客户端登陆

要实现登录必然涉及到客户端与服务器端的交互，即客户端需要将用户输入的账号和密码传给服务器端，服务器端连接数据库对其进行验证。

细化问题，先研究一下客户端向服务器端传值的方法。。

新建一个web工程，建一个Servlet如下：

    private static final long serialVersionUID = 1L;
    public UserServlet() {
        super();
    }
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String userName=request.getParameter("userName");
        String passWord=request.getParameter("passWord");
        //在服务器端解决中文乱码问题
        userName=NewString.getNewString(userName);
        passWord=NewString.getNewString(passWord);
        System.out.println("账号："+userName);
        System.out.println("密码："+passWord);
    }
    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

public class UserServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;   
	public UserServlet() {
		super();
	}
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String userName=request.getParameter("userName");
		String passWord=request.getParameter("passWord");
		//在服务器端解决中文乱码问题
		userName=NewString.getNewString(userName);
		passWord=NewString.getNewString(passWord);
		System.out.println("账号："+userName);
		System.out.println("密码："+passWord);	
	}	
	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		this.doGet(request, response);
	}
}

客户端登录界面如下，布局比较简单。

Activity代码：

public class LoginActivity extends Activity {
    private EditText userName;
    private EditText passWord;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        userName=(EditText)this.findViewById(R.id.userName);
        passWord=(EditText)this.findViewById(R.id.passWord);
    }
     /**
      * 用户登录的方法
      */
    public void login(View v)
    {
        //取得用户输入的账号和密码
        String name=userName.getText().toString();
        String pass=passWord.getText().toString();
        boolean result=UserService.check(name,pass);
        if(result)
        {
            Toast.makeText(getApplicationContext(),R.string.success,1).show();
        }else
        {
            Toast.makeText(getApplicationContext(),R.string.fail,1).show();
        }
    }
}

public class LoginActivity extends Activity {
    private EditText userName;
	private EditText passWord;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);        
        userName=(EditText)this.findViewById(R.id.userName);
        passWord=(EditText)this.findViewById(R.id.passWord);       
    }
     /**
      * 用户登录的方法
      */
    public void login(View v)
    {  
    	//取得用户输入的账号和密码
    	String name=userName.getText().toString();
    	String pass=passWord.getText().toString();
    	boolean result=UserService.check(name,pass);
    	if(result)
    	{
    		Toast.makeText(getApplicationContext(),R.string.success,1).show();
    	}else
    	{
    		Toast.makeText(getApplicationContext(),R.string.fail,1).show();
    	}  	
    }
}

具体实现的工具类：

public class UserService {
    /**
     * 验证用户登录是否合法
     * 返回值：请求是否成功
     */
    public static boolean check(String name, String pass) {
        String path="http://135.32.89.17:8080/lss/UserServlet";
        //将用户名和密码放入HashMap中
        Map<String,String> params=new HashMap<String,String>();
        params.put("userName", name);
        params.put("passWord", pass);
        try {
            return sendGETRequest(path,params,"UTF-8");
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return false;
    }
    private static boolean sendGETRequest(String path,
        Map<String, String> params,String encode) throws MalformedURLException, IOException {
        StringBuilder url=new StringBuilder(path);
        url.append("?");
        for(Map.Entry<String, String> entry:params.entrySet())
        {
            url.append(entry.getKey()).append("=");
            url.append(URLEncoder.encode(entry.getValue(),encode));
            url.append("&");
        }
        //删掉最后一个&
        url.deleteCharAt(url.length()-1);
        HttpURLConnection conn=(HttpURLConnection)new URL(url.toString()).openConnection();
        conn.setConnectTimeout(5000);
        conn.setRequestMethod("GET");
        if(conn.getResponseCode()==200)
         {
           return true;
         }
           return false;
         }
}

public class UserService {
	/**
	 * 验证用户登录是否合法
	 * 返回值：请求是否成功
	 */
	public static boolean check(String name, String pass) {
		String path="http://135.32.89.17:8080/lss/UserServlet";
		//将用户名和密码放入HashMap中
		Map<String,String> params=new HashMap<String,String>();
		params.put("userName", name);
		params.put("passWord", pass);		
		try {
			return sendGETRequest(path,params,"UTF-8");
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return false;
	}
	private static boolean sendGETRequest(String path,
		Map<String, String> params,String encode) throws MalformedURLException, IOException {
		StringBuilder url=new StringBuilder(path);
		url.append("?");
		for(Map.Entry<String, String> entry:params.entrySet())
		{
			url.append(entry.getKey()).append("=");
			url.append(URLEncoder.encode(entry.getValue(),encode));
			url.append("&");
		}
		//删掉最后一个&
		url.deleteCharAt(url.length()-1);
        HttpURLConnection conn=(HttpURLConnection)new URL(url.toString()).openConnection();
        conn.setConnectTimeout(5000);
        conn.setRequestMethod("GET");
        if(conn.getResponseCode()==200)
         {
    	   return true;
         }
		   return false;
	     }
}

运行结果：

服务器端接收内容：