Android连接Tomcat服务器
在保证服务器是正常状态时,将从Android模拟器上发送请求给服务端并接收服务端返回来的响应。
保证HttpServlet配置正常。可以通过在浏览器输入配置的地址,若能正常响应,那么在Android中去请求的话也是能正常响应的。
这里列举的Demo是在activity中有两个按钮,分别执行get请求和post请求的同时传递参数到服务端,并将服务端返回的信息显示到textview上。
客户端
一、get请求:
第一步:建立请求,连接服务器。
String name = URLEncoder.encode("小红", "utf-8"); //中文输入先指定编码,不然会出现乱码//get请求带参数的URL地址 http://192.168.1.112:8080/app/myweb?username=小红&password=abcd URL url = new URL(httpUrl+"?username="+name+"&password=abcd"); HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("GET");//请求方式conn.setConnectTimeout(15000); //设置连接超时conn.setReadTimeout(10000); //设置读取超时conn.connect(); //建立连接
这里已经将参数加进去了。由于get请求的参数是直接加在URL地址之后,形式如同 http://192.168.1.112:8080/app/myweb?username=小红&password=abcd 问号后面就是携带的参数,中文参数需要先指定编码集,防止乱码。若没有参数则构造URL时就只需要协议地址。 第二步:服务器请求连接成功后,服务器接到参数,并作出响应,客户端只需从连接中的流中读出响应即可。
InputStream in = conn.getInputStream();BufferedReader br = new BufferedReader(new InputStreamReader(in, "utf-8")); //得到连接服务器的缓冲流String line;StringBuilder sb = new StringBuilder();while((line=br.readLine()) != null){ //从服务中读取请求返回的数据sb.append(line);}
最后看看get请求的完整Demo:
/*get请求方式连接服务器 get请求传递参数在url后面加参数*/public String getHttpDoget(String httpUrl){try {String name = URLEncoder.encode("小红", "utf-8"); //中文输入先指定编码,不然会出现乱码//get请求带参数的URL地址 http://192.168.1.112:8080/app/myweb?username=小红&password=abcd URL url = new URL(httpUrl+"?username="+name+"&password=abcd"); HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("GET");//请求方式conn.setConnectTimeout(15000); //设置连接超时conn.setReadTimeout(10000); //设置读取超时conn.connect(); //建立连接InputStream in = conn.getInputStream();BufferedReader br = new BufferedReader(new InputStreamReader(in, "utf-8")); //得到连接服务器的缓冲流String line;StringBuilder sb = new StringBuilder();while((line=br.readLine()) != null){ //从服务中读取请求返回的数据sb.append(line);}return sb.toString();} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}return null;}
按钮监听中,由于请求服务器连接是耗时操作,需要放到子线程中,这里采用的是AsyncTask异步操作实现,若需要学习AsyncTask异步操作请参见:http://blog.csdn.net/tom_xiaoxie/article/details/49803413
mConnecyBtn = (Button) findViewById(R.id.http_doget_btn);mConnecyBtn.setOnClickListener(new OnClickListener() {String httpUrl = "http://192.168.1.112:8080/app/myweb";@Overridepublic void onClick(View v) {new AsyncTask(){@Overrideprotected String doInBackground(String... params) {return getHttpDoget(params[0]); //调用请求响应方法}protected void onPostExecute(String result) {mShowMsgTxt.setText(result);};}.execute(httpUrl);}});
URL url = new URL(httpUrl);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("POST"); //请求方法conn.setConnectTimeout(15000); //设置连接超时conn.setReadTimeout(10000); //设置读取超时conn.connect(); //建立连接/*得到流向服务器传数据*/OutputStream out = conn.getOutputStream();PrintWriter pr = new PrintWriter(out);pr.print("username=小明&password=1234");pr.flush();
获取服务器响应的数据跟gen请求一样。直接获取输入流来读取数据即可。
/*读取服务端数据*/InputStream in = conn.getInputStream();BufferedReader br = new BufferedReader(new InputStreamReader(in, "utf-8")); //得到连接服务器的缓冲流String line;StringBuilder sb = new StringBuilder();while((line=br.readLine()) != null){ //从服务中读取请求返回的数据sb.append(line);}
还是贴上整个方法的Demo和按钮事件Demo:
post方式请求:
/*post请求方式连接服务器,给服务器传递参数用流写入的方式*/public String getHttpDopost(String httpUrl){try {URL url = new URL(httpUrl);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("POST"); //请求方法conn.setConnectTimeout(15000); //设置连接超时conn.setReadTimeout(10000); //设置读取超时conn.connect(); //建立连接/*得到流向服务器传数据*/OutputStream out = conn.getOutputStream();PrintWriter pr = new PrintWriter(out);pr.print("username=小明&password=1234");pr.flush();/*读取服务端数据*/InputStream in = conn.getInputStream();BufferedReader br = new BufferedReader(new InputStreamReader(in, "utf-8")); //得到连接服务器的缓冲流String line;StringBuilder sb = new StringBuilder();while((line=br.readLine()) != null){ //从服务中读取请求返回的数据sb.append(line);}return sb.toString();} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}return null;}
