开发环境：win7，Android Studio 1.2，

1、Model

Crime,数据模型，每个Crime有一个UUID作为唯一标识。

package tina.criminalintent;import java.util.Date;import java.util.UUID;/** * Created by CW3479 on 2015/7/13. */public class Crime {    private UUID mId;    private  String mTitle;    private Date mDate;    private boolean mSolved;    public Crime(){        //Genetate unique identifier        mId=UUID.randomUUID();    }    public UUID getId() {        return mId;    }    public String getTitle() {        return mTitle;    }    public void setTitle(String title) {        mTitle = title;    }    public Date getDate() {        if(mDate==null)            mDate=new Date();        return mDate;    }    public void setDate(Date date) {        mDate = date;    }    public boolean isSolved() {        return mSolved;    }    public void setSolved(boolean solved) {        mSolved = solved;    }    @Override    public String toString() {        return mTitle;    }}

CrimeLab，数据库，用了单例模式，保证了应用运行过程中使用同一个数据库。目前还是简单应用，CrimeLab里面的数据（Crime）是初始化时设定的，只能查询和更改，以后会进行改造，对CrimeLab进行增删操作。

package tina.criminalintent;import android.content.Context;import java.util.ArrayList;import java.util.UUID;/** * Created by CW3479 on 2015/7/13. */public class CrimeLab {    private ArrayList
      
        mCrimes;    private static CrimeLab sCrimeLab;    private Context mAppContext;    public static CrimeLab getInstance(Context context) {        if(sCrimeLab==null) {            sCrimeLab = new CrimeLab(context.getApplicationContext());        }        return sCrimeLab;    }    private CrimeLab(Context appContext) {        mAppContext=appContext;        mCrimes=new ArrayList
       
        ();        for(int i=0;i<10;i++){            Crime crime=new Crime();            crime.setTitle("Crime #"+i);            crime.setSolved(i%2==0);            mCrimes.add(crime);        }    }    public ArrayList
        
          getCrimes() {        return mCrimes;    }    public Crime getCrime(UUID id){        for(Crime crime:mCrimes){            if(crime.getId().equals(id)){                return crime;            }        }        return null;    }}
        
       
      

2、Controller & View

以往都是直接用Activity进行应用的设计，从这个demo开始，使用Fragment来完成应用的设计，增加应用程序的灵活性。关于Fragment，可以参考这篇文章。需要注意的是，有关Fragment的类，有静态支持库版本和标准包版本（不知道这么说合不合适），前者是为了兼容Android3.0以下版本，需要导入Android Support库（android.support.v4.*），后者就在android.app.*包里，两者的使用方法大致相同，写程序的时候考虑是否向下兼容来做选择即可。

这个Demo按照书上，使用静态支持库。

首先，SingleFragmentActivity，可看做一个放置有FragmentContainer的Activity抽象类。其中的抽象方法createFragment可以用来实现不同的Fragment。书上的例程继承的是FragmentActivity类，但是我在用模拟器运行的时候发现没有像书中一样出现ActionBar。查了一番，原来ActionBarActivity是FragmentActivity的子类，所以我直接就继承了ActionBarActivity，这个也是Android Studio的Blank Activity模板中默认使用的Activity类。

package tina.criminalintent;import android.os.Bundle;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentManager;import android.support.v7.app.ActionBarActivity;/** * Created by CW3479 on 2015/7/13. */public abstract class SingleFragmentActivity extends ActionBarActivity {    protected abstract Fragment createFragment();    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_fragment);         FragmentManager fm=getSupportFragmentManager();         Fragment fragment=fm.findFragmentById(R.id.fragmentContainer);        if(fragment==null){            fragment=createFragment();            fm.beginTransaction()                    .add(R.id.fragmentContainer,fragment)                    .commit();        }    }}

其对应的布局文件activity_fragment.xml如下，只有一个id为fragmentContainer的FrameLayout，FrameLayout里面不放置任何子控件。

上面有了基本的模板了，接下来就是第一个页面啦。应用一打开，就是一个列表页面，显示CrimeLab中的Crime。

CrimeListActivity继承上面的SingleFragmentActivity，创建一个CrimeListFragment，放置到fragmentContainer中。

package tina.criminalintent;import android.support.v4.app.Fragment;/** * Created by CW3479 on 2015/7/13. */public class CrimeListActivity extends SingleFragmentActivity {    @Override    protected Fragment createFragment() {        return new CrimeListFragment();    }}

