Android开发实例-健康食谱应用(一)

转载请注明出处：http://blog.csdn.net/einarzhang/article/details/44774635

本系列文章主要介绍如何利用Android开发一个简单的健康食谱软件。用到的相关技术如下所示：

提供GridView和ListView的基本使用
利用universal-image-loader异步加载网络图片
通过HttpClient获取网络http请求数据
滑动分页加载数据

软件所用的所有数据均来源于http://doc.yi18.net/cookwendang提供的食谱接口，感谢他们！

软件文件结构如下所示：



MainActivity：主界面Acitivity
MListActivity：子分类列表Acitivity
CListActivity：食谱列表Activity
DetailActivity：食谱详情Activity

MainGridAdapter：主界面食谱分类适配器
CListAdapter：食谱列表适配器
Cook：用于保存食谱信息的pojo

HttpUtils：提供Http请求相关功能
MUtils：提供食谱相关的处理逻辑功能

软件主界面设计开发

主界面主要提供了健康食谱的主分类控件，用户可以选择自己感兴趣的分类进行食谱查看。为了便于用户更好的找到自己需要的食谱，我们提供一个全局搜索功能，用户可以输入关键词搜索自己想要的食谱信息，如：萝卜，将加载出所有与萝卜相关的食谱

主界面最终效果图如下所示：



主界面共分为两大块：全局搜索布局和Grid分类布局，其布局xml如下所示：

<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="@drawable/list_item_bg"
tools:context=".MainActivity" >

<RelativeLayout
android:id="@+id/top_layout"
android:layout_width="match_parent"
android:layout_height="160dp"
android:layout_alignParentTop="true"
android:background="@drawable/main_top" >

<TextView
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="@drawable/main_title"
android:text="@string/app_name"
android:gravity="center"
android:textColor="@android:color/white"
android:textSize="18sp"
android:layout_alignParentTop="true" >
</TextView>

<EditText
android:id="@+id/main_input"
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_alignParentBottom="true"
android:layout_margin="20dp"
android:background="@drawable/edit_shape"
android:hint="@string/search_tip"
android:lines="1"
android:paddingLeft="32dp"
android:paddingRight="32dp"
android:singleLine="true"
android:textSize="16sp" >
</EditText>

<ImageView
android:id="@+id/main_clear_btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/main_input"
android:layout_alignLeft="@+id/main_input"
android:layout_alignTop="@+id/main_input"
android:src="@drawable/clear" />

<ImageView
android:id="@+id/main_search_btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/main_input"
android:layout_alignRight="@+id/main_input"
android:layout_alignTop="@+id/main_input"
android:src="@drawable/search" >
</ImageView>
</RelativeLayout>

<GridView
android:id="@+id/main_grid"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@id/top_layout"
android:layout_marginTop="20dp"
android:gravity="center_horizontal"
android:numColumns="3"
android:scrollbars="none"
android:verticalSpacing="20dp" >
</GridView>

</RelativeLayout>

通过 http://api.yi18.net/cook/cookclass接口可以获取到所有的主分类信息。我们通过定制自有的MainGridAdapter实现GridView的渲染，源码如下所示：

import java.util.List;

import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class MainGridAdapter extends BaseAdapter {

private List<Item> items;
private Context ctx;

public MainGridAdapter(List<Item> items, Context ctx) {
this.items = items;
this.ctx = ctx;
}

@Override
public int getCount() {
return items.size();
}

@Override
public Object getItem(int arg0) {
return items.get(arg0);
}

@Override
public long getItemId(int arg0) {
return arg0;
}

@Override
public View getView(final int position, View view, ViewGroup arg2) {
if(view == null) {
view = LayoutInflater.from(ctx).inflate(R.layout.item, null);
}
final Item item = items.get(position);
ImageView icon = (ImageView) view.findViewById(R.id.item_icon);
icon.setImageResource(item.icon);
TextView text = (TextView) view.findViewById(R.id.item_text);
text.setText(ctx.getString(item.text));
view.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.putExtra("id", position+1);
intent.putExtra("title", ctx.getString(item.text));
intent.setClass(ctx, MListActivity.class);
ctx.startActivity(intent);
}
});
return view;
}

static class Item {

public Item() {

}

public Item(int bgColor, int icon, int text) {
super();
this.bgColor = bgColor;
this.icon = icon;
this.text = text;
}

public int bgColor;
public int icon;
public int text;
}

}

其中Item为保存了背景图、分类图标和分类名称的模型对象。我们为了实现方便，将背景图忽略。MainGridAdapter为每个分类提供了单击事件，点击后将进入子分类列表：

view.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.putExtra("id", position+1);
intent.putExtra("title", ctx.getString(item.text));
intent.setClass(ctx, MListActivity.class);
ctx.startActivity(intent);
}
});

