Android学习-第29天

今天的任务为读取数据库，其中包含了使用CursorWrapper以及创建模型层对象，详细代码如下：

CrimeLab.java:

package com.bignerdranch.android.criminallntent;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

import com.bignerdranch.android.criminallntent.database.CrimeDbSchema.CrimeCursorWrapper;
import com.bignerdranch.android.criminallntent.database.CrimeDbSchema.CrimeDbSchema;

import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

public class CrimeLab {
    private static CrimeLab sCrimeLab;
    private Context mContext;
    private SQLiteDatabase mDatabase;

    public static CrimeLab get(Context context){
        if(sCrimeLab==null){
            sCrimeLab=new CrimeLab(context);
        }
        return sCrimeLab;
    }
    private CrimeLab(Context context){
        mContext=context.getApplicationContext();
        mDatabase=new CrimeBaseHelper(mContext)
                .getWritableDatabase();
    }

    public void addCrime(Crime c){
        ContentValues values=getContentValues(c);

        mDatabase.insert(CrimeDbSchema.CrimeTable.NAME,null,values);
    }

    public List<Crime> getCrimes(){
        List<Crime> crimes=new ArrayList<>();

        CrimeCursorWrapper cursor=queryCrimes(null,null);

        try {
            cursor.moveToFirst();
            while(!cursor.isAfterLast()){
                crimes.add(cursor.getCrime());
                cursor.moveToNext();
            }
        } finally {
            cursor.close();
        }

        return crimes;
    }

    public Crime getCrime(UUID id){
        CrimeCursorWrapper cursor=queryCrimes(
                CrimeDbSchema.CrimeTable.Cols.UUID + " = ?",
                new String[]{id.toString()}
        );

        try {
            if(cursor.getCount()==0){
                return null;
            }

            cursor.moveToFirst();
            return cursor.getCrime();
        } finally {
            cursor.close();
        }
    }

    public void updateCrime(Crime crime){
        String uuidString=crime.getId().toString();
        ContentValues values=getContentValues(crime);
        mDatabase.update(CrimeDbSchema.CrimeTable.NAME,values,
                CrimeDbSchema.CrimeTable.Cols.UUID + "= ?",
                new String[] {uuidString});
    }

    //private Cursor queryCrimes(String whereClause,String[] whereArgs){
    private CrimeCursorWrapper queryCrimes(String whereClause,String[] whereArgs){
        Cursor cursor=mDatabase.query(
                CrimeDbSchema.CrimeTable.NAME,
                null, //Columns - null selects all columns
                whereClause,
                whereArgs,
                null, //groupBy
                null, //having
                null //orderBy
        );

        return new CrimeCursorWrapper(cursor);
    }

    private static ContentValues getContentValues(Crime crime){
        ContentValues values=new ContentValues();
        values.put(CrimeDbSchema.CrimeTable.Cols.UUID,crime.getId().toString());
        values.put(CrimeDbSchema.CrimeTable.Cols.TITLE,crime.getTitle());
        values.put(CrimeDbSchema.CrimeTable.Cols.DATE,crime.getDate().getTime());
        values.put(CrimeDbSchema.CrimeTable.Cols.SOLVED,crime.isSolved() ? 1:0);

        return values;
    }

}

CrimeListFragment.java:

package com.bignerdranch.android.criminallntent;

import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;

import org.w3c.dom.Text;

import java.util.List;

public class CrimeListFragment extends Fragment {
    private static final String SAVED_SUBTITLE_VISIBLE="subtitle";

    private RecyclerView mCrimeRecyclerView;
    private CrimeAdapter mAdapter;
    private boolean mSubtitleVisible;

    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setHasOptionsMenu(true);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_crime_list, container, false);

        mCrimeRecyclerView = (RecyclerView) view.findViewById(R.id.crime_recycler_view);
        mCrimeRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

        if (savedInstanceState!=null){
            mSubtitleVisible=savedInstanceState.getBoolean(SAVED_SUBTITLE_VISIBLE);
        }
        updateUI();

        return view;
    }

    @Override
    public void onResume(){
        super.onResume();
        updateUI();
    }

    @Override
    public void onSaveInstanceState(Bundle outState){
        super.onSaveInstanceState(outState);
        outState.getBoolean(SAVED_SUBTITLE_VISIBLE,mSubtitleVisible);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater){
        super.onCreateOptionsMenu(menu,inflater);
        inflater.inflate(R.menu.fragment_cime_list,menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item){
        switch (item.getItemId()){
            case R.id.new_crime:
            Crime crime=new Crime();
            CrimeLab.get(getActivity()).addCrime(crime);
            Intent intent=CrimePagerActivity.newIntnet(getActivity(),crime.getId());
            startActivity(intent);
            return true;
            case R.id.show_subtitle:
                updateSubtitle();
                return true;
            default:
                return  super.onOptionsItemSelected(item);
        }
    }

    private void updateSubtitle(){
        CrimeLab crimeLab=CrimeLab.get(getActivity());
        int crimeCount=crimeLab.getCrimes().size();
        String subtitle=getString(R.string.subtitle_format,crimeCount);

