自动更新检测，结合网上资料编写

import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.text.TextUtils;
import android.util.Log;
import android.util.Xml;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.view.WindowManager;
import android.view.animation.AlphaAnimation;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONObject;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Map;

public class MainActivity extends AppCompatActivity {
//常量定义
public static final int UNKNOWN_ERROR = 99;
public static final int GET_INFO_SUCCESS = 100;
public static final int SERVER_ERROR = 101;
public static final int SERVER_URL_ERROR = 102;
public static final int PROTOCOL_ERROR = 103;
public static final int IO_ERROR = 104;
public static final int XML_PARSER_ERROR = 105;
public static final int DOWN_ERROR = 106;
public static final String TAG = "SplashActivity";

//获取的服务器端的更新信息
UpdateInfo updateinfo;
//下载进度条
private ProgressDialog pBar;
//显示版本号的tv控件
private TextView tv_splash_version;

//布局控件
private RelativeLayout r1_splash;

@Override
protected void onCreate(Bundle savedInstanceState) {

4000
super.onCreate(savedInstanceState);
ActivityManager.getInstance().addActivity(this);//将当前Activity加入到管理器，用于退出使用
setContentView(R.layout.activity_main);
//设置全屏模式
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

r1_splash = (RelativeLayout)findViewById(R.id.r1_splash);
tv_splash_version = (TextView)findViewById(R.id.tv_splash_version);
tv_splash_version.setText("版本号：" + getVersion());

//显示渐进动画
AlphaAnimation aa = new AlphaAnimation(0.3f, 1.0f);
aa.setDuration(2000);
r1_splash.startAnimation(aa);

//检查更新
new Thread(new checkUpdate()) {
}.start();
}

@Override
protected void onResume() {
/**
* 设置为横屏
*/
if(getRequestedOrientation()!= ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE){
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
}
super.onResume();
}

//获取当前应用程序的版本号
private String getVersion() {
String version = "";

//获取系统包管理器
PackageManager pm = this.getPackageManager();
try {
PackageInfo info = pm.getPackageInfo(getPackageName(), 0);
version = info.versionName;
} catch (Exception e) {
e.printStackTrace();
}
return version;
}

/**
* 消息处理器
*/
private Handler handler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case GET_INFO_SUCCESS:
String serverVersion = updateinfo.getVersion();
String currentVersion = getVersion();
if (currentVersion.equals(serverVersion)) {
Log.i(TAG, "版本号相同无需升级，直接进入主界面");
LoginMain();
}else {
Log.i(TAG, "版本号不同需升级，显示升级对话框");
showUpdateDialog();
}
break;
case SERVER_ERROR:
Toast.makeText(getApplicationContext(), "服务器内部异常", Toast.LENGTH_SHORT).show();
LoginMain();
break;
case SERVER_URL_ERROR:
Toast.makeText(getApplicationContext(), "服务器路径错误", Toast.LENGTH_SHORT).show();
LoginMain();
break;
case PROTOCOL_ERROR:
Toast.makeText(getApplicationContext(), "协议错误", Toast.LENGTH_SHORT).show();
LoginMain();
break;
case XML_PARSER_ERROR:
Toast.makeText(getApplicationContext(), "XML解析错误", Toast.LENGTH_SHORT).show();
LoginMain();
break;
case IO_ERROR:
Toast.makeText(getApplicationContext(), "I/O错误", Toast.LENGTH_SHORT).show();
LoginMain();
break;
case UNKNOWN_ERROR:
Toast.makeText(getApplicationContext(), "未知错误", Toast.LENGTH_SHORT).show();
LoginMain();
break;
case DOWN_ERROR:
Toast.makeText(getApplicationContext(), "下载失败", Toast.LENGTH_SHORT).show();
LoginMain();
break;
}
}
};

/**
* 检查更新
*/
private class checkUpdate implements Runnable {
public void run() {
long startTime = System.currentTimeMillis();
long endTime = startTime;
Message msg = Message.obtain();
try {
//获取服务器更新地址
String serverurl = getResources().getString(R.string.serverurl);
URL url = new URL(serverurl);
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5000);
int code = conn.getResponseCode();
if (code == 200) {
//success
InputStream is = conn.getInputStream();
//解析出更新信息
updateinfo = UpdateInfoParser.getUpdateInfo(is);
endTime = System.currentTimeMillis();
long time = endTime - startTime;
if (time < 2000) {
try {
Thread.sleep(2000 - time);
} catch (InterruptedException e) {
e.printStackTrace();
}
}

msg.what = GET_INFO_SUCCESS;
handler.sendMessage(msg);
} else {
//服务器错误
msg.what = SERVER_ERROR;
handler.sendMessage(msg);
endTime = System.currentTimeMillis();
long time = endTime - startTime;
if (time < 2000) {
try {
Thread.sleep(2000 - time);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}

