Android实现简洁的APP登录界面

<?xml version="1.0" encoding="utf-8"?>
<relativelayout          xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="#2197db"
  >
 <imageview
    android:id="@+id/loginbutton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerhorizontal="true"
    android:layout_margintop="40dp"
    android:src="@drawable/login_pic"/>
  
<linearlayout
    android:id="@+id/input"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@+id/loginbutton"
    android:layout_marginleft="28dp"
    android:layout_marginright="28dp"
    android:background="#fff"
    android:orientation="vertical">
<linearlayout
    android:layout_width="fill_parent"
    android:layout_height="44dp"
    android:background="#fff"
    android:gravity="center_vertical"
    android:orientation="horizontal" >

 <edittext
      android:id="@+id/userid"
      android:layout_width="wrap_content"
      android:layout_height="fill_parent"
      android:layout_weight="1"
      android:background="@null"
      android:imeoptions="actiondone"
      android:textsize="16sp"
      android:ems="10"
      android:hint="请输入用户名"
      >
  </edittext>
<button
      android:id="@+id/button_bar"
      android:layout_width="20dp"
      android:layout_height="20dp"
      android:layout_marginright="8dp"
      android:layout_marginleft="1dp"
      android:background="@drawable/login_input_arrow"
      />

 </linearlayout>
 <view
      android:layout_width="fill_parent"
      android:layout_height="1.0px"
      android:layout_marginleft="1.0px"
      android:layout_marginright="1.0px"
      android:background="#ffc0c3c4" />
<edittext
      android:id="@+id/pass"
      android:layout_width="fill_parent"
      android:layout_height="44.0dip"
      android:background="#00ffffff"
      android:gravity="center_vertical"
      android:inputtype="textpassword"
      android:maxlength="16"
      android:maxlines="1"
      android:textcolor="#ff1d1d1d"
      android:textcolorhint="#ff666666"
      android:textsize="16.0sp"
      android:hint="请输入密码"
      />
  </linearlayout>
 <button
   android:id="@+id/loginbtn"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:layout_below="@+id/input"
   android:layout_margintop="10dp"
   android:background="#3aadfd"
   android:text="登  录"
   android:textcolor="#ffffff"
   android:textsize="18dp"
    android:layout_centerhorizontal="true"
    android:layout_marginleft="28dp"
    android:layout_marginright="28dp"/>
  <textview
    android:text=""
    android:layout_width="wrap_content"
    android:layout_below="@+id/loginbtn"
    android:layout_height="wrap_content"
    android:layout_centerhorizontal="true"
    android:id="@+id/prompttext"
    android:textcolor="#ff0000"
    android:layout_margintop="10dp"
    android:textsize="18sp"/>

</relativelayout>

public class loginactivity extends activity implements view.onclicklistener{
    private static final string tag = "login";
      button loginbtn = null;
      edittext useridet = null;
      edittext passet = null;
      textview prompttext = null;
     @override
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.activity_login);
    loginbtn = (button) findviewbyid(r.id.loginbtn);
    loginbtn.setonclicklistener(this);
    useridet = (edittext) findviewbyid(r.id.userid); 
    passet = (edittext) findviewbyid(r.id.pass);
    prompttext = (textview) findviewbyid(r.id.prompttext);
    okhttpclient okhttpclient = new okhttpclient.builder()
        .connecttimeout(10000l, timeunit.milliseconds)
        .readtimeout(10000l, timeunit.milliseconds)
        .build();
    okhttputils.initclient(okhttpclient);

  @override
  public void onclick(view v) {
    string userid = useridet.gettext().tostring().trim();
    string pass = passet.gettext().tostring().trim();
    if(userid.equals("")){
      prompttext.settext(r.string.useriderror);
      return ;
    }
    if(pass.equals("")){
      prompttext.settext(r.string.passerror);
      return ;
    }
 webconstant.digest = ("basic " + new string(base64.encode((userid + ':' + pass).getbytes(), base64.default))).replace("\n", "");

      string url = webconstant.requestpath+"/users/" + userid+"?getall=true";
      okhttputils.get()
          .url(url).addheader("authorization", webconstant.digest).addheader("accept-language","zh-cn")
          .build().execute(new callback()
          {
            @override
            public string parsenetworkresponse(response response, int id) throws exception {
              string string = response.body().string();
              jsonobject jsonobj = new jsonobject(string);
              if(jsonobj.get("username")!=null){
                webconstant.userid = (string)jsonobj.get("userid");
                webconstant.username = (string)jsonobj.get("username");
                return (string) jsonobj.get("username");
              }
              return null;
            }

            @override
            public void onerror(call call, exception e, int id) {
              webconstant.digest = null;
              prompttext.settext(r.string.loginerror);
              log.i(tag,e.getmessage());
              e.printstacktrace();
            }

            @override
            public void onresponse(object response, int id) {
              prompttext.settext(r.string.loginsuccess+" "+response);
              intent intent = new intent();
              loginactivity.this.setresult(webconstant.result_ok, intent);
              loginactivity.this.finish();
            }
          });

  }
}