        AppCompatActivity activity=(AppCompatActivity) getActivity();
        activity.getSupportActionBar().setSubtitle(subtitle);
    }

    private void updateUI() {
        CrimeLab crimeLab=CrimeLab.get(getActivity());
        List<Crime> crimes=crimeLab.getCrimes();

        if(mAdapter==null) {
            mAdapter = new CrimeAdapter(crimes);
            mCrimeRecyclerView.setAdapter(mAdapter);
        }else{
            mAdapter.setCrimes(crimes);
            mAdapter.notifyDataSetChanged();
        }
    }

    private class CrimeHolder extends RecyclerView.ViewHolder implements View.OnClickListener{

        private TextView mTitleTextView;
        private TextView mDateTextView;
        private Crime mCrime;

        public CrimeHolder(LayoutInflater inflater,ViewGroup parent) {
            super(inflater.inflate(R.layout.list_item_crime,parent,false));
            itemView.setOnClickListener(this);

            mTitleTextView=(TextView)itemView.findViewById(R.id.crime_title);
            mDateTextView=(TextView)itemView.findViewById(R.id.crime_date);
        }

        public void bind(Crime crime){
            mCrime=crime;
            mTitleTextView.setText(mCrime.getTitle());
            mDateTextView.setText((mCrime.getDate().toString()));
        }

        @Override
        public void onClick(View view) {
            //Intent intent=new Intent(getActivity(),CrimeActivity.class);
            //Intent intent=CrimeActivity.newIntent(getActivity(),mCrime.getId());
            Intent intent=CrimePagerActivity.newIntnet(getActivity(),mCrime.getId());
            startActivity(intent);
        }
    }

    private class CrimeAdapter extends RecyclerView.Adapter<CrimeHolder>{
        private List<Crime> mCrimes;
        public CrimeAdapter(List<Crime> crimes){
            mCrimes=crimes;
        }

        @Override
        public CrimeHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            LayoutInflater layoutInflater=LayoutInflater.from(getActivity());

            return new CrimeHolder(layoutInflater,parent);
        }

        @Override
        public void onBindViewHolder(CrimeHolder holder, int position) {
            Crime crime=mCrimes.get(position);
            holder.bind(crime);
        }

        @Override
        public int getItemCount() {
            return mCrimes.size();
        }

        public void setCrimes(List<Crime> crimes){
            mCrimes=crimes;
        }
    }
}

CrimeCursorWrapper.java:

package com.bignerdranch.android.criminallntent.database.CrimeDbSchema;

import android.database.Cursor;
import android.database.CursorWrapper;

import com.bignerdranch.android.criminallntent.Crime;

import java.util.Date;
import java.util.UUID;

public class CrimeCursorWrapper extends CursorWrapper {
    public CrimeCursorWrapper(Cursor cursor) {
        super(cursor);
    }

    public Crime getCrime(){
        String uuidString=getString(getColumnIndex(CrimeDbSchema.CrimeTable.Cols.UUID));
        String title=getString(getColumnIndex(CrimeDbSchema.CrimeTable.Cols.TITLE));
        long date=getLong(getColumnIndex(CrimeDbSchema.CrimeTable.Cols.DATE));
        int isSolved=getInt(getColumnIndex(CrimeDbSchema.CrimeTable.Cols.SOLVED));

        Crime crime=new Crime(UUID.fromString(uuidString));
        crime.setTitle(title);
        crime.setDate(new Date(date));
        crime.setSolved(isSolved!=0);

        return crime;
    }
}

Crime.java:

package com.bignerdranch.android.criminallntent;

import java.util.Date;
import java.util.UUID;

public class Crime {
    private UUID mId;
    private String mTitle;
    private Date mDate;
    private boolean mSolved;

    private String mSuspect;

    public Crime() {
        this(UUID.randomUUID());
    }

    public Crime(UUID id){
        mId=id;
        mDate=new Date();
    }

    public UUID getId() {

        return mId;
    }

    public String getTitle() {

        return mTitle;
    }

    public void setTitle(String title) {

        mTitle = title;
    }

    public Date getDate() {

        return mDate;
    }

    public void setDate(Date date) {

        mDate = date;
    }

    public boolean isSolved() {

        return mSolved;
    }

    public void setSolved(boolean solved) {

        mSolved = solved;
    }

    public String getSuspect(){
        return mSuspect;
    }

    public void setSuspect(String suspect){
        mSuspect=suspect;
    }
}

截图如下：