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从Android调用Java servlet

httpclient servlets android java
  •  5
  • Berty  · 技术社区  · 14 年前

    我正在尝试从Android手机上的servlet获取输出。

    这是我的servlet: 

    。/*
*要更改此模板,请选择“工具”“模板”
*并在编辑器中打开模板。
*/
包装主体;

导入java.io.ioexception;
导入java.io.printwriter;
导入javax.servlet.servletexception;
导入javax.servlet.http.http servlet;
导入javax.servlet.http.httpservletrequest;
导入javax.servlet.http.httpservletresponse;

/**
*
*@作者bert verhelst<verhelst_bert@hotmail.com>
*/
公共类servlet1扩展了httpservlet{

/**
*处理对http<code>get</code>和<code>post</code>方法的请求。
*@参数请求servlet请求
*@参数响应servlet响应
*@如果发生servlet特定的错误,则引发servletexception
*@如果发生I/O错误,则引发IOException
*/
受保护的void processrequest(httpservletrequest请求,httpservletresponse响应)
引发ServletException,IOException{
response.setContentType(“文本/html;charset=utf-8”);
printWriter out=response.getWriter();
out.println(“<html>”);
out.println(“<head>“);
out.println(“<title>servlet servlet1</title>“);
out.println(“</head>”);
out.println(“<body>”);
out.println(“<h1>正在处理…</h1>”);
out.println(“</body>”);
out.println(“</html>”);
}

//<editor fold defaultstate=“colled”desc=“httpservlet方法。单击左侧的+符号编辑代码。“>
/**
*处理http<code>get</code>方法。
*@参数请求servlet请求
*@参数响应servlet响应
*@如果发生servlet特定的错误,则引发servletexception
*@如果发生I/O错误,则引发IOException
*/
@重写
受保护的void doget(httpservletrequest请求,httpservletresponse响应)
引发ServletException,IOException{
处理请求(请求、响应);
printWriter out=response.getWriter();
out.println(“<!doctype html public\“-//w3c//dtd html 4.0”
+“过渡//en\”>“\n”
+“<html>\n”
+“<head><title>您好,www</title></head>\n”
+“正文\n”
+“<h1>狗…</h1>\n”
+“</body></html>”);
}

/**
*处理http<code>post</code>方法。
*@参数请求servlet请求
*@参数响应servlet响应
*@如果发生servlet特定的错误,则引发servletexception
*@如果发生I/O错误,则引发IOException
*/
@重写
受保护的void dopost(httpservletrequest请求,httpservletresponse响应)
引发ServletException,IOException{
处理请求(请求、响应);
printWriter out=response.getWriter();
out.println(“<!doctype html public\“-//w3c//dtd html 4.0”
+“过渡//en\”>“\n”
+“<html>\n”
+“<head><title>您好,www</title></head>\n”
+“正文\n”
+“<h1>doPost…</h1>\n”
+“</body></html>”);
}

/**
*返回servlet的简短描述。
*@返回包含servlet描述的字符串
*/
@重写
公共字符串getServletInfo()。{
返回“简短描述”;
}//</editor折叠>
}
< /代码> 


    这是我的Android主页:
    


    package be.smarttelecom.mytest;

导入android.app.activity;
导入android.os.bundle;
导入android.widget.textview;

公共类主扩展活动{
/**在首次创建活动时调用。*/
@重写
public void oncreate(bundle savedinstanceState){
super.oncreate(保存的状态);
setContentView(r.layout.main);
textView输出=(textView)findView byid(r.id.output);
尝试{
output.append(“开始\n”);
restclient client=new restclient(“http://10.0.0.188:8084/servlet_1/servlet1”);

尝试{
client.execute(requestmethod.get);
}catch(例外e){
e.printstacktrace();
}

output.append(“在执行之后\n”);