该Adapter使用方式如下所示：

private void initGrid() {
List<Item> items = new ArrayList<Item>();
items.add(new Item(R.color.item1, R.drawable.item1, R.string.item1));
items.add(new Item(R.color.item2, R.drawable.item2, R.string.item2));
items.add(new Item(R.color.item3, R.drawable.item3, R.string.item3));
items.add(new Item(R.color.item4, R.drawable.item4, R.string.item4));
items.add(new Item(R.color.item5, R.drawable.item5, R.string.item5));
items.add(new Item(R.color.item6, R.drawable.item6, R.string.item6));
items.add(new Item(R.color.item7, R.drawable.item7, R.string.item7));
items.add(new Item(R.color.item8, R.drawable.item8, R.string.item8));
items.add(new Item(R.color.item9, R.drawable.item9, R.string.item9));
items.add(new Item(R.color.item9, R.drawable.item10, R.string.item10));
items.add(new Item(R.color.item9, R.drawable.item11, R.string.item11));
items.add(new Item(R.color.item9, R.drawable.item12, R.string.item12));
items.add(new Item(R.color.item9, R.drawable.item13, R.string.item13));
items.add(new Item(R.color.item9, R.drawable.item14, R.string.item14));
grid.setAdapter(new MainGridAdapter(items, this));
}

下面给出主界面Activity：

import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.EditText;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

private GridView grid;
private ImageView clearButton, searchButton;
private EditText input;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
clearButton = (ImageView) findViewById(R.id.main_clear_btn);
clearButton.setOnClickListener(this);
searchButton = (ImageView) findViewById(R.id.main_search_btn);
searchButton.setOnClickListener(this);
input = (EditText) findViewById(R.id.main_input);
grid = (GridView) findViewById(R.id.main_grid);
initGrid();
}

private void initGrid() {
List<Item> items = new ArrayList<Item>();
items.add(new Item(R.color.item1, R.drawable.item1, R.string.item1));
items.add(new Item(R.color.item2, R.drawable.item2, R.string.item2));
items.add(new Item(R.color.item3, R.drawable.item3, R.string.item3));
items.add(new Item(R.color.item4, R.drawable.item4, R.string.item4));
items.add(new Item(R.color.item5, R.drawable.item5, R.string.item5));
items.add(new Item(R.color.item6, R.drawable.item6, R.string.item6));
items.add(new Item(R.color.item7, R.drawable.item7, R.string.item7));
items.add(new Item(R.color.item8, R.drawable.item8, R.string.item8));
items.add(new Item(R.color.item9, R.drawable.item9, R.string.item9));
items.add(new Item(R.color.item9, R.drawable.item10, R.string.item10));
items.add(new Item(R.color.item9, R.drawable.item11, R.string.item11));
items.add(new Item(R.color.item9, R.drawable.item12, R.string.item12));
items.add(new Item(R.color.item9, R.drawable.item13, R.string.item13));
items.add(new Item(R.color.item9, R.drawable.item14, R.string.item14));
grid.setAdapter(new MainGridAdapter(items, this));
}

@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.main_clear_btn:
input.setText("");
break;
case R.id.main_search_btn:
String searchStr = input.getText().toString();
if(searchStr == null || searchStr.trim().equals("")) {
Toast.makeText(this, "请输入要搜索的菜谱!", Toast.LENGTH_SHORT).show();
} else {
Intent intent = new Intent();
intent.putExtra("keyword", searchStr);
intent.setClass(this, CListActivity.class);
startActivity(intent);
}
break;

default:
break;
}
}

}

子分类界面设计开发

当用户点击主界面的主分类条目时，将进入该分类的子分类列表界面。子分类接口为：http://api.yi18.net/cook/cookclass?id=myid
我们在MUtils中提供获取子分类的方法：

