        import java.io.InputStream;
        import java.io.InputStreamReader;
    
        import org.apache.catalina.util.URLEncoder;
        import org.apache.http.HttpEntity;
        import org.apache.http.HttpResponse;
        import org.apache.http.client.ClientProtocolException;
        import org.apache.http.client.HttpClient;
        import org.apache.http.client.methods.HttpGet;
        import org.apache.http.impl.client.DefaultHttpClient;
        import org.apache.http.util.EntityUtils;
    
        public class HttpClient01 {
    
            public static void main(String[] args) {
                // TODO Auto-generated method stub
                //HttpGet登录验证的实现
                String path = "http://192.168.125.102:8080/ApacheTest/LoginServlet?username=何海涛&password=123";
                //获得HttpClient
                HttpClient client = new DefaultHttpClient();
                //获得HttpGet
                HttpGet httpGet = new HttpGet(path);
    
                try {
                    //获得HttpResponse响应
                    HttpResponse httpResponse = client.execute(httpGet);
                    //获得响应码
                    int code = httpResponse.getStatusLine().getStatusCode();
    
                    if(code==200){
                        //获得响应实体
                        HttpEntity entity = httpResponse.getEntity();
                        //获得响应内容
                        InputStream inputStream = entity.getContent();
                        //利用流进行输出
                        BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
                        System.out.println(br.readLine());
                        //第二种输出方式
                        //System.out.println(EntityUtils.toString(entity,"utf-8"));
    
                    }
                } catch (ClientProtocolException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
    
            }
            ```
    
    Servlet
    package com.hht.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /**
     * Servlet implementation class LoginServlet
     */
    public class LoginServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;
    
        /**
         * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
         */
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // TODO Auto-generated method stub
    
            response.setCharacterEncoding("UTF-8");
            PrintWriter out = response.getWriter();
            request.setCharacterEncoding("UTF-8");
            //在这个地方进行两次转码来避免中文在get方式中的乱码
            String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");
            String psw = request.getParameter("password");
    
            if (username.equals("何海涛") && psw.equals("123")) {
                out.println("欢迎" + username + "登陆");
    
            } else {
                out.println("登陆失败,请检查用户名或者密码是否输入正确....");
    
            }
        }
    
        /**
         * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
         */
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // TODO Auto-generated method stub
    
            response.setCharacterEncoding("UTF-8");
            PrintWriter out = response.getWriter();
            request.setCharacterEncoding("UTF-8");
            String username = request.getParameter("username");
            String psw = request.getParameter("password");
    
            if (username.equals("何海涛") && psw.equals("123")) {
                out.println("欢迎" + username + "登陆");
    
            } else {
                out.println("登陆失败,请检查用户名或者密码是否输入正确....");
    
            }
        }
    
    }
    
    
    下载网络资源的写法
    package com.hht.apache;
    
    import java.io.BufferedReader;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.io.OutputStream;
    
    import org.apache.catalina.util.URLEncoder;
    import org.apache.http.HttpEntity;
    import org.apache.http.HttpResponse;
    import org.apache.http.client.ClientProtocolException;
    import org.apache.http.client.HttpClient;
    import org.apache.http.client.methods.HttpGet;
    import org.apache.http.impl.client.DefaultHttpClient;
    import org.apache.http.util.EntityUtils;
    
    public class HttpClient01 {
    
        public static void main(String[] args) {
            // TODO Auto-generated method stub
            //HttpGet下载百度logo的实现
            String path = "http://www.baidu.com/img/bdlogo.gif";
            //获得HttpClient
            HttpClient client = new DefaultHttpClient();
            //获得HttpGet
            HttpGet httpGet = new HttpGet(path);
    
            try {
                //获得HttpResponse响应
                HttpResponse httpResponse = client.execute(httpGet);
                //获得响应码
                int code = httpResponse.getStatusLine().getStatusCode();
    
                if(code==200){
                    //获得响应实体
                    HttpEntity entity = httpResponse.getEntity();
    //                //获得响应内容
    //                InputStream inputStream = entity.getContent();
    //                //利用流进行输出
    //                BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
    //                System.out.println(br.readLine());
                    //System.out.println(EntityUtils.toString(entity,"utf-8"));
                    //下载网络图片,很简单吧.....
                    FileOutputStream outputStream = new FileOutputStream("c:/baidu.gif");
                    outputStream.write(EntityUtils.toByteArray(entity));
                    outputStream.flush();
                    outputStream.close();
                }
            } catch (ClientProtocolException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
    
        }
    
    }
    ```

    此例接口回调的实现
    工具类:

        package com.hht.apachetils;
    
        import java.io.FileOutputStream;
        import java.io.IOException;
    
        import org.apache.http.HttpEntity;
        import org.apache.http.HttpResponse;
        import org.apache.http.client.ClientProtocolException;
        import org.apache.http.client.HttpClient;
        import org.apache.http.client.methods.HttpGet;
        import org.apache.http.impl.client.DefaultHttpClient;
        import org.apache.http.util.EntityUtils;
    
        public class HttPUtils {
            public static void saveImage(String path,SaveImage image){
                //获得HttpClient
                        HttpClient client = new DefaultHttpClient();
                        //获得HttpGet
                        HttpGet httpGet = new HttpGet(path);
    
                        try {
                            //获得HttpResponse响应
                            HttpResponse httpResponse = client.execute(httpGet);
                            //获得响应码
                            int code = httpResponse.getStatusLine().getStatusCode();
    