要显示列表，CrimeListFragment继承了ListFragment，从CrimeLab单例中获取Crime数据，再根据mCrimes构建ArrayAdapter，给列表中的每一行赋予数据，然后对item点击事件做响应，跳转到相应的Detail页面。

package tina.criminalintent;import android.content.Intent;import android.os.Bundle;import android.support.v4.app.ListFragment;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ArrayAdapter;import android.widget.CheckBox;import android.widget.ListView;import android.widget.TextView;import java.util.ArrayList;public class CrimeListFragment extends ListFragment {    private ArrayList
     
       mCrimes;    private CrimeAdapter mAdapter;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        getActivity().setTitle(R.string.crimes_title);        mCrimes=CrimeLab.getInstance(getActivity()).getCrimes();        mAdapter=new CrimeAdapter(mCrimes);        setListAdapter(mAdapter);    }    @Override    public void onListItemClick(ListView l, View v, int position, long id) {        super.onListItemClick(l, v, position, id);        Crime crime=((CrimeAdapter)getListAdapter()).getItem(position);//        Intent intent=new Intent(getActivity(),CrimeActivity.class);        Intent intent=new Intent(getActivity(),CrimePagerActivity.class);        intent.putExtra(CrimeFragment.EXTRA_CRIME_ID, crime.getId());        startActivity(intent);    }    private class CrimeAdapter extends ArrayAdapter
      
       {        public CrimeAdapter(ArrayList
       
         crimes) {            super(getActivity(), 0, crimes);        }        @Override        public View getView(int position, View convertView, ViewGroup parent) {            if(convertView==null){                convertView=getActivity().getLayoutInflater()                        .inflate(R.layout.list_item_crime,null);            }            Crime c=getItem(position);            TextView titleTextView=(TextView)convertView.findViewById(R.id.crime_list_item_title);            titleTextView.setText(c.getTitle());            TextView dateTextView=(TextView)convertView.findViewById(R.id.crime_list_item_date);            dateTextView.setText(c.getDate().toString());            CheckBox solvedCheckBox=(CheckBox)convertView.findViewById(R.id.crime_list_item_solvedCheckBox);            solvedCheckBox.setChecked(c.isSolved());            return convertView;        }    }    @Override    public void onResume() {        super.onResume();        ((CrimeAdapter)getListAdapter()).notifyDataSetChanged();    }}
       
      
     

上面的列表对应的item布局文件list_item_crime.xml如下：

Detail页面CrimePagerActivity，用ViewPager来实现。点击列表项进入相应的Detail页面，页面标题对应相应的Crime Title，向左（向右）进入前一项（后一项）的Detail页面，也就是通过FragmentManager加载相应的CrimeFragment到ViewPager中。

1 import android.os.Bundle; 2 import android.support.v4.app.Fragment; 3 import android.support.v4.app.FragmentManager; 4 import android.support.v4.app.FragmentStatePagerAdapter; 5 import android.support.v4.view.ViewPager; 6 import android.support.v7.app.ActionBarActivity; 7  8  9 import java.util.ArrayList;10 import java.util.UUID;11 12 public class CrimePagerActivity extends ActionBarActivity {13 14     private ViewPager mViewPager;15     private ArrayList
      
        mCrimes;16 17     @Override18     protected void onCreate(Bundle savedInstanceState) {19         super.onCreate(savedInstanceState);20 21         mViewPager=new ViewPager(this);22         mViewPager.setId(R.id.viewPager);23         setContentView(mViewPager);24 25         mCrimes=CrimeLab.getInstance(this).getCrimes();26 27         FragmentManager fm=getSupportFragmentManager();28         mViewPager.setAdapter(new FragmentStatePagerAdapter(fm) {29             @Override30             public Fragment getItem(int position) {31                 Crime crime=mCrimes.get(position);32                 return CrimeFragment.newInstance(crime.getId());33             }34 35             @Override36             public int getCount() {37                 return mCrimes.size();38             }39         });40 41 //        匹配UUID，跳转到当前选中的crime项对应的ViewPager Item42         final UUID crimeId=(UUID)getIntent().getSerializableExtra(CrimeFragment.EXTRA_CRIME_ID);43         for(int i=0;i
      

CrimeFragment继承Fragment，点击显示时间的DateButton，弹出DatePickerFragment对话框，用于选择时间，在onActivityResult方法中接收选中的事件信息，并作出响应。此外，为了得到对应的Crime数据，CrimeFragment的类方法newInstance(UUID crimeId)中，在fragment中设置Crime Id作为arguments。以便使用newInstance产生实例，能在onCreate中取回数据，对frament做初始化。