@SuppressWarnings("serial")
public static ArrayList<HashMap<String, Object>> getChildClass(final int pid) {
String url = "http://api.yi18.net/cook/cookclass";
String result = HttpUtils.httpGet(url, new HashMap<String, Object>(){{
put("id", pid);
}});
ArrayList<HashMap<String, Object>> dataMap = new  ArrayList<HashMap<String, Object>>();
if(result != null) {
try {
JSONObject root = new JSONObject(result);
if(root.getBoolean("success")) {
JSONArray datas = root.getJSONArray("yi18");
for(int i = 0, len = datas.length(); i < len; i++) {
HashMap<String, Object> data = new HashMap<String, Object>();
JSONObject obj = datas.getJSONObject(i);
data.put("id", obj.getInt("id"));
data.put("name", obj.getString("name"));
dataMap.add(data);
}
}
} catch (Exception e) {
}
}
return dataMap;
}

返回ArrayList<HashMap>是为了便于SimpleAdapter直接使用，使用见如下的MListActivity中的相关代码：

import java.util.ArrayList;
import java.util.HashMap;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

import com.my.lib.Utils;

public class MListActivity extends Activity implements OnClickListener, OnItemClickListener, Runnable {

private ImageView unconnect;
private ListView mlist;
Handler handler;
ArrayList<HashMap<String, Object>> mdata;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.list);
findViewById(R.id.list_return).setOnClickListener(this);
mlist = (ListView) findViewById(R.id.mlist);
mlist.setOnItemClickListener(this);
unconnect = (ImageView) findViewById(R.id.list_unconnect);
unconnect.setOnClickListener(this);
((TextView)findViewById(R.id.list_title)).setText(getIntent().getStringExtra("title"));
handler = new Handler() {
@Override
public void handleMessage(Message msg) {
if(mdata == null) {
change(true);
} else {
change(false);
mlist.setAdapter(new SimpleAdapter(MListActivity.this, mdata, R.layout.list_item, new String[]{"name"}, new int[]{R.id.list_item_text}));
}
}
};
new Thread(this).start();
}

@Override
@SuppressWarnings("unchecked")
public void onItemClick(AdapterView<?> av, View v, int position, long arg3) {
HashMap<String, Object> item = (HashMap<String, Object>)av.getItemAtPosition(position);
Intent intent = new Intent();
intent.putExtra("id", (Integer)item.get("id"));
intent.putExtra("title", (String)item.get("name"));
intent.setClass(this, CListActivity.class);
startActivity(intent);
}

@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.list_return:
MListActivity.this.finish();
break;
case R.id.list_unconnect:
new Thread(this).start();
break;
default:
break;
}
}

@Override
public void run() {
if(Utils.canAccessNetwork(MListActivity.this)) {
mdata = MUtils.getChildClass(getIntent().getIntExtra("id", 1));
}
handler.sendEmptyMessage(1);
}

void change(boolean flag) {
if(flag) {
mlist.setVisibility(View.GONE);
unconnect.setVisibility(View.VISIBLE);
} else {
mlist.setVisibility(View.VISIBLE);
unconnect.setVisibility(View.GONE);
}
}
}

需要注意的是：Http请求处理不能在主线程中调用，需要开启新的线程调用。子分类点击后将进入该子分类的食谱列表

分类列表布局XML如下所示：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/list_item_bg"
android:orientation="vertical" >

<RelativeLayout
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="@drawable/title_bg" >

<ImageView
android:id="@+id/list_return"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:layout_marginLeft="20dp"
android:src="@drawable/arrowl" />

<TextView
android:id="@+id/list_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:textColor="@android:color/white"
android:textSize="18sp"
android:textStyle="bold" />
</RelativeLayout>

<ListView
android:id="@+id/mlist"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="none" >
</ListView>

<ImageView
android:id="@+id/list_unconnect"
android:layout_marginTop="160dp"
android:layout_gravity="center"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/unconnect"
android:visibility="gone"/>

</LinearLayout>

Item布局xml如下所示：

<?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="50dp"
android:background="@drawable/list_selector" >

<ImageView
android:id="@+id/mlist_item_icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:src="@drawable/list_item_icon"
android:layout_marginLeft="20dp"
android:layout_marginRight="20dp" />

<TextView
android:id="@+id/list_item_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_toRightOf="@+id/mlist_item_icon"
android:textColor="@android:color/white"
android:textSize="16sp" />

<ImageView
android:id="@+id/mlist_item_arrow"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/arrowr"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:layout_marginRight="20dp" />

</RelativeLayout>