字符串响应=client.getResponse();
output.append(“class-”+response+“\n”);
output.append(响应);
output.append(“完成\n”);
}
catch(异常ex){
output.append(“错误:”+ex.getmessage()+“”\n“+ex.toString()+”\n“;”
}
}
}
< /代码> 


    最后我们有了restclient:
    


    package be.smarttelecom.mytest;

导入java.io.bufferedreader;
导入java.io.ioexception;
导入java.io.inputstream;
导入java.io.inputstreamreader;
导入java.util.arraylist;

导入org.apache.http.httpentity;
导入org.apache.http.httpresponse;
导入org.apache.http.namevaluepair;
导入org.apache.http.client.clientProtocolException;
导入org.apache.http.client.http client;
导入org.apache.http.client.entity.urlencodedformentity;
导入org.apache.http.client.methods.httpget;
导入org.apache.http.client.methods.httppost;
导入org.apache.http.client.methods.httpurirequest;
导入org.apache.http.impl.client.defaulthttpclient;
导入org.apache.http.message.basicNameValuePair;
导入org.apache.http.protocol.http;

公共类RestClient{
private arraylist<名称值对>参数;
private arraylist<nameValuePair>标题;

私有字符串URL;

私人内部响应代码;
私有字符串消息;

私有字符串响应;

公共字符串getResponse()。{
回复;
}

公共字符串getErrorMessage()。{
返回消息;
}

public int getResponseCode()。{
返回响应代码;
}

public restclient(字符串URL)
{
URL=URL;
params=new arraylist<名称值对>();
headers=new arraylist<nameValuePair>();
}

public void addparam(字符串名称、字符串值)
{
params.add(new basicNameValuePair(name,value));
}

public void addheader(字符串名称、字符串值)
{
headers.add(new basicNameValuePair(name,value));
}

public void execute(requestMethod方法)引发异常
{
开关(方法){
案例获取:
{
//添加参数
字符串CombinedParams=“”;
如果(!)参数.isEmpty()){
CombinedParams+=“?”;
for(名称值对p:params)
{
字符串参数string=p.getname()+“=”+p.getvalue();
if(combinedParams.length()>1)
{
CombinedParams+=“&”+ParamString;
}
其他的
{
CombinedParams+=参数字符串;
}
}
}

httpget请求=new httpget(url+combinedparams);

//添加标题
for(名称值对h:标题)
{
request.addheader(h.getname(),h.getvalue());
}
ExecuteRequest(请求,URL);
断裂;
}

案例:
{
httppost请求=新httppost(url);

//添加标题
for(名称值对h:标题)
{
request.addheader(h.getname(),h.getvalue());
}

如果(!)参数.isEmpty()){
request.setentity(新的urlencodedformentity(params,http.utf_8));
}

ExecuteRequest(请求,URL);
断裂;
}
}
}

private void executerequest(httpurirequest请求,字符串url)
{
httpclient client=new defaulthttpclient();

HTT响应HTT响应;

尝试{
httpResponse=client.execute(请求);
responseCode=httpResponse.getStatusLine().getStatusCode();
message=httpResponse.getStatusLine().getReasonPhrase();

httpEntity实体=httpResponse.getEntity();

如果(实体)!{NULL){
inputstream instream=entity.getContent();
响应=ConvertStreamToString(流内);

//关闭输入流将触发连接释放
instream.close();
}
}
catch(客户端协议例外){
client.getConnectionManager().shutdown();
e.printstacktrace();
}捕获(IOException E){
client.getConnectionManager().shutdown();
e.printstacktrace();
}
}

私有静态字符串convertstreamToString(inputstream is){
bufferedreader reader=新bufferedreader(新inputstreamreader(is));
StringBuilder sb=new StringBuilder();

字符串行=空;
尝试{
同时((line=reader.readline())!{NULL){
附加(行+“\n”);
}
}
捕获(IOException E){
e.printstacktrace();
}
最后{
尝试{
是。
}捕获(IOException E){
e.printstacktrace();
}
}
返回sb.toString();
}
}
< /代码> 


    不幸的是,这行不通。这是我为输出(空)所得到的,
    


    


    我做错什么了?
    


