Android之网络编程

本文主要包括三方面内容

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

HttpClient中doGet与doPost方法实现提交数据到服务器

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