<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#E6E6E6"  android:orientation="vertical">  <ImageView    android:id="@+id/iv_head"   android:layout_width="150dp"   android:layout_height="150dp"   android:layout_centerHorizontal="true"   android:layout_marginTop="40dp"   android:src="@drawable/ic_launcher"/>  <LinearLayout    android:id="@+id/layout"   android:layout_width="match_parent"   android:layout_height="wrap_content"   android:layout_below="@+id/iv_head"   android:layout_margin="10dp"   android:background="#FFFFFF"   android:orientation="vertical">   <RelativeLayout     android:id="@+id/rl_username"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_margin="10dp">    <TextView      android:id="@+id/tv_name"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_centerVertical="true"     android:text="賬號"/>    <EditText      android:id="@+id/et_number"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:layout_marginLeft="5dp"     android:layout_toRightOf="@+id/tv_name"     android:background="@null"/>   </RelativeLayout>   <View     android:layout_width="match_parent"    android:layout_height="2dp"    android:background="#E6E6E6"/>   <RelativeLayout     android:id="@+id/rl_userpsd"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_margin="10dp">    <TextView      android:id="@+id/tv_psw"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_centerVertical="true"     android:text="密碼"/>    <EditText      android:id="@+id/et_password"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:layout_marginLeft="5dp"     android:layout_toRightOf="@+id/tv_psw"     android:inputType="textPassword"     android:background="@null"/>   </RelativeLayout>     </LinearLayout>  <Button    android:id="@+id/login"   android:onClick="login"   android:layout_width="match_parent"   android:layout_height="40dp"   android:layout_below="@+id/layout"   android:layout_centerHorizontal="true"   android:layout_marginLeft="10dp"   android:layout_marginRight="10dp"   android:layout_marginTop="20dp"   android:background="#3C8DC4"   android:text="登錄"   android:textColor="#FFFFFF"/>  <Button    android:id="@+id/signUp"   android:layout_width="wrap_content"   android:layout_height="wrap_content"   android:text="注冊"   android:background="#E6E6E6"   android:textColor="#000000"   android:layout_marginTop="21dp"   android:layout_centerHorizontal="true"   android:layout_marginRight="10dp"   android:layout_below="@+id/login"   android:layout_alignParentRight="true"/>  <CheckBox   android:id="@+id/save"   android:layout_width="wrap_content"   android:layout_height="wrap_content"   android:layout_alignBaseline="@+id/signUp"   android:layout_alignBottom="@+id/signUp"   android:layout_alignLeft="@+id/login"   android:layout_marginLeft="14dp"   android:text="記住密碼" /> </RelativeLayout>

package com.itcast.test03;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.UnsupportedEncodingException;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.util.ArrayList;import java.util.List;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.NameValuePair;import org.apache.http.ParseException;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.HttpClient;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.HttpPost;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.message.BasicNameValuePair;import org.apache.http.util.EntityUtils;import org.json.JSONArray;import org.json.JSONObject;import android.os.Build;import android.os.Bundle;import android.os.StrictMode;import android.annotation.SuppressLint;import android.annotation.TargetApi;import android.app.Activity;import android.content.Intent;import android.content.SharedPreferences;import android.text.TextUtils;import android.util.Log;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.view.View.OnFocusChangeListener;import android.widget.Button;import android.widget.CheckBox;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends Activity implements OnClickListener { private EditText et_username; private EditText et_userPsd; private Button login; private Button signUp; private CheckBox save; private String user,pass; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);  et_username = (EditText)findViewById(R.id.et_number);  et_userPsd = (EditText)findViewById(R.id.et_password);  login=(Button)findViewById(R.id.login);  signUp=(Button)findViewById(R.id.signUp);  save = (CheckBox)findViewById(R.id.save);  save.setOnClickListener(new CheckBox.OnClickListener(){   public void onClick(View v) {    SharedPreferences pre = getSharedPreferences("loginvalue",             MODE_WORLD_WRITEABLE);    pass = MD5( et_userPsd.getText().toString());    user = et_username.getText().toString();    if (!pass.equals("") && !user.equals("")) {       pre.edit().putString("username",         et_username.getText().toString())         .putString("password", encryptmd5(pass)).commit();    Toast.makeText(getApplicationContext(),"保存成功!",    Toast.LENGTH_SHORT).show();    } else{    Toast.makeText(getApplicationContext(),"密碼不能為空！",    Toast.LENGTH_LONG).show();  }    }  });  login.setOnClickListener(new Button.OnClickListener() {       @Override   public void