package tina.criminalintent;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentManager;import android.text.Editable;import android.text.TextWatcher;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.Button;import android.widget.CheckBox;import android.widget.CompoundButton;import android.widget.EditText;import java.util.Date;import java.util.UUID;public class CrimeFragment extends Fragment {    public static final String EXTRA_CRIME_ID="tina.criminalintent.crime_id";    private static final String DIALOG_DATE="date";    private static final int REQUEST_DATE=0;    private Crime mCrime;    private EditText mTitleField;    private Button mDateButton;    private CheckBox mSolvedCheckBox;    public CrimeFragment() {        // Required empty public constructor    }    public static CrimeFragment newInstance(UUID crimeId){        Bundle args=new Bundle();        args.putSerializable(EXTRA_CRIME_ID,crimeId);        CrimeFragment fragment=new CrimeFragment();        fragment.setArguments(args);        return fragment;    }    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        UUID id=(UUID) getArguments().getSerializable(EXTRA_CRIME_ID);        mCrime=CrimeLab.getInstance(getActivity()).getCrime(id);    }    public void updateDate(){        mDateButton.setText(mCrime.getDate().toString());    }    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,                             Bundle savedInstanceState) {        // Inflate the layout for this fragment        View v=inflater.inflate(R.layout.fragment_crime, container, false);        mTitleField=(EditText)v.findViewById(R.id.crime_title);        mTitleField.setText(mCrime.getTitle());        mTitleField.addTextChangedListener(new TextWatcher() {            @Override            public void beforeTextChanged(CharSequence s, int start, int count, int after) {                mCrime.setTitle(s.toString());            }            @Override            public void onTextChanged(CharSequence s, int start, int before, int count) {            }            @Override            public void afterTextChanged(Editable s) {            }        });        mDateButton=(Button)v.findViewById(R.id.crime_date);        updateDate();        mDateButton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                FragmentManager fm=getActivity().getSupportFragmentManager();                DatePickerFragment dialog=DatePickerFragment.newInstance(mCrime.getDate());                dialog.setTargetFragment(CrimeFragment.this,REQUEST_DATE);                dialog.show(fm,DIALOG_DATE);            }        });        mSolvedCheckBox=(CheckBox)v.findViewById(R.id.crime_solved);        mSolvedCheckBox.setChecked(mCrime.isSolved());        mSolvedCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {            @Override            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {                mCrime.setSolved(isChecked);            }        });        return v;    }    @Override    public void onActivityResult(int requestCode, int resultCode, Intent data) {        if(resultCode!= Activity.RESULT_OK)            return;        if(requestCode==REQUEST_DATE){            Date date=(Date)data.getSerializableExtra(DatePickerFragment.EXTRA_DATE);            mCrime.setDate(date);            updateDate();        }    }}

对应的布局文件fragment_crime.xml如下：

在手机横着的时候，需要对布局进行调整。在res文件夹中新建一个Android Resource Directory，name设置为layout-land，resource type选择layout，source set默认为main。注意，项目显示结构选择Project来能看到layout-land文件夹，选择Android的话，会把所有的layout文件都整合显示在layout目录下面。把fragment_crime.xml复制到layout-land文件夹中，对布局进行调整，调整后的布局内容如下：

 再回到页面实现，上面提到显示DatePickerFragment对话框，这个对话框继承的是DialogFragment类，使用date数据作为arguments，用一个DatePicker控件来选择日期。

在上面，CrimeFragment用DatePickerFragment的setTargetFragment()方法，指定了DatePickerFragment返回时传递数据给自己。

DatePickerFragment实现了DatePickerDialog.OnDateSetListener这个接口，使得类可以在onDateSet()方法中监听日期的选择，并将用getTargetFragment().onActivityResult()，把时间数据传递给CrimeFragment实例。

1 import android.app.Activity; 2 import android.app.AlertDialog; 3 import android.app.DatePickerDialog; 4 import android.app.Dialog; 5 import android.content.DialogInterface; 6 import android.content.Intent; 7 import android.os.Bundle; 8 import android.support.v4.app.DialogFragment; 9 import android.util.Log;10 import android.view.View;11 import android.widget.DatePicker;12 13 import java.util.Calendar;14 import java.util.Date;15 import java.util.GregorianCalendar;16 17 18 public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener{19     public static final String EXTRA_DATE="tina.criminalintent.date";20 21     private Date mDate;22 23     public static DatePickerFragment newInstance(Date date){24         Bundle args=new Bundle();25         args.putSerializable(EXTRA_DATE, date);26 27         DatePickerFragment fragment=new DatePickerFragment();28         fragment.setArguments(args);29         return fragment;30     }31 32 33     @Override34     public Dialog onCreateDialog(Bundle savedInstanceState) {35         mDate=(Date)getArguments().getSerializable(EXTRA_DATE);36         Calendar calendar=Calendar.getInstance();37         calendar.setTime(mDate);38         int year=calendar.get(Calendar.YEAR);39         final int month=calendar.get(Calendar.MONTH);40         final int day=calendar.get(Calendar.DAY_OF_MONTH);41 42         return new DatePickerDialog(getActivity(),this,year,month,day);43     }44 45     @Override46     public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {47         mDate = new GregorianCalendar(year, monthOfYear, dayOfMonth).getTime();48         if(getTargetFragment()==null)49             return;50 51         Intent intent=new Intent();52         intent.putExtra(EXTRA_DATE,mDate);53         getTargetFragment().onActivityResult(getTargetRequestCode(),Activity.RESULT_OK,intent);54     }55 56 }

至此，Demo的布局文件和Activity设计完毕。

下面是上面的文件中用到的Value文件：

strings.xml

         
      
       CriminalIntent
      
          
      
       Hello blank fragment
          
      
       CrimeActivity
          
      
       Enter a title for the crime.
          
      
       title
          
      
       details
          
      
       Solved?
          