} catch (MalformedURLException e) {
msg.what = SERVER_URL_ERROR;
handler.sendMessage(msg);
e.printStackTrace();
} catch (ProtocolException e) {
msg.what = PROTOCOL_ERROR;
handler.sendMessage(msg);
e.printStackTrace();
} catch (IOException e) {
msg.what = IO_ERROR;
handler.sendMessage(msg);
e.printStackTrace();
} catch (XmlPullParserException e) {
msg.what = XML_PARSER_ERROR;
handler.sendMessage(msg);
e.printStackTrace();
} catch (Exception e) {
msg.what = UNKNOWN_ERROR;
handler.sendMessage(msg);
e.printStackTrace();
}

}
}
/**
* 显示升级提示对话框
*/
protected void showUpdateDialog() {
//创建对话框构造器
AlertDialog.Builder builder = new AlertDialog.Builder(this);
//设置对话框图标
//builder.setIcon(getResources().getDrawable(R.drawable.notification));
//设置对话框标题
builder.setTitle("升级提示");
//设置更新信息为对话框提示内容
builder.setMessage(updateinfo.getDesc());
//设置升级按钮及响应事件
builder.setPositiveButton("升级", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
downLoadApk();
}
});
//设置取消按钮及响应事件
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {

}
});

//创建并显示对话框
builder.create().show();
}

public static File getFileFromServer(String path, ProgressDialog pd) throws Exception{
//如果相等的话表示当前的sdcard挂载在手机上并且是可用的
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
URL url = new URL(path);
HttpURLConnection conn =  (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(5000);
//获取到文件的大小
pd.setMax(conn.getContentLength());
InputStream is = conn.getInputStream();
File file = new File(Environment.getExternalStorageDirectory(), "update.apk");
FileOutputStream fos = new FileOutputStream(file);
BufferedInputStream bis = new BufferedInputStream(is);
byte[] buffer = new byte[1024];
int len ;
int total=0;
while((len =bis.read(buffer))!=-1){
fos.write(buffer, 0, len);
total+= len;
//获取当前下载量
pd.setProgress(total);
}
fos.close();
bis.close();
is.close();
return file;
}
else{
return null;
}
}

/*
* 从服务器中下载APK
*/
protected void downLoadApk() {
final ProgressDialog pd;    //进度条对话框
pd = new  ProgressDialog(this);
pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
pd.setMessage("正在下载更新");
pd.show();
new Thread(){
@Override
public void run() {
try {
File file = getFileFromServer(updateinfo.getApkurl(), pd);
sleep(3000);
installApk(file);
pd.dismiss(); //结束掉进度条对话框
} catch (Exception e) {
Message msg = new Message();
msg.what = DOWN_ERROR;
handler.sendMessage(msg);
e.printStackTrace();
}
}}.start();
}

//安装apk
protected void installApk(File file) {
Intent intent = new Intent();
//执行动作
intent.setAction(Intent.ACTION_VIEW);
//执行的数据类型
intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");
startActivity(intent);
}

/*
* 进入程序的主界面
*/
private void LoginMain(){
Intent intent = new Intent(this,Login.class);
startActivity(intent);
//结束掉当前的activity
this.finish();
}
}

/**
* Created by cangyun on 2016-09-21.
*/
public class UpdateInfo {

//服务器端版本号
private String version;

//服务器端升级提示
private String desc;

//服务器端apk下载地址
private String apkurl;

public String getVersion() {
return version;
}

public void setVersion(String version) {
this.version = version;
}
public String getDesc() {
return desc;
}

public void setDesc(String desc) {
this.desc = desc;
}

public String getApkurl() {
return apkurl;
}

public void setApkurl(String apkurl) {
this.apkurl = apkurl;
}
}

import android.util.Xml;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import java.io.IOException;
import java.io.InputStream;
/**
* Created by cangyun on 2016-09-21.
*/
public class UpdateInfoParser {
/**
*解析一个utf-8格式的xml输入流，返回一个UpdateInfo对象
* XmlPullParser解析bug参考解决：http://blog.csdn.net/nxh_love/article/details/7109762
* @param is
* @return UpdateInfo对象
* @throws XmlPullParserException
* @throws IOException
*/
public static UpdateInfo getUpdateInfo(InputStream is) throws XmlPullParserException, IOException {
UpdateInfo info = new UpdateInfo();

//获取一个pull解析的实例
XmlPullParser parser = Xml.newPullParser();

//解析xml
parser.setInput(is, "UTF-8");
parser.nextTag();
int type = parser.getEventType();
while (parser.nextTag() == XmlPullParser.START_TAG) {
String tag = parser.getName();
String text = parser.nextText();
if (parser.getEventType() != XmlPullParser.END_TAG) {
parser.nextTag();
}
if (tag.equals("ver")) {
info.setVersion(text);
} else if (tag.equals("desc")) {
info.setDesc(text);
} else if (tag.equals("apkurl")) {
info.setApkurl(text);
}
}

return info;
}
}

<?xml version="1.0" encoding="utf-8"?>
<info>
<version>1.1</version>
<apkurl>http://www.xxxxxx.com:8080/xx/xx-debug.apk</apkurl>
<desc>检测到最新版本，请及时更新！</desc>
</info>

android:versionName="1.1"

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />