android客户端采用Post和Get方式向web服务器传递参数

android客户端向web服务器传递参数主要用到了HttpURLConnection类，通过这个类，我们可以获取到指定url的连接，在其中我们可以通过设定请求的方法是Post还是get，采用get方法相对容易，我们通过观察浏览器中url可以发现，提交的参数和参数值都被附着到了URL的后面，因此在android客户端中同样是将参数和参数值直接附着在URL后面，而post方法向对方复杂，需要我们设置一些参数，并且以输出流的形式向服务器端传递参数。

下面代码实现了 将客户端中用户名和密码传递到服务器端

public class MainActivity extends Activity {

private Button loginButton;
private EditText usernameText;
private EditText passwordText;


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

loginButton = (Button) this.findViewById(R.id.login);
usernameText = (EditText) this.findViewById(R.id.username);
passwordText = (EditText) this.findViewById(R.id.password);

loginButton.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View v) {
String username = usernameText.getText().toString();
String password = passwordText.getText().toString();

Map<String,String> map = new HashMap<String,String>();
map.put("username", username);
map.put("password",password);

boolean result = RequestHandler.sendGetRequest(map);
if(result){
Toast.makeText(MainActivity.this, "登陆成功", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(MainActivity.this, "登陆失败", Toast.LENGTH_SHORT).show();
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

}

下面是RequestHandler类的代码

public class RequestHandler {
/*
 * 通过get方法向服务器发送请求，主要是将请求的参数和参数值附着在请求地址后面。
 */
public static boolean sendGetRequest(Map<String,String> params){
StringBuilder path = new StringBuilder("http://169.254.220.210:8080/android/LoginServlet?");
for(Map.Entry<String, String> entry:params.entrySet()){

path.append(entry.getKey());
path.append("=");
path.append(entry.getValue());
path.append("&");
}
path.deleteCharAt(path.length()- 1);  //去掉最后一个参数后面多余的&

try {
URL url = new URL(path.toString());
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setConnectTimeout(500);
connection.setRequestMethod("GET");
if(connection.getResponseCode() == HttpURLConnection.HTTP_OK){
return true;
}

} catch (Exception e) {

e.printStackTrace();
return false;
}
return false;
}

public static boolean sendPostRequest(Map<String,String> params){

StringBuilder data = new StringBuilder();
for(Map.Entry<String, String> entry : params.entrySet()){  //设置请求的参数
data.append(entry.getKey());
data.append("=");
data.append(entry.getValue());
data.append("&");
}

data.deleteCharAt(data.length() - 1);

try {
HttpURLConnection post = (HttpURLConnection) new URL("http://169.254.220.210:8080/android/LoginServlet").openConnection();
post.setConnectTimeout(500);
post.setDoOutput(true);  //一定要将可以输出参数设置为true
post.setRequestProperty("Content-Length",String.valueOf(data.length())); //必须设定请求的长度
post.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");//必须设定请求的内容
OutputStream out = post.getOutputStream();  
out.write(data.toString().getBytes());  //通过输出流将参数输出

//在输出参数之后一定要获取响应的某项内容，才能真正的发出post请求，在这里获取响应的状态码

if(post.getResponseCode() == HttpURLConnection.HTTP_OK){   
return true;
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
return true;
}

return false;
}
}