      
       Crimes
          
      
       Date of crime:
      
     

还有，为ViewPager创建的ids.xml。由于这里的ViewPager是用代码产生的（mViewPager = new ViewPager(this)），而ViewPager是一个Fragment的Container，必须提供一个resource id才能被FragmentManager使用。

至此，Demo结束。

 

3、Android Studio中的Fragment模板

AndroidStudio中的Fragment(Blank)模板使用的是android.app.Fragment。

Fragment(List)模板是用Frament和布局文件中的ListView相结合，没有直接使用ListFragment，模板里面有很多东西，初看有点复杂，有两个布局文件，分别用于大小屏幕（也就是手机和平板吧），大屏的那个布局文件可以放GridView。

对于上面的Demo，用模板写的CrimeListFragment大致如下：

package tina.criminalintent;import android.content.Intent;import android.os.Bundle;import android.app.Fragment;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.AbsListView;import android.widget.AdapterView;import android.widget.ArrayAdapter;import android.widget.CheckBox;import android.widget.TextView;import java.util.ArrayList;/////**// * A fragment representing a list of Items.// * 
// * Large screen devices (such as tablets) are supported by replacing the ListView// * with a GridView.// * 
// * Activities containing this fragment MUST implement the {@link OnFragmentInteractionListener}// * interface.// */public class CrimeListFragment2 extends Fragment implements AbsListView.OnItemClickListener {    private ArrayList
      
        mCrimes;//    private OnFragmentInteractionListener mListener;    /**     * The fragment's ListView/GridView.     */    private AbsListView mListView;    /**     * The Adapter which will be used to populate the ListView/GridView with     * Views.     */    private CrimeAdapter mAdapter;    /**     * Mandatory empty constructor for the fragment manager to instantiate the     * fragment (e.g. upon screen orientation changes).     */    public CrimeListFragment2() {    }    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        getActivity().setTitle(R.string.crimes_title);        mCrimes=CrimeLab.getInstance(getActivity()).getCrimes();        mAdapter=new CrimeAdapter(mCrimes);    }    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,                             Bundle savedInstanceState) {        View view = inflater.inflate(R.layout.fragment_crimelist, container, false);        // Set the adapter        mListView = (AbsListView) view.findViewById(android.R.id.list);        ((AdapterView) mListView).setAdapter(mAdapter);        // Set OnItemClickListener so we can be notified on item clicks        mListView.setOnItemClickListener(this);        return view;    }    @Override    public void onItemClick(AdapterView
        parent, View view, int position, long id) {        Crime crime=((CrimeAdapter)(parent.getAdapter())).getItem(position);//        Intent intent=new Intent(getActivity(),CrimeActivity.class);        Intent intent=new Intent(getActivity(),CrimePagerActivity.class);        intent.putExtra(CrimeFragment.EXTRA_CRIME_ID, crime.getId());        startActivity(intent);    }    private class CrimeAdapter extends ArrayAdapter
       
        {        public CrimeAdapter(ArrayList
        
          crimes) {            super(getActivity(), 0, crimes);        }        @Override        public View getView(int position, View convertView, ViewGroup parent) {            if(convertView==null){                convertView=getActivity().getLayoutInflater()                        .inflate(R.layout.list_item_crime,null);            }            Crime c=getItem(position);            TextView titleTextView=(TextView)convertView.findViewById(R.id.crime_list_item_title);            titleTextView.setText(c.getTitle());            TextView dateTextView=(TextView)convertView.findViewById(R.id.crime_list_item_date);            dateTextView.setText(c.getDate().toString());            CheckBox solvedCheckBox=(CheckBox)convertView.findViewById(R.id.crime_list_item_solvedCheckBox);            solvedCheckBox.setChecked(c.isSolved());            return convertView;        }    }    @Override    public void onResume() {        super.onResume();        ((CrimeAdapter)mListView.getAdapter()).notifyDataSetChanged();    }}
        
       
      

刚刚接触Fragment，除了模板不兼容Android3.0以下版本以外，我觉得里面的结构也有点复杂，不过Fragment的使用方法很多，具体不知道这种模板是不是用得比较普遍。以后再看吧。

 

4、运行效果