Android之网络编程

本文主要包括三方面内容

1. Httpurlconnection中doGet与doPost方法实现提交数据到服务器

2. HttpClient中doGet与doPost方法实现提交数据到服务器

3. android-async-http开源库方法实现提交数据到服务器

首先是服务器端的实现

public class LoginServlet extends HttpServlet {

    /**
     * The doGet method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to get.
     *
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String username = request.getParameter("username"); // 采用的编码是: iso-8859-1
        String password = request.getParameter("password");

        // 采用iso8859-1的编码对姓名进行逆转, 转换成字节数组, 再使用utf-8编码对数据进行转换, 字符串
        username = new String(username.getBytes("iso8859-1"), "utf-8");
        password = new String(password.getBytes("iso8859-1"), "utf-8");

        System.out.println("姓名: " + username);
        System.out.println("密码: " + password);

        if("lisi".equals(username) && "123".equals(password)) {
            /*
             * getBytes 默认情况下, 使用的iso8859-1的编码, 但如果发现码表中没有当前字符,
             * 会使用当前系统下的默认编码: GBK
             */
            response.getOutputStream().write("登录成功".getBytes("utf-8"));
        } else {
            response.getOutputStream().write("登录失败".getBytes("utf-8"));
        }
    }

    /**
     * The doPost method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to post.
     *
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        System.out.println("doPost");
        doGet(request, response);
    }

}

Httpurlconnection实现提交数据到服务器

public class NetUtils {

    private static final String TAG = "NetUtils";

    /**
     * 使用post的方式登录
     * @param userName
     * @param password
     * @return
     */
    public static String loginOfPost(String userName, String password) {
        HttpURLConnection conn = null;
        try {
            URL url = new URL("http://10.0.2.2:8080/ServerItheima28/servlet/LoginServlet");

            conn = (HttpURLConnection) url.openConnection();

            conn.setRequestMethod("POST");
            conn.setConnectTimeout(10000); // 连接的超时时间
            conn.setReadTimeout(5000); // 读数据的超时时间
            conn.setDoOutput(true); // 必须设置此方法, 允许输出
//          conn.setRequestProperty("Content-Length", 234);     // 设置请求头消息, 可以设置多个

            // post请求的参数
            String data = "username=" + userName + "&password=" + password;

            // 获得一个输出流, 用于向服务器写数据, 默认情况下, 系统不允许向服务器输出内容
            OutputStream out = conn.getOutputStream();
            out.write(data.getBytes());
            out.flush();
            out.close();

            int responseCode = conn.getResponseCode();
            if(responseCode == 200) {
                InputStream is = conn.getInputStream();
                String state = getStringFromInputStream(is);
                return state;
            } else {
                Log.i(TAG, "访问失败: " + responseCode);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(conn != null) {
                conn.disconnect();
            }
        }
        return null;
    }

    /**
     * 使用get的方式登录
     * @param userName
     * @param password
     * @return 登录的状态
     */
    public static String loginOfGet(String userName, String password) {
        HttpURLConnection conn = null;
        try {
            String data = "username=" + URLEncoder.encode(userName) + "&password=" + URLEncoder.encode(password);
            URL url = new URL("http://10.0.2.2:8080/ServerItheima28/servlet/LoginServlet?" + data);
            conn = (HttpURLConnection) url.openConnection();

            conn.setRequestMethod("GET");       // get或者post必须得全大写
            conn.setConnectTimeout(10000); // 连接的超时时间
            conn.setReadTimeout(5000); // 读数据的超时时间

            int responseCode = conn.getResponseCode();
            if(responseCode == 200) {
                InputStream is = conn.getInputStream();
                String state = getStringFromInputStream(is);
                return state;
            } else {
                Log.i(TAG, "访问失败: " + responseCode);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(conn != null) {
                conn.disconnect();      // 关闭连接
            }
        }
        return null;
    }

    /**
     * 根据流返回一个字符串信息
     * @param is
     * @return
     * @throws IOException
     */
    private static String getStringFromInputStream(InputStream is) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = -1;

        while((len = is.read(buffer)) != -1) {
            baos.write(buffer, 0, len);
        }
        is.close();

        String html = baos.toString();  // 把流中的数据转换成字符串, 采用的编码是: utf-8

//      String html = new String(baos.toByteArray(), "GBK");

        baos.close();
        return html;
    }
}

HttpClient实现提交数据到服务器

public class NetUtils2 {

    private static final String TAG = "NetUtils";

    /**
     * 使用post的方式登录
     * @param userName
     * @param password
     * @return
     */
    public static String loginOfPost(String userName, String password) {
        HttpClient client = null;
        try {
            // 定义一个客户端
            client = new DefaultHttpClient();

            // 定义post方法
            HttpPost post = new HttpPost("http://10.0.2.2:8080/ServerItheima28/servlet/LoginServlet");

            // 定义post请求的参数
            List<NameValuePair> parameters = new ArrayList<NameValuePair>();
            parameters.add(new BasicNameValuePair("username", userName));
            parameters.add(new BasicNameValuePair("password", password));

            // 把post请求的参数包装了一层.

