HttpURLConnection的使用步骤

• 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：PUT conn.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();

StreamTool.java:

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();
    }
}

1）HttpURLConnection发送GET请求代码示例

获取数据类：GetData.java:

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：

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);
        setViews();
    }

    private void setViews() {
        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);
    }

    @Override
    // 重写上下文菜单的创建方法
    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
    @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;
    }
}

布局：activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:id="@+id/txtMenu"
        android:layout_width="match_parent"
        android:layout_height="48dp"
        android:background="#4EA9E9"
        android:clickable="true"
        android:gravity="center"
        android:text="长按我，加载菜单"
        android:textSize="20sp" />

    <ImageView
        android:id="@+id/imgPic"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="gone" />

    <ScrollView
        android:id="@+id/scroll"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="gone">

        <TextView
            android:id="@+id/txtshow"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </ScrollView>

    <WebView
        android:id="@+id/webView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

最后别忘了加上联网权限：

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

2）HttpURLConnection发送POST请求代码示例

PostUtils.java

public class PostUtils {
    public static String LOGIN_URL = "http://172.16.2.54:8080/HttpTest/ServletForPost";
    public static String LoginByPost(String number,String passwd)
    {
        String msg = "";
        try{
            HttpURLConnection conn = (HttpURLConnection) new URL(LOGIN_URL).openConnection();
            //设置请求方式,请求超时信息
            conn.setRequestMethod("POST");
            conn.setReadTimeout(5000);
            conn.setConnectTimeout(5000);
            //设置运行输入,输出:
            conn.setDoOutput(true);
            conn.setDoInput(true);
            //Post方式不能缓存,需手动设置为false
            conn.setUseCaches(false);
            //我们请求的数据:
            String data = "passwd="+ URLEncoder.encode(passwd, "UTF-8")+
                    "&number="+ URLEncoder.encode(number, "UTF-8");
            //这里可以写一些请求头的东东...
            //获取输出流
            OutputStream out = conn.getOutputStream();
            out.write(data.getBytes());
            out.flush();
             if (conn.getResponseCode() == 200) {  
                    // 获取响应的输入流对象  
                    InputStream is = conn.getInputStream();  
                    // 创建字节输出流对象  
                    ByteArrayOutputStream message = new ByteArrayOutputStream();  
                    // 定义读取的长度  
                    int len = 0;  
                    // 定义缓冲区  
                    byte buffer[] = new byte[1024];  
                    // 按照缓冲区的大小，循环读取  
                    while ((len = is.read(buffer)) != -1) {  
                        // 根据读取的长度写入到os对象中  
                        message.write(buffer, 0, len);  
                    }  
                    // 释放资源  
                    is.close();  
                    message.close();  
                    // 返回字符串  
                    msg = new String(message.toByteArray());  
                    return msg;
             }
        }catch(Exception e){e.printStackTrace();}
        return msg;
    }
}

3）使用HttpURLConnection发送PUT请求

public static String LoginByPut(Context mContext, String mobile, String password, int from, 
          String devid,String version_name, int remember_me) {
    String resp = "";
    try {
        HttpURLConnection conn = (HttpURLConnection) new URL(LOGIN_URL).openConnection();
        conn.setRequestMethod("PUT");
        conn.setReadTimeout(5000);
        conn.setConnectTimeout(5000);
        conn.setDoOutput(true);
        conn.setDoInput(true);
        conn.setUseCaches(false);

        String data = "mobile=" + mobile + "&password=" + password + "&from=" + from + "&devid=" + "devid"
                + "&version_name=" + "version_name" + "&remember_me=" + remember_me;
        ;
        // 获取输出流:
        OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
        writer.write(data);
        writer.flush();
        writer.close();

        // 获取相应流对象:
        InputStream in = conn.getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        StringBuilder response = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null)
            response.append(line);
        SPUtils.put(mContext, "session", conn.getHeaderField("Set-Cookie"));
        // 资源释放:
        in.close();
        // 返回字符串
        Log.e("HEHE", response.toString());
        return response.toString();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return "";
}