基本原理是Android客户端通过HttpClient向服务器发出请求，服务器向Android客户端返回JSON字符串，Android客户端解析JSON字符串获得数据。
1. 新建一个Android项目，主要文件如下：
其中MainActivity是UI，CommThread是通信线程，负责和服务器通信，Util是工具类，Var存放变量。
2. Var.java:
package com.hzhi.school.util; import java.util.ArrayList;
import java.util.List; public class Var { // 访问的URL
public static String strHost = new String("http://192.168.1.100:8080/School/");
public static String strAct = new String("aclasquery");
public static String strURL = strHost + strAct; // 列表
public static List lstId = new ArrayList();
public static List lstName = new ArrayList();
public static List lstComm = new ArrayList(); // 屏幕的尺寸
public static int wid_scr;
public static int hei_scr; // 消息类型
public static final int msg_connect = 1;
public static final int msg_error = 2;
public static final int msg_con_start = 3;
public static final int msg_con_stop = 4; }
3. Util.java:
package com.hzhi.school.util; import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader; import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject; import android.util.Log; public class Util { // 构造类
public Util(){ } // 将InputStream格式转化为StringBuilder格式
public static StringBuilder is2sb (InputStream is) { String ln = "";
StringBuilder sb = new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
try{
while ((ln=br.readLine()) != null){
sb.append(ln);
} }catch(Exception e){
e.printStackTrace();
}
return sb; } // JSON转换成List
public static void json2list(String strJson) throws JSONException { JSONObject jsonObject = new JSONObject(strJson);
JSONArray jsonClas = jsonObject.getJSONArray("Classes");
for (int i=0; i<jsonClas.length(); i++){
Var.lstId.add(i, jsonClas.getJSONObject(i).getString("id"));
Var.lstName.add(i, jsonClas.getJSONObject(i).getString("name"));
Var.lstComm.add(i, jsonClas.getJSONObject(i).getString("comment"));
} } }
4. CommThread.java：
package com.hzhi.school.comm; import java.io.InputStream;
import java.util.ArrayList;
import java.util.List; import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient; import android.os.Bundle;
import android.os.Message;
import android.util.Log; import com.hzhi.school.MainActivity;
import com.hzhi.school.util.Util;
import com.hzhi.school.util.Var; public class CommThread extends Thread{ // 消息变量
private Message msg;
private Bundle bdl; // 构造函数
public void run(){ InputStream resIS;
StringBuilder resSB;
String resStr; resIS = getIS(Var.strURL);
if (resIS == null)
{
return;
}
else
{
resSB = Util.is2sb(resIS);
resStr = resSB.toString();
try{
Util.json2list(resStr);
sendMessage(Var.msg_connect,"");
}catch (Exception e){
e.printStackTrace();
sendMessage(Var.msg_error,e.toString());
}
} } // 通过GET方法获取信息
public InputStream getIS (String url){ InputStream is=null; try{
// 取得默认HttpClient实例
HttpClient hc = new DefaultHttpClient();
// 连接到服务器
HttpResponse hr = hc.execute(new HttpGet(url));
// 获取数据内容
is = hr.getEntity().getContent();
}catch (Exception e){
e.printStackTrace();
sendMessage(Var.msg_error,e.toString());
} return is; } // 发送消息(用于更新UI)
public void sendMessage(int x, String s){ msg = new Message();
bdl = new Bundle();
bdl.putString("1",s);
msg.what = x;
msg.setData(bdl);
MainActivity.mainHandler.sendMessage(msg); } }
使用HttpClient向服务器发出请求，服务器返回的是一个InputStream，调用Util里面的函数将InputStream转换成StringBuilder，获得JSON字符串，再解析JSON字符串，获得数据。
5. MainActivity.java:
package com.hzhi.school; import java.util.ArrayList;
import java.util.List; import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Context;
import android.graphics.Typeface;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast; import com.hzhi.school.comm.CommThread;
import com.hzhi.school.util.Var; public class MainActivity extends ListActivity{ static list_clas_adaptor myAdaptor;
static Context mCtx;
static ProgressDialog progressDialog;
static Toast toast;
CommThread myThread;
static int numGet = 0;
ListView lv;
int id;
item_clas it; @Override
protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_clas);
mCtx = getApplicationContext();
getScreen();
myAdaptor = new list_clas_adaptor(this);
progressDialog = ProgressDialog.show(MainActivity.this,
"连接", "正在连接服务器:" + Var.strURL, true, false);
setListAdapter(myAdaptor); myThread = new CommThread();
myThread.start();
} protected void onListItemClick(ListView l, View v, int position, long id) {
id = Integer.parseInt((String) myAdaptor.list_data.get(position).txtNum.getText());
it = (item_clas) myAdaptor.getItem((int)id);
super.onListItemClick(l, v, position, id);
} // 获得课程列表
public static void getData(){
