<!-- 访问Internet资源 -->

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

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:id="@+id/activity_main"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context="com.mythmayor.gettime.MainActivity">

    <TextView

        android:id="@+id/tv_nettime"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:gravity="center"

        android:text="Hello World!"

        android:textSize="22sp" />

    <Button

        android:id="@+id/btn_nettime"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_marginTop="20dp"

        android:text="获取当前网络时间"

        android:textSize="20sp" />

    <Button

        android:id="@+id/btn_localtime"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_marginTop="20dp"

        android:text="获取当前系统时间"

        android:textSize="20sp" />

</LinearLayout>

package com.mythmayor.gettime;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.TextView;

import android.widget.Toast;

import java.net.URL;

import java.net.URLConnection;

import java.text.DateFormat;

import java.text.SimpleDateFormat;

import java.util.Calendar;

public class MainActivity extends Activity implements View.OnClickListener {

    private TextView tvNetTime;

    private Button btnNetTime;

    private Button btnLocalTime;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        /** 初始化控件 */

        initView();

        /** 处理用户输入 */

        handleUserInput();

    }

    private void initView() {

        tvNetTime = (TextView) findViewById(R.id.tv_nettime);

        btnNetTime = (Button) findViewById(R.id.btn_nettime);

        btnLocalTime = (Button) findViewById(R.id.btn_localtime);

    }

    private void handleUserInput() {

        btnNetTime.setOnClickListener(this);

        btnLocalTime.setOnClickListener(this);

    }

    private void getNetTime() {

        URL url = null;//取得资源对象

        try {

            url = new URL("http://www.baidu.com");

            //url = new URL("http://www.ntsc.ac.cn");//中国科学院国家授时中心

            //url = new URL("http://www.bjtime.cn");

            URLConnection uc = url.openConnection();//生成连接对象

            uc.connect(); //发出连接

            long ld = uc.getDate(); //取得网站日期时间

            DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

            Calendar calendar = Calendar.getInstance();

            calendar.setTimeInMillis(ld);

            final String format = formatter.format(calendar.getTime());

            runOnUiThread(new Runnable() {

                @Override

                public void run() {

                    Toast.makeText(MainActivity.this, "当前网络时间为: \n" + format, Toast.LENGTH_SHORT).show();

                    tvNetTime.setText("当前网络时间为: \n" + format);

                }

            });

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    private void getLocalTime() {

        URL url = null;//取得资源对象

        try {

            DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

            Calendar calendar = Calendar.getInstance();

            calendar.setTimeInMillis(System.currentTimeMillis());

            String format = formatter.format(calendar.getTime());

            Toast.makeText(this, "当前系统时间为: \n" + format, Toast.LENGTH_SHORT).show();

            tvNetTime.setText("当前系统时间为: \n" + format);

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    @Override

    public void onClick(View v) {

        switch (v.getId()) {

            case R.id.btn_nettime:

                //获取网络时间

                //请求网络资源是耗时操作。放到子线程中进行

                new Thread(new Runnable() {

                    @Override

                    public void run() {

                        getNetTime();

                    }

                }).start();

                break;

            case R.id.btn_localtime:

                //获取系统时间

                getLocalTime();

                break;

            default:

                break;

        }

    }

}