            // 不写编码名称服务器收数据时乱码. 需要指定字符集为utf-8
            UrlEncodedFormEntity entity = new UrlEncodedFormEntity(parameters, "utf-8");
            // 设置参数.
            post.setEntity(entity);

            // 设置请求头消息
//          post.addHeader("Content-Length", "20");

            // 使用客户端执行post方法
            HttpResponse response = client.execute(post);   // 开始执行post请求, 会返回给我们一个HttpResponse对象

            // 使用响应对象, 获得状态码, 处理内容
            int statusCode = response.getStatusLine().getStatusCode();  // 获得状态码
            if(statusCode == 200) {
                // 使用响应对象获得实体, 获得输入流
                InputStream is = response.getEntity().getContent();
                String text = getStringFromInputStream(is);
                return text;
            } else {
                Log.i(TAG, "请求失败: " + statusCode);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(client != null) {
                client.getConnectionManager().shutdown();   // 关闭连接和释放资源
            }
        }
        return null;
    }

    /**
     * 使用get的方式登录
     * @param userName
     * @param password
     * @return 登录的状态
     */
    public static String loginOfGet(String userName, String password) {
        HttpClient client = null;
        try {
            // 定义一个客户端
            client = new DefaultHttpClient();

            // 定义一个get请求方法
            String data = "username=" + userName + "&password=" + password;
            HttpGet get = new HttpGet("http://10.0.2.2:8080/ServerItheima28/servlet/LoginServlet?" + data);

            // response 服务器相应对象, 其中包含了状态信息和服务器返回的数据
            HttpResponse response = client.execute(get);    // 开始执行get方法, 请求网络

            // 获得响应码
            int statusCode = response.getStatusLine().getStatusCode();

            if(statusCode == 200) {
                InputStream is = response.getEntity().getContent();
                String text = getStringFromInputStream(is);
                return text;
            } else {
                Log.i(TAG, "请求失败: " + statusCode);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(client != null) {
                client.getConnectionManager().shutdown();   // 关闭连接, 和释放资源
            }
        }
        return null;
    }

    /**
     * 根据流返回一个字符串信息
     * @param is
     * @return
     * @throws IOException
     */
    private static String getStringFromInputStream(InputStream is) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = -1;

        while((len = is.read(buffer)) != -1) {
            baos.write(buffer, 0, len);
        }
        is.close();

        String html = baos.toString();  // 把流中的数据转换成字符串, 采用的编码是: utf-8

//      String html = new String(baos.toByteArray(), "GBK");

        baos.close();
        return html;
    }
}

在onCreate方法中的调用

public class MainActivity extends Activity {

    private EditText etUserName;
    private EditText etPassword;

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

        etUserName = (EditText) findViewById(R.id.et_username);
        etPassword = (EditText) findViewById(R.id.et_password);
    }

    public void doGet(View v) {
        final String userName = etUserName.getText().toString();
        final String password = etPassword.getText().toString();

        new Thread(
                new Runnable() {

                    @Override
                    public void run() {
                        // 使用get方式抓去数据
                        final String state = NetUtils.loginOfGet(userName, password);

                        // 执行任务在主线程中
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                // 就是在主线程中操作
                                Toast.makeText(MainActivity.this, state, 0).show();
                            }
                        });
                    }
                }).start();
    }

    public void doPost(View v) {
        final String userName = etUserName.getText().toString();
        final String password = etPassword.getText().toString();

        new Thread(new Runnable() {
            @Override
            public void run() {
                final String state = NetUtils.loginOfPost(userName, password);
                // 执行任务在主线程中
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        // 就是在主线程中操作
                        Toast.makeText(MainActivity.this, state, 0).show();
                    }
                });
            }
        }).start();
    }
}

使用runOnUiThread方法，可以在子线程中实现对主线程的操作

使用android-async-http开源库方法实现提交数据到服务器 ,使用方法也是将src文件夹中的内容复制到程序中即可

public class MainActivity2 extends Activity {

    protected static final String TAG = "MainActivity2";
    private EditText etUserName;
    private EditText etPassword;

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

        etUserName = (EditText) findViewById(R.id.et_username);
        etPassword = (EditText) findViewById(R.id.et_password);
    }

    public void doGet(View v) {
        final String userName = etUserName.getText().toString();
        final String password = etPassword.getText().toString();

        AsyncHttpClient client = new AsyncHttpClient();

        String data = "username=" + URLEncoder.encode(userName) + "&password=" + URLEncoder.encode(password);

        client.get("http://10.0.2.2:8080/ServerItheima28/servlet/LoginServlet?" + data, new MyResponseHandler());
    }

    public void doPost(View v) {
        final String userName = etUserName.getText().toString();
        final String password = etPassword.getText().toString();

        AsyncHttpClient client = new AsyncHttpClient();

        RequestParams params = new RequestParams();
        params.put("username", userName);
        params.put("password", password);

        client.post("http://10.0.2.2:8080/ServerItheima28/servlet/LoginServlet",
                params,
                new MyResponseHandler());
    }

    class MyResponseHandler extends AsyncHttpResponseHandler {

        @Override
        public void onSuccess(int statusCode, Header[] headers,
                byte[] responseBody) {
//          Log.i(TAG, "statusCode: " + statusCode);

            Toast.makeText(MainActivity2.this,
                    "成功: statusCode: " + statusCode + ", body: " + new String(responseBody),
                    0).show();
        }

        @Override
        public void onFailure(int statusCode, Header[] headers,
                byte[] responseBody, Throwable error) {
            Toast.makeText(MainActivity2.this, "失败: statusCode: " + statusCode, 0).show();
        }
    }
}

可以看到使用开源框架可以更加简单，高效，安全的实现相同的效果.

完成