    我请求我的servlet的doget方法并将输出转换为字符串,但它似乎是空的。
    


    我允许在应用程序右括号后的清单文件中进行Internet连接,
    

使用权限android:name=“android.permission.internet”/>
< /代码> <
    


    这是我的servlet:
    


        /*
     * To change this template, choose Tools | Templates
     * and open the template in the editor.
     */
    package main;

    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;

    /**
     *
     * @author Bert Verhelst <verhelst_bert@hotmail.com>
     */
    public class servlet1 extends HttpServlet {

        /**
         * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
         * @param request servlet request
         * @param response servlet response
         * @throws ServletException if a servlet-specific error occurs
         * @throws IOException if an I/O error occurs
         */
        protected void processRequest(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            response.setContentType("text/html;charset=UTF-8");
            PrintWriter out = response.getWriter();
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet servlet1</title>");
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>processing...</h1>");
            out.println("</body>");
            out.println("</html>");
        }

        // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
        /**
         * Handles the HTTP <code>GET</code> method.
         * @param request servlet request
         * @param response servlet response
         * @throws ServletException if a servlet-specific error occurs
         * @throws IOException if an I/O error occurs
         */
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            processRequest(request, response);
            PrintWriter out = response.getWriter();
            out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 "
                    + "Transitional//EN\">\n"
                    + "<html>\n"
                    + "<head><title>Hello WWW</title></head>\n"
                    + "<body>\n"
                    + "<h1>doget...</h1>\n"
                    + "</body></html>");
        }

        /**
         * Handles the HTTP <code>POST</code> method.
         * @param request servlet request
         * @param response servlet response
         * @throws ServletException if a servlet-specific error occurs
         * @throws IOException if an I/O error occurs
         */
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            processRequest(request, response);
            PrintWriter out = response.getWriter();
            out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 "
                    + "Transitional//EN\">\n"
                    + "<html>\n"
                    + "<head><title>Hello WWW</title></head>\n"
                    + "<body>\n"
                    + "<h1>dopost...</h1>\n"
                    + "</body></html>");
        }

        /**
         * Returns a short description of the servlet.
         * @return a String containing servlet description
         */
        @Override
        public String getServletInfo() {
            return "Short description";
        }// </editor-fold>
    }

    


    这是我的Android主页:
    


         package be.smarttelecom.MyTest;

     import android.app.Activity;
     import android.os.Bundle;
     import android.widget.TextView;

     public class Main extends Activity {
         /** Called when the activity is first created. */
         @Override
         public void onCreate(Bundle savedInstanceState) {
             super.onCreate(savedInstanceState);
             setContentView(R.layout.main);
             TextView output = (TextView) findViewById(R.id.output);
             try {
                 output.append("starting\n");
                 RestClient client = new  RestClient("http://10.0.0.188:8084/Servlet_1/servlet1");

                 try {
                     client.Execute(RequestMethod.GET);
                 } catch (Exception e) {
                     e.printStackTrace();
                 }

                 output.append("after execute\n");

                 String response = client.getResponse();
                 output.append("class - " + response  +  "\n" );
                 output.append(response);
                 output.append("done\n");
             }
             catch (Exception ex) {
                 output.append("error: " + ex.getMessage() + "\n" + ex.toString() +  "\n");
             }
         }
     }

    


    最后我们有了restclient:
    


         package be.smarttelecom.MyTest;

     import java.io.BufferedReader;
     import java.io.IOException;
     import java.io.InputStream;
     import java.io.InputStreamReader;
     import java.util.ArrayList;