onClick(View v) {       SharedPreferences sp = getSharedPreferences("loginvalue",MODE_WORLD_READABLE);   String loginuser = sp.getString("username",null);   String loginpass = sp.getString("password",null);       user = et_username.getText().toString();   pass = et_userPsd.getText().toString();       String passmd5 = MD5(pass);   String encryptmd5 = encryptmd5(passmd5);       System.out.println("username="+ loginuser   + "-------------password="+ loginpass);   System.out.println("user=="+ user   + "-------------encryptmd5=="+ encryptmd5);   if (!user.equals("") && !pass.equals("")) {   if (user.equals(loginuser) && encryptmd5.equals(loginpass)) {   Intent intent = new Intent();   intent.setClass(MainActivity.this, StudentMainActivity.class);   MainActivity.this.startActivity(intent);   finish();   } else{   Toast.makeText(getApplicationContext(),"密碼是錯誤的！",   Toast.LENGTH_LONG).show();   }   } else{   Toast.makeText(getApplicationContext(),"密碼不能為空！",   Toast.LENGTH_LONG).show();   }       }       });  initWidget();//  } private void initWidget() {    login.setOnClickListener(this);  signUp.setOnClickListener(this);  et_username.setOnFocusChangeListener(new OnFocusChangeListener()  {   @Override   public void onFocusChange(View v, boolean hasFocus) {    // TODO Auto-generated method stub    if(!hasFocus){     String username=et_username.getText().toString().trim();     if(username.length()<4){      Toast.makeText(MainActivity.this, "用戶名不能小于4個字符", Toast.LENGTH_SHORT);     }    }   }     });  et_userPsd.setOnFocusChangeListener(new OnFocusChangeListener()  {   @Override   public void onFocusChange(View v, boolean hasFocus) {    // TODO Auto-generated method stub    if(!hasFocus){     String password=et_userPsd.getText().toString().trim();     if(password.length()<4){      Toast.makeText(MainActivity.this, "密碼不能小于4個字符", Toast.LENGTH_SHORT);     }    }   }     }); }  public void onClick(View v) {  // TODO Auto-generated method stub  switch(v.getId())  {  case R.id.login:   if(checkEdit())   {    login();   }      break;  case R.id.signUp:   Intent intent2=new Intent(MainActivity.this,SignUp.class);   startActivity(intent2);   break;  } }  private boolean checkEdit(){  if(et_username.getText().toString().trim().equals("")){   Toast.makeText(MainActivity.this, "用戶名不能為空", Toast.LENGTH_SHORT).show();   Intent intent=new Intent(MainActivity.this,StudentMainActivity.class);   startActivity(intent);  }else if(et_userPsd.getText().toString().trim().equals("")){   Toast.makeText(MainActivity.this, "密碼不能為空", Toast.LENGTH_SHORT).show();  }else{   return true;  }  return false; }  private void login(){  //這個網址需要改動  String httpUrl="http://192.168.1.102:8080/web-test/login.jsp";  HttpPost httpRequest=new HttpPost(httpUrl);  List<NameValuePair> params=new ArrayList<NameValuePair>();  params.add(new BasicNameValuePair("username",et_username.getText().toString().trim()));  params.add(new BasicNameValuePair("password",et_userPsd.getText().toString().trim()));  HttpEntity httpentity = null;  try {   httpentity = new UrlEncodedFormEntity(params,"utf8");  } catch (UnsupportedEncodingException e) {   // TODO Auto-generated catch block   e.printStackTrace();  }  httpRequest.setEntity(httpentity);  HttpClient httpclient=new DefaultHttpClient();  HttpResponse httpResponse = null;  try {   httpResponse = httpclient.execute(httpRequest);  } catch (ClientProtocolException e) {   // TODO Auto-generated catch block   e.printStackTrace();  } catch (IOException e) {   // TODO Auto-generated catch block   e.printStackTrace();  }  if(httpResponse.getStatusLine().getStatusCode()==200)  {   String strResult = null;   try {    strResult = EntityUtils.toString(httpResponse.getEntity());   } catch (ParseException e) {    // TODO Auto-generated catch block    e.printStackTrace();   } catch (IOException e) {    // TODO Auto-generated catch block    e.printStackTrace();   }   Toast.makeText(MainActivity.this, strResult, Toast.LENGTH_SHORT).show();   Intent intent=new Intent(MainActivity.this,StudentMainActivity.class);   startActivity(intent);  }  else     {   Toast.makeText(MainActivity.this, "登錄失敗！", Toast.LENGTH_SHORT).show();  }   } public static String MD5(String str){   MessageDigest md5 = null;  try {  md5 = MessageDigest.getInstance("MD5"); } catch (NoSuchAlgorithmException e) {  // TODO Auto-generated catch block  e.printStackTrace();  return ""; }  char[] charArray = str.toCharArray();  byte[] byteArray = new byte[charArray.length];  for (int i = 0; i < charArray.length; i++) {  byteArray[i] = (byte)charArray[i]; }  byte[] md5Bytes = md5.digest(byteArray);  StringBuffer hexValue = new StringBuffer();  for (int i = 0; i < md5Bytes.length; i++) {  int val = ((int)md5Bytes[i])&0xff;  if(val<16){   hexValue.append("0");  }  hexValue.append(Integer.toHexString(val)); }  return hexValue.toString();   } public static String encryptmd5(String str){  char[] a = str.toCharArray();  for (int i = 0; i < a.length; i++) {  a[i] = (char)(a[i]^'1'); }  String s = new String(a);  return s; } }

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /><uses-permission android:name="android.permission.INTERNET" />