按钮监听:
mDopostBtn = (Button) findViewById(R.id.http_dopost_btn);mDopostBtn.setOnClickListener(new OnClickListener() {String http = "http://192.168.1.112:8080/app/myweb";@Overridepublic void onClick(View v) {new AsyncTask(){@Overrideprotected String doInBackground(String... params) {return getHttpDopost(params[0]);}protected void onPostExecute(String result) {mShowMsgTxt.setText(result);};}.execute(http);}});
服务端:
最后看看服务端做了什么?服务端就是将客服端传来的参数获取到并且返回给客服端。
package CatServelet;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 WebTestServelet extends HttpServlet {protected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {resp.setContentType("text/html;charset=utf-8"); //防止中文乱码String name = req.getParameter("username");//name = new String(name.getBytes("ISO-8859-1"),"UTF-8"); //解决乱码问题方式一System.out.println(name);String password = req.getParameter("password");resp.getWriter().print("password:" + password +"\n" +"username:"+name);}protected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {req.setCharacterEncoding("UTF-8");//设定请求编码resp.setContentType("text/html;charset=utf-8"); //设定响应编码 防止中文乱码String name = req.getParameter("username");String password = req.getParameter("password");System.out.println(name);resp.getWriter().print("password:" + password +"\n" +"username:"+name);}}
乱码问题:首先肯定是统一所有编译器的编码集如UTF-8.
解决doGet请求乱码问题,这里设置了两处的编码集,一是在客户端请求服务端是传入的参数先指定编码集UTF-8。
String name = URLEncoder.encode("小红", "utf-8"); //中文输入先指定编码,不然会出现乱码
二是服务端响应时设置响应编码集。
resp.setContentType("text/html;charset=utf-8"); //设置响应编码集 防止中文乱码
至于doPost请求的乱码,只需要在服务端设定请求编码和响应编码就行了。
req.setCharacterEncoding("UTF-8");//设定请求编码resp.setContentType("text/html;charset=utf-8"); //设定响应编码 防止中文乱码
延生:
get请求和post请求的区别与比较:
Get请求只有一个流,参数附加在url后面,地址行显示要传送的信息,大小个数有严格的限制且只能是字符串。
Post请求的参数通过另外的流传递,不通过URL,所以可以很大,也可以传递二进制数据如文件。
就是参数传递方式,参数大小,参数类型有区别。
1、安全性:get请求参数显示在url地址后面,可能存在安全性。如密码,post请求可以解决这个问题。
2、服务器接收方式 服务器随机接收get请求的数据,一旦断电等意外原因,服务器不会知道信息是否传送完毕。而post请求是服务器先接收数据信息长度,在接受数据。
3、form运行方式。当form框里面的method为get时,执行doGet()方法。为post时,执行doPost()方法。
4、信息容量限制 get请求的参数信息有限制,post请求没有限制。
get请求乱码:
设定接受参数(客服端发送来的参数)编码集有两种方式,一是更改服务器配置文件,打开Tomcat--->conf目录下的server.xml文件
找到
另一种方式是得到参数后转码
String name = req.getParameter("username");name = new String(name.getBytes("ISO-8859-1"),"UTF-8"); //解决乱码问题方式一
而响应请求(发送给客户端的参数)参数则用resp.setContentType("text/html;charset=utf-8"); //防止中文乱码
post请求乱码:
设定接受参数(客服端发送来的参数)编码集 req.setCharacterEncoding("UTF-8");//设定请求编码
响应请求(发送给客户端的参数)参数 resp.setContentType("text/html;charset=utf-8"); //设定响应编码 防止中文乱码
特别注意在doget()中req.setCharacterEncoding("UTF-8")来设置接收参数编码是没有作用的。还是需要name = new String(name.getBytes("ISO-8859-1"),"UTF-8"); 这种方式来转码。req.setCharacterEncoding("UTF-8")只在post()中有作用。
最后上图并贴上完整代码:
activity代码:主布局就只有两个按钮加一个textview控件。
