Android开发学习笔记-实现联网检测程序版本

package com.frank.mobilesafe;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URL;

import javax.net.ssl.HttpsURLConnection;

import org.apache.http.HttpClientConnection;
import org.apache.http.client.methods.HttpUriRequest;
import org.json.JSONObject;

import com.frank.mobilesafe.utils.FileHelper;

import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.Window;
import android.widget.TextView;
import android.widget.Toast;

public class SplashActivity extends Activity {

    private static final int SHOW_UPDATE_DIALOG = 0;
    protected static final int REQUEST_FAILURE = 1;
    protected static final int REQUEST_ERROR = 2;
    private static final int SHOW_HOME = 3;
    private Handler handler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            HandlerStartMessage(msg.what);
        }

    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // requestWindowFeature(Window.FEATURE_NO_TITLE);设置无标题
        setContentView(R.layout.activity_splash);
        TextView tv_version = (TextView) findViewById(R.id.tv_version);
        tv_version.setText(getVersion());
        CheckUpdate();
    }

    protected void HandlerStartMessage(int what) {
        switch (what) {
        case SHOW_UPDATE_DIALOG:
            Toast.makeText(this, "该升级了", 0).show();
            break;
        case SHOW_HOME:
            //Toast.makeText(this, "show home activity", 0).show();
            ShowMainActivity();
            break;
        case REQUEST_FAILURE:
            Toast.makeText(this, "REQUEST_FAILURE", 0).show();
            break;
        default:
            break;
        }

    }
/**
 * 显示主界面
 */
    private void ShowMainActivity() {
        // TODO Auto-generated method stub
        Intent intent = new Intent(this,MainActivity.class);
        startActivity(intent);
        finish();

    }

    /**
     * 检查升级
     */
    protected void CheckUpdate() {
        new Thread() {
            public void run() {
                long startTime = System.currentTimeMillis();
                Message msg = Message.obtain();
                try {
                    URL url = new URL("http://192.168.1.104/1.html");// 网络链接地址
                    HttpURLConnection conn = (HttpURLConnection) url
                            .openConnection();// 创建连接对象
                    conn.setRequestMethod("GET");// 设置请求方式
                    conn.setReadTimeout(5000);// 设置请求超时时间

                    if (200 == conn.getResponseCode())// 当请成功的时候执行
                    {
                        InputStream inputStream = conn.getInputStream();
                        FileHelper helper = new FileHelper();
                        String content = helper.StreamToString(inputStream);
                        Log.i("a", content);
                        JSONObject obj = new JSONObject(content);
                        String version = (String) obj.get("version");
                        Log.i("version", version);
                        if (version == getVersion()) {
                            msg.what = SHOW_UPDATE_DIALOG;
                        }
                        else
                        {
                            msg.what = SHOW_HOME;
                        }

                    } else {
                        Log.i("a", "请求失败！");
                        msg.what = REQUEST_FAILURE;
                    }
                } catch (Exception e) {
                    Log.i("a", "shibai");
                    msg.what = REQUEST_ERROR;
                    e.printStackTrace();
                } finally {
                    long endTime = System.currentTimeMillis();
                    long spanTime = endTime-startTime;
                    if (spanTime<2000) {
                        try {
                            Thread.sleep(2000-spanTime);
                        } catch (InterruptedException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                    handler.sendMessage(msg);
                }
            };

        }.start();

    }

    /**
     * 获取版本信息
     *
     * @return
     */
    protected String getVersion() {
        String versionStr = "";
        PackageManager packManger = getPackageManager();
        try {
            PackageInfo info = packManger.getPackageInfo(getPackageName(), 0);
            versionStr = info.versionName;// 获取的版本信息
        } catch (NameNotFoundException e) {
            // TODO Auto-generated catch block
            versionStr = "";
            e.printStackTrace();
        }
        return versionStr;

    }
}

问题总结：

1、在解析JSON的时候需要情况一直遇到异常，出错异常信息为org.json.JSONException: Value ? of type java.lang.String cannot be converted to JSONObject，经查得是在保存json文本的时候是使用的记事本造成的，这也就是说在保存JSON的使用应该使用editplus等文本编辑器进行保存，保存的格式应该为utf8 无bom格式，这样在进行解析的时候就不会造成异常。

2、在联网获取数据的时候，因为是在本机iis上配置的站点，不过在请求数据的时候一直请求不到，遇到的第一个原因就是没有对请求设置请求方式以及请求时间，之后对百度等其他网站进行请求都没问题，却对自己配置的请求不了，经过抓耳挠腮之后，查的原因竟是http后面的反斜线少了一个。大意了！

3、在线程内访问线程外的资源的时候，需要使用java事件机制进行处理。主要方法如下：

    private Handler handler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            HandlerStartMessage(msg.what);
        }

    };

protected void CheckUpdate() {
        new Thread() {
            public void run() {
                long startTime = System.currentTimeMillis();
                Message msg = Message.obtain();
              msg.what = SHOW_UPDATE_DIALOG;
              handler.sendMessage(msg);
                }
            };
        }.start();