android通过HttpClient与服务器JSON交互

package com.tp.soft.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
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.protocol.HTTP;

public class HttpUtil {
public static String postRequest(String serverPath, Map<String, String> params, String encoding){
List<NameValuePair> paramPair = new ArrayList<NameValuePair>();
if(params != null && !params.isEmpty()){
for(Map.Entry<String, String> entry : params.entrySet()){
paramPair.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));
}
}
try {
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(serverPath);
post.setEntity(new UrlEncodedFormEntity(paramPair, HTTP.UTF_8));
HttpResponse response = client.execute(post);
if(response.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
BufferedReader br = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
//数据
String reqData = null;
String responseData = "";
while((reqData = br.readLine()) != null){
responseData += reqData;
}
br.close();
return responseData;
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return "postRequest error";
}
}

package com.tp.soft.app;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.app.Activity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import com.tp.soft.entity.User;
import com.tp.soft.util.HttpUtil;

public class MainActivity extends Activity {

private ListView mListView;
private TextView mContentTxt;
private TextView mTimeTxt;

private String serverPath = "http://122.226.178.54:8080/uploadApp/LoginServlet";
private static final String ENCODING = "utf-8";
private List<User> userList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
loadList();
mListView = (ListView) findViewById(R.id.list_id);
mListView.setAdapter(new BaseAdapter() {

@Override
public View getView(int position, View convertView, ViewGroup parent) {
if(null == convertView){
convertView = LayoutInflater.from(getApplicationContext()).inflate(R.layout.item, null);
}

TextView textView = (TextView) convertView.findViewById(R.id.contentTxt);
textView.setText(userList.get(position).getUsername());
return convertView;
}

@Override
public long getItemId(int position) {
return position;
}

@Override
public Object getItem(int position) {
return position;
}

@Override
public int getCount() {
return userList.size();
}
});
}

private List<User> loadList() {
Map<String, String> params = new HashMap<String, String>();
String data = HttpUtil.postRequest(serverPath, params, ENCODING);
userList = new Gson().fromJson(data, new TypeToken<List<User>>() {}.getType());
return userList;
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setCharacterEncoding("utf-8");
String uname = request.getParameter("uname");
String pwd = request.getParameter("pwd");

PrintWriter pw = response.getWriter();
Gson gson = new GsonBuilder().create();
List<User> userList = new ArrayList<User>();
User user = new User();
user.setUsername("zs");
user.setPassword("1");
userList.add(user);

User user1 = new User();
user1.setUsername("lisi");
user1.setPassword("2");
userList.add(user1);
String json = gson.toJson(userList);
pw.print(json);
}