myAdaptor.list_data.clear();
if (Var.lstId.size()>0){
for (int i=0; i<Var.lstId.size(); i++){
myAdaptor.addItem(Var.lstId.get(i).toString(),
Var.lstName.get(i).toString(), Var.lstComm.get(i).toString(), 1); }
}
numGet++;
} // 消息处理Handler
public static Handler mainHandler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what)
{ // 出错
case Var.msg_error:
toast = Toast.makeText(mCtx,
"错误:" + msg.getData().getString("1"), Toast.LENGTH_LONG);
toast.show();
break;
// 已连接成功
case Var.msg_connect:
progressDialog.dismiss();
getData();
myAdaptor.notifyDataSetChanged();
toast = Toast.makeText(mCtx,
"连接服务器并返回数据成功!", Toast.LENGTH_LONG);
toast.show();
break; }
super.handleMessage(msg);
}
}; // 获得屏幕尺寸
public void getScreen(){
Var.wid_scr = getWindowManager().getDefaultDisplay().getWidth();
Var.hei_scr = getWindowManager().getDefaultDisplay().getHeight();
} } //课程列表
class list_clas_adaptor extends BaseAdapter implements OnClickListener{ public Context ctx;
public List<item_clas> list_data;
public String s1, s2; public list_clas_adaptor(Context context){
ctx =context;
list_data = new ArrayList<item_clas>();
} @Override
public int getCount() {
// TODO Auto-generated method stub
return list_data.size();
} @Override
public Object getItem(int id) {
// TODO Auto-generated method stub
s2 = String.valueOf(id);
for (int i=0; i<list_data.size(); i++){
s1 = (String) list_data.get(i).txtNum.getText();
if (s1.equals(s2))
return list_data.get(i);
} return null; } @Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return list_data.indexOf(position);
} @Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub item_clas my_item;
if (convertView == null)
{
my_item = new item_clas(ctx,
(String)list_data.get(position).txtNum.getText(),
(String)list_data.get(position).txtName.getText(),
(String)list_data.get(position).txtComm.getText()
,1);
}
else
{
my_item = (item_clas)convertView;
my_item.txtNum.setText(list_data.get(position).txtNum.getText());
my_item.txtName.setText(list_data.get(position).txtName.getText());
my_item.txtComm.setText(list_data.get(position).txtComm.getText());
} // 点击删除按钮
my_item.btnDel.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) { } }); // 点击修改按钮
my_item.btnMdf.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) { }
}); return my_item;
} public void addItem(String num, String name, String comm, int x)
{
list_data.add(new item_clas(ctx, num, name, comm, x));
} @Override
public void onClick(View v) { } } // clas列表的一行
class item_clas extends LinearLayout{ public TextView txtNum;
public TextView txtName;
public TextView txtComm;
public TextView txtMdf;
public TextView txtDel;
public Button btnMdf;
public Button btnDel; public item_clas(Context ctx, String num, String name, String comm, int x)
{
super(ctx);
this.setOrientation(HORIZONTAL);
int hei = 60; txtNum = new TextView(ctx);
txtNum.setText(num);
txtNum.setGravity(Gravity.CENTER);
txtNum.setTypeface(Typeface.DEFAULT_BOLD, Typeface.BOLD);
addView(txtNum, new LinearLayout.LayoutParams((int)(Var.wid_scr*0.1),hei)); txtName = new TextView(ctx);
txtName.setText(name);
txtName.setGravity(Gravity.CENTER);
txtName.setTypeface(Typeface.DEFAULT_BOLD, Typeface.BOLD);
addView(txtName, new LinearLayout.LayoutParams((int)(Var.wid_scr*0.2),hei)); txtComm = new TextView(ctx);
txtComm.setText(comm);
Gravity g = new Gravity();
txtComm.setGravity(Gravity.LEFT);
addView(txtComm, new LinearLayout.LayoutParams((int)(Var.wid_scr*0.4),hei)); if (x==0){
txtDel = new TextView(ctx);
txtDel.setText("删除");
txtDel.setGravity(Gravity.CENTER);
addView(txtDel, new LinearLayout.LayoutParams((int)(Var.wid_scr*0.15),hei));
Log.i("addView", txtDel.getText().toString()); txtMdf = new TextView(ctx);
txtMdf.setText("更新 ");
txtMdf.setGravity(Gravity.CENTER);
addView(txtMdf, new LinearLayout.LayoutParams((int)(Var.wid_scr*0.15),hei));
Log.i("comm=", comm);
Log.i("addView", txtMdf.getText().toString());
} else{
btnDel = new Button(ctx);
btnDel.setText("删除");
btnDel.setGravity(Gravity.CENTER);
btnDel.setTypeface(Typeface.DEFAULT_BOLD, Typeface.BOLD);
btnDel.setFocusable(false);
addView(btnDel, new LinearLayout.LayoutParams((int)(Var.wid_scr*0.15),hei)); btnMdf = new Button(ctx);
btnMdf.setText("更新");
btnMdf.setGravity(Gravity.CENTER);
btnMdf.setTypeface(Typeface.DEFAULT_BOLD, Typeface.BOLD);
btnMdf.setFocusable(false);
addView(btnMdf, new LinearLayout.LayoutParams((int)(Var.wid_scr*0.15),hei));
}
} }
MainActivity调用CommThread访问服务器，获得数据后通过BaseAdaptor显示出来。在item_clas类中，由于点击每一行会被系统误以为是在点击Button，所以要给Button加上:
setFocusable(false);
运行结果：