package webview;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStream;import java.io.OutputStreamWriter;import java.io.PrintWriter;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;import java.net.URLEncoder;import java.sql.Connection;import android.app.Activity;import android.os.AsyncTask;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.TextView;import com.example.call.R;public class HttpServeletActivity extends Activity {private TextView mShowMsgTxt;private Button mConnecyBtn,mDopostBtn;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.httpservelet_main_layout);mShowMsgTxt = (TextView) findViewById(R.id.http_text);mConnecyBtn = (Button) findViewById(R.id.http_doget_btn);mConnecyBtn.setOnClickListener(new OnClickListener() {String httpUrl = "http://192.168.1.112:8080/app/myweb";@Overridepublic void onClick(View v) {new AsyncTask(){@Overrideprotected String doInBackground(String... params) {return getHttpDoget(params[0]);}protected void onPostExecute(String result) {mShowMsgTxt.setText(result);};}.execute(httpUrl);}});mDopostBtn = (Button) findViewById(R.id.http_dopost_btn);mDopostBtn.setOnClickListener(new OnClickListener() {String http = "http://192.168.1.112:8080/app/myweb";@Overridepublic void onClick(View v) {new AsyncTask(){@Overrideprotected String doInBackground(String... params) {return getHttpDopost(params[0]);}protected void onPostExecute(String result) {mShowMsgTxt.setText(result);};}.execute(http);}});}/*post请求方式连接服务器,给服务器传递参数用流写入的方式*/public String getHttpDopost(String httpUrl){try {URL url = new URL(httpUrl);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("POST"); //请求方法conn.setConnectTimeout(15000); //设置连接超时conn.setReadTimeout(10000); //设置读取超时conn.connect(); //建立连接/*得到流向服务器传数据*/OutputStream out = conn.getOutputStream();PrintWriter pr = new PrintWriter(out);pr.print("username=小明&password=1234");pr.flush();/*读取服务端数据*/InputStream in = conn.getInputStream();BufferedReader br = new BufferedReader(new InputStreamReader(in, "utf-8")); //得到连接服务器的缓冲流String line;StringBuilder sb = new StringBuilder();while((line=br.readLine()) != null){ //从服务中读取请求返回的数据sb.append(line);}return sb.toString();} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}return null;}/*get请求方式连接服务器 get请求传递参数在url后面加参数*/public String getHttpDoget(String httpUrl){try {String name = URLEncoder.encode("小红", "utf-8"); //中文输入先指定编码,不然会出现乱码//get请求带参数的URL地址 http://192.168.1.112:8080/app/myweb?username=小红&password=abcd URL url = new URL(httpUrl+"?username="+name+"&password=abcd"); HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("GET");//请求方式conn.setConnectTimeout(15000); //设置连接超时conn.setReadTimeout(10000); //设置读取超时conn.connect(); //建立连接InputStream in = conn.getInputStream();BufferedReader br = new BufferedReader(new InputStreamReader(in, "utf-8")); //得到连接服务器的缓冲流String line;StringBuilder sb = new StringBuilder();while((line=br.readLine()) != null){ //从服务中读取请求返回的数据sb.append(line);}return sb.toString();} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}return null;}}
服务端代码:
package CatServelet;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 WebTestServelet extends HttpServlet {protected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {resp.setContentType("text/html;charset=utf-8"); //防止中文乱码String name = req.getParameter("username");//name = new String(name.getBytes("ISO-8859-1"),"UTF-8"); //解决乱码问题方式一System.out.println(name);String password = req.getParameter("password");resp.getWriter().print("password:" + password +"\n" +"username:"+name);}protected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {req.setCharacterEncoding("UTF-8");//设定请求编码resp.setContentType("text/html;charset=utf-8"); //设定响应编码 防止中文乱码String name = req.getParameter("username");String password = req.getParameter("password");System.out.println(name);resp.getWriter().print("password:" + password +"\n" +"username:"+name);}}
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