Android开发中网络编程之HttpURLConnection的基本用法（总结）

HttpURLConnection的使用步骤

使用HttpURLConnection的步骤如下：

• 创建一个URL对象：URL url = new URL(http://www.baidu.com);
• 调用URL对象的openConnection( )来获取HttpURLConnection对象实例：HttpURLConnection conn = (HttpURLConnection) url.openConnection();
• 设置HTTP请求使用的方法:GET或者POST，或者其他请求方式比如：PUTconn.setRequestMethod("GET");
• 设置连接超时，读取超时的毫秒数，以及服务器希望得到的一些消息头conn.setConnectTimeout(6*1000);conn.setReadTimeout(6 * 1000);
• 调用getInputStream()方法获得服务器返回的输入流，然后输入流进行读取了InputStream in = conn.getInputStream();
• 最后调用disconnect()方法将HTTP连接关掉conn.disconnect();

实例效果图如下：

首先，附上两个工具类：GetData.java（获取网络图片），StreamTool.java（将流转化为二进制数组的工具类）。

StreamTool.java

package com.deepreality.httpurlconnectiondemo;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;

/**
 * 将流转化为二进制数组的工具类
 */
public class StreamTool {
    //从流中读取数据
    public static byte[] read(InputStream inStream) throws Exception{
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = 0;
        while((len = inStream.read(buffer)) != -1)
        {
            outStream.write(buffer,0,len);
        }
        inStream.close();
        return outStream.toByteArray();
    }
}

GetData.java

package com.deepreality.httpurlconnectiondemo;

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


/**
 * 这个类主要用于获取网络图片之类的
 */
public class GetData {
    // 定义一个获取网络图片数据的方法:
    public static byte[] getImage(String path) throws Exception {
        URL url = new URL(path);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        // 设置连接超时为5秒
        conn.setConnectTimeout(5000);
        // 设置请求类型为Get类型
        conn.setRequestMethod("GET");
        // 判断请求Url是否成功
        if (conn.getResponseCode() != 200) {
            throw new RuntimeException("请求url失败");
        }
        InputStream inStream = conn.getInputStream();
        byte[] bt = StreamTool.read(inStream);
        inStream.close();
        return bt;
    }

    // 获取网页的html源代码
    public static String getHtml(String path) throws Exception {
        URL url = new URL(path);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setConnectTimeout(5000);
        conn.setRequestMethod("GET");
        if (conn.getResponseCode() == 200) {
            InputStream in = conn.getInputStream();
            byte[] data = StreamTool.read(in);
            String html = new String(data, "UTF-8");
            return html;
        }
        return null;
    }
}

MainActivity.java的代码如下：

package com.deepreality.httpurlconnectiondemo;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.webkit.WebView;
import android.widget.ImageView;
import android.widget.ScrollView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private TextView txtMenu, txtshow;
    private ImageView imgPic;
    private WebView webView;
    private ScrollView scroll;
    private Bitmap bitmap;
    private String detail = "";
    private boolean flag = false;
    private final static String PIC_URL = "http://ww2.sinaimg.cn/large/7a8aed7bgw1evshgr5z3oj20hs0qo0vq.jpg";
    private final static String HTML_URL = "http://www.baidu.com";

    // 用于刷新界面
    private Handler handler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            switch (msg.what) {
                case 0x001:
                    hideAllWidget();
                    imgPic.setVisibility(View.VISIBLE);
                    imgPic.setImageBitmap(bitmap);
                    Toast.makeText(MainActivity.this, "图片加载完毕", Toast.LENGTH_SHORT).show();
                    break;
                case 0x002:
                    hideAllWidget();
                    scroll.setVisibility(View.VISIBLE);
                    txtshow.setText(detail);
                    Toast.makeText(MainActivity.this, "HTML代码加载完毕", Toast.LENGTH_SHORT).show();
                    break;
                case 0x003:
                    hideAllWidget();
                    webView.setVisibility(View.VISIBLE);
                    webView.loadDataWithBaseURL("", detail, "text/html", "UTF-8", "");
                    Toast.makeText(MainActivity.this, "网页加载完毕", Toast.LENGTH_SHORT).show();
                    break;
                default:
                    break;
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bindViews();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (bitmap.isRecycled()) {
            bitmap.recycle();
        }
    }

    private void bindViews() {
        txtMenu = (TextView) findViewById(R.id.txtMenu);
        txtshow = (TextView) findViewById(R.id.txtshow);
        imgPic = (ImageView) findViewById(R.id.imgPic);
        webView = (WebView) findViewById(R.id.webView);
        scroll = (ScrollView) findViewById(R.id.scroll);
        registerForContextMenu(txtMenu);
    }

    // 定义一个隐藏所有控件的方法:
    private void hideAllWidget() {
        imgPic.setVisibility(View.GONE);
        scroll.setVisibility(View.GONE);
        webView.setVisibility(View.GONE);
    }

    /**
     * 重写上下文菜单的创建方法
     * @param menu
     * @param v
     * @param menuInfo
     */
    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
        MenuInflater inflator = new MenuInflater(this);
        inflator.inflate(R.menu.menus, menu);
        super.onCreateContextMenu(menu, v, menuInfo);
    }

    /**
     * 上下文菜单被点击是触发该方法
     * @param item
     * @return
     */
    @Override
    public boolean onContextItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.one:
                new Thread() {
                    public void run() {
                        try {
                            byte[] data = GetData.getImage(PIC_URL);
                            bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                        handler.sendEmptyMessage(0x001);
                    }
                }.start();
                break;
            case R.id.two:
                new Thread() {
                    public void run() {
                        try {
                            detail = GetData.getHtml(HTML_URL);
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                        handler.sendEmptyMessage(0x002);
                    }
                }.start();
                break;
            case R.id.three:
                if (detail.equals("")) {
                    Toast.makeText(MainActivity.this, "先请求HTML先嘛~", Toast.LENGTH_SHORT).show();
                } else {
                    handler.sendEmptyMessage(0x003);
                }
                break;
        }
        return true;
    }
}

其中，menus.xml是创建于res/menu/下面的菜单文件。

menus.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context="com.example.menutest.MainActivity" >

    <item
        android:id="@+id/one"
        android:orderInCategory="100"
        android:title="加载图片"/>

    <item
        android:id="@+id/two"
        android:orderInCategory="200"
        android:title="加载HTML"/>

    <item
        android:id="@+id/three"
        android:orderInCategory="200"
        android:title="加载网页"/>

</menu>