     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.HttpGet;
     import org.apache.http.client.methods.HttpPost;
     import org.apache.http.client.methods.HttpUriRequest;
     import org.apache.http.impl.client.DefaultHttpClient;
     import org.apache.http.message.BasicNameValuePair;
     import org.apache.http.protocol.HTTP;

     public class RestClient {
         private ArrayList <NameValuePair> params;
         private ArrayList <NameValuePair> headers;

         private String url;

         private int responseCode;
         private String message;

         private String response;

         public String getResponse() {
             return response;
         }

         public String getErrorMessage() {
             return message;
         }

         public int getResponseCode() {
             return responseCode;
         }

         public RestClient(String url)
         {
             this.url = url;
             params = new ArrayList<NameValuePair>();
             headers = new ArrayList<NameValuePair>();
         }

         public void AddParam(String name, String value)
         {
             params.add(new BasicNameValuePair(name, value));
         }

         public void AddHeader(String name, String value)
         {
             headers.add(new BasicNameValuePair(name, value));
         }

         public void Execute(RequestMethod method) throws Exception
         {
             switch(method) {
                 case GET:
                 {
                     //add parameters
                     String combinedParams = "";
                     if(!params.isEmpty()){
                         combinedParams += "?";
                         for(NameValuePair p : params)
                         {
                             String paramString = p.getName() + "=" + p.getValue();
                             if(combinedParams.length() > 1)
                             {
                                 combinedParams  +=  "&" + paramString;
                             }
                             else
                             {
                                 combinedParams += paramString;
                             }
                         }
                     }

                     HttpGet request = new HttpGet(url + combinedParams);

                     //add headers
                     for(NameValuePair h : headers)
                     {
                         request.addHeader(h.getName(), h.getValue());
                     }
                     executeRequest(request, url);
                     break;
                 }

                 case POST:
                 {
                     HttpPost request = new HttpPost(url);

                     //add headers
                     for(NameValuePair h : headers)
                     {
                         request.addHeader(h.getName(), h.getValue());
                     }

                     if(!params.isEmpty()){
                         request.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
                     }

                     executeRequest(request, url);
                     break;
                 }
             }
         }

         private void executeRequest(HttpUriRequest request, String url)
         {
             HttpClient client = new DefaultHttpClient();

             HttpResponse httpResponse;

             try {
                 httpResponse = client.execute(request);
                 responseCode = httpResponse.getStatusLine().getStatusCode();
                 message = httpResponse.getStatusLine().getReasonPhrase();

                 HttpEntity entity = httpResponse.getEntity();

                 if (entity != null) {
                     InputStream instream = entity.getContent();
                     response = convertStreamToString(instream);

                     // Closing the input stream will trigger connection release
                     instream.close();
                 }
             }
             catch (ClientProtocolException e)  {
                 client.getConnectionManager().shutdown();
                 e.printStackTrace();
             } catch (IOException e) {
                 client.getConnectionManager().shutdown();
                 e.printStackTrace();
             }
         }

         private static String convertStreamToString(InputStream is) {
             BufferedReader reader = new BufferedReader(new InputStreamReader(is));
             StringBuilder sb = new StringBuilder();

             String line = null;
             try {
                 while ((line = reader.readLine()) != null) {
                     sb.append(line + "\n");
                 }
             }
             catch (IOException e) {
                 e.printStackTrace();
             }
             finally {
                 try {
                     is.close();
                 } catch (IOException e) {
                     e.printStackTrace();
                 }
             }
             return sb.toString();
         }
     }

    


    不幸的是,这行不通。这是我得到的输出值(空),
    


    Screenshot of 
    


    我做错什么了?
    


    我请求servlet的doget方法并将输出转换为字符串,但它似乎是空的。
    


    我允许清单文件中的互联网连接在应用程序的右括号之后,
    


    <uses-permission android:name="android.permission.INTERNET" />
    1 回复  |  直到 6 年前
        1
  •  3
  •   Community Lee Campbell    7 年前

    Romain Hippeau 在评论中写道:

    呼叫是否到达servlet?服务器看到什么正在发送?服务器正在发送什么?

    这就是问题所在!我禁用了防火墙,现在它工作了:)

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