                            if(code==200){
                                //获得响应实体
                                 HttpEntity entity = httpResponse.getEntity();
                                 image.downLoad(entity);
                            }
                        } catch (ClientProtocolException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
            }
    
        }
        ```
    
    接口
    package com.hht.apachetils;
    
    import org.apache.http.HttpEntity;
    
    public interface SaveImage {
        public void downLoad(HttpEntity entity);
    
    }
    
    主线程类的具体实现
    package com.hht.apache;
    
    import java.io.FileNotFoundException;
    import java.io.FileOutputStream;
    import java.io.IOException;
    
    import org.apache.http.HttpEntity;
    import org.apache.http.util.EntityUtils;
    import java.io.File;
    
    import com.qianfeng.apachetils.HttPUtils;
    import com.qianfeng.apachetils.SaveImage;
    
    public class HttpClient01 {
    
        public static void main(String[] args) {
            // TODO Auto-generated method stub
            //HttpGet下载百度logo的实现
            String path = "http://www.baidu.com/img/bdlogo.gif";
            HttPUtils.saveImage(path,new SaveImage() {
    
                @Override
                public void downLoad(HttpEntity entity) {
                    // TODO Auto-generated method stub
                    FileOutputStream outputStream = null;
                    File file  = new java.io.File("c:/baidu.gif");
                    int  i = 1;
                    while(file.exists()){
                        file = new File("c:/baidu("+i+").gif");
                        i++;
                    }
                    try {
                        outputStream = new FileOutputStream(file);
                        outputStream.write(EntityUtils.toByteArray(entity));
                        outputStream.flush();
                        outputStream.close();
                    } catch (FileNotFoundException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
    
                }
            });
    
        }
    
    }
    ```

    Apache使用POST方式访问HTTP
    得到访问地址 HttpPost
    使用HttpPost写入参数
    得到网络访问对象HttpClient,进行连接
    得到返回值
    如果返回值正常,返回得到的数据对象HttpEntity,得到数据流

    代码示例:

        package com.hht.apache;
    
        import java.io.IOException;
        import java.io.UnsupportedEncodingException;
        import java.util.ArrayList;
        import java.util.List;
    
        import org.apache.http.HttpEntity;
        import org.apache.http.HttpResponse;
        import org.apache.http.NameValuePair;
        import org.apache.http.client.ClientProtocolException;
        import org.apache.http.client.HttpClient;
        import org.apache.http.client.entity.UrlEncodedFormEntity;
        import org.apache.http.client.methods.HttpPost;
        import org.apache.http.impl.client.DefaultHttpClient;
        import org.apache.http.message.BasicNameValuePair;
        import org.apache.http.util.EntityUtils;
    
        public class HttpClient02 {
            public static void main(String[] args) throws UnsupportedEncodingException {
                // TODO Auto-generated method stub
                // HttpPost登录验证的实现
                String path = "http://192.168.125.102:8080/ApacheTest/LoginServlet";
                // 获得HttpClient
                HttpClient client = new DefaultHttpClient();
                // 获得HttpPost
                HttpPost httpPost = new HttpPost(path);
    
                // 产生参数对
    
                NameValuePair pair = new BasicNameValuePair("username", "hht");
    
                NameValuePair pair2 = new BasicNameValuePair("password", "123");
    
                List nameValuePairs = new ArrayList();
                nameValuePairs.add(pair2);
                nameValuePairs.add(pair);
    
                try {
                    HttpEntity httpEntity = new UrlEncodedFormEntity(nameValuePairs);
                    httpPost.setEntity(httpEntity);
                } catch (UnsupportedEncodingException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }
    
                try {
                    // 获得HttpResponse响应
                    HttpResponse httpResponse = client.execute(httpPost);
                    // 获得响应码
                    int code = httpResponse.getStatusLine().getStatusCode();
    
                    if (code == 200) {
                        // 获得响应实体
                        HttpEntity entity = httpResponse.getEntity();
                        // //获得响应内容
                        // InputStream inputStream = entity.getContent();
                        // //利用流进行输出
                        // BufferedReader br = new BufferedReader(new
                        // InputStreamReader(inputStream));
                        // System.out.println(br.readLine());
                        // 第二种输出方式
                        System.out.println(EntityUtils.toString(entity, "utf-8"));
    
                    }
                } catch (ClientProtocolException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
    
        }

    Servlet类:
    ```
    package com.hht.servlet;

    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /**
     * Servlet implementation class LoginServlet
     */
    public class LoginServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;
    
        /**
         * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
         */
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // TODO Auto-generated method stub
    
            response.setCharacterEncoding("UTF-8");
            PrintWriter out = response.getWriter();
            request.setCharacterEncoding("UTF-8");
            //在这个地方进行两次转码来避免中文在get方式中的乱码
            String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");
            String psw = request.getParameter("password");
    
            if (username.equals("hht") && psw.equals("123")) {
                out.println("欢迎" + username + "登陆");
    
            } else {
                out.println("登陆失败,请检查用户名或者密码是否输入正确....");
    
            }
        }
    
        /**
         * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
         */
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // TODO Auto-generated method stub
    
            response.setCharacterEncoding("UTF-8");
            PrintWriter out = response.getWriter();
            request.setCharacterEncoding("UTF-8");
            String username = request.getParameter("username");
            String psw = request.getParameter("password");
             System.out.println(username+" "+psw);
            if (username.equals("hht") && psw.equals("123")) {
                out.println("欢迎" + username + "登陆");
    
            } else {
                out.println("登陆失败,请检查用户名或者密码是否输入正确....");
    
            }
        }
    
    }
    ```
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