SSH服务器与Android通信(2)--Android